severe concrete scaling - help???

[uprightmonkeyuk007]

Hi,

After a recent damp survey that found dry rot along a single living/dining room wall, I have taken of the plaster/mortar on the walls and removed the carpet to putdown a masonry treatment. The plan was then to paint in a liquid DPM.
I did a quick brush followed by a hoover which is when it all went a bit grim.
The hoover was pulling up the concrete as I was going along. I switched to a stiff brush but in large areas, the brush was as bad.
As a bit of an experiment I decided in a few places I'd see how deep i could get. After reaching > 1" I decided I need some help.
You can see floor leveller where the previous guys must have had the same problem as there are quite a few patches of it.

At the edge of the room, there were a few patches of leveller I took up (with some local concrete) and there appears to be a damp membrane under there. The damp guy said the floor was dry where he tested along the wet wall.

Anyway, we're having a baby soon and i need to fix this. It would be nice if I could clean it up but any attempts to brush it clean of dust just keep pulling more up - mortar and grit/aggregate. This seems to rule out patching it with any products known to man.

Any advice? we just spent a fortune on IVF. We cant really afford tradesmen but I am prepared to rip it all out if there is no other solution. This effects 40% of floor area 8.5M x 4.5M. One half of the room is 90% solid

Cheers in advance

 

[JohnD]

I think you mean the surface is flaky. This is probably due to a poor mix or possibly drying too fast. Is it worse next to the wall?

Why do you want to paint on a "damp proofer?" You need to find out where the water is coming from and repair the fault.

Plaster is damaged by damp but concrete is not. You seem to mention both.

 

[uprightmonkeyuk007]

I think you mean the surface is flaky. This is probably due to a poor mix or possibly drying too fast. Is it worse next to the wall?

Why do you want to paint on a "damp proofer?" You need to find out where the water is coming from and repair the fault.

Plaster is damaged by damp but concrete is not. You seem to mention both.

I thought we had rising damp as the skirting boards were rotten and the carpet felt damp with salt tides on the wall paper.
The surveyor said the wall was wet but the floor was comparatively dry and he thought it might be penetrating - confident it wasn't rising. It's a shared wall and the neighbours brought their house 18 months ago and took the lot back to brick but didnt find anything on their side.
There is no sensible cause of damp on our side - no pipes anywhere near it.
The previous owner mentioned they had a fault years ago - possibly they did some work and now the moisture can only travel one way.
We lifted the carpet and the dry rot veins extended about 900mm into the room from that wall.
plan was to remove plaster to 1M (done) and treat the bare wall with Lignum pro M50 (done) and do the same to the concrete under the carpet and then paint on a liquid DPM - just to be sure and put a plastic membrane on the wall. Carpet was gonna get changed in any case. Possibly could have cleaned it up but - you know - new baby crawling around, thought better to get rid and start again.

It's not worse next to the wall. I think it probably was a poor mix of the concrete. it's probably freeze/thaw damage and possibly salts. It could even be sulphite attack with the age of the house. But a guy who has had half the houses in the street had this place and the rest of the work here is nothing short of awful. Downstairs has been knocked through. Walls look like they used a Mars bar in lieu of a trowel...

 

[JohnD]

It's a shared wall and the neighbours brought their house 18 months ago and took the lot back to brick but didnt find anything on their side.
There is no sensible cause of damp on our side - no pipes anywhere near it.

Do you mean it is an internal wall, with a room on the other side of it?

Is there a chimneybreast?

Was the house originally built with a concrete floor, or was it filled in later?

What is the path of the underground supply pipe between the pavement and your indoor stopcock?

You mention a damp membrane. Is it plastic sheet? How old is the house?

 

[uprightmonkeyuk007]

Do you mean it is an internal wall, with a room on the other side of it?

Is there a chimneybreast?

Was the house originally built with a concrete floor, or was it filled in later?

What is the path of the underground supply pipe between the pavement and your indoor stopcock?

You mention a damp membrane. Is it plastic sheet? How old is the house?

yeah its an internal wall. Their hall way is on the other side of our wall.
The chimney breasts are on the opposite side of the house. Damp survey showed that entries side of the house to be dry.
I don't actually know if the original floor was concrete.
The supply pipe comes out of the ground on the other side of the house in the kitchen and the stop in the street is is not quite in a straight line to it but I'm assuming it would run in the straightest possible line?
House is about 100 years old. Possibly pre sulphite use.
In fact, I can only see the membrane edges on the damp side of the house - it doesn't appear to run completely to the wall either - it's a black plastic sheet.

 

[JohnD]

Black plastic sheet in a 100 year old house indicates a replacement floor. Quite likely put down to hide water ingress without repairing the cause.

Are any airbricks visible at about floor level?

 

[uprightmonkeyuk007]

Black plastic sheet in a 100 year old house indicates a replacement floor. Quite likely put down to hide water ingress without repairing the cause.

Are any airbricks visible at about floor level?

yeah air bricks visible to exterior of the house on the chimney side seem to be below floor level.

Posted some more images here as I've now raked out to hard floor level in a few places with the claw of a hammer - approx 2" and then I get a concussive shock when I whack it.

That bit seems to be sound.

The self levelling patch was fairly sound until I gently lifted one end and was essentially lying on top and not adhered. Not sure if you can make out in the wider shot but there are obvious patches of spalling/flaking. I can brush that down to the harder floor with enough patience. The other areas are fairly solid and some areas will crumble with a little more effort.

Probably strip that pathetic paint job off the staircase while the bottom floor is uninhabitable. I was just looking at the big open space. I thought you're only buying 4 walls and a roof. I did kinda think assume a floor in that though.

 

[JohnD]

I'd be inclined to take up whatever you can lift with a club hammer and bolster.

It's not something I've done, but if you reach a firm, consolidated base, a few inches of good concrete will give you a floor.

I don't know what to do about the damp, though.

As you've found traces of old air bricks, I think there was probably persistent damp, and somebody tried to hide it by pouring concrete on top. There must be a source of the water.

A spring or underground stream is very unlikely, it's usually water escaping from a pipe or drain.