Damp walls rendered below soil and floor level

[Gothicsera]

We moved in to an old (circa 1860's) house a few years ago and have been slowly sorting out various damp issues around the place.

Right now we are trying to sort out some 'rising damp' along the front wall of the property. There is what appears to be a very old attempt at sorting it out, a gulley filled with gravel, although it doesn't drain to anywhere and it's now mostly soil rather than free draining gravel.

The bottom of the wall is wet inside, and the skirting and the carpet is damp too in various places.

The wall of the house is rendered, but the skirting around the bottom, under the drip rail has also been rendered below ground level, some of which bridges where the solid concrete floor is inside. You can see the state of that render in the photo below.

As best we can tell there is no damp course installed.

The picture below shows the trench we have emptied of gravel for a short distance. Down to the top of the foundation bricks. The red line is where the solid floor is inside, 8" below the outside ground level. You can see the top of the foundation too.

Am I right in thinking we would be better off chipping off all the render below the drip rail and installing a proper franch drain around this section of the house where the soil is above the internal floor level?

We do also need to give the render further up the walls some attention, but that's another issue!

Thanks in advance for any help!

 

[JohnD]

You can see the state of that render in the photo below.

no, I can't see any pics. Try Copy and Paste, or use the "upload a file" button

Am I right in thinking we would be better off chipping off all the render below the drip rail and installing a proper franch drain around this section of the house where the soil is above the internal floor level?

very probably. Try to identify where ground level used to be when the house was built. Depending on quality and location of house, there might be a damp course, possibly slate, lead, or engineering bricks. If you have solid floors, try to decide if they are original, or were put in to replace wooden floors that had rotted due to uncorrected damp. You can line the trench with landscape fabric to prevent mud washing in. Clean cobbles or pebbles do not support "rising damp" through capillarity as they are do not have small pores, with no fine material, sand or mud.

If you can expose a foot or so of clean bare brickwork on both sides of the wall, water can evaporate off, and will not travel by capillarity, so the wall can dry out. This is more easily eachieved when there is a ventilated void under the floor, rather than a solid one like you have.

While you have the trench open, look for any sources of water. In a house this age there will typically be cracked, broken and leaking downpipes, soilpipes, gullies and drains. The water supply pipe is also likely to be leaking. There may be spillage from gutters, which may be blocked or rusted through.

Below ground level, lime mortar is likely to have washed away near leaks. You can hose the mud out of the joints and repack with mortar. Cement mortar is not usually suitable for old houses, but below ground I think it is OK because there is no evaporation or "breathing" taking place.

 

[Gothicsera]

no, I can't see any pics. Try Copy and Paste, or use the "upload a file" button



very probably. Try to identify where ground level used to be when the house was built. Depending on quality and location of house, there might be a damp course, possibly slate, lead, or engineering bricks. If you have solid floors, try to decide if they are original, or were put in to replace wooden flo9ors that had rotted due to uncorrected damp.

While you have the trench open, look for any sources of water. In a house this age there will typically be cracked, broken and leaking downpipes, soilpipes, gullies and drains. The water supply pipe is also likely to be leaking. There may be spillage from gutters, which may be blocked or rusted through.

Thanks @JohnD. Odd that you can't see the photos, they are hosted on Flickr, try this:

https://www.flickr.com/photos/184840581@N07/51837098957/

The house is located in Fenland, on the Norfolk/Cambridgeshire border, not far from March.

The mains water supply for the house comes in from the back of the house and is on blue poly pipe. The opposite side of the house to this. The front of the house where this issue is is around 6' from the road, which is about the same level as the soil level.

We also replaced the guttering along the front of the house last year and it's working well, no leaks. We originally thought this was the major contributor but its not made much difference to this area, althpugh has helped elsewhere. The soakaway for the guttering is at the opposite end of the house and we don't have any damp issues there.

 

[JohnD]

Try Copy and Paste, or use the "upload a file" button

 

[Gothicsera]

Hopefully this will work

 

[JohnD]

Are there no downpipes or gullies at the side of the house that is damp?

 

[Gothicsera]

Are there no downpipes or gullies at the side of the house that is damp?

The damp is confined to one end of the house. The opposite end to where the downpipe is.

 

[JohnD]

yes, I can see those pics. The render needs to come off (it looks like it's coming off on its own) and there has probably been water collecting behind it. It looks like it might have been painted black with bituminous paint in an unsuccessful attempt to keep water out. The brickwork looks badly perished, possibly through freezing when wet.

If you're putting in a French Drain, make it deep enough, or lead it away from the house, with a fall, and give it a new soakaway.

 

[JohnD]

sometimes people build a retaining wall, a foot or two from the house, to protect the trench filled with cobbles. It can look rather attractive, and will prevent soil running into the drain.

p.s.

I think I can see the beginnings of footings. They will be OK if you don't undermine them or dig deeper, but I'd certainly pack mortar into the joints to reduce the risk of movement. work along, digging out and repairing in strips of a metre at a time, or so. Line your trench to prevent water getting underneath.

 

[Gothicsera]

yes, I can see those pics. The render needs to come off (it looks like it's coming off on its own) and there has probably been water collecting behind it. It looks like it might have been painted black with bituminous paint in an unsuccessful attempt to keep water out. The brickwork looks badly perished, possibly through freezing when wet.

If you're putting in a French Drain, make it deep enough, or lead it away from the house, with a fall, and give it a new soakaway.

sometimes people build a retaining wall, a foot or two from the house, to protect the trench filled with cobbles. It can look rather attractive, and will prevent soil running into the drain.

p.s.

I think I can see the beginnings of footings. They will be OK if you don't undermine them or dig deeper, but I'd certainly pack mortar into the joints to reduce the risk of movement. work along, digging out and repairing in strips of a metre at a time, or so. Line your trench to prevent water getting underneath.

Thanks John. It's going to be a long project this one I think.

The render below the soil is coming off in places. The brick behind isn't too bad, considering, but isn't perfect.

I'll chip the render off and repair the mortar a section at a time. It's all lime mortar so will need to get some supplies in. We only dug down to the top of the first foundation brick, which is one course under the internal floor level. The trench was all loose gravel and soil to that level.