what is a "check reveal"
sm_jamieson
relation to fitting windows in exposed positions.
Cheers,
Simon.
Tony Bryer
> Anyone know what a window "check reveal" is. I came across the
> term in relation to fitting windows in exposed positions.
This is a guess, but I suspect it means that the outer skin of
brickwork extends over the face of the window fame.
BBBBBBB
WWWWWWWWWWWW
BBBBBBBB
--
Tony Bryer, Greentram: 'Software to build on' Melbourne, Australia
www.superbeam.co.uk www.superbeam.com www.greentram.com
Jim
> Anyone know what a window "check reveal" is. I came across the term in
> relation to fitting windows in exposed positions.
We have them on our house - it means that the window fits behind the
outer skin of the cavity wall. If you'll excuse the ASCII art:
Normal: (out on top)
BBBBBWWWWWWWWWWWBBBBBBBB
cavitWWWWWWWWWWWtycavity
BBBBB BBBBBBBB
Check reveal:
BBBBBB BBBBBBBBB
cavitWWWWWWWWWWWcavityca
BBBBBWWWWWWWWWWWBBBBBBBB
The opening in the internal skin tends to be somewhat wider to
accomodate the window frame. It works quite well with sliding sash since
the sash box sits into the reveal.
You can see how the joint between window and brick is better protected
from the weather. Although I suspect it's less of a relevant issue with
modern technology.
The tricky bit is getting the details correct to minimise damp and cold
bridging. The UPVC window installers that I've talked to are quite
unfamiliar with the concept unfortunately. We ended up getting custom
wooden windows made.
The sills can be tricky. You can get UPVC windows with sills which are
long enough (they would need to have a projection of about 120mm to
overlap the external brick) but they will probably need cutting to fit
at the ends. We ended up using a cast concrete sub-sill to a custom
design that I did.
Cavity closers (to stop cold bridging from the cavity through the window
frame) to suit check reveal are difficult to get hold of.
It will look better if the window head has a concrete lintel rather than
a steel one, because the steel lintel will be exposed.
sm_jamieson
Its interesting since building regs now want you to put the windows
further back than before, projecting up to 30mm into the cavity area,
so that the internal reveal is protected from cold bridging by more of
the insulated cavity closer. This makes them harder to fix, and I'm
making sure I get 70mm PVCu profiles so more of the frame is on the
outer skin. The requirements leave more of the lintel visible as you
described. It also means there is less amount of frame to prevent
water tracking through. You can use the vertical DPC fixed to the
insulated closers to create a "flap" alongside the window frame which
would block any water tracking through. This vertical DPC would
otherwise serve no purpose for PVCu windows, since unlike wood, they
are waterproof.
Simon.
Jim
You can get an combination cavity closer/DPC for sash windows:
http://www.cavitytrays.co.uk/closers/view/3/176/1/sash-frame-insulated-dpc
I've been unable to get samples or measurements though.