Tanking Victorian House Footings

[ToastyToes]

In some areas of my house under the suspended floor (especially in the corners), is rather damp.

It doesn't go above the DPC which is great, but the old joists became rotten so we replaced them, and opened up more ventilation bricks to prevent is happening again.

However, the kitchen has a particularly damp corner which doesn't get much ventilation as both sides to it are concrete slabs from new extensions.

I'm planning to 'tank' the footings and ground on the damp kitchen corner to prevent problems in the future.

Is it okay to tank only a section of the footings and ground or am I just going to move the damp further into the room?

 

[JohnD]

No, yes

You say there is a damp area in the kitchen.

Does this kitchen contain water pipes and drains?

 

[ToastyToes]

No, yes

You say there is a damp area in the kitchen.

Does this kitchen contain water pipes and drains?

Not for the last 12 months.
However on the outside of the house diagonal to the damp corner is the soil stack. I plan to dig it up soon to see if that is causing the issue but wanted to get the floor down sooner then digging the garden.

 

[JohnD]

If there's a leak in the ground or under the floor (very common) the sooner you find and fix it, the better.

Damp is water, and it must be coming from somewhere.

Clay gullies and bends are usually broken.

 

[Deleted member 174758]

If you tank walls and the water is coming from the water table you can end up just pushing the water else where. I've had that exact same scenario on a previous house which had rubble infill stone walls

 

[bobasd]

if you have damp "especially in the corners" of the kitchen suspended floor an youve already replaced the joists an instaled air bricks then youve got to check the ground level outside the kitchen an do the new air bricks provide a strong through ventilation in the floor void.

post photos of the damp void areas
an stay away from any kind of tankin

is the floor now boarded an are ther units in the kitchen?

 

[ToastyToes]

@JohnD @JobAndKnock @bobasd

It seems to be worse after a spell of wet weather. We dug the kitchen up to reinstate the suspended floor after the old owner filled it with soil while doing the side extension. I can only imagine the same has been done to the side extensions floor (on the right side).

Photos below. Rather dry at the moment...

Last picture shows why I can't get airbricks in the area due to it being surrounded by concrete floors. We've added two air bricks to the 3m stretch of wall on the left side (out of the shot)

 

[JohnD]

The dampness has the appearance of coming through the footings of that wall, not rising from the ground through the oversite, so I think the source is on the other side of the wall.

It's often a leaking pipe or drain, sometimes a forgotten one. But if you think it is rain related, look for gullies or outside paving that slopes towards the house.

P.s.

You might consider using timber preservative in those damp areas.

 

[ToastyToes]

The dampness has the appearance of coming through the footings of that wall, not rising from the ground through the oversite, so I think the source is on the other side of the wall.

It's often a leaking pipe or drain, sometimes a forgotten one. But if you think it is rain related, look for gullies or outside paving that slopes towards the house.

P.s.

You might consider using timber preservative in those damp areas.

Thanks. The area is rather dry. Normally the corner is more damp and the oversite damp about 1ft from each edge.

The timbers were purchased treated and have since had another coat of treatment for rot.

Do you think tanking the footings and 2ft of oversite would help prevent it coming through, at least until I dig the ground outside and ensure no leaks are there?

 

[JohnD]

Tanking will not stop the water, it will just come out somewhere else.

 

[ToastyToes]

Tanking will not stop the water, it will just come out somewhere else.

Thanks for your input