Alternative to tanking

[sheikyerbouti]

Hi all,

My garage and stable wall are currently showing signs of water ingress at the base. This is caused by the usual culprit - the ground level on the outside is around 5 brick courses higher than my floor. Unfortunately this land is part of a car lot and, as such not owned by me. There is also no guttering on the garage at the moment.

I've had someone out to look at the problem, and they have recommended digging a short trench next to the wall, and coating of some chemical tanking product on the bricks/mortar to seal it, then backfill. I'm not overly keen on this method.

I have looked in to things and come up with a solution - see screenshots below. The first pic is how things are now, the second has my solution. I wondered what people thought of this as a longer term fix?

 

[sheikyerbouti]

Just to add - here is a picture of the brickwork on the inside of the garage - the external ground level is self explanatory!

http://img818.imageshack.us/img818/3494/innergarage2.jpg

 

[middi]

It all depends how far you want to go to eliminate the damp . Short of placing a dpm membrane against the outer wall and lapped into a dpc membrane which itself is lapped under a floor membrane anything else wil be a compromise, The best and most effective option,under the circumstances, would be to dig away the soil against the wall to just below garage floor level, build a retaining wall up to exterior floor level and leave a 150 mm gap between retaining wall and garage wall, cover the gap with removable grids, lay some shingle at the bottom of the trench to just below gar.floor level and make provision for surface water to run away from the trench. This would require permission from the land owners.

Of course anything you can do apart from the existing set up, including as you describe in you photo, will be better than nothing, As to how effective this would be it depends on the natural rate of drainage below the gravel, a fast removal of surface water will depend on it otherwise the gravel itself could become saturated with water and therefore defeat the objective.

Middi

 

[MdB]

With a drainage pipe at the bottom of your gravel which discharges somewhere sensible then I can see your idea working. Without any method for water to escape, the moisture level will quickly be the same on both sides of the DPM.

A previous owner here tried to do something similar (though it was dirt on both sides of the DPM). It didn't work as the moisture just went underneath leaving us with a damp kitchen wall.

 

[Zebra]

Does your wall have a dpc? I assume not. I have had a similar problem with my house, and have created a solution very much along the lines of what middi describes, a retaining wall on the outside (it's the churchyard on the other side so similarly not my land) with around a 150mm gap, but I do still get damp internally. I won't say it isn't an improvement but it hasn't solved the problem entirely. I don't know what will to be honest, or whether the wall will ever be dry. From the outside it's wetter down inside the gully than higher up, and from the inside there is still damp up to external ground level. Must be sucking it up from the ground, as I have very soft porous bricks.
Sorry, not an answer to your question at all, just commiserating I suppose, and hoping there is a magic answer....

 

[MatthewC]

I don't know how old your garage is, but on a modern garage with the same problem, I used Thompson Weatherseal on both sides (in substantial quantities) to good effect, after digging down a foot or so on the outside. The garage was still dry when I sold it 10 years later.

Of course, if it's an old building then I wouldn't want to be seen suggesting such a thing...