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PeterC PeterC is offline
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Default Porous brickwork and treatment

On Tue, 17 Aug 2010 02:18:37 -0700 (PDT), wrote:

On 17 Aug, 09:25, PeterC wrote:
Last Autumn there was a mention in a thread about 1950's brickwork being
porous.
About that time I had to drill a couple of holes in the gable wall - it
faces SW - and the debris was like a crumbly paste rather than dust for
about 15 - 20mm in.
The bricks are heavily patterned - a vertical herringbone groove - which I
think are Rustic(?) from c. 1950.

Is it worth treating the wall and, if so, what sort of gunk to put on it?

There are 2 possibilities on this page

http://www.everbuild.co.uk/products/...s/26,Surface-T...

although the solvent-based one looks a bit nasty!

Any suggestions please?
--
Peter.
The gods will stay away
whilst religions hold sway


AIUI, there's 2 families of waterproofing treatments - there's the non-
breathable silicon-based ones (Thompsons WaterSeal being the best
known http://www.thompsonsweatherproofing....oduct.jsp?id=1
) - and there's the much more expensive but water-vapour-permeable
silane/siloxane based ones (which are less well known, but Liquid
Plastics K501 is an example http://www.liquidplastics.co.uk/Deco...ngs-for-Walls).

As you've already found out, there's also a division between water-
based and solvent-based versions of silicone treatment. AIUI solvent-
based are the older generation products (I believe silane/siloxane
treatments were also solvent based at one time, but have already been
discontinued).


Thanks for this info - wondered about the relative merits of solvent/non.

I've treated a large Victorian building built from very soft red
bricks with K501, because the brickfaces were spalling from frost
damage. This was 2 years ago - and the last 2 winters have shown the
spalling has been completely halted.

No spalling of bricks at all; some shallow, inadequate, repointing coming
off on the gable triangle but the rest is OK.

With my building it was wise to bear the considerable extra cost of a
breathable treatment, as it's unlikely that all points of water (rain)
penetration could be sealed - and the solution relies on controlling
the level of moisture in the brickfaces (by permitting it to pass out
again as water vapour) down to the point that spalling is stopped.

I can't tell you what will be right for your building, or even if it
is necessary, but bear in mind these treatments are non-reversible -
so do you homework before plunging in.

Can you post a close-up pic of the damage, and another showing the
extent of the problem?


Apart from the minor bit mentioned above, there's none to see. It's only
the obvious slight dampness to 20mm or so that worried me. It also must
remove a lot of heat from the wall in cold weather when there's a goodly
wind.
--
Peter.
The gods will stay away
whilst religions hold sway