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Posted: Sat Nov 28, 2009 6:01 am
by mickg
I can only think its to stop water penetrating through from the outside brickwork and onto the reveals showing up as a damp spot when the 150mm vertical damp course has not been installed correctly.
by pushing the window frame 30mm into the cavity there is no way in theory any plaster reveal can get driving rain onto it, well thats OK if you just use window fixings but these days its mainly expanding foam which could bridge that gap anyway
what i have alway done is to use 150mm vertical damp and install the window as you normally would, dry line the reveal and then cut the surplus damp course off very carefully after the walls are skimmed
Posted: Sat Nov 28, 2009 10:30 am
by GB_Groundworks
so where do we stand on this as we've just had 40 windows fitted in our new build by the aluminium window company inc a 50 foot high curtain wall, they are recessed slightly but not sure its 30mm?
just picked up a knock down and rebuild for a prem footballer be starting the demo early next year, means i can stop being a joiner and get back on the fun stuff.
Posted: Sat Nov 28, 2009 1:08 pm
by Bob_A
lutonlagerlout wrote:..........its gonna look cat ,windows set at different reveals.........
Perhaps that might be your get out.
Planning officers are keen for extensions to harmonise with the existing building?
Posted: Mon Nov 30, 2009 8:17 pm
by GB_Groundworks
checked ours today all recessed back...
Posted: Mon Nov 30, 2009 8:20 pm
by mickg
how far are the windows recessed back off the face of the brickwork ?
and how thick are the windows ?
Posted: Mon Nov 30, 2009 8:40 pm
by mickg
Thermal Bridging could be the reason why windows are now fixed 30mm or so into the cavity
http://www.greenbuildingforum.co.uk/newforu....ID=3774
http://www.aecb.net/forum/index.php?topic=1737.0
did you ask the building inspector for the info LLL ?
Posted: Mon Nov 30, 2009 8:55 pm
by lutonlagerlout
thermal bridging is indeed the issue mick,
link to it
30 mm is the minimum,effectively what they are looking for is the window to be in line with the insulation
problem is ,its enforced by some local authorities and not by others ta-ra
so without knowing which ones want it and which dont you are at their mercy
the chipies took all the frames out today and recessed them 30mm farther back
new window boards tomorrow then plasterers
decoration thursday
this has always been my biggest gripe with BCOs ,they are a law unto themselves and if the notion takes them you are out of pocket
the thing that amazes me with all this is that they insist on trickle vents in all new windows,if they are that worried about heat loss why not insist that no windows can be opened??
thanks for all your help guys
btw most windows are 70mm profile,so they will be looking for >= 60mm reveals showing now ,same on door jambs
LLL
Posted: Mon Nov 30, 2009 9:24 pm
by mickg
are the BCO insisting on thermabate too or just fix the frames 30mm minimum into the cavity ?
Posted: Mon Nov 30, 2009 9:45 pm
by GB_Groundworks
mickg wrote:how far are the windows recessed back off the face of the brickwork ?
and how thick are the windows ?
ours?
about 40=50mm recess and windows are about 60mm thick aluminum, talking to the guys ftting them they showed me a profile cross section and its thermally insulated inside as well. so no cold bridge.
Posted: Mon Nov 30, 2009 9:51 pm
by mickg
cheers Giles
Posted: Mon Nov 30, 2009 10:01 pm
by GB_Groundworks
18mm of Krend going on when its stops bloody raining as well !!! one coat stuff no scratch coat comes in 25kg bags.
Posted: Wed Dec 02, 2009 11:59 am
by danensis
I once had an interesting debate with a BCO about installing fresh air vents in a kitchen. They insisted on a "well ventilated larder". I pointed out that the kitchen had a fridge, and that the regulations only required a food storage area - can't remember the exact wording now. As I happened to know the guy in the DOE (as it was at that time) who'd written the regulations, I phoned him up, and he more or less said "It doesn't matter what it says inthe regulations, if the BCO wants it that way you have to do it". He then pointed out that once the BCO had gone away there was nothing to stop us bricking up the vents!
Posted: Wed Dec 02, 2009 4:38 pm
by lutonlagerlout
dont worry danesis , we wont be moving the frames back out 30mm ,i can assure you of that!
LLL
Posted: Wed Dec 02, 2009 5:24 pm
by dig dug dan
i know that its too late now, a syou have started to do the re fit, but try and have a drive round and find a new build or a recent extension done elsewhere and see if they have had thier windows recessed. if they have not, you can turn round and say "you signed that one off, so you can sign off ours too!"
seems to be one rule for one and one for someone else in my book!
Posted: Wed Dec 02, 2009 6:45 pm
by rab1
on a block of flats 6 stories high, 5no blocks. 4 of them have no hardwood strip under the doors, 1 of them dose. the bco changed and the guy refused to sign them off without the strips in case of fire. ???