Water Pooling under decking! Help

Soldato
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it is pressure treated timber but yes they are sitting on the plastic

its about 4m x 3.2m and the cost is all in with a lot of other work that he is doing

I told them to stop working on this for now and work on other bits they have to do til the main boss comes back monday

Have to consider my options and making them start again
 
Soldato
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The point of the membrane is to prevent weeds / grass growing. Not much point if there's pvc beneath it.

the idea was to cover the pvc with holes to allow drainage, which would also allow weeds

hence the membrane on top to stop the weeds

and thank you for your help.
 
Associate
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I wouldn't layer another membrane on top of the existing plastic sheet. It'll be a waste of time and money and would likely make things worse. Similar to how you wouldn't have two anti virus programs running on your computer at the same time. It's one or the other.

Weeds need sunlight to grow, so once your decking boards are laid on top of the joists and there aren't great big gaps between each decking board there would be very minimal weeds if any at all.
 
Soldato
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Peircing the DPM is a bodge, and I doubt it'll be that effective anyway as the water will find the low points which will undoubtdly be where the supports are sitting.
 
Soldato
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so the correct solution is to make them take it up and remove the PVC ? and replace it with proper membrane ?
or take out the supports,put a concrete slab down,bit of membrane on top and ten refit the timber supports

so once your decking boards are laid on top of the joists and there aren't great big gaps between each decking board there would be very minimal weeds if any at all.
Ahhh no imh experience damn weeds grow just as well under the decking and sprout up between even a small gap in the planks
 
Soldato
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No i would keep the membrane ,put slabs on top of membrane then the short vertical `post` ontop of slab with a piece of membrane under the post but on top of the slab
Ideally you should replace the membrane with the weed control fabric
 
Soldato
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The supports should be sunk into concrete, and if you're really doing it right they should be in steel sleeves in that concrete. More should be added in a mound after to prevent water pooling on the wood. Then add your weed control and a layer of gravel.

Cut ends shouldnt be exposed to anything really.

It depends what you're doing I guess. If you're smashing up a deck to last a few years and moving out then meh. If you want it to last 10-15 years it ought to be sunk into concrete. It'll still rot eventually.

Here's a basic thing.
 
Soldato
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@DC
good guide there.bit ottt imho but well setout.
re concrete the posts in surely that encourages rot as well?even sloping the concrete away from the posts,they still are in contact with damp/wet ground
 
Soldato
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You'll never escape rot, it's wood outdoors. You could use concrete posts with composite boards I guess but your joists and noggins will still go eventually.

I'm just saying if I was paying someone, i'd expect them to do all the work I can't be arsed to do! Theres many ways to boof a donkey after all.
 
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