Damp in walls breached internal DPC

[seth whitcher]

Hi. A builder replaced the wooden floors in my house for concrete, before I bought it. I did have walls damp proofed using a water based render waterproofer, which has now failed leaving blown plaster and effervescent salts. I've tried to explain using the diagram below. The green area is brick rubble and type 1.
Water is migrating around the internal dpc traveling through the hardcore sub base and into the walls. Bar ripping out the floor anything else I can do? I was thinking of digging down and putting in a sump pump to remove all water from under the floor that the hardcore is sitting on!

Thank you in advance

 

[JohnD]

Silicone fluids are useless.

Sometimes the cause is an old leaking waterpipe under the floor, or a broken drain, or some other source of water This causes the damp that makes the original wooden floor rot.

Very annoyingly, pouring concrete over the fault does not repair it, but gives much more work to the person who deals with it later.

Do you have a water meter?

Draw a plan showing the routes of nearby pipes, drains, stopcocks, manholes

 

[Mr Chibs]

Is the new concrete floor a replacement for a suspended wooden floor?

Were there any air vents in the 'concrete floor' room exterior walls?

Was there lots of sitting water before the concrete went in?

Can you take some photos of the problem walls.

 

[seth whitcher]

Silicone fluids are useless.

Sometimes the cause is an old leaking waterpipe under the floor, or a broken drain, or some other source of water This causes the damp that makes the original wooden floor rot.

Very annoyingly, pouring concrete over the fault does not repair it, but gives much more work to the person who deals with it later.

Do you have a water meter?

Draw a plan showing the routes of nearby pipes, drains, stopcocks, manholes

I've checked water meter over 48hrs and no movement on meter. No drains underneath which are all outside to rear. The problem is the high water table getting into the hardcore as previously outlined. Thanks

 

[seth whitcher]

Is the new concrete floor a replacement for a suspended wooden floor?

Were there any air vents in the 'concrete floor' room exterior walls?

Was there lots of sitting water before the concrete went in?

Can you take some photos of the problem walls.

Concrete would have been poured onto 2 X membranes, sitting on top of hardcore blinded by sand. The concrete floor is bone dry. It's the walls are the problem. Air bricks do exist on outside walls. Have also had cavity wall insulation put in during this period which was blown fibre. Don't think this has caused problems it's more on lower internal walls. I'll post pictures of plaster. Thanks

 

[seth whitcher]

The walls don't feel wet or even damp. The house is well heated and ventilated. I think the house flooded in 1953 which would have left the substrate with salts which then migrate through walls and blow off plaster. I'll post photo of salts forming on plaster.

 

[Koolpc]

Was there water under the suspended floor before concrete was put in?

Wall insulation you say. Pumped in? What type?

 

[seth whitcher]

Yes water under suspended floor...all houses have that in our road which. Cavity wall insulation was blown in. It's like the white fluffy fibre!