Plastering Damp Walls!!

Edz · Post by **Edz** » Tue Oct 10, 2006 11:44 am

Hi y'all. Plastering damp walls I am told is a waste of time as it won't cure the problem.

I've bought an old house with damp in the walls in some odd places such as occassional "blobs" of damp half way up an interior wall. It can't be rising damp as it's not joined to the floor and it can't be penetration of rain as it's not an outside wall.

There is no dpc fitted but then again I have heard so much said against them that I'm left feeling it's a waste of time and money anyhow.

So, I intend to strip all this plaster off of course but what then? Plaster up and hope for the best? Are there any specialist products/techniques I should use? Grateful of any advice. Cheers.

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Post by **ultimatehandyman** » Tue Oct 10, 2006 11:52 am

Hi,

welcome to the forum,

Instead of using backing plaster such as bonding or browning you can render it with sand and cement+ integral waterproofer.

Mix the sand and cement to a ratio of about 5 sand to 1 cement and add some integral waterproofer to the mix, when you get close to the desired thickness that you require minus 5mm, scratch the coat and then apply a coat of finish plaster.

If you allow the render to go off fully before applying the skim coat it would be a good idea to pva the the scratch coat first.

I don't know what you have heard about Damp proof courses but I have had electro osmosis
installed in a few houses and it is great

Edz · Post by **Edz** » Tue Oct 10, 2006 12:49 pm

Wow. That's great info, and thanks for getting back to me so quickly. Funnily enough I have come across some "cement" like plaster upstairs on the inside wall of an end gable (now built off so longer a problem).

I have scraped away all of the old "regular" plaster but this other stuff is rock hard so I thought I'd leave it on and run bonding plaster to fill in the blanks, then skim. Does that make sense?

Also, what make of integral waterproofer would you recommend?

I'll check up on this osmosis thing and see what it is all about. What I have done on the one old wall that is still an outside wall is to dig a French Drain which I have filled with pea gravel. I thought that might help.

Post by **ultimatehandyman** » Wed Oct 11, 2006 11:21 am

The walls that have the patches of Damp on are not dry lined with plasterboard by any chance are they? If they are it could be damp that is soaking through the adhesive ( if they have been direct bonded).

As for the integral waterproofer I just purchased some from screwfix last time, but there are plenty of makes available that will do the trick. I think Feb and everbuild will make it.

Edz · Post by **Edz** » Thu Oct 12, 2006 12:52 pm

Thanks for that. I'll check out Screwfix.

BTW .. the walls are not dry lined.

Jasper · Post by **Jasper** » Sat Oct 21, 2006 1:31 pm

If the damp patch is not on an outside wall you need to be thinking about the cause and not just covering it up!

Have you considered you may have a slight leak from a Gutter/downpipe or internal plumbing?