How do I plasterboard and insulate my conservatory roof..?

[jon-]

Following on from another thread I'm going to try and change a stty conservatory into a office for 12 months, until I can afford to extend.

As it's double glazed, most of the heat will be disappearing through the roof, which currently looks like this:



The main beams are very strong, I'm not sure about the cross beams.

I'm trying to do this on a budget so plan A will be to plasterboard with loft insulation above, or thermal plasterboard screwed to the cross beams (perhaps adding a few more in). Maybe silver tape the outside.

It doesn't need to look too pretty, and I'm not fussed about losing the light.

Is there much of a weight difference between plasterboard and thermal boarding? Will loft insulation be an effective and lighter replacement?

[gazzarose]

What about using some board type insulation, celotex or kingspan, cut around the beams and stuck up with glue of some kind. 4 inches of kingspan is pretty close to 8 inches of normal rockwool. It'll be alot better than plater board and a couple of inches of rockwool. And would probably be reasonably easy to put back to standard after.

[jon-]

gazzarose said:

What about using some board type insulation, celotex or kingspan, cut around the beams and stuck up with glue of some kind. 4 inches of kingspan is pretty close to 8 inches of normal rockwool. It'll be alot better than plater board and a couple of inches of rockwool. And would probably be reasonably easy to put back to standard after.

Great idea, but how heavy are these boards? You couldn't stick directly to the plastic, but I like the idea of using boarding where possible for simplicity.

I guess I'd need to vent it too, that shouldn't be a problem though, just cut into one of the side panels.

[gazzarose]

They don't weigh much. They sell it in wickes and bandq. Is basically more efficient begin of polystyrene board.comes in various thicknesses. Not cheap of your doing an entire building but for what you need won't be much I'm it between them and plasterboard/rockwool. Where I've used it on my extension roof. I cut it between the roof joists, probably 16"x 36", and after supporting temporally with bits of wood, I squirted expanding foam in the gap around the board and after its set it stays up fine. Weight wide you could easily carry a few balanced on your head.

[Rosscow]

Simple really, if the main beams are that strong then I'd suggest cutting and fitting some new cross beams so that they finish flush with the main beams (space them to suit plasterboard sheet size).

Then I'd cut celotex so it was a tight push-fit size (in other words, push it in and it won't fall out).

Then screw plasterboard to the underside of the beams.

As it's only temporary I'd suggest some 9mm tapered edge boards, then tape and joint it.

You should be able to get the new beams in, celotex cut and the plasterboard fixed in a day

[GreenDog]

Rosscow said:

Simple really, if the main beams are that strong then I'd suggest cutting and fitting some new cross beams so that they finish flush with the main beams (space them to suit plasterboard sheet size).

Then I'd cut celotex so it was a tight push-fit size (in other words, push it in and it won't fall out).

Then screw plasterboard to the underside of the beams.

As it's only temporary I'd suggest some 9mm tapered edge boards, then tape and joint it.

You should be able to get the new beams in, celotex cut and the plasterboard fixed in a day

A joinery company local to us advertise this service. They line the inside of the roof with space blanket insulation, screw cross beams to the existing roof bars, fill between the new cross beams with Celotex, plaster board over the top and skim it. Their brochure did mention venting the existing roof to prevent condensation but didn't go into any more detail than that.

[barryrs]

Do you have a window that overlooks it?

You dont want it to look crap from above if its your bedroom window so it might be worth covering the underside of the polycarb with something like a black plasti kote spray?

[Jonboy_t]

Would it be worthwhile removing the plastic completely, replacing with marine ply and felting it? Might help cut down a bit on the sound when it rains and it would also make lining and boarding a bit easier I would have thought (more solid base to secure to)?

[jon-]

gazzarose said:

They don't weigh much. They sell it in wickes and bandq. Is basically more efficient begin of polystyrene board.comes in various thicknesses. Not cheap of your doing an entire building but for what you need won't be much I'm it between them and plasterboard/rockwool. Where I've used it on my extension roof. I cut it between the roof joists, probably 16"x 36", and after supporting temporally with bits of wood, I squirted expanding foam in the gap around the board and after its set it stays up fine. Weight wide you could easily carry a few balanced on your head.

Rosscow said:

Simple really, if the main beams are that strong then I'd suggest cutting and fitting some new cross beams so that they finish flush with the main beams (space them to suit plasterboard sheet size).
Then I'd cut celotex so it was a tight push-fit size (in other words, push it in and it won't fall out).
Then screw plasterboard to the underside of the beams.
As it's only temporary I'd suggest some 9mm tapered edge boards, then tape and joint it.
You should be able to get the new beams in, celotex cut and the plasterboard fixed in a day

Thanks guys, looks like I have a plan Not sure about the day part, I'll be happy if I cut the celotex to the right size and stuck it on at the end of day 1!

barryrs said:

Do you have a window that overlooks it?

You dont want it to look crap from above if its your bedroom window so it might be worth covering the underside of the polycarb with something like a black plasti kote spray?

The master bedroom window overlooks it, but the bed is under the window so you can't really look out. A black spray does sound smart, but I presume will also attract a little more heat which is something I need to avoid on sunny days, even with the insulation layer!

[jon-]

Jonboy_t said:

Would it be worthwhile removing the plastic completely, replacing with marine ply and felting it? Might help cut down a bit on the sound when it rains and it would also make lining and boarding a bit easier I would have thought (more solid base to secure to)?

It would be worth it if it was free I like a little rain noise anyway!

[Gtom]

Have you got enough space to screw timber to the main supports? What is the spacings between them?

You could counter batten the main supports with something like 1 1/2" square at 450mm centres the use 1800x900 9.5mm plasterboard. The put the insulation behind all that.

For a different way you could insulate between and clad it with 300mm t&g soffit board or even the shower wall stuff, no plastering involved then. Not too sure about condensation though. And looks would be down to personal taste!

I would look at these for the roof too

http://www.roofingsuperstore.co.uk/product/tapco-s...

[jon-]

Update, the roof now looks like this:



Now I need to work out how to plug the gaps where the cross beams are. I tried expanding foam and it just fell all over my face and floor and clothes and eyes constantly.

And made me very angry.

I now have expanding foam all over the floor.

Help.

[Spare tyre]

could you tape the joints up, then inject the expanding foam

or some variant of the above

[jon-]

Spare tyre said:

could you tape the joints up, then inject the expanding foam

or some variant of the above

Simple yet effective. I like the way you think!

[edc]

For a 12 month period is the additional cost that much less than any increase in utilities cost? Why not just crank up the heating when needed?

[jon-]

edc said:

For a 12 month period is the additional cost that much less than any increase in utilities cost? Why not just crank up the heating when needed?

I don't know, probably not, but it gets VERY cold in the winter and as I work from home, I'd rather a nice feeling room than freezing my ass off with an electric heater under the desk.

[RJD223]

I did this with mine... Was advised not to use the Cellortex insulation as there wasn't enough of a vapour barrier?...

Anyhow - it's ace - glad I did it - we now use the room all year round!

The insulation was from http://source4me.co.uk/store/insulation/multi-foil... (Foil Insulation SF19)

[Jonboy_t]

RJD223 said:

I did this with mine... Was advised not to use the Cellortex insulation as there wasn't enough of a vapour barrier?...

Anyhow - it's ace - glad I did it - we now use the room all year round!

The insulation was from http://source4me.co.uk/store/insulation/multi-foil... (Foil Insulation SF19)

That's almost identical to mine and is exactly what I want to do in the next few weeks! How does it look from outside? I'm assuming you've just left the plastic sheeting on the roof rather than felting/tiling it?

Also, did you seal (silicone etc) the bars to the plastic sheets before you did it? I'm a bit worried about condensation behind the insulation and I know the plastic can move a bit, so was wondering if silicone would stop any chance of the plaster cracking?

[RJD223]

Jonboy_t said:

That's almost identical to mine and is exactly what I want to do in the next few weeks! How does it look from outside? I'm assuming you've just left the plastic sheeting on the roof rather than felting/tiling it?

Also, did you seal (silicone etc) the bars to the plastic sheets before you did it? I'm a bit worried about condensation behind the insulation and I know the plastic can move a bit, so was wondering if silicone would stop any chance of the plaster cracking?

I just left the outside as it was.

If I was doing it again I'd probably paint the inside of the panels before the insulation goes up - you can see a tint of silver but it's nothing worth worrying about.

Not sure what you mean about seal the bars to the plastic sheets? The wooden batons were screwed into the aluminium struts with strong self tapping screws (taking care not to protrude through into the water overflow channels).

The wood screwed into the batons makes the whole structure rigid and we've never had any problems with cracking/etc and it's been up over 12 months now.

[Jonboy_t]

RJD223 said:

I just left the outside as it was.

If I was doing it again I'd probably paint the inside of the panels before the insulation goes up - you can see a tint of silver but it's nothing worth worrying about.

Not sure what you mean about seal the bars to the plastic sheets? The wooden batons were screwed into the aluminium struts with strong self tapping screws (taking care not to protrude through into the water overflow channels).

The wood screwed into the batons makes the whole structure rigid and we've never had any problems with cracking/etc and it's been up over 12 months now.

Sorry bud, probably not describing it well, I meant the plastic roofing sheets that are already there - the actual conservatory roof itself. The bars that already support it (the metal bars), did you do anything with them to seal them first? With mine, I could push the plastic roofing and it would move within it's existing supports a little, I was just worried that this movement would let moisture in or allow movement behind the insulation that might lead to cracking.