On Aug 18, 2:04*pm, PeterC wrote:
On Tue, 17 Aug 2010 04:24:44 -0700 (PDT), Tabby wrote:
On Aug 17, 9:25*am, 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?

More or less all above ground wall bricks are porous. What you propose
is a classic mistake. Read SPAB's guidance on such things if you're
still tempted.

NT

Well, there's no spalling and post-war ex-council house isn't historic!

SPAB says that one cause is frost on damp bricks; I can't stop frost or
rain, so doing nothing might eventually lead to spalling.
A poromeric coating would shift the equilibrium by excluding water and
allowing vapour to pass through. With heating inside and heat from the sun
outside this should work.


You need to get the problem udnerstood before looking at solutions.
And in your case there is no problem. Pretty much all bricks are
porous and get wet and freeze, this doesnt cause spalling. Spalling
only happens if the bricks are so saturated with water that the only
way for the freezing water to expand is by pushing the brick face off.

No problem, nothing to solve. This is well demonstrated by the fact
that the brickwok has been coping just fine for 50 years.


Siloxane coatings, if repeated, clog the evaporations paths, then
damage can result.

SPAB is criticised here by those that havent read what they say &
taken the time to understand it. However they do know their stuff on
this topic. It turns out the way old houses handle dampness is a fair
bit different to what people thought a couple of decades ago, and to
some degree some of the same principles apply to more modern builds
too.


NT