Damp Wall - Under Floor Level

[hamd01]

Part of our house is a joining a public highway (b road). However the road is around 5 feet above what is the floor inside the house. The property is around 200 years old.

The wall which ajoins the road, is constantly damp. It isnt dripping, but its damp to the touch. However, its only damp on the bottom 3 feet or so, not the full height.

The wall is around 400mm thich, with a cavity, which has rubble infilling.

Once I get the existing project out the way, I plan to stud the wall,with a thick membrain attached to the wall. However, I am concious that this might leave the dampness nowhere to evaporate, build up, and then cause problems. Ive never seen damp drip down the wall, its just damp to touch....but I imagine if it were to build up, that could result in problems.

Can anyone suggest a solution to tank it, that doesnt risk build up?

 

[DAZB]

You don't mention if you have any airbricks but with any tanking work the key to it all working properly is ventilation and so you would built in several airbricks on that wall to the outside and then once tanking, studwork, insulation and plasterboards are fitted you have a well ventilated void between the existing wall and the new inner wall which will help evaporate dampness.

 

[hamd01]

You don't mention if you have any airbricks but with any tanking work the key to it all working properly is ventilation and so you would built in several airbricks on that wall to the outside and then once tanking, studwork, insulation and plasterboards are fitted you have a well ventilated void between the existing wall and the new inner wall which will help evaporate dampness.

Thank you that makes sense.

Would there be an alternative to air-bricks? The wall is a good 40cm thick and rubble in-filled...so an air brick wouldnt be viable.

Could for example, vents be installed at the top of the wall?

 

[ree]

OP,
Is the building listed?
If you only have the bottom three feet showing damp then what a recom for 200 yrs old masonry and rubble walls.
Pics of the outside at ground/road level might show a way to use air bricks but venting more than one a/b into the living space could rob much heat.
Some methods of Tanking could also drive the dampness up the wall.

Perhaps hack off all plaster(?) back to masonry & use a render of 3:1 sand & NH lime
This might work for, say, 20yrs & then need re-doing.
I presume that your floors are solid - when were the floors installed?

 

[hamd01]

OP,
Is the building listed?
If you only have the bottom three feet showing damp then what a recom for 200 yrs old masonry and rubble walls.
Pics of the outside at ground/road level might show a way to use air bricks but venting more than one a/b into the living space could rob much heat.
Some methods of Tanking could also drive the dampness up the wall.

Perhaps hack off all plaster(?) back to masonry & use a render of 3:1 sand & NH lime
This might work for, say, 20yrs & then need re-doing.
I presume that your floors are solid - when were the floors installed?

No the building isnt listed (thankfully).

After some further investigatoion today, the wall does actually already have what your decribe a sand and lime mix). I always wondered why it only went a few feet up the wall!!

The floors are solid concrete, but i dont know when....im guessing 1980s.

My current train of thought;

Add a membrain between the studs and wall around half way up the wall....so well above the damp line.... but not fastened tightly to the wall, thus enabling air flow, but most importantly protecting the base studs and wall studs from any damp.

As an additional method, install 2 vents into the ceiling, which will have a duct into the cavity, with an attached fan, to extract and encourage air-flow. I might put a humidity sensory in there which can automatically switch the fans on.

 

[ree]

OP,
Have you considered contacting an Independent Damp Surveyor to come & have a look? Why not Email one and discuss your case, and possible survey costs?

A 1980's solid floor should have a membrane (DPM) under the concrete.
If you install elec devices or appliances then Heat/Smoke alarms are a must.