Lime mortar or not? Will cement render be ok?

P

peaps2

i take it black ash render is bad? will be if i got it suppose. Does it need removing internally or ok if water problem solved?

I would only remove hollow parts if you have any. I would remove as much of the gypsum skim I could.

For the outside wall I would lime render with NHL 5. Coastal area have problems with salt that creates extra problems that need thinking through.Cement based renders are no good if your house is lime constructed. Movement causes it to crack allowing water in.

The render needs to go on when it's warm and dry weather. NHL lime with stiffen after a few hours but will take 6/8 weeks to cure. If you can get a few dry days it would be ok but the more dry days the better until it's cured.

You then need to find a good micro porous paint for the lime wall, it will protect the lime render from the salt air. Paint regular.

Clean off brick below bell cast bead and re-point replacing any degraded brick.

NHL 5 is good for weather exposed walls.
 
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This is too wearisome to go on with, you are error writ large. Just for the record, the pic that you claim to show bridging DPC shows nothing of the sort, and your notion that cavity walls were only introduced around 1930 is ludicrous.
 
P

peaps2

This is too wearisome to go on with, you are error writ large. Just for the record, the pic that you claim to show bridging DPC shows nothing of the sort, and your notion that cavity walls were only introduced around 1930 is ludicrous.

Cavity wall construction was introduced in the 1900s and became popular in the 20s/30s

Arguing what you do or don't see in a picture doesn't change the fact that 90% of isolated penetrating damp problems are due to bridging and dpc fail for what ever reason. Slate dpc used in the 1930s were a cause of bridging, fallen mortar and on and on.

Notice the first dpc is slate...?

Yes it is becoming wearisome.
 
P

peaps2

2. salts are specific to all contaminated surfaces, wet or dry.I have seen them on weeping wet wallpaper.

"Even if soluble alkali sulfates exist in a masonry wall, before
the sulfates can cause efflorescence the salts must be dissolved
into solution by water. If no moisture reaches the sulfates then
they cannot be rendered into solution and migrate to the
surface where the water will evaporate, leaving the sulfate salts
on the surface to crystallize and become efflorescence.
Attention must be given to preventing any soluble alkaline
sulfates from being rendered into solution by water.
This is difficult since during construction water is naturally
used in the mortar and grout, therefore the amount of water in
the wall should be controlled to only that amount necessary for
actual construction. The majority of the water is absorbed into
the masonry and used to chemically react with the Portland
cement and hydrated lime and is thus not free water."


http://www.masonryinstitute.org/pdf/612.pdf

Mmm.




"The damaging effects of soluble salts are intimately linked with wetting and drying cycles at the masonry face."

http://www.buildingconservation.com/articles/salts/salts.htm

Mmm.
 

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