Damp retaining wall for deck

[mws2000]

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.  It's about 1m up from the ground and encloses a 50m2 area. The builder has filled it with rubble from the house.

 

We've had a delay because of COVID and have not put the decking on top as yet, but are planning that now.  However, the deck wall has got damp as you can see in the picture.

 

The builder suggested putting pipes through the wall to let it drain, but don't think it should be getting damp to start with. 

 

Any thoughts about this?

 

Thanks,

 

Matthew

[Mr Punter]

Forget the softwood timber deck.  It will go crappy in a couple of years.  Infill with hardcore and slab finish.

[mws2000]

Thanks. My wife wanted hardwood.  I had thought of paving it but I think that's 25m3 of hardcore... would you put that much in?  I think that should stop the damp though. (And the joists are already done for the decking).

Edited January 29, 2021 by mws2000

[Temp]

Timber decking gets very slippery. Woukdnt have one personally.

 

How about a beam and block top with some sort of paving or stone? Think the blocks would need to be frost resistant.

 

Given the height i think you need railings.

 

[mws2000]

Yes, beam and block would do it I think. Filling with aggregate would cost around £1,000 from my calculation, which is probably cheaper than beam and block. What if we keep with decking, how do you think we get the walls to dry out and stop getting damp in the future? Thanks

[Mr Punter]

I have hardwood on some balconies because I wanted it to last.  I used iroko bearers fitted with stainless bolts and ipe decking with stainless screws.  Massively expensive.  Your setup is much better paved.

[Declan52]

What did the builder do with regards drainage. Unless there is something there then with the rain falling in such a large area its always going to get damp.There should have been weep holes in the block and brickwork to allow the rain to drain out. As it sits it's building up and soaking through and forming the damp patch. I would go with the easy fix as he has mentioned and drill a few holes to let the rain out. 

[Temp]

+1

 

If water can get in the top through decking it needs to get out somehow. In a down pour could be several inches of water in there needing to drain out.  

 

Its normal to put drainage holes through retaining walls, which is essentially what you have now its full of hardcore.   From Paving Expert website..

 

 

 

 

 

 

[mws2000]

Hi .Thanks for the replies. I don't think the builder has put a DPC in but I will check with him. Fairly certain there is no drainage at all.  The wall is on 150mm concrete. There are some weep holes but they are a bit all over the place. One is close to some damp as you can see in this picture.  I'm beginning to think that filling it with aggregate and paving is the only way forward here. Even if I do that, the wall may take some time to dry out as it is damp right now.