Water Pooling under decking! Help

[Paul11]

Our builders have built a frame for the decking sittting on plastic sheeting

over night rain have come back to pools of water collected on the plastic all touchiing the wooden supports

I am assuming this will rot the wood over time if allowed to collect after every rain

Is it ok to make holes in the plastic to allow drainage or does that risk weeds growing up?

any other ideas?

 

[Paul11]

the water will still run in the gaps and gather..

I wasnt sure about felt/ membrane or other but the builder says hard plastic is normal

 

[Paul11]

There are no concrete posts

Half the area is sitting on concrete drive way

Other parts is attached to the house

Rest is just on supports on the grass.

I'll get photos

 

[Paul11]

double post

 

[Paul11]

 

[Paul11]

On the grass?

yes

the right hand side is sitting on concrete
bottom is attached to the house
top left is sitting on grass

1) is that ok or does it really need a contrete post top left?

2) how to deal with the water pooling around each leg post as the ground is not flat?

 

[Paul11]

someone else has suggested just poking lots of holes in the plastic to allow water drainage and then lay membrane on top to stop weeds/letter water run away.

 

[Paul11]

Yes he is a professional

doing some research some people say its fine as long as the weight is spread over a larger area, which it is.

thank you for your help, much appreciated . ill keep researching

 

[Paul11]

Thanks Kaka

 

[Paul11]

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

 

[Paul11]

At the least, get them to put a concrete slab under each of those feet.

Yes, that sounds like a plan.

Someone else said to pierce holes in all the plastic and then to put a membrane down on top of it, do you think that will do it ?

 

[Paul11]

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.

 

[Paul11]

so the correct solution is to make them take it up and remove the PVC ? and replace it with proper membrane ?

 

[Paul11]

or take out the supports,put a concrete slab down,bit of membrane on top and ten refit the timber supports

you mean remove the PVC ?