In article ,
Phil Addison writes:
On 20 Jun 2004 01:05:33 GMT, (Andrew
Gabriel) wrote:
These actually sound like original rendered brick window sills.
I have these too, and thought they were concrete until one was
removed by a bricky.
That is most interesting, Andrew. I have not heard of that construction
before. Do you mean original brickwork sills, rendered at a later date?
Rendered when built. All the houses in the terrace have the same
sills (1895). The render is very hard -- I was bashing away with
a scraper on it to get 100 years of paint off, and it doesn't
damage or even mark it. It is vulnerable if the render cracks
though -- water can get in and then freeze in the brickwork,
causing large chunks of the brickwork to fall off, which had
happened on one of mine.
I didn't think sand/cement render was available that early (1890's) or
Cement goes back to roman times. However, prior to Portland cement,
it was more expensive, so it wasn't used for everything like it is
today.
am I wrong there? If it is rendered brick, I may be able to remove and
replace the render with proper waterproofer additive and hopefully make
a better finish of the slope.
I think the only way the sill will be letting water in is if
there are cracks in the render.
I'm going to have a good look at that and perhaps drill to see if I can
hit brick. My daughter would be relieved not to have the upheaval of new
sills. On the other hand, the sills do look like cast ones - there is
evidence of framework marks on the front, and there is a cast drip
channel underneath.
Mine also has a drip channel. It's a bit far back for my liking
though.
I am leaving it for a few days to see how this wet dries out, now that
it can via the exposed inner brick surface.
It takes weeks for wet walls to dry out. IIRC, it took about
6 weeks for the single brick front wall of my fireplace to
dry out after I reopened the fireplace (blocked up with no
ventilation for probably 20 years).
Hopefully not that long as there is only about a height of 2ft of bricks
below the sill to dry out. Your fireplace presumably had wet brickwork
to a much greater height replenishing the opening as it evaporated from
there?
It was about a 2' square (plus much of the bricked up area which was
removed). It was quite waterlogged though.
What I need now is advice on is what to do to make good the inside wall.
I am not convinced that re-rendering it is a good idea - I want to stop
the damp at source, and the original render put on to contain it has not
worked very well. Is a 'waterproof' rendering really waterproof? I
suspect that under the pressure of a couple of feet of water inside the
brickwork wet will seep through; or could it be that the builder didn't
mix the render correctly?
Given that I have exposed a 4' x 2' patch of brickwork, what is the
appropriate materials to make this good? I was planning on a background
of Carlite Browning with a skim of finish or multi-finish. Any hints
anyone?
If you stop the water entry and let it all dry out, you can use
pretty much anything (personally, I use bonding coat as the scratch
coat). However, none of the gypsom-based plasters are suitable if
it's damp.
I have done a scratch (base) coat of cement (and lime if you like it)
and sand in a 1:1:6 ratio, with waterproofer added. Follow up 24 hours
later with regular plaster finish coat (no PVA required unless you
leave it much longer and the scratch coat has dried). The sand and
cement is very effective at keeping the water away from the plaster
finish coat. However, you'll probably need to let the wall dry out
first, at least so it doesn't feel and look wet.
--
Andrew Gabriel