Garden room build project
Discussion
This is a tale of project creep and naked ambition that will hopefully culminate in a slightly atypical garden room. The story starts with me enthusiastically doing some clearance in April 2020 in a part of the garden that was essentially closed off from the rest by a 3m tall and 2m deep laurel hedge. We decided to take down the laurel hedge and open up this end of the garden, but what to do with it? After clearing the area and fixing the fence (the old panels had just rotted away) we were left with this sloping site:
It's slightly shady, and not an area of the garden that you would go to for any other reason, and inspired by some other garden room build threads I've seen on PH, I suggested to the wife we could build a small garden room. I was thinking something maybe 4m x 3m, using second hand French doors off eBay, and standard cedar cladding. Something relatively simple. Something I could knock together myself. Oh how naive I was!
I presented the idea to my wife, who agreed with the principle, but when we looked at the site and the space she suggested we upsized as there wasn't much else we could do in that area. I wanted to keep 2m away from all the boundaries to get greater flexibility under PD, and we wanted to keep a couple of apple trees. This left us with an area just about 6m wide, and making the room 5m deep would give us just under 30m2 gross internal floor area and therefore outside of Building Regs.
I then spent quite a bit of time investigating various garden room designs and build methods. I showed various options to my wife and I had also come to realise that a 30m2 building was quite a big ask to do on my own, so we began to look at off the shelf solutions. My wife wasn't particularly enthused about any of the commercial offerings nor my attempts at clones, saying that a cedar clad box was too contemporary and wasn't in keeping with our house. In desperation I asked her what she had in mind. Mistake #1 was thus made...she gave me the following pictures as inspiration:
After giving it a lot of thought, I realised that she was right (as usual), this would look a whole lot better, and buying this was now not an affordable option, I was going to have to build it myself. Undaunted, I gave it a lot of thought about how the build would work, incorporating the breakfront, a large roof lantern and the front elevation with timber detailing. Timber cladding wouldn't be in keeping, so I decided to go with a thin coat render system for the outside walls and a GRP roof as the lantern roof meant that anything like felt or EPDM just wouldn't be weathertight for very long. We also wanted a 3.4m opening with bifold or slide/fold doors, and the advice I got was that a timber structure would move too much with the seasons and take the doors out of alignment, requiring constant adjusting, so steel would be required for the door surround. The construction details would now dictate a concrete slab, except that the site was 150m away from the nearest accessible point for lorries - although at least it was downhill.
This all sounded great, except that although I'm reasonably good at general DIY, I've not built a concrete slab before, nor installed a lantern roof, applied a GRP coating, done thin coat render or indeed many of the skills that would be needed for this build. I've commissioned lots of building works in the past and seen many of these things done, but theory is very different from practice.
The site was interesting as it was sloping both left to right and front to back as you look at it. I wanted to keep this within Permitted Development, and as I was more than 2m from the boundary this gave me a 2.5m eaves height and 3.0m maximum height to play with. However, thanks to the arcane rules of Permitted Development, the elevation changes actually work in my favour, as by digging down to get a level site the height restrictions are measured from the original highest ground height, so every cm I dug down I could gain back internally inside the room for additional head height.
As it happens, the height difference between the highest and lowest corners of my building was 500mm, so this gave me new maximum heights of 3.0m eaves height and 3.5m tallest point (which would be the apex of the lantern roof). Using the concrete slab foundation approach meant I could put the floor insulation below ground, gaining another 100mm internally. Given the generous height available, I decided to go with a warm roof design for the ease of build and thermal efficiency over a cold roof, and I still had 2.35m internal head height, which was plenty.
I sketched the front elevation...
...and then got cold feet on pressing ahead as I didn't want to have interpreted the PD rules incorrectly. I was also concerned that when I come to sell the house down the line, the buyer's solicitor might ask for compliance documentation. I decided to apply for a Lawful Development Certificate with the Council, which was duly granted 8 weeks later. This proves that the building is compliant with PD and should satisfy future conveyancers. There are also covenants on my property about building outbuildings, and the entity with the benefit of the covenant is both known and active in that regard, so I sought and obtained permission to proceed.
The above process had taken us from April 2020 through to November 2020, and it was time to start. Luckily I am on good terms with a local builder who has worked with me on a number of projects over the last 15 years, and he agreed to make some of his team available to help me when needed.
Starting in winter and driving plant machinery around the garden was always going to completely trash the lawn. As it happens, the lawn as I inherited it from the previous owner was pretty much totally moss and yarrow weed, and was going to need to be completely re-done anyway, so I wasn't bothered.
It's slightly shady, and not an area of the garden that you would go to for any other reason, and inspired by some other garden room build threads I've seen on PH, I suggested to the wife we could build a small garden room. I was thinking something maybe 4m x 3m, using second hand French doors off eBay, and standard cedar cladding. Something relatively simple. Something I could knock together myself. Oh how naive I was!
I presented the idea to my wife, who agreed with the principle, but when we looked at the site and the space she suggested we upsized as there wasn't much else we could do in that area. I wanted to keep 2m away from all the boundaries to get greater flexibility under PD, and we wanted to keep a couple of apple trees. This left us with an area just about 6m wide, and making the room 5m deep would give us just under 30m2 gross internal floor area and therefore outside of Building Regs.
I then spent quite a bit of time investigating various garden room designs and build methods. I showed various options to my wife and I had also come to realise that a 30m2 building was quite a big ask to do on my own, so we began to look at off the shelf solutions. My wife wasn't particularly enthused about any of the commercial offerings nor my attempts at clones, saying that a cedar clad box was too contemporary and wasn't in keeping with our house. In desperation I asked her what she had in mind. Mistake #1 was thus made...she gave me the following pictures as inspiration:
After giving it a lot of thought, I realised that she was right (as usual), this would look a whole lot better, and buying this was now not an affordable option, I was going to have to build it myself. Undaunted, I gave it a lot of thought about how the build would work, incorporating the breakfront, a large roof lantern and the front elevation with timber detailing. Timber cladding wouldn't be in keeping, so I decided to go with a thin coat render system for the outside walls and a GRP roof as the lantern roof meant that anything like felt or EPDM just wouldn't be weathertight for very long. We also wanted a 3.4m opening with bifold or slide/fold doors, and the advice I got was that a timber structure would move too much with the seasons and take the doors out of alignment, requiring constant adjusting, so steel would be required for the door surround. The construction details would now dictate a concrete slab, except that the site was 150m away from the nearest accessible point for lorries - although at least it was downhill.
This all sounded great, except that although I'm reasonably good at general DIY, I've not built a concrete slab before, nor installed a lantern roof, applied a GRP coating, done thin coat render or indeed many of the skills that would be needed for this build. I've commissioned lots of building works in the past and seen many of these things done, but theory is very different from practice.
The site was interesting as it was sloping both left to right and front to back as you look at it. I wanted to keep this within Permitted Development, and as I was more than 2m from the boundary this gave me a 2.5m eaves height and 3.0m maximum height to play with. However, thanks to the arcane rules of Permitted Development, the elevation changes actually work in my favour, as by digging down to get a level site the height restrictions are measured from the original highest ground height, so every cm I dug down I could gain back internally inside the room for additional head height.
As it happens, the height difference between the highest and lowest corners of my building was 500mm, so this gave me new maximum heights of 3.0m eaves height and 3.5m tallest point (which would be the apex of the lantern roof). Using the concrete slab foundation approach meant I could put the floor insulation below ground, gaining another 100mm internally. Given the generous height available, I decided to go with a warm roof design for the ease of build and thermal efficiency over a cold roof, and I still had 2.35m internal head height, which was plenty.
I sketched the front elevation...
...and then got cold feet on pressing ahead as I didn't want to have interpreted the PD rules incorrectly. I was also concerned that when I come to sell the house down the line, the buyer's solicitor might ask for compliance documentation. I decided to apply for a Lawful Development Certificate with the Council, which was duly granted 8 weeks later. This proves that the building is compliant with PD and should satisfy future conveyancers. There are also covenants on my property about building outbuildings, and the entity with the benefit of the covenant is both known and active in that regard, so I sought and obtained permission to proceed.
The above process had taken us from April 2020 through to November 2020, and it was time to start. Luckily I am on good terms with a local builder who has worked with me on a number of projects over the last 15 years, and he agreed to make some of his team available to help me when needed.
Starting in winter and driving plant machinery around the garden was always going to completely trash the lawn. As it happens, the lawn as I inherited it from the previous owner was pretty much totally moss and yarrow weed, and was going to need to be completely re-done anyway, so I wasn't bothered.
Start by levelling the site with Simon the digger driver working some of his magic and Philbo the numpty driving the 1 tonne dumper. The soil here has been pretty much untouched for decades and was a lovely dark colour, so we put that carefully to one side elsewhere in the garden. No wonder the weeds loved it...
More site levelling and...300mm down, we've hit chalk.
Keep going, beginning to get down to our target of 350mm below lowest point, which means 850mm down from highest point. That's quite a lot of material, and quite hard work when most of it is chalk, but the 1.8ton Kubota was up to the job.
Finally got down to a level site, and graded the left hand bank to make it steeper to get down to the new level.
20 tons of MOT type 1 was delivered. Stuck lucky here as a public road goes behind the flint wall and the grab lorry was able to park the other side of the wall and literally drop the material over the side where there was a hole in the tree line just big enough to get the bucket through. This saved me a huge amount of time and effort in not having to have loose material delivered to the front of the house and then handballing it 150m down to site.
250mm MOT installed and compacted with the digger tracks. We designed a "toe" on the downhill edge of the slab so that it would bite into the soil and resist any movement, so the MOT tapers down at this edge. The MOT at the front is for the patio and is lower than the MOT for the room slab so that the room will be about 150mm higher than the patio when finished.
I wanted a soakaway to handle the rain rather than just letting it fall off the back of the building, so we dug a trench for that and put a 1m3 soakaway 600mm below ground, which involved digging down 1m:
I now had a fairly impressive pile of chalky spoil on the left and re-usable topsoil on the right dumped in the middle of my lawn:
More site levelling and...300mm down, we've hit chalk.
Keep going, beginning to get down to our target of 350mm below lowest point, which means 850mm down from highest point. That's quite a lot of material, and quite hard work when most of it is chalk, but the 1.8ton Kubota was up to the job.
Finally got down to a level site, and graded the left hand bank to make it steeper to get down to the new level.
20 tons of MOT type 1 was delivered. Stuck lucky here as a public road goes behind the flint wall and the grab lorry was able to park the other side of the wall and literally drop the material over the side where there was a hole in the tree line just big enough to get the bucket through. This saved me a huge amount of time and effort in not having to have loose material delivered to the front of the house and then handballing it 150m down to site.
250mm MOT installed and compacted with the digger tracks. We designed a "toe" on the downhill edge of the slab so that it would bite into the soil and resist any movement, so the MOT tapers down at this edge. The MOT at the front is for the patio and is lower than the MOT for the room slab so that the room will be about 150mm higher than the patio when finished.
I wanted a soakaway to handle the rain rather than just letting it fall off the back of the building, so we dug a trench for that and put a 1m3 soakaway 600mm below ground, which involved digging down 1m:
I now had a fairly impressive pile of chalky spoil on the left and re-usable topsoil on the right dumped in the middle of my lawn:
I deliberately over-ordered on the MOT as I wanted to lay some paths around the garden to link up some areas and access the new room. I had built the compost heap, leaf mulcher, log store and shed over the summer as part of the clearance process getting ready for the build, so we took the chance to lay a path connecting the patio to this area.
The shed already had power from a dedicated 20A feed, so we ran some SWA to the garden room a buried it 600mm down, with some marker tape at 300mm just in case anyone goes digging.
Installed some sand blinding
and the shuttering (we just used 4x3" timber for the patio as the slab is only 100mm):
Installed 100mm PIR slab insulation and a DPM. The green ducting is for some services to come up out of the slab inside the room when finished (more on this later):
Second DPM over the PIR and steel reinforcing mesh on mini castles:
The shed already had power from a dedicated 20A feed, so we ran some SWA to the garden room a buried it 600mm down, with some marker tape at 300mm just in case anyone goes digging.
Installed some sand blinding
and the shuttering (we just used 4x3" timber for the patio as the slab is only 100mm):
Installed 100mm PIR slab insulation and a DPM. The green ducting is for some services to come up out of the slab inside the room when finished (more on this later):
Second DPM over the PIR and steel reinforcing mesh on mini castles:
Then got the concrete installed. I had to pay extra to get it pumped 150m from the front of the house, luckily it was downhill. We had a near crisis in the concrete pour, the pumping team like to keep it wet to begin with to avoid the mix sticking to the pipe, however they kept it too wet for far too long despite us shouting at them to thicken it up. After they'd pumped about 3 cubic metres they finally thickened the mix...but initial mix was basically water and the PIR began to float. Then the thick mix got under the PIR and pushed it further up. With about 4m3 of mix having come down the pipe and our PIR and mesh sticking out above finished level there was only one option. We got the mix turned off and then all 4 of us jumped in and began shovelling the mix from the room slab out onto the patio slab. This was...hard work. Then we had to pull out all the mesh and PIR, get rid of any mix underneath and then re-lay it all as best we could. All the while the pumping team were making threats about what would happen if the mix went off in their pipes. One of them nearly got a shovel to the back of the head, if only I'd had the strength. Luckily we managed to get it all back together and got the slab tamped down by lunchtime. In the end we had 10m3 of mix down the pipes, that was a morning I won't forget.
The room is too far from the house to get adequate wifi so we dug a trench (having to snake around some buried obstacles in the ground) and laid some 50mm ducting. I pulled through a couple of Cat6a cables (second one for redundancy) and left the pullthrough in place for futureproofing. These will get joined up to the wired network in the garage, which was the closest convenient access.
One month after we started, we were able to pull off the shuttering. This picture shows what plant machinery will do to your lawn in the middle of a wet winter...
The room is too far from the house to get adequate wifi so we dug a trench (having to snake around some buried obstacles in the ground) and laid some 50mm ducting. I pulled through a couple of Cat6a cables (second one for redundancy) and left the pullthrough in place for futureproofing. These will get joined up to the wired network in the garage, which was the closest convenient access.
One month after we started, we were able to pull off the shuttering. This picture shows what plant machinery will do to your lawn in the middle of a wet winter...
January was spent doing some other landscaping on the garden and building a path down to the site so that bringing materials in meant I wasn't wading through mud. By February I was ready to start work on the building. I had the steel goalpost on site that was going to surround the doors, so first job was to assemble that, lift it up using a hired in Genie, and bolt it to the slab.
Assembled the studwork on the ground using a nailgun, and lifted into place. I decided to use 6x2" timber for extra strength, and extra depth in the walls to have insulation and install services easily.
End of day 3 and got all 4 walls up although not finished the noggins. The roof will fall from front to back, and the sides are higher to form a parapet to enclose the roof. A false parapet will be built at the front later on top of the steelwork and side window headers. The studs were tripled up at the rear of the building to carry 3 joists either side of the lantern roof opening.
End of day 4 and carried some more materials down to side, finished the wall noggins and got a couple of joists up. The span tables indicated an 8x2" joist would be just enough, but I upsized it to 9x2" for extra strength as I would lose a few joists for the lantern roof.
Another 3 days go by and the shuttering ply is installed on the outside walls (I chose shuttering ply as it's much stronger than OSB and has waterproof adhesive, but is only a few £ more expensive per sheet), and 100mm PIR is installed and pushed back flush to the ply skin.
Another few days and the ceiling joists are up with noggins and the front parapet built up. We used joist hangers at the front of the building and sat the joists on the back wall over studs, flying the joists past the back to create a drip detail for the roof and a fascia for the guttering.
At this point lots of time was spent on small jobs that aren't highly visible. I did my first fix for the electrics around the room in the safety zones. I'm installing 4 circuits using SWA for various details in the garden (path lights, effect/tree lights, water feature) and 4 lighting circuits for the room (2 lights on the rear wall, ceiling downlights, lights on the front of the building and of course the ubiquitous LED strip lights around the lantern roof opening. These will all be on a smart system (LightwaveRF) so that we can control the room and garden lights from inside the main house.
All these circuits are going to come back to a big junction box which I'll mount on the wall next to the consumer unit and the various other gubbins to support the room - LED strip transformer, smart lighting control system, wifi access point and a media system to drive the TV and sound system - I've put in the wiring for a 5.4.1 system, though I plan to run it as a 5.1 system only, if I change my mind the wires will be there ready.
Apart from the cable runs, I added an extra 40mm PIR to bring it pretty much flush with the front of the studwork and making the walls have 140mm PIR insulation, pretty much solid like a SIPP. Not shown in this picture but added later is some 75mm aluminium tape across all of the exposed studwork, which acts as the first vapour control layer in conjunction with the metal lining on the PIR.
With the internals pretty much done until we were weathertight, I dressed the steelwork in timber and used leftover PIR to insulate around the parapet. I put a roof subdeck on of ply, then a DPM, 100mm PIR and I did a dry fit of the OSB deck which is a requirement of the GRP product I'll be using (CureIt).
At this point I got a bit lazy with my photographs so we jump forward to where it stands at the end of a very wet May. The timber dressing/facade at the front of the building has lots of details like the breakfront and some column and pilasters with pliths and headers, and lots of endgrain will be exposed. I bought some hardwood (ireki) in made to measure lengths & widths so that it will have some durability, primed it and covered the front. The top facade is made out of several layers of hardwood, with a swan neck moulding at the top, a scotia and bead detail lower down (these cover some end grain and a join in the panels respeectively) and finally a cock bead moulding on the bottom edge to give a clean finish.
The facade detail continues around the 2 sides of the building, but this time using marine ply on cost grounds and all the laminated edges are covered.
The shuttering ply on the sides of the building were covered in Tyvek, then battened off, insect mesh applied to the bottom, and finally some Knauf exterior cement boards installed as render carriers using mega expensive stainless steel screws (any other sort of screws will rust and bleed through the render eventually).
Jobs left to do as soon as the weather permits are:
- install GRP to roof
- fit roof lantern
- decorate front timberwork
- fit doors and side windows - haven't ordered these yet, have just decided to go for timber units as they will look best
- apply thin coat render - I've selected EWI for this, but have bottled out of doing it myself
- apply levelling compound to internal slab
- internal fit out - I've decided to have some panelling on the bottom third of the walls and plasterboard above
- second fit electrics
- fit flooring - probably glue down LVT
So still quite a lot to do.
Assembled the studwork on the ground using a nailgun, and lifted into place. I decided to use 6x2" timber for extra strength, and extra depth in the walls to have insulation and install services easily.
End of day 3 and got all 4 walls up although not finished the noggins. The roof will fall from front to back, and the sides are higher to form a parapet to enclose the roof. A false parapet will be built at the front later on top of the steelwork and side window headers. The studs were tripled up at the rear of the building to carry 3 joists either side of the lantern roof opening.
End of day 4 and carried some more materials down to side, finished the wall noggins and got a couple of joists up. The span tables indicated an 8x2" joist would be just enough, but I upsized it to 9x2" for extra strength as I would lose a few joists for the lantern roof.
Another 3 days go by and the shuttering ply is installed on the outside walls (I chose shuttering ply as it's much stronger than OSB and has waterproof adhesive, but is only a few £ more expensive per sheet), and 100mm PIR is installed and pushed back flush to the ply skin.
Another few days and the ceiling joists are up with noggins and the front parapet built up. We used joist hangers at the front of the building and sat the joists on the back wall over studs, flying the joists past the back to create a drip detail for the roof and a fascia for the guttering.
At this point lots of time was spent on small jobs that aren't highly visible. I did my first fix for the electrics around the room in the safety zones. I'm installing 4 circuits using SWA for various details in the garden (path lights, effect/tree lights, water feature) and 4 lighting circuits for the room (2 lights on the rear wall, ceiling downlights, lights on the front of the building and of course the ubiquitous LED strip lights around the lantern roof opening. These will all be on a smart system (LightwaveRF) so that we can control the room and garden lights from inside the main house.
All these circuits are going to come back to a big junction box which I'll mount on the wall next to the consumer unit and the various other gubbins to support the room - LED strip transformer, smart lighting control system, wifi access point and a media system to drive the TV and sound system - I've put in the wiring for a 5.4.1 system, though I plan to run it as a 5.1 system only, if I change my mind the wires will be there ready.
Apart from the cable runs, I added an extra 40mm PIR to bring it pretty much flush with the front of the studwork and making the walls have 140mm PIR insulation, pretty much solid like a SIPP. Not shown in this picture but added later is some 75mm aluminium tape across all of the exposed studwork, which acts as the first vapour control layer in conjunction with the metal lining on the PIR.
With the internals pretty much done until we were weathertight, I dressed the steelwork in timber and used leftover PIR to insulate around the parapet. I put a roof subdeck on of ply, then a DPM, 100mm PIR and I did a dry fit of the OSB deck which is a requirement of the GRP product I'll be using (CureIt).
At this point I got a bit lazy with my photographs so we jump forward to where it stands at the end of a very wet May. The timber dressing/facade at the front of the building has lots of details like the breakfront and some column and pilasters with pliths and headers, and lots of endgrain will be exposed. I bought some hardwood (ireki) in made to measure lengths & widths so that it will have some durability, primed it and covered the front. The top facade is made out of several layers of hardwood, with a swan neck moulding at the top, a scotia and bead detail lower down (these cover some end grain and a join in the panels respeectively) and finally a cock bead moulding on the bottom edge to give a clean finish.
The facade detail continues around the 2 sides of the building, but this time using marine ply on cost grounds and all the laminated edges are covered.
The shuttering ply on the sides of the building were covered in Tyvek, then battened off, insect mesh applied to the bottom, and finally some Knauf exterior cement boards installed as render carriers using mega expensive stainless steel screws (any other sort of screws will rust and bleed through the render eventually).
Jobs left to do as soon as the weather permits are:
- install GRP to roof
- fit roof lantern
- decorate front timberwork
- fit doors and side windows - haven't ordered these yet, have just decided to go for timber units as they will look best
- apply thin coat render - I've selected EWI for this, but have bottled out of doing it myself
- apply levelling compound to internal slab
- internal fit out - I've decided to have some panelling on the bottom third of the walls and plasterboard above
- second fit electrics
- fit flooring - probably glue down LVT
So still quite a lot to do.
essayer said:
looks awesome! you've had great weather for it 
Thanks, April was great, May...not so much! Was almost back to the same conditions when we were digging out the foundations in November! Is now getting really irritating as I can't get on to anything internally until we're properly weathertight with the GRP on and some leadwork around the parapet. For that I need 3 consecutive guaranteed dry days...ho hum.
About 5 more days put in to the timberwork around the building. Lots of fettling, sanding and filling to get things looking good when the building is not 100% square. The picture below shows the buildup for the facade; from the top down:
- 18mm ply with a 15mm overhang to cover the parapet wall and provide a drip detail (this will be covered with lead eventually). This isn't finally fixed yet.
- 103mm swan neck cornice moulding in yellow pine (sourced online, about £12/m)
- 85mm top fascia in utile hardwood
- 18mm scotia moulding off the shelf from Wickes
- 300mm fascia in utile
- 40mm astagal bead moulding in sapele hardwood (same source as swan neck moulding)
- 85mm lower fascia ni utile hardwood
- 8mm cock bead moulding (same online source)
The cock bead moulding gives a nice "finish" to the facade and has the benefit of covering end grain from the utile plank above. Below there is the pilaster buildup for the columns, which is made from:
- 311mm wide front planks in utile to form the columns
- side returns to help form the window reveals
- 282mm wide planks to form the pilaster columns
- plinth block column headers and footers made from more utile planks. These were made in 3 sections (to form the wide front face and the 2 shorter returns) with mitred corners. This was to get a good sharp corner and also to avoid end grain being exposed. Finally the top/bottom edge of the plinth blocks was taken off to a 45degree edge using a electric plane.
I can't take all the credit for the timberwork, I was lucky enough to have a very skilled joiner working with me doing all the really tricky stuff.
After the timberwork was done, I spent about 5 days doing prep, sanding everything smooth, filling in around 300 screw holes and panel pins, priming and finally got an undercoat on, which made it all look a lot tidier. Another undercoat and then a top coat in the same finish as the doors will finish the timberwork and let me get on with the rendering on the sides.
Unfortunately just when the weather window that I've been waiting for has opened up to get the GRP roof done, I've had to go away for a couple of weeks. Hopefully when I come back the weather will still be good and I can get the roof on, lantern roof installed and then I'll be weathertight to start work on the interior.
In the picture above you can just about see the green membrane I've installed as a vapour control layer. This is the second one (in conjunction with the foil backed PIR and metal tape over the studwork) so should hopefully keep the as much moisture as possible from migrating into the stucture.
- 18mm ply with a 15mm overhang to cover the parapet wall and provide a drip detail (this will be covered with lead eventually). This isn't finally fixed yet.
- 103mm swan neck cornice moulding in yellow pine (sourced online, about £12/m)
- 85mm top fascia in utile hardwood
- 18mm scotia moulding off the shelf from Wickes
- 300mm fascia in utile
- 40mm astagal bead moulding in sapele hardwood (same source as swan neck moulding)
- 85mm lower fascia ni utile hardwood
- 8mm cock bead moulding (same online source)
The cock bead moulding gives a nice "finish" to the facade and has the benefit of covering end grain from the utile plank above. Below there is the pilaster buildup for the columns, which is made from:
- 311mm wide front planks in utile to form the columns
- side returns to help form the window reveals
- 282mm wide planks to form the pilaster columns
- plinth block column headers and footers made from more utile planks. These were made in 3 sections (to form the wide front face and the 2 shorter returns) with mitred corners. This was to get a good sharp corner and also to avoid end grain being exposed. Finally the top/bottom edge of the plinth blocks was taken off to a 45degree edge using a electric plane.
I can't take all the credit for the timberwork, I was lucky enough to have a very skilled joiner working with me doing all the really tricky stuff.
After the timberwork was done, I spent about 5 days doing prep, sanding everything smooth, filling in around 300 screw holes and panel pins, priming and finally got an undercoat on, which made it all look a lot tidier. Another undercoat and then a top coat in the same finish as the doors will finish the timberwork and let me get on with the rendering on the sides.
Unfortunately just when the weather window that I've been waiting for has opened up to get the GRP roof done, I've had to go away for a couple of weeks. Hopefully when I come back the weather will still be good and I can get the roof on, lantern roof installed and then I'll be weathertight to start work on the interior.
In the picture above you can just about see the green membrane I've installed as a vapour control layer. This is the second one (in conjunction with the foil backed PIR and metal tape over the studwork) so should hopefully keep the as much moisture as possible from migrating into the stucture.
Edited by PhilboSE on Tuesday 1st June 12:57
Bit of background on some of the landscaping I've done alongside this in order to bring this area of the garden into more use.
Started off with an abandoned wilderness that had been used to dump building waste and garden rubbish for about 60 years:
This pile of leaf mulch and tree trimmings was taller than me:
So I began the clearance work, sorting into composted material, fuel for the woodburner, and stuff for the bonfire. After a bit of digging and sorting I found the remains of a pair of composting boxes made from concrete posts and kickboards. The timber frame had long since rotted away, hence the random piles of accumulated crap.
I bought some treated ungraded scaffold planks (about the cheapest form of timber for this) and cut them to size with a chainsaw. Also made a leaf mulcher to the side out of some more planks and some chicken wire. As I cleared this area by hand I kept coming across 1960's concrete paving slabs...
Clearance gradually starting to take shape. I had some cracking bonfires with all the extremely old and dry twigs that were too small to keep.
I built a log store out of the remaining scaffold planks, some roof battens, and some concrete roof tiles that I liberated from the ground during the clearance process. The little Stihl battery powered chainsaw was just perfect for all the pruning and logging for this stuff.
Some of the composted matter/top soil I dug out as I did the clearance. It was about this time that I began thinking about diggers! In the background are some of the building materials that were dumped down here from when the house was built - some coping stones, stone blocks for some outside walls, paving slabs and bricks. While I was digging away I kept on thinking of ways to use up these materials around the garden rather than go to the effort of getting rid of them...
Some granite setts and bricks were cleaned up and used to make a path to access the new "waste management" part of the garden. The eagle eyed will notice that I decided the log store was in the wrong place, so I dismantled it enough to move it and rebuilt it again.
One day I found a deer from the woodland getting itself into trouble with the ivy-covered wire mesh fence along the boundary (you can see the mesh 2 pictures back), so I decided to tidy that up. After clearing the area I found the original small concrete boundary posts, so I bolted some fence posts to those and made a fence out of roof battens. In this picture you can also see (under the barrow) the base I made for a shed. The base was made from the concrete paving slabs I found, on a bed of 4:1 dry mortar mix on some road scalpings hardcore that had been dumped in that area.
Shed eventually arrived (Empire Sheds Pent 4000) so was duly assembled, painted and made slightly more secure with some coach bolts and a decent hasp and lock.
Time to improve access to the garden room as it would be needed long term and it would also make it a lot easier and cleaner to ferry materials down there for the build. Time to call for Simon to bring his digger and dumper again.
Dug out a path 75mm deep, 1m wide. One metre was chosen partly because it felt a decent size, but mainly because that was the width of the bucket on the digger! We lined the path with Everedge, which was pricey but won't need to be maintained again, and laid a weed membrane.
60mm of MOT was dumped in, levelled and whacked down. SWA cable was laid under the path, with loops sticking out every 5 metres or so. These will eventually be used to power some lights for the path.
The MOT served as an adequate path down to the garden room and around this point the weather improved in February so I got on with building the room itself a bit. Finally the path was topped up with Breedon Golden Amber self binding gravel and whacked down in a couple of layers. In all we (Simon and I) laid around 200m of paths down and around the garden, but it didn't take that long - around 10 days start to finish.
Also bought some oak sleepers and built some raised beds. Used up the last few bricks (a Bertie Bassett collection of about 5 styles and both Imperial and metric sizes) to make a "rustic" stand for a £10 ceramic butler sink I found on Gumtree.
There's a water feed via a PTFE pipe from the main house down here, so I brought around to the side of the sink and will eventually be brought into some taps for the sink and hoses.
Started off with an abandoned wilderness that had been used to dump building waste and garden rubbish for about 60 years:
This pile of leaf mulch and tree trimmings was taller than me:
So I began the clearance work, sorting into composted material, fuel for the woodburner, and stuff for the bonfire. After a bit of digging and sorting I found the remains of a pair of composting boxes made from concrete posts and kickboards. The timber frame had long since rotted away, hence the random piles of accumulated crap.
I bought some treated ungraded scaffold planks (about the cheapest form of timber for this) and cut them to size with a chainsaw. Also made a leaf mulcher to the side out of some more planks and some chicken wire. As I cleared this area by hand I kept coming across 1960's concrete paving slabs...
Clearance gradually starting to take shape. I had some cracking bonfires with all the extremely old and dry twigs that were too small to keep.
I built a log store out of the remaining scaffold planks, some roof battens, and some concrete roof tiles that I liberated from the ground during the clearance process. The little Stihl battery powered chainsaw was just perfect for all the pruning and logging for this stuff.
Some of the composted matter/top soil I dug out as I did the clearance. It was about this time that I began thinking about diggers! In the background are some of the building materials that were dumped down here from when the house was built - some coping stones, stone blocks for some outside walls, paving slabs and bricks. While I was digging away I kept on thinking of ways to use up these materials around the garden rather than go to the effort of getting rid of them...
Some granite setts and bricks were cleaned up and used to make a path to access the new "waste management" part of the garden. The eagle eyed will notice that I decided the log store was in the wrong place, so I dismantled it enough to move it and rebuilt it again.
One day I found a deer from the woodland getting itself into trouble with the ivy-covered wire mesh fence along the boundary (you can see the mesh 2 pictures back), so I decided to tidy that up. After clearing the area I found the original small concrete boundary posts, so I bolted some fence posts to those and made a fence out of roof battens. In this picture you can also see (under the barrow) the base I made for a shed. The base was made from the concrete paving slabs I found, on a bed of 4:1 dry mortar mix on some road scalpings hardcore that had been dumped in that area.
Shed eventually arrived (Empire Sheds Pent 4000) so was duly assembled, painted and made slightly more secure with some coach bolts and a decent hasp and lock.
Time to improve access to the garden room as it would be needed long term and it would also make it a lot easier and cleaner to ferry materials down there for the build. Time to call for Simon to bring his digger and dumper again.
Dug out a path 75mm deep, 1m wide. One metre was chosen partly because it felt a decent size, but mainly because that was the width of the bucket on the digger! We lined the path with Everedge, which was pricey but won't need to be maintained again, and laid a weed membrane.
60mm of MOT was dumped in, levelled and whacked down. SWA cable was laid under the path, with loops sticking out every 5 metres or so. These will eventually be used to power some lights for the path.
The MOT served as an adequate path down to the garden room and around this point the weather improved in February so I got on with building the room itself a bit. Finally the path was topped up with Breedon Golden Amber self binding gravel and whacked down in a couple of layers. In all we (Simon and I) laid around 200m of paths down and around the garden, but it didn't take that long - around 10 days start to finish.
Also bought some oak sleepers and built some raised beds. Used up the last few bricks (a Bertie Bassett collection of about 5 styles and both Imperial and metric sizes) to make a "rustic" stand for a £10 ceramic butler sink I found on Gumtree.
There's a water feed via a PTFE pipe from the main house down here, so I brought around to the side of the sink and will eventually be brought into some taps for the sink and hoses.
Edited by PhilboSE on Tuesday 1st June 14:15
It's been quite a while since the last update which was primarily dictated by the weather. The next job to do on the garden room was to GRP the roof and install the roof lantern. For this I needed 4 consecutive dry days of max 25 degrees, so I became an avid weather watcher. In May it rained. In June it rained. In July it didn't rain for a couple of weeks, but I had to go away at that precise time, and when I came back it was raining again. In the meantime I was doing lots of other work on the garden landscaping - planting up some beds, weeding, mulching etc. Finally in late August it looked like a weather window opened for the roof...but it was too hot! In 30 degree heat you just can't do the resin for GRP, it goes off and hardens before you get a chance to push it around. Finally in early September the weather was perfect so we cracked on.
Originally I had planned to use lead on the coping detail on the top of the parapets, but when I worked out how much it was going to cost I decided to look at other options. The GRP supplier recommended we used their trims and simply continued the GRP up the sides, over the top, and down the outer edge to form a drip detail. Therefore the whole roof would be a single seamless entity.
Day 1, finish installing the roof deck in OSB, leaving 20mm gaps where they meet verticals. Here you can see the fall from the front of the building (on the right hand side of the picture) to the rear. I also put in an apex detail to the roof in front of the upstand, so that any rain falling in this area would be encouraged down the sides of the lantern upstand rather than pooling. The upstand remains 150mm above the deck at the front of the opening, and somewhat more at the rear due to the fall in the roof.
Day 2, install the trims using a polymer adhesive and clout nails. The trims are supplied as prefabricated mouldings by the GRP supplier, different profiles for drip trims, coping edges, internal corners and gutters. Some of these (the drip trims) had to be cut to size as one of the edges was too long. We found the easiest way to get a straight edge was a circular saw and a fence. Apparently some GRP installers minimise their use of trims to save money, but as this was my first GRP roof I wanted to do things by the book.
Every joint was then sealed using a glassfibre bandage and a resin mix which had to be worked in.
Day 3, lay the GRP matting and apply the resin. The instructions suggested apply the resin using a paint roller then working in with some metal edge rollers. We found it easier to "paint" the resin onto the OSB with the roller and then simply pour a load of resin onto the matting and push it around and work it in with the metal rollers. The matting goes from opaque to transparent when it's fully worked in, which makes it pretty easy to progress knowing you are getting complete coverage. If in doubt (like on corners) we just added more matting and more resin!
Day 4, give the cured resin from Day 3 a sanding to remove any lumps or spikey bits with an orbital sander. Wipe down whole area with acetone to clean, then literally "paint" on the topcoat using rollers. The topcoat is also a resin based product to which you add an accelerant to start the cure.
A few days after we finished there was a big storm so next day I jumped up to inspect the state of the roof...pleased to observe no leaks or pooling and the water was beading up nicely on the topcoat.
A few days later we installed the lantern roof. I was holding my breath on this one as any mistakes in the sizing or construction of the upstand (done 6 months earlier!) would make this job trickier or in the worst case a non-starter if the dimensions were too far out. Fortunately everything was bang on, the upstand was square and level to within a mm and although the GRP coating had added about 10mm to the size of the upstand, this was all within tolerance for the lantern roof itself.
The unit came from Stratus and I chose it as an aluminium unit with good thermal properties but also because it had a very shallow profile and a pitch of just 20 degrees, which helped reduce the height of the apex to stay within my limits under Permitted Development of 3.5m and still maximise internal head height inside the room. We found this was a really good unit, well designed and manufactured, and went together pretty easily. Unlike many lantern roofs on the market, the only silicone sealant involved was around the ring beam to seal where it sits on the timber upstand.
By the time this was done most of September had gone and the room looked like this.
Originally I had planned to use lead on the coping detail on the top of the parapets, but when I worked out how much it was going to cost I decided to look at other options. The GRP supplier recommended we used their trims and simply continued the GRP up the sides, over the top, and down the outer edge to form a drip detail. Therefore the whole roof would be a single seamless entity.
Day 1, finish installing the roof deck in OSB, leaving 20mm gaps where they meet verticals. Here you can see the fall from the front of the building (on the right hand side of the picture) to the rear. I also put in an apex detail to the roof in front of the upstand, so that any rain falling in this area would be encouraged down the sides of the lantern upstand rather than pooling. The upstand remains 150mm above the deck at the front of the opening, and somewhat more at the rear due to the fall in the roof.
Day 2, install the trims using a polymer adhesive and clout nails. The trims are supplied as prefabricated mouldings by the GRP supplier, different profiles for drip trims, coping edges, internal corners and gutters. Some of these (the drip trims) had to be cut to size as one of the edges was too long. We found the easiest way to get a straight edge was a circular saw and a fence. Apparently some GRP installers minimise their use of trims to save money, but as this was my first GRP roof I wanted to do things by the book.
Every joint was then sealed using a glassfibre bandage and a resin mix which had to be worked in.
Day 3, lay the GRP matting and apply the resin. The instructions suggested apply the resin using a paint roller then working in with some metal edge rollers. We found it easier to "paint" the resin onto the OSB with the roller and then simply pour a load of resin onto the matting and push it around and work it in with the metal rollers. The matting goes from opaque to transparent when it's fully worked in, which makes it pretty easy to progress knowing you are getting complete coverage. If in doubt (like on corners) we just added more matting and more resin!
Day 4, give the cured resin from Day 3 a sanding to remove any lumps or spikey bits with an orbital sander. Wipe down whole area with acetone to clean, then literally "paint" on the topcoat using rollers. The topcoat is also a resin based product to which you add an accelerant to start the cure.
A few days after we finished there was a big storm so next day I jumped up to inspect the state of the roof...pleased to observe no leaks or pooling and the water was beading up nicely on the topcoat.
A few days later we installed the lantern roof. I was holding my breath on this one as any mistakes in the sizing or construction of the upstand (done 6 months earlier!) would make this job trickier or in the worst case a non-starter if the dimensions were too far out. Fortunately everything was bang on, the upstand was square and level to within a mm and although the GRP coating had added about 10mm to the size of the upstand, this was all within tolerance for the lantern roof itself.
The unit came from Stratus and I chose it as an aluminium unit with good thermal properties but also because it had a very shallow profile and a pitch of just 20 degrees, which helped reduce the height of the apex to stay within my limits under Permitted Development of 3.5m and still maximise internal head height inside the room. We found this was a really good unit, well designed and manufactured, and went together pretty easily. Unlike many lantern roofs on the market, the only silicone sealant involved was around the ring beam to seal where it sits on the timber upstand.
By the time this was done most of September had gone and the room looked like this.
I wanted to get the exterior of the room finished before winter set in, so that it was weathertight and I could work on the internal fit out during colder months. Because of the rain induced delays I had to get a hustle on, so I brought 200 concrete blocks down and built a retaining wall and some steps to access. The ground level was 600mm higher that the patio slab at the tallest point, and I worked out that 4 steps would be required keeping the risers at a comfortable height, so I chose larger concrete blocks of 140mm high rather than the usual 100mm as these meant I could just use each course as a step. It also meant less mortaring! Only downside was each block weighed 20kg which made for a sore back. This was my first attempt at blocklaying, although I deliberately kept it as simple as possible working to whole blocks where I could, I was still quite pleased with my efforts. The pug joints weren't very special but I knew I could get away with my hamfistedness as it would all be covered up eventually.
When this was done I got a man in to render the walls of the building and the steps. As the finish here was important I didn't trust my pretty crappy plastering skills to deliver an adequate job.
I did a bit of landscaping around the retaining walls to build up the soil and make it relatively flat. I backfilled the retaining wall with shingle and then built some shuttering to take some MOT which will form the rest of the top step which is going to have a deeper tread than the rest of the steps.
Next stop, the patio, which I'm doing in limestone to match other patios by the house. I'm going to use the smaller pieces to form a coping detail on top of the wall which should tidy it all up. I've booked some time off work to get this done in the first week of November, and then hopefully that will be pretty much the outside done.
Had a bit of a saga with the doors - originally I thought I was going to use aluminium glazed units and bifolds, but I was advised that timber would look much better with my facade. I ordered some units in May and was advised a November 2021 delivery date, which was fine. Unfortunately in September they got back in touch and said the delivery had slipped...to July 2022! Basically they didn't want my business (even though the company supplied the property with about 40 windows and doors as part of a refurb some years earlier and was even a case study on their website!). Luckily I know a local joiner who kindly agreed to slot me in to his schedule so I hopefully will get the room closed up in early January.
When this was done I got a man in to render the walls of the building and the steps. As the finish here was important I didn't trust my pretty crappy plastering skills to deliver an adequate job.
I did a bit of landscaping around the retaining walls to build up the soil and make it relatively flat. I backfilled the retaining wall with shingle and then built some shuttering to take some MOT which will form the rest of the top step which is going to have a deeper tread than the rest of the steps.
Next stop, the patio, which I'm doing in limestone to match other patios by the house. I'm going to use the smaller pieces to form a coping detail on top of the wall which should tidy it all up. I've booked some time off work to get this done in the first week of November, and then hopefully that will be pretty much the outside done.
Had a bit of a saga with the doors - originally I thought I was going to use aluminium glazed units and bifolds, but I was advised that timber would look much better with my facade. I ordered some units in May and was advised a November 2021 delivery date, which was fine. Unfortunately in September they got back in touch and said the delivery had slipped...to July 2022! Basically they didn't want my business (even though the company supplied the property with about 40 windows and doors as part of a refurb some years earlier and was even a case study on their website!). Luckily I know a local joiner who kindly agreed to slot me in to his schedule so I hopefully will get the room closed up in early January.
essayer said:
Looking fab
I really like the fence - roof battens you say - what sort of sizes?
Thanks - 25mm x 50mm nominal (about 47mm finished). They got delivered in a mixture of lengths 3.0m & 3.6m which meant about 500mm of wastage from each length. I set them out so the gap was a batten on edge so it's about 24mm gaps and 47mm of batten repeated.I really like the fence - roof battens you say - what sort of sizes?
They've really mellowed down in the summer compared with those pictures, nice pale colour now rather than the somewhat vibrant treated colour they come as.
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