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Damp Kitchen Wall - Need a little advice

Posted: Mon Sep 15, 2008 3:48 pm
by exeterphil
Over the past week I've ripped out the horrible old kitchen, and this weekend, taken all the old knackered plaster back to bare brick. The kitchen wall to the garden (see photos) showed signs of damp, and when I hacked off the plaster, revealed some kind of old ribbed bitumen sheeting pinned all the way across the external wall and 1 metre along each adjoining walls. (The outside of this wall rarely gets the full sun, so tends to be a damp spot and often takes a long time to dry out after a lot of rain).

I'm assuming I should inject a modern type of chemical damp proof... and re-tank the outside of the wall.

What I'm struggling to know is:
1. Which injected chemical should I be looking at (so far have read about 'Dryzone')
2. Should I go over board tank the internal brickwork prior to plastering?
3. How soon after application can we replaster?
- (Currently have no downstairs water, cooker, or washing machine)

I welcome any other comments and suggestions I should investigate...


PS: Spot what some idiot did below the side window... :wtf:


Posted: Mon Sep 15, 2008 4:10 pm
by ultimatehandyman
It looks like you are getting penetrating damp rather than
Rising damp.

Or is the damp only a couple of feet above the floor level?

Is the ground outside higher or lower than the kitchen walls.

Is the outside of the kitchen rendered and if so is it in good condition?

Tanking is normally a very expensive option.

If it is Rising damp then the injection creme should work, once it has dried out I would give it a skim of render mixed 1 sand to 5 plastering sand with integral waterproofer mixed in and then I would dryline it.

Posted: Mon Sep 15, 2008 4:46 pm
by exeterphil
Below is a shot of the outside wall... (Taken 1 day since heavy rain fall).

The kitchen floor is about 1 course of bricks higher than the outside ground level. The concrete slopes towards the drain, so surface run off disappears pretty quick, only remains touch damp as its such a sheltered spot. The wall with the plant pot you see is the height of the garden (about 3ft up).

The far corner is the wettest part of the wall. On the inside the damp appears to be restricted to a couple of feet above floor level and only really obvious very low down and in the right corner. No obvious signs of damp in any of the other walls


Posted: Mon Sep 15, 2008 6:09 pm
by dewaltdisney
It looks to me like there is a mixture of brickwork here. The lower courses are a queens bond, a solid wall construction which would allow damp penetration from splashing and it would take a while to dry out. Higher up the wall there are different brick patterns which might show that a cavity type construction was done when a new window was put in? Rising damp uses the porosity of the bricks to suck up moisture and it would seem that this is not the case as the damp s localised.

I would suggest that the problem is this outside drainage area and I think that you should consider rendering and aqua coating as a first step.


Posted: Tue Sep 16, 2008 5:49 am
by Sir Harry
I disagree in part.

From what my old eyesight can make out the wall has occasional headers its full height and appears to be of solid construction.

From the external photo I would guess that the original DPC is sited 1 course above the concrete, yet the dampness is clearly evident at least 3 courses above.

I would suggest replacing like for like. Inject Dryzone or Ultracure damp proof cream in the bed joint 2 courses above external ground level (1 above internal floors) and line the wall with a dimpled slimline mesh membrane that allows direct plaster application.

This will counter both rising and penetrating damp and, more importantlly allow the wall to breathe and the moisture to evaporate.

Posted: Tue Sep 16, 2008 6:54 am
by thescruff
looking at the last photo, its obvious the area is underwater/flooded for most of the time, I would expect the wall the have problems.

I think if you sort the outside out, the inside will sort itself.

Dig the concrete out, lower the level about 20cm and fill with pea gravel, sort the outside tap and the rainwater pipe out.

Posted: Tue Sep 16, 2008 8:41 am
by exeterphil
Thanks for the replies, all very interesting to read, but the difference of opinions has got me scratching my head with confusion. I guess its like many things, with a number of different solutions to solve the same problem. And suppose the more I do to the wall the more likely it will last?

That said, I'm really not sure about lowering the outside path... and had not heard of using a dimpled mesh membrane... but from this website its claimed to be affective in very damp areas (although quite expensive).

Either way I need to sort something out by this weekend, as we can't live without a kitchen and washing machine for too long.

I've read and read both Dryzone and Ultracure's literature but can't seem to find out how long I need to leave the walls after injecting before replastering? (They both only indicate a minimum of 1 month before redecorating).


Posted: Tue Sep 16, 2008 9:08 am
by Sir Harry
In theory a wall takes 1 month per inch thickness to dry ot [9" wall = 9 months]. During this drying period hygroscopic ground salts that have been deposited in the wall may migrate to the wall surfaces. Therefore the longer you leave the wall to dry the less likely you will have a problem with the new plaster.

If you need to plaster right away a dimpled waterproof membrane system allows the plaster to be isolated from the wall surface, thus alleviating further problems during and after the drying out process.

You should shop around for a slimline mesh membrane as you will find it much cheaper than on 'DIY Doctor' affiliated site that you have provided a link to!!

Posted: Tue Sep 16, 2008 7:35 pm
by exeterphil
Harry - Oops - sorry, didn't realise that site was related to DIY Doc. Was just the first site I found relating to the product you mentioned.

Anyway.. it sounds like you have experience of dealing with mesh membranes in this capacity. And from what I've read up on so far, sounds like part of a good viable solution to our problem. Especially the appeal of plastering directly onto the material, without having to wait for the wall to dry out for months (although waiting a little while at least sounds sensible).

Question 1: Sorry if this sounds stupid but... when it comes to fixing pipe work and kitchen cabinets etc. to that wall, should I be thinking about any special screw fixings or does it not matter if the membrane is punctured for a small number screws?

Question 2: Just so I'm clear, were you suggesting I inject damp proof cream externally, internally or both?

Many thanks

Posted: Wed Sep 17, 2008 8:04 am
by Sir Harry
Two very apt questions Phil

Answer 1: If you are using a mesh membrane you should only use adhesives to attach articles to the wall. If you need a mechanical attachment
you should use a conventional 'dimpled water proof membrane' and dry lining system. This waterproof membrane uses fixings having an appeture in the heads, which house the screws when fitting the battens. You can then use any dry wall fixings for attaching articles to the wall. See ... oofing.htm

Answer 2: If the wall is solid you can inject a BBA approved damp proofing cream from either side as you are in effect applying a series of cream cylinders along the wall for its full thickness. If the wall turns out to be a cavity wall then you should trat each leaf separately from its face side. See ... oofing.htm

I hope this helps.

Posted: Wed Sep 17, 2008 9:16 am
by exeterphil
aha... then I shall investigate...
Thanks for your help, much appreciated.

Will run all this by my plasterer, and begin to prep the walls ready for DPC treatment.


PS: One final question
The adjoining wall in the right corner.. I presume I'll only need to damp proof a meter or so along.. the rest of the wall is dry. (The wall on the other side is no long an external wall, and has long since dried out).

Posted: Wed Sep 17, 2008 10:19 am
by Sir Harry
Absolutely. No need to spend out on damp proofing a wall that you know to be dry.

Posted: Wed Sep 17, 2008 10:49 am
by thescruff
The other wall would dry out as well if you get rid of the lake outside

Posted: Wed Sep 17, 2008 11:48 am
by exeterphil
Due to some added complications and the cost involved, lowering the path isn't a viable option available at this time. But you are totally right. - The ducks haven't found it yet, but I've a stale loaf handy just in case.

Posted: Wed Sep 17, 2008 12:26 pm
by thescruff
It would cost virtually nothing to sort the drain pipe, and a couple of hours work.