Patching in after chimney removal

[tombodge]

i was wondering if i could get some advice.

Ive just removed my chimney breast from the ground into the loft.

Most of the party wall brick work is flush but the last 2 meters just under the upstairs ceiling drops back 50/60mm.


Would i be able to use bonding to build this out. Perhaps in 2 coats?

This wall is to be tiled afterwards as its going to be a new bathroom. Im unsure if this makes a differents.

Also the wall has still got sut and is still damp from when rain was coming down the chimney. Does the sut need cleaning off and do i need to wait untill the wall had dryed out.

Any help would be appreated.

Tom

 

[Alastairreid]

Let it dry out first ,then use a sand and cement mix with waterproofer to block it out...that will stop any leeching coming through the plaster.

Then you can use bonding and multi to straighten and finish.

 

[roughcaster]

Putting Bonding Coat plaster directly onto damp, sooty, brick/blockwork, would be a total disaster!!

Do it exactly the way Alastair has said, let the affected area of wall dry out, give it a good clean down to remove as much of the soot as possible, also making sure you have a good key on the wall, then use a cement render mix with waterproofer added. I'd put a render coat on, scratch it, then put another one on the next day, scratch it again, then use Bonding/ Hardwall to bring it out flush, ready for the multi finish.

 

[ree]

As above for letting it dry out before doing anything. Perhaps ask your neighbour to sweep his party wall flues?

Wire brush back to clean'ish brickwork, then apply a SBR slurry to the brickwork.

While the slurry is tacky, apply three coats of sand and lime and cement at 4:1:1 mix getting weaker as you pull it out. Allow each float to dry before applying the next coat.

Skim finish with a remedial skim eg. Limelite. Dont use any other kind of powder.

 

[tombodge]

Really appreciate the help. Thats spot on.

Can i use PVA instead of the SBR slurry and is the lime essential?

What ratios should i use if i just use plastering sand and cement?

Its just that ive already got the PVA plastering sand and cement at hand.

 

[ree]

Yes, use PVA in two coats: allow the first to dry, and go at it when the second coat of PVA is tacky - scratch on a very tight coat of S&C, and then fill out to 20mm.

Do a 3:1 sand to cement mix.

 

[tombodge]

Brillant thanks. Regarding the PVA shall i just do the standard 1/5 mixture on both coats?

 

[ree]

I dont know where you get the idea that there is a standard dilution for PVA - but for your purpose i would use 50/50 or near enough.

 

[Micilin]

All good advice there, but I would take the PVA back. SBR is better in damp conditions as it is a waterproofer and flexible. Also to get soot sealed up properly it will take a few applications of the slurry, letting each one dry fully before the next. But it will cure it.

You could use a couple of thin coats of w/p render to seal up as suggested, but make sure each coat is dry so that soot isn't soaking through.

 

[tombodge]

Ok thanks. I couldn't have asked for more.


It doesn't really matter about the soot leaking though as the wall is to be tiled. Ill have a look around for this slurry

 

[ree]

It actually does matter a great deal that "soot is leaking through". Soot and acidic "liquids" can present thro the grout and even thro some kinds of tile. It can also blow the background and cause the adhesion to fail - the tile will fall off the wall.

 

[Micilin]

It actually does matter a great deal that "soot is leaking through". Soot and acidic "liquids" can present thro the grout and even thro some kinds of tile. It can also blow the background and cause the adhesion to fail - the tile will fall off the wall.

Yes, it might take a while but eventually it will work its way through if not dealt with.