Damp in rendered single brick wall

[loverly9]

Hi,
I wonder if anyone is able to let me know my options for making good the wall at the end of my kitchen extension. It would really help.

Our house is Victorian and probably the original kitchen has been extended by knocking through into a coal shed.

The walls at the sides of the extension and the original kitchen look thick enough to be double brick or breeze block, but not thick enough for cavity. The wall at the end of the extension has double doors and is no thicker than the width of a single brick.
The whole house, including the kitchen and extension has been rendered top to bottom. There is no sign of an injected damp proof course in the kitchen or kitchen extension walls.
The wall at the end of the extension has alot of damp at the bottom. Paint doesn't stick to this wall properly. The kitchen worktop goes right to the wall on one side and on the other the gap is only just big enough for our fridge.

What can we do about this? What is our cheapest option?

 

[ajrobb]

Gypliner and foil-backed plasterboard could be used to line solid masonry external walls. This should be adequate to prevent condensation (likely problem in a kitchen) and penetrating damp (unlikely with modern render and paint).

If your Local Authority Building Control get wind that you are re-doing more than 25% of a wall, they could insist you bring insulation up to modern regulations. You could stick Kingspan K18 to the Gypliner frame or treated timber batons or use Celotex against the brick then non-treated batons and plasterboard. Batons on Celotex give a handy service cavity.

 

[loverly9]

Thanks ajobb,
So your first suggestion is to do with putting an internal lining on the wall? Thats right isn't it.
Also how thin can the lining be? - i think if i loose more than 2 cm i'll loose space for appliances

So with this option I need to:
* cut and fit the lining
* redecorate internally
* shuffle units in the kitchen
* pray that the council don't find out!

Its interesting & perhaps reassuring that you think that the problem is likely just condensation
Though I never realised that this could trigger problems with the council, its bad enough that whoever built the extention didn't get building regs and we are already praying that the council will continue to think its been there too long to bother with.

 

[loverly9]

ajobb, your second suggestion is to do with creating a cavity on the inside, such that the council won't complain.

So with this option I need to:
* cut and fit the lining
* create a wooden frame and mount plasterboard
* redecorate internally
* shuffle units in the kitchen

Interesting that the council wouldn't need to have 2 layers of brick to meet their standards.


Thats 2 options - how about options for adding to the outside or replacing the wall - would these options be feasable?

 

[ajrobb]

If you want to comply with building regs (which is always preferable), I suggest you have a free chat with your Local Authority Building Control, but you should be prepared to lose about 100mm inside. The links I gave give manufacturers' instructions for Kingspan K18 and Celotex GA4000 solutions to internal insulation. MIs should be acceptable to LABC. I suspect they might want a U-value below 0.3 but they have some latitude.

Condensation could well be the main cause of damp in a solid half-brick (4") kitchen wall. The wall is newly rendered so might not suffer from frost damage that affects bare brick. Using PIR insulation (Celotex or Kingspan) should prevent condensation from the inside causing damp in the brick and should prevent penetrating damp from outside damaging the plasterboard.

Have a look at Heritage House page on damp. I suspect a lot of builders would disagree with them. Without hygroscopic salts, rising damp might not be much of a problem; there is a German site that claims success with damp in Medieval buildings by removing salts from centuries of passing animal dung.

Simply lining with foil-backed plasterboard on treated timber or metal batons might fix the damp but would not satisfy LABC. The foil backing would form a vapour-proof reflective cavity with an R-value of 0.6. This will more than halve the heat lost through the half-brick solid wall.

 

[ajrobb]

how about options for adding to the outside or replacing the wall - would these options be feasible?

As you say, there is the option of insulating externally; have a look around the Celotex site for alternative applications. I don't know how this could be finished at the top if there is no existing overhang.

An old coal bunker wall might not have adequate foundations for a kitchen. Worse case is you rip the whole thing down and rebuild.

 

[loverly9]

An old coal bunker wall might not have adequate foundations for a kitchen. Worse case is you rip the whole thing down and rebuild.

Yeah, depressing hey - probably an activity too big for DIY if it comes to that. Though, at least the extension bit isn't too big (1mx2.5m) so maybe I could get it reasonably priced.

 

[ajrobb]

If the only problem you have is a damp end wall and the structure is a typical Victorian shed, there might not be much point worrying about insulation regs. You might as well try dry-lining with foil-backed plasterboard and accept it is a bodge.

Excuse the impertinence, but as this seems to be your first post, there are things you might want to read up on to help your decision:

• permitted development
  Party Wall etc. Act 1996
  How much scope you have to add value (there is generally a practical ceiling on house prices in any given area)

Good luck.

 

[loverly9]

It's been a while I know, been busy with moving in.
We had some 'damp proof expert' people come round. They say its rising damp because they can see something that looks like 'salts' on the inside. They say to put in a damp proof course and put sand and cement on the inside. After discussion, putting up an extra layer of plaster board using dot and dab was also suggested, though only on the lower half of wall. The cost from either company was approx. £1500.

Not sure about trusting these guys.

We have also discovered by drilling that in fact the end wall is made of breeze blocks/concrete blocks and not brick.
Also by digging, i have found out that the wall has been rendered twice and that there is some kind of crumbling brick foundation.

Still don't know whats best to do...

Does it being breeze block change anything?
Is a timber frame and plaster board still right?
Could I just put this on the bottom?