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New foundation for deck / paving is getting damp - help please

Holes and wood deck or fill/cover and pave?

1. Put on deck and don't worry about it
No votes
2. Put holes in wall as the builder suggests and put deck on and it should be ok
No votes
3. Fill with hardcore and pave it
No votes
4. Put new OSB on joists and hardcore and then pave
No votes
5. Add beam and block and pave
No votes
6. Do something else
No votes
Total votes : 0

Postby mws2000 » Mon Jan 25, 2021 12:55 pm

Hi everyone,

We've just refurbished our house with a builder who has done a great job on the house and interior.

Unfortunately, he followed the wrong plans for a deck and instead of building pillars for a suspended deck, he built a brick and block wall laid on a concrete foundation. The wall comes out from the house, goes along in front of the house and returns back to the other end of the house. It's about 70cm high at the house and 1m high at the garden. The deck area is about 50m2. The builder filled it with rubble from in the house to about 40cm below the top and then covered that with a plastic tarp. The joists have been put on ready to take the decking. That was back in June 2020.

We then had a delay because of covid etc and have covered most of the deck with OSB as a temporary measure. Since then, after alot of rain, the deck walls have got damp in several places. There was alot of water going into the area as a drain pipe was not fitted properly (and now is).

Given that we go aheadd and put the wood decking on, water is always going to get through to the plastic and rubble in the 50m2 area.

The builder says that if we put pipes through the deck wall 1m apart and all along then any water should run through and out into the garden and the wall will stop getting damp and will dry out over summer and be fine in the future. The holes would be drilled from the outside and pipes pushed through and mortared in. I imagined 2" circular holes. I'm not sure it will look great.

I think we have 3 options but are open to suggestions:
1. Continue with decking but make sure that the area can drain somehow (like with the holes)
2. Empty out all the rubble (with digger) and lay drainage into the garden below ground level
3. Fill entire area to floor level or do beam and block or osb and hardcore on the joists, and then pave it (instead of decking). But that could be expensive (and require 20m3 filler on a rubble base or attachments for beams).

My questions are:
1. Do you think the holes through will work? (Is this a normal thing to do?)
2. Given we put decking on is there a better way to ensure it dries out and stays dry without putting holes through the walls?
3. If we put deck on, should we remove all the rubble and put in drainage?
4. Is our safest bet to fill/cover the whole area and pave it? If so, how would you do that?

Thank you very much for any advice and recommendations.

Deck damp and fill - scaled.jpg
Deck area - scaled.jpg
3d Deck.jpg
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