Damp Proofing Question

White salt patches on chimney breast above skirting

Hi all tradesman

I very much appreciate all your help as i have posted before to ask advice.

From my recent post im not going to do what i said i was doing from all the great advice i have.

To put all the advice together, hack off down to brick.

Put on some anti sulphate stuff to cure salts? where will i buy this what is it called?

Then mix up sand and cement is this portland cement and sand, but to what mix.

And then multi finish.

Or is it some kind of water proof specialist plaster by thistle etc but what is this called where buy from before i put the multi finish on to trt try again.

Ive read not to repaper straight away my biggets mistake i made from my last attempt, i didnt hack enough off, didnt go to brick, but did do a ready mixed mortar and multi but lasted days, and it never really dried.

Hear from you all soon and kind regards

3 Answers

Best Answer

Hi Phil,
So you have now decided to do it yourself.
I would suggest, as you said, hack of right back to the brick, and go a bit further than the problem area.
Give it a good wire brushing and leave it to fully dry out, mix up your sand/cement to a ratio 4 sand to 1 cement with a salt retardent in it, such as, Rendgaurd Gold.
Then apply a 2 coat plaster finish.
Wait for this to dry out fully, then if painting use a anti mould paint.
I am sure some other trades will be along later to explain their methods and what chemicals to add, so you will have plenty of info to choose from.
Dont use the ready mix stuff from diy outlets, you want good washed plastering sand and blue circle cement,or similar, you can get this all at good builders merchants.

Answered 2nd Apr 2011


Member since 29 Oct 2008

BJD I agree with your post. But are we not forgetting the obvious here? Phil, you have rising damp and you need to cure that problem before anything else! Its like saying to your Doctor I have a constant headach and paracetamols take away the pain for a short while but then the headache comes back again! My honest advice would be to get a professional Damp Proof company in to sort the problem out. Chimney breasts are nutorious for rising damp by the very nature of the construction. If you want the problem solving properly you would also be advised to apply an SBR slurry to a mtr high and a raglet joint at the base of the bricks if the floor is concrete. You may also wish to consider a chemical damp proof course to prevent any further rising damp and not forgetting vertical joints where the chimney breast is built into the wall and at either end of the point of where your taking the plaster back to. Seriously bite the bullet and get a pro in to sort it out.

Answered 2nd Apr 2011

RMH Contractors Ltd

Member since 23 Feb 2009

No feedback

yes,all above seem to cover the problem,i always go with hacking back to bricks,a sand cement render at 3 and 1 with sbr added (waterproofer)also mixed at 3 to 1.let this cure over a couple of days then apply tanking slurry,and finally finish off with plasterworks.what dampness rises up,will not penatrate inwords,into your room.this system holds back all. but the underlying problem is riseing damp.

Answered 18th Apr 2011

Handyman Portsmouth

Member since 2 Oct 2007

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