DIY Damp Proof Injection

[sawdust1]

And importantly if going down the Lime route to use breathable paint finishes !

 

[Woody2Shoes]

...The wall is really wet, the stair string against it has rotted and so have the skirting boards, I presume it has never had any kind of damp course in it.....

The thing is, in a building of this vintage, it's highly unlikely that any wall - internal or external - would be built without a dpc. And, as has already been mentioned, only slightly less unlikely that any dpc is not working substantially as well as it did on day one.

How old is the house? I don't think it's been mentioned?

Based on the description and photos in an earlier thread, somewhere between 1860 and 1935 give or take - probably Edwardian.

 

[Doug71]

How old is the house? I don't think it's been mentioned?

The main part of the house I would guess is 150 years old, an extension was added maybe 40 years ago.

Will add some more pictures later but here is one under the stairs, you can see how the damp has come out of the wall and soaked in to the plasterboard under the stairs and landing. This is an open space, it's not an under stair cupboard. This is the wall that was the old external wall but now internal at the bottom with a flat roof coming off it so still external at the top if that makes sense. The photo actually makes it look worse.

 

[owen]

That's definitely coming from above or through the wall not rising

 

[owen]

........ What about older places with solid stone walls? Is tanking acceptable then? ......

Again, the lime mortar in the walls, and lime plaster internally, is what moderates the moisture content of these buildings. The key thing is to get all the fundamentals right (ground levels, service penetrations, no sources of concentrated damp, ventilation, etc), and to keep the materials consistent (avoiding gypsum-based plasters, for instance). I currently have a project on the go in Butterton, in your neck of the woods, having done 4 or 5 projects in the Peak District previously, all old stone buildings. There are no damp issues in any of the finished projects, and not a single DPC or DPM anywhere. The current project has a stream running under the flags of the kitchen floor. A torrent really, that you can hear even when the kettle is boiling. This house will be dry when we've finished, and there'll be no plastic or gypsum anywhere in the building. Tanking is never the answer, and lime plaster always is.

Fair enough, the last one I did, a pub in the center of Longnor, the one wall had the main road passing the external wall of the pub, and the road height was in some places 4 foot higher than the internal ground floor. What would you do in that situation? Some kind of surface drainage on the roadside? We tanked it and it's not been a problem, but I would like to know the proper way to do it?

 

[MikeG.]

That's a nightmare situation. I think the ideal answer is to remove the build up from against the outside of the wall. If that isn't possible, then dig out, tank the outside if necessary (to about 6 inches above the finished ground level), and if it is essential that the ground level carry on as before all the way to the wall then try to get some soft stuff such as shingle in against the wall, with a drain at the bottom. Internally, lime plaster and lots of ventilation.

The thing which lime plaster with the correct paint does which gypsum plaster doesn't is absorb moisture when there is an excess, and then dissipate it slowly and generally (ie from a large area). Gypsum plaster concentrates it, as it is a barrier. Any internal barrier such as tanking (or gypsum plaster) will push the damp elsewhere, or it will just fail. Your internal tanking will eventually shove the damp to just above the line of the tanking, or to the adjacent internal walls, and what started off as a small issue will then look like the entire side of the house is soaking.

 

[owen]

I figured it would be something like that. The tanking is plastered over with renderlite which does absorb moisture and stop condensation against the plaster side of the tanking. The whole house has been tanked so in theory it should be ok but only time will tell, we only finished roughly two years ago so plenty of time for it to fail yet! Is lime plaster a lot more expensive/time consuming to apply/waiting for it to dry etc?

 

[toolsntat]

A nice old house I have the pleasure of working in always has a damp cellar. I love playing the house detective and have come to the conclusion that the great big granite boulders at the bottom of the cellar walls would have been the original damp course.
The key to this working , in my opinion, would have been an excavation around the outside of the cellar wall. Unfortunately over the years this has become filled in beyond the height of the boulders and is now plant borders or paths.
If they ever wanted a solution it would be interesting to see if re-excavation would be the answer?
Cheers Andy

 

[Suffolkboy]

Be cautious with Timberwise.

I moved with my employer about about 12ish years ago and they were asked to do a survey on my house.

They found all sorts of problems and put forward a hefty quote of a little over £12,000 for the work that needed doing including injecting the walls, fixing some dry rot etc etc.

My employer wouldn't touch the house needing that much work so I persuaded them to get a second opinion.

Two quotes later, one from an independent builder and another from another company and no dry rot was found, not was any damp.

The independent builder noted that the house had double glazing fitted and could do with some more ventilation as a result as there was some condensation. Did £300 worth of work for me which included some re-pointing on the brickwork outside.

As it happens the house has been sold again since then and I know the new owner... Guess what. Still no damp issues or dry rot.

Timberwise are Shysters.

 

[Doug71]

Timberwise are Shysters.

I won't be using them, I only really got them out as some of the timbers have rotted and I wasn't sure if it was wet rot or dry rot. They said wet rot so at least they didn't try selling me dry rot treatment as well!

The fact they recommended just injecting a dpc into a wall which clearly has damp problems about 6' above the ground did set the alarm bells ringing..

My 76 year old mother did say the salesman sorry I mean surveyor was a really nice chap :roll:

 

[Doug71]

Just an update on this.

Had a local independent firm out to look at the damp problems, the chap was smartly dressed in a suit, probably about 70 yrs old, was the owner of the business.

He spent over 2 hrs with me, went through everything in detail, explained all about hygroscopic salts etc. What made me chuckle was he said he would like a closer look at the flat roof, with that he climbed out of the bedroom window to check it all out, also checked the valleys, guttering etc while out there (he did struggle a bit getting back in through the window).

The outcome was he gave me a few pointers as to what he thought could be causing the problems none of which involved any work for his company. He said if I had these things done and the damp didn't clear up in a few months get back to him and he would come out for another look.

There was no charge. It's refreshing to know people like this are still around, so different to Timberwise and their opinion that the whole house needed injecting at a cost of £2k.