5m x 4m deck with gazebo and glass roof

[jakesmith]

I have thi in my garden already. Some of the decking boards are droopy, on inspection the problem is a few rafters underneath are rotting at the top

Also the main legs of which there are 9, appear to go straight into the soil and are looking a bit rotten

I would like to repair not replace

First question is rather than going to the hassle of concreting the legs in, could I individually support each leg, cut away the existing leg, put a couple of concrete pavers underneath and attach a a new leg Resting on them. The ground is level. But is that too much weight for this method

If that isn’t viable can anyone recommend a good concrete solution for a decent amateur diy guy with no concrete experience. Would post Crete be the least hassle for the job?

[AlmostUseful]

postcrete is an expensive way of doing it at.
Just buy a bag or two of cement at £5ea, a few bags of sharp sand at £2ea and some ballast as required at £2ea too.

Mix the materials as directed on the bag, something like 3 ballast, 2 sand and 1 cement (for example, I cant remember what I used but it was directed on the bags. mix it together and add water.

When I did my decking I dug holes about 450mm deep and put a broken piece of paving slab in the base under the legs, then poured the concrete around it until just above ground level, that allowed me to trowel a slope down to ensure there was no ponding around the timber.

Wasn't much science to what I did to be fair, and I dug the holes after building part of the frame so worked in a similar sort of way to you.

I wouldn't worry too much about supporting the joists until you've got the posts in - just get the posts level and then fix the joists once it's set.

Now delete this thread before everybody tells you to use composite decking or rip it up and put a patio in.

[xstian]

You don't want to concrete wooden posts in the ground, they will rot quicker.

[jakesmith]

Really? Why is that as I thought concrete was impervious. I would have brought the concrete up above ground level and put a fall on it

Could you suggest a better alternative? How about galvanised post holders concreted in, so the metal separates the wood and concrete?

[Europa1]

jakesmith said:

First question is rather than going to the hassle of concreting the legs in, could I individually support each leg, cut away the existing leg, put a couple of concrete pavers underneath and attach a a new leg Resting on them. The ground is level. But is that too much weight for this method

No idea on the weight bearing question, but will you fix the posts to anything?

If not, what happens when [cliche alert] one of your powerfully built director friends from PH [end cliche] comes round for a barbie, pours themselves a refreshing glass of fruit cup, then leans against one of the posts?

[sgtBerbatov]

jakesmith said:

Really? Why is that as I thought concrete was impervious. I would have brought the concrete up above ground level and put a fall on it

Could you suggest a better alternative? How about galvanised post holders concreted in, so the metal separates the wood and concrete?

Wood's gonna rot regardless, in my opinion.

I'm in a similar position and I'm planning on ripping up my decking over the Easter holiday. The plan is to reinstate the decking, but I'm going to use scaffolding poles and build a base with that. Then lay wooden planks on top of it.

I reasoned that wood rots at some point, and scaffolding poles are galvanised. So they'd last longer than the wood which would lower the maintenance headache decking gives.

[jakesmith]

The legs go into the soil at the moment. If I was going to rest them on pavers instead, which doesn’t seem like such a good idea, the guy would have to be quite powerfully built as the structure is: 4mx5m of decking resting on 2x4 grid of bearers and joists, with a roof of approx 20sq m of 12mm glass. Must weigh 2 tons at least. Fat bloke is what 100kg max?

[Drumroll]

The problem with wooden posts in concrete is the concrete acts like a bucket and the water has no where to go apart from into the wood.

Wood and concrete expand/contact at different rates so water will find it's way into the hole.

[jakesmith]

sgtBerbatov said:

Wood's gonna rot regardless, in my opinion.

I'm in a similar position and I'm planning on ripping up my decking over the Easter holiday. The plan is to reinstate the decking, but I'm going to use scaffolding poles and build a base with that. Then lay wooden planks on top of it.

I reasoned that wood rots at some point, and scaffolding poles are galvanised. So they'd last longer than the wood which would lower the maintenance headache decking gives.

Very interesting idea, and it’s v heavy sonare you just going to rest the frame on the ground, or concrete rising poles in?

Also how are you going to affix the decking to the scaf? Surely still some wooden sub frame to get all the screws into that hold the boards down. Please share your thoughts it sounds like a very interesting solution

[V8RX7]

We always just hammered treated 2x2 posts into the ground and built the decking off them - lasts approx 10 yrs IME.

So if you can lift the odd board I'd simply add a few posts - unless the joists are very rotten.

[shedweller]

How high off the ground is it???

I use jouplast risers and extensions on paving slabs, you could probably leave the original posts in situ and wind the jouplast up from underneath, the cost is offset by the time saving and much less dikking around.

Drill a 15+mm diagonal hole down into existing posts from just above ground level to below and inject with old engine oil (or creosote) - top up as needed monthly and then anually once looking suitably preserved.

[jakesmith]

shedweller said:

How high off the ground is it???

I use jouplast risers and extensions on paving slabs, you could probably leave the original posts in situ and wind the jouplast up from underneath, the cost is offset by the time saving and much less dikking around.

Drill a 15+mm diagonal hole down into existing posts from just above ground level to below and inject with old engine oil (or creosote) - top up as needed monthly and then anually once looking suitably preserved.

Jouplast risers look good, a lot of hassle saved

Whats the second bit how deep would you drill, is the idea just to drill a small channel within the posts for the creosote to sit in and gradually seep out into the posts to make the rate of rot advance slow right down? How do you stop rain water going into the hole you just made?

[threadlock]

When I had decking foundations professionally laid the chap dug holes, filled them with concrete and set lengths of 4" x 4" angle iron in, to which I then bolted the 4"-square pressure-treated uprights for the frame. For the pergola frame the uprights just carry on up past deck level so the pergola is stiff. The uprights go no lower than at least an inch above the concrete so water can't soak in. This was 12 years ago and there's been no movement at all.

[PositronicRay]

jakesmith said:

How do you stop rain water going into the hole you just made?

[sgtBerbatov]

jakesmith said:

sgtBerbatov said:

Wood's gonna rot regardless, in my opinion.

I'm in a similar position and I'm planning on ripping up my decking over the Easter holiday. The plan is to reinstate the decking, but I'm going to use scaffolding poles and build a base with that. Then lay wooden planks on top of it.

I reasoned that wood rots at some point, and scaffolding poles are galvanised. So they'd last longer than the wood which would lower the maintenance headache decking gives.

Very interesting idea, and it’s v heavy sonare you just going to rest the frame on the ground, or concrete rising poles in?

Also how are you going to affix the decking to the scaf? Surely still some wooden sub frame to get all the screws into that hold the boards down. Please share your thoughts it sounds like a very interesting solution

The plan is to dig a trench and treat it like I'm building a wall. So put the hardcore down, level it so that it's solid and the poles will then stand on top of it. I may concrete the feet of the poles for stability.

Fixing the boards to the scaffolding, I've had several ideas. I think it helps that I'm planning on using scaffolding boards too (not the normal decking planks - can't afford it). One way I've thought about is to fix the boards to the poles, either drilling in to the pole and fixing the screw to it, or using brick straps(?) underneath and strapping it to the pole underneath. Another route would be to use small metal rods and join the planks to each other, like doweling joints. Then I'd fix the rear and front planks to the poles, relying on the weight of the wood and the rods to hold everything down. I don't get much wind in the garden, it's fairly sheltered, so it may work.

I've thought about the wooden subframe too, and it'll probably be an easier path really as the wood is sacrificial in my opinion.

[jakesmith]

There are zinc coated scaffolding accessories that clamp onto a tube and have a hoist holder on too, for £2 each, saw them online

[sgtBerbatov]

jakesmith said:

There are zinc coated scaffolding accessories that clamp onto a tube and have a hoist holder on too, for £2 each, saw them online

Yeah I saw them as well. I haven't tallied up how many I'd need of those yet, not really contemplated them much either. But I should have my mind made up soon.

But that's why I'm going down this scaffold route, it's cheaper than putting out a load of wood that needs replacing and, if it's done right, won't look like the front of a building but look quite nice.

[bernhund]

Have you considered the effects of strong wind lifting the structure? That'll be a big old surface area for the wind to catch!

[jakesmith]

bernhund said:

Have you considered the effects of strong wind lifting the structure? That'll be a big old surface area for the wind to catch!

So I am now thinking of doing it as a patio as a continuation of the path as the rot is considerable and I don't really want to spend £1k putting something in and redoing it again in 10 years. We have Indian Sandstone paths and the decking is raised so I would build a retaining wall, put the patio on

I would like to get something like this to put on top:



The manufacturer Dunster House states that it just sits on the patio. Does this sound right? Ideally it would be anchored but how could I do that so that it is secure on the patio and doesn't rot where feet touch the ground?

[bernhund]

jakesmith said:

bernhund said:

Have you considered the effects of strong wind lifting the structure? That'll be a big old surface area for the wind to catch!

So I am now thinking of doing it as a patio as a continuation of the path as the rot is considerable and I don't really want to spend £1k putting something in and redoing it again in 10 years. We have Indian Sandstone paths and the decking is raised so I would build a retaining wall, put the patio on

I would like to get something like this to put on top:



The manufacturer Dunster House states that it just sits on the patio. Does this sound right? Ideally it would be anchored but how could I do that so that it is secure on the patio and doesn't rot where feet touch the ground?

If that were mine I'd be tempted to core into the bottom of each post and slip it over some stainless/galvanised tubing that's set in concrete under the patio. If you're really clever you could drill through the sides into the tubing and get some bolts through to lock it in. I guess ultimately it depends how exposed it is. If I did that on my deck, there's nothing but open fields between it and the north east wind. It'd take off!