A permanent damp solution?

The history of my drive way next to the house has been a voyage of discovery thanks to my neighbour. I live at an end terrace and there is a shared driveway between it and next door. It is a concrete drive that butts right up against both houses.

Now this drive way was originally two garden paths and a stone wall, but it was converted to a driveway to open up access to the back. This is a fine thing, but it has been through a few changes over the years. I have been discovering these and the also living with some of the consequences.

The paths were not taken up, just tarmac put over the top. Several years later concrete was put directly onto the tarmac. Of course this should not be done as the tarmac disintegrates under the concrete, but more important for me was that the height of the roadway was now above the level of the floor in the house! No wonder we have damp in that wall.

So I have had to cut out the roadway using a disc cutter (a diamond blade worked a treat) to get a ‘straight’ edge. I marked out a line with chalk, but the dust from the cutter obscured this quite badly so care needs to be taken when doing this.

My attempt at a straight cut to make the initial trench at the side of the house

I then set about smashing up the concrete with the breaker I had hired. Fair Dos the breaker was great. However I discovered the tarmac. So my first pass with the cutter only got me through the concrete. The tarmac though had failed and so was quite easy to remove. I did though have to use the breaker again. After a third round of breaking and shovelling (well using a trowel) I eventually got to a difference of between 20cm and 10cm between the floor level and the outside ground. So I now have a 15cm drain between the road and the house.

The concrete road broke up nicely with the breaker

The work involved taking off the render off of the walls from this low level. Knocking this render off was really satisfying. You could also feel the walls breathing a great sigh of relief as the old render and road way were removed and bricks and stone exposed (with their sodden lime mortar!) Surprisingly the wall from the door back turned out to be a brick cavity wall! This is an 1880’s house with solid stone walls at the front and back. Finding a brick wall was therefore quite strange.

The damp was in evidence when the road level had been lowered down

I then repaired the road way using a concrete mix to shore up the edges. I did this as the road despite being a good 5cm thick could have failed along the edge. I also then did a lime and cement mix for the base of the drain. This will allow any rainwater to flow down to the road and away from the house. I angled the drain so that any water is kept away from the wall. Using a lime mix was there to ensure that there was some breathability in the structure so that it was not just trapping ground water in the area next to the house. To give an extra bit of strength I used some lime tolerant mesh in the structure as this should give it a bit of extra stability and strength. The lime will also help ensure that there is no cracking since it can flex a bit unlike a pure cement mix.

The new trench was lined with mesh and then thinly covered with a lime rich cement
This shows the re-rendered wall, the exposed lower wall and the new lined trench

So the job looks OK now and the water is draining away nicely. Only time will tell if this is the long term solution to the damp in the wall, but already I can see the walls drying to the outside. Fingers crossed they will continue to dry now that they are not constantly damp from being under road level.