Damp damp and more damp

[Sian1890]

Battling the never ending damp in my 1890 property. I think I’ve figured out the damp issues on the external walls. The house was painted with “waterproof” paint which is trapping moisture and destroying my brickwork. The slate DPC is breached by the pavement out the front of the house completely covering it, I’m not sure the council will remove this, can I dig a trench myself? Out the back and sides of my property the ground level is about 12 inches too high, a previous owner has put in a chemical DPC 6 inches higher than the slate but that has completely failed and possibly made the damp issues worse, is my best option to dig out trenches? Also what on earth is the issue on the internal walls? Unfortunately I can’t take up the floor and see what’s going on, I know the floor is solid concrete but of course it has asbestos tiles covering it and I can’t start smashing those up. Why would the solid floor be getting damp and what is my best option if I’m not able to dig into it? My house has no air brick vents but I’m not sure if that would help considering it’s a solid floor. I’m unsure what kind of paint or plaster has been used internally.

 

[Ralph]

Dig a French drain around the house at a depth of about 12 inches lower than your finish floor inside your house. Fill the drain with granular drainage stone and your problem will be solved. Just make sure your french drain is draining away from the house down hill or into a soak pit. Its not a big job depending on ground conditions. Keep drain about 1 metre away from the outside of the house and as I say go right around it and finally into a soak pit or a fall away from the property. Drain does not need to be wide, 6 inch trench will do. You will need a mini digger, dumper, load of granular drainage stone (about 6 tonne) (20mm size), a shovel and knowledge of any services crossings / locations (Power, water, sewage. Broadband etc).

If you think about it logically, of course you have damp if the ground level outside is higher than your internal floor, it is similiar to a bath over flowing at its edges, the footpath outside being the bath and your hoise being the overflow sump. In my opinion its a complete lack of knowledge by the council and they probably should rectify the levels. You see this often as they resurface roads etc and continiously rise the road but the local properties remain at their original heights and thus have issues with moisture.

One simple rule to ALWAYS remember: Water will always flow downhill and water will always find a way. A river meanders but eventually gets to its destination.

 

[Sian1890]

Dig a French drain around the house at a depth of about 12 inches lower than your finish floor inside your house. Fill the drain with granular drainage stone and your problem will be solved. Just make sure your french drain is draining away from the house down hill or into a soak pit. Its not a big job depending on ground conditions. Keep drain about 1 metre away from the outside of the house and as I say go right around it and finally into a soak pit or a fall away from the property. Drain does not need to be wide, 6 inch trench will do. You will need a mini digger, dumper, load of granular drainage stone (about 6 tonne) (20mm size), a shovel and knowledge of any services crossings / locations (Power, water, sewage. Broadband etc).

If you think about it logically, of course you have damp if the ground level outside is higher than your internal floor, it is similiar to a bath over flowing at its edges, the footpath outside being the bath and your hoise being the overflow sump. In my opinion its a complete lack of knowledge by the council and they probably should rectify the levels. You see this often as they resurface roads etc and continiously rise the road but the local properties remain at their original heights and thus have issues with moisture.

One simple rule to ALWAYS remember: Water will always flow downhill and water will always find a way. A river meanders but eventually gets to its destination.

So the external ground level isn’t actually higher than my internal floor, but it is much higher than the DPC line. My house is on quite a steep slope, so a French drain would run into my neighbours property, not sure how to get around that one

 

[Ralph]

So if its higher than the DPC, of course thats the problem. A decent digger driver would get the fall correct so that any run off draining into, say, a purpose dug, soak pit (basically a hole filled with stone for soakage) wouldnt affect your neighbour. The Soak pit would be on your property and lower than your and neighbours affected levels. So basically your neighbour wouldnt be affected.

 

[Sian1890]

So if its higher than the DPC, of course thats the problem. A decent digger driver would get the fall correct so that any run off draining into, say, a purpose dug, soak pit (basically a hole filled with stone for soakage) wouldnt affect your neighbour. The Soak pit would be on your property and lower than your and neighbours affected levels. So basically your neighbour wouldnt be affected.

Ok fab! I’ll give it a go, thank you

 

[paulc]

A decent digger driver would get the fall correct so that any run off draining into, say, a purpose dug, soak pit (basically a hole filled with stone for soakage)

A stone filled pit is likely to get clogged up with detritus and roots over time. Might be five years, or it could be ten. I'm quite taken with using SUDS crates wrapped with a geotextile. Buried at a decent depth and capped with some concrete slabs, they will support a decent amount of weight. Also very quick to install once a suitable sized pit has been dug.
I used a pair of these crates when doing a soakaway for the garage roof. Had a guy with a minidigger for the day, and it didn't take long to dig the pit. Dropped the wrapped crates in, back filled with gravel and dropped a couple of 2" thick reinforced slabs on top. Being under a newly laid driveway, I needed the extra load capacity. Whilst the setup may get clogged with detritus eventually, I reckon it has a life span of at least 25 years before anything needs doing. Also have a debris interceptor on the pipe feeding in to it, so if the trap is cleaned out on a regular basis, it could last 100 years.