damp wall - recommendations

[mickthetree]

Afternoon all

I've been asking over on another forum, but wondered if anyone here had any suggestions.

Our house is end terrace, 1890s and with a raised ground level against one external wall.

We tried selling the house last year and one of the surveys noted a "slightly raised moisture level" in this wall. He said it was nothing to worry about and has probably been like it since it was built. The wall is four brick thick up to the ground level, then reduces to two brick thick. However, despite his recommendations it scared a seller off after he had a quote from a national damp specialist firm who quoted him 6k+ to fix.

My misses wants this sorted before we try and sell the house again.

I've been looking at fancy membranes that can be plastered over. Reckon I could get the whole job done for sub £500.

I'm told the best option would be to dig a trench on the other side of the wall, paint the wall with a bitumen and fill with gravel. This maybe a bit cheaper, but the ground forms part of a very old graveyard and I don't think I'd get permission from the church.

Anyone dealt with this sort of situation and have any recommendations?

 

[RogerS]

When you say 'raised ground level' do you mean higher than where it reduces from four to two bricks wide?

I'm guessing that they might have built the house with a slate damp proof course at the junction between four/two bricks. So if the outside soil level is higher than this junction then it defeats the object of the slate. Reducing the level of the soil to below the junction is a good start.

 

[mickthetree]

Sorry if I wasn't clear Roger. The wall is four bricks thick up to and just above the ground level. It then reduces to two brick thick above the ground level and to the roof.

The area in question is quite sheltered and does not get a lot of rain so the problem isn't too bad.

Don't really want to hide anything. Would rather get it sorted for good.

 

[treeturner123]

Mick, I assume that the wall is solid brick so therefore there will be some horizontal and vertical damp penetration. Digging a gap to backfill with gravel (a French Drain) would be a good start and provided you replaced some top soil over the last few cms I can not see that there would be any problem from the church yard. Also it will allow you to paint the briefly exposed wall.

However this will not deal with any damp rising UP the 4 brick thick section and I would suggest hat you remove the plaster, and use a vertical damp membrane internally as well.

By the way, an injection DPC would be of no use in this situation

Phil

 

[RogerS]

.....
By the way, an injection DPC would be of no use in this situation

Phil

Why not? That's what I'd get done and just along that wall.

At the end of the day, all that any potential purchaser wants to see is a bit of paper and a guarantee that the work has been done. You know and I know that that guarantee might not be worth very much but that is all the purchaser is interested in....that bit of paper. Mick could pay a bit extra and pay for an Indemnity Guarantee which gives an even more cosy feeling to the would-be purchaser.

 

[mickthetree]

Thanks for the suggestions. It all comes down to a potential buyer I suppose. The first one (chain fell through) didn't give a hoot. Second one thought it was the end of the world!.

Phil - Would you have a suggestion as to the height a membrane should go in this instance? floor to ceiling? or just to above the outside ground level?

Cheers

 

[Lons]

I would do the same as suggested by Roger and ask the same question as to why an injected DPC wouldn't work :?

I've completed several conversions with solid walls up to 600mm thick and had them injected by secialist companies with out problem. All of which satisfied the customers and building control officers and as said, with the relevant written guarantee.
As long as there is no damp rising through the floor, which has to be treated seperately, I don't see a problem.

Bob

 

[Wildman]

is it indeed a solid wall or is it a cavity wal, if a cavity the DPC is almost certainly breached by dust and rounble falling down the cavity over the years. opening the wall and raking it out will usually cure the problem, replace the bricks with a vent to allow air flow. An injected DPC in a cavity wall just bypasses the muck and what is probably a good existing DPC. 2 brick wide is almost certainly a cavity.

 

[Dusty]

My brother in law has a business doing damp proof injection and tanking , as Tree Turner has said , injection is off no use as it is there to stop rising damp by injecting the joints and masonary . it will create a vertical barrier but may not be 100% effective as the wall is so thick and it only works on the bricks you can inject , so the two outer coarses would be "sealed " but the internal bricks would still be damp / porous .

Your only real action is as has been said , to dig a french drain on the outside to prevent water from resting up against the wall but it will need somewhere to drain away too . The only 100% way to deal with it is to strip all the render and plaster off to a height of 1500 mm above the highest point of ground level ( ie outside level ) , as damp when blocked will rise when blocked at a lower level . you will need to complete the affected area and 1500mm past the effected area . There are many different tanking systems but the one we use is by a company called Sovereign . It has never failed me or him and we have used it on basements below ground level that were streaming . Then all the the render and plaster will need reinstating with recommended products . Doing it properly by a recommended installer should provide you with a ten year plus guarantee .

But what ever you do , do NOT use bitumen as it is rubbish .!!

Hope this helps , Sam

 

[RogerS]

My brother in law has a business doing damp proof injection and tanking , as Tree Turner has said , injection is off no use as it is there to stop rising damp by injecting the joints and masonary . it will create a vertical barrier but may not be 100% effective as the wall is so thick and it only works on the bricks you can inject , so the two outer coarses would be "sealed " but the internal bricks would still be damp / porous .

......Sam

Yes but I have been working on the assumption that the four brick width is effectively below ground. In other words forms the foundations for the wall. So the injection DPC would go at the bottom of the two brick part and so no problem.

We are in danger of sending Mick on a wild goose chase with talk of membranes etc. That all is messing about with internal replastering and redecorating etc. And for what? He is not going to live there if he sells the place. The damp seems to be marginal at best. So the easiest, simplest option is to whack an injection DPC .....cost £1k maybe? Piece of paper guaranteeing the work. Job done.

 

[Dusty]

Hi Roger , I do agree that it is alot of work for little reward , if you did inject it at the double thickness point you would need to be sure that it corresponds with the floor level inside , ideally the 1st brick above the floor at the most as otherwise you will be trapping the damp behind the skirting , so you would need to remove the skirting to do this , both skins would need to be done . in most cases we drill two or three 8mm or 10mm holes per brick ( depending on who's machine we use ) and we inject until you can visually see the fluid leech out of the brick and into the joint , injecting joints is pointless if done properly . All holes on the outside will need to be plugged to prevent water sitting in them and the freezing resulting in split bricks and spalding .

I know you will still get your certificate but some mortgage lenders will stipulate a survey and if there are problems then they require the owner to put the money up front for the works .

I didnt mean to come here and sound all knowledgeable , just trying to help as we have been back to correct others "work" but as they say there is many different ways to skin a cat .

kind regards Sam

 

[No skills]

I have virtualy the same problem at out house (also 1890's spookly!), damp proof specialist's solution was dry line the wall. True story, got the certificate.

 

[mickthetree]

I have virtualy the same problem at out house (also 1890's spookly!), damp proof specialist's solution was dry line the wall. True story, got the certificate.

Can I have their number? :wink: :wink:

 

[RogerS]

.....
I didnt mean to come here and sound all knowledgeable , just trying to help as we have been back to correct others "work" but as they say there is many different ways to skin a cat .

kind regards Sam

Hi Sam....didn't take your post in any other way other than helpful.

Rog

 

[No skills]

I have virtualy the same problem at out house (also 1890's spookly!), damp proof specialist's solution was dry line the wall. True story, got the certificate.

Can I have their number? :wink: :wink:

Cant imagine the cowboys will still be in business but I can look if you want?

 

[Dusty]

Cheers Roger , I must learn to use the smiley faces more as I just worry that what would normaly be a friendly toned conversation can be taken as sarcastic or condescending or arrogant remark .....note to self , must use smileys .

No-Skills , that is the sort of repair we have been back to correct , just a quick cover up . We went to one where they had duct taped polythene to the wall , then battened and boarded it with foil backed plaster board and skimmed . then added small vents in the skirting to allow ventilation in a hope it would not go mouldy .........which it did . you can dot & dab but not until the problem is cured other wise the damp will show through the Dot & Dab adhesive in patches .

Mick the Tree , I would for your own piece of mind , look on the net for manufacturers advice and get 3 quotes and ask them for a detailed brief of their intended methods and if there is anything fishy , dont bother . I will ask my B- inlaw what he charges per linear metre to give you a rough idea of what to expect .. just bare in mind we are Devon and Somerset based and I would not know what is charged for your area , but if it is only one wall double skin then its a 3 to 4 hour job max

Kind regards Sam

 

[mickthetree]

many thanks for all your suggestions guys. Truely appreciated!!

Thanks Sam, I'll do just that.

 

[mickthetree]

Morning all!

I've managed to get round the other side today and possibly found the issue.

There is water dripping off the gable end roof onto the soil pipe that runs horizontaly (well on a small slope) along the bottom of that wall.

Where it hits the soil pipe it is splashing onto the wall and causing two damp patches, exactly in line with the damp patches on the otherside (albeit higer).

Is there any reason why I couldn't put a gutter on the gable end wall? This is the only way I can see of stopping the dripping.

 

[Phil Pascoe]

There's probably no reason at all why you shouldn't put up guttering. If you've any pipe work whatsoever on a house of this age, check that it's not attached with wooden plugs - water will track through them. I replaced a ceiling and found a water mark on a joist (approx 2' into the room) :it was no longer wet, but it made me think. When I looked outside I realised that I had moved a downpipe a couple of years before, and had filled in a hole where a large wooden peg had been. The peg was rotten and had been about 2' above joist height. The joist had dried out since I had done the repair.