Render damp external wall

[Robertspaw]

Hi
I have a large brick retaining wall between my and my neighbours garden. My neighbors garden is about 1m higher than ours and we have painted the wall but there are signs of damp coming through the wall so we want a permanent solution. We'd love to have the wall rendered but will this work and will it be a long term solution if there remains water seeping through the wall? Thanks in advance

 

[KenGMac]

Robertspaw, good evening.

Short answer to your question is that is if water is seeping through the retaining wall below the level of your neighbours garden then, sorry, the proposed render will not assist your aesthetic problem of water staining / seepage.

Rational for my reply is that by now the area of the retaining wall below the level of your neighbours garden will in effect be saturated, as such the sheer "Head of water" will simply blow off the render, not to mention if there is a very cold snap and the accumulating water behind the render freezes and expands when thawing.

I am assuming that the wall is not a recent addition, in that it has stood for many years?

I n the glorious bright light of the famous "hindsight" the area of the wall below your neighbours land should have been in some way waterproofed but if there is no waterproofing then water will get at the wall and slowly percolate into it.

At the same time [again in hindsight ] there should be a so called french drain and drain pipe which if constructed correctly will reduce the load of water damming up against the wall.

Question? are there any drain pipes sticking through the wall on your side of the wall below the neighbours ground level? If not then have a word with your neighbour about you drilling some weep holes through the wall to release the build up of water that will be occurring on your neighbours side of the wall, this will to a certain extent releave the overall water pressure trying to force its way through the wall.

Ken.

 

[vinn]

Render will do nothing for your wall or your issues.
Neither, as you have probably discovered, will paint - masonry paint or not.
You would best just live with it - certainly the cheapest option.

 

[John D v2.0]

I'm not sure you should be waterproofing the wall even if it were possible, if the flow of groundwater is down hill imagine the weight of water - the wall would collapse. Really you need to make sure the water can drain safely through, if you were starting from scratch you could fill the high side of the wall with some kind of drain fill gravel and land drain pipes and take it somewhere unobtrusive at the base of the wall, but as it is you might have to just deal with it once it comes through.

 

[KenGMac]

John D v2.0, good evening.

Sorry I disagree insofar that a well designed new [There is the difference in the on-going discussion here?]retaining wall can be made water tight.
1/. The ground facing side of the wall can be made water proof with the use of say? Bituthene? X 2 layers, or as a poor second painted on liquid DPM
2/. Install a "French Drain" with a perforated plastic pipe at the lower area of this drain, the perforated pipe taken to a suitable sump then into a surface drain.
3/. The "French Drain" should be surrounded on 3 sides with Geotextile, and that material wrapped over the top of the "French Drain"
4/. At regular intervals over the length of the wall a weep hole [Pipe] can be inserted so that any " Ground Water Over Pressure" can be relieved by the simple action of the build up of water escaping Via these pipes, hence in my OP I asked if there were any pipes poking through the wall??

As to what the O/P - Robertspaw - can do is limited, and probably the only thing is with the agreement of the neighbour, given the "Party Wall Act" Etc, Etc. [thank goodness it does not apply where I live] is to drill a series of 40.MM holes right though the wall in an effort to release the worst effects of water build up?, then install a plastic pipe

As Vinn has commented rendering is ineffectual and a total waste of money.

Why? because the wall has no DPM applied to the uphill surface of the wall, and there is no way of installing it in that position. followed by no Geotextile to stop the fine particles [Mud] from blocking the drain holes.

Ken.

 

[John D v2.0]

Ken yeah I class watertight as not having any pipes to relieve pressure! So sounds like we agree basicallyneed some way to release the water, ideally somewhere unobtrusive.