Another quick querie regarding the house we're doing. Personally don't think its a good idea to render the window reveals without removing the Silicone, nightmare of a job, alternative is to fit PVC stop beads over the Silicone butted up to the window frame, i would normally dab them on with S&C so technically the Silicone is still there. Anybody any suggestions?
Rendering over silicone
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Chris W
Well-Known Member
as for the silicon...
upvc windows need expansion gaps all round (usually 5mm) timber windows dont..
a properly fitted timber window doesnt need sealing, whatever gets in, comes right back out again when it hits the cill and is deflected outwards (in theory, and proper installation)
if i were you.. i'd leave the silicon in place up the sides and along the head (purely because of the required expansion gap - its a filler if nothing else) butt the stop bead tight up the window, render it and bloody well leave it...
low modulus silicon (which is what is required for upvc framework due to the high expansion coefficient of upvc) will go yellow, brown or even black with traffic and polution... so dont use it... or if you must, use clear and keep yer lines nice and tight...
your render will stop wind blowing the rain in and watever does seep in should come out again at cill level, so make SURE you let it.... or guess what? youll be getting water ingress and damp problems around the window internally...
using the wrong type of silicon is a big no-no...
heres why...
low modulus basically means 'high expansion' - the stuff sticks like sh't to a blanket and will move and expand with the frame ensuring long lasting adhesion...
acetoxy or high modulus is no good..... acetoxy releases acetic acid on curing which destroys the bond to the window and high modulus (similar stuff really) wont move with the window.. both of these types of silicon are the stuff you can get your fingernail behind and pull out in one long strip... you wont do that with low modulus...
once youve lost adhesion youve basically created a tiny little gap, that gap is small enough to encourage capillary action and it will SUCK water in...
:RpS_wink:
upvc windows need expansion gaps all round (usually 5mm) timber windows dont..
a properly fitted timber window doesnt need sealing, whatever gets in, comes right back out again when it hits the cill and is deflected outwards (in theory, and proper installation)
if i were you.. i'd leave the silicon in place up the sides and along the head (purely because of the required expansion gap - its a filler if nothing else) butt the stop bead tight up the window, render it and bloody well leave it...
low modulus silicon (which is what is required for upvc framework due to the high expansion coefficient of upvc) will go yellow, brown or even black with traffic and polution... so dont use it... or if you must, use clear and keep yer lines nice and tight...
your render will stop wind blowing the rain in and watever does seep in should come out again at cill level, so make SURE you let it.... or guess what? youll be getting water ingress and damp problems around the window internally...
using the wrong type of silicon is a big no-no...
heres why...
low modulus basically means 'high expansion' - the stuff sticks like sh't to a blanket and will move and expand with the frame ensuring long lasting adhesion...
acetoxy or high modulus is no good..... acetoxy releases acetic acid on curing which destroys the bond to the window and high modulus (similar stuff really) wont move with the window.. both of these types of silicon are the stuff you can get your fingernail behind and pull out in one long strip... you wont do that with low modulus...
once youve lost adhesion youve basically created a tiny little gap, that gap is small enough to encourage capillary action and it will SUCK water in...
:RpS_wink:
Chris W
Well-Known Member
doesnt normally work like that though half the time mate... you see their eyes sort of glaze over and you can hear em thinking 'wonder whats for tea tonight'.... i could be talking swaheli... all they wanna know is 'how much' and 'when'
then the other half the time you get some tit thats got a mate whos cousin was married to a bird that once went out with a plasterer... and you can prolly guess the rest :RpS_laugh:
then the other half the time you get some tit thats got a mate whos cousin was married to a bird that once went out with a plasterer... and you can prolly guess the rest :RpS_laugh:
lucius
Well-Known Member
Its called a Ribbon joint
s.p.t plastering
Active Member
bodplasterer
Active Member
Yeah chris you are far too inteligent to be a spread plasterers are usually thick as **** well you gotta be to do this crappy job lol
Chris W
Well-Known Member
probably not bubbles... its doors that are the worst for it but we've all planed the ribs off and mullered em in with the butt end of a lump hammer before today, on plenty of occasions i might add..
problem is theyve gotta go in square or youll be toe and heeling the sash/door leaf off square and it just creates problems...
expansion coeff of plastic is about a mil in a metre for 10 degrees or so if i remember right...
the 5mil gap is just a guideline that'll get you round most problems... just try not to muller resi doors in in winter cos in summer i guarantee you theyll catch...
but do you mean to say youve done the survey and measured em tight up the brickwork? not a good plan mate... specially since 90% of the holes youll find arent bang on square.. gives you a bit of play, and 5 mil is f'ck all to gun up...
some of the newbuilds on cavity closers... jeez man... you were looking at a tin of foam per window! 15 mil gaps all round... thats what happens when firms try to cover themselves when the windows made to fit a closer thats gonna be bricked in by muppets on sh't rates on a newbuild site...
ive had french doors 25mil to nothing and the reverse on the other jamb...
usual scenario, brick to brick, 3 measurements, take the smallest and deduct 10 mil...
nowt worse than having to get the plane out when youre on price...
problem is theyve gotta go in square or youll be toe and heeling the sash/door leaf off square and it just creates problems...
expansion coeff of plastic is about a mil in a metre for 10 degrees or so if i remember right...
the 5mil gap is just a guideline that'll get you round most problems... just try not to muller resi doors in in winter cos in summer i guarantee you theyll catch...
but do you mean to say youve done the survey and measured em tight up the brickwork? not a good plan mate... specially since 90% of the holes youll find arent bang on square.. gives you a bit of play, and 5 mil is f'ck all to gun up...
some of the newbuilds on cavity closers... jeez man... you were looking at a tin of foam per window! 15 mil gaps all round... thats what happens when firms try to cover themselves when the windows made to fit a closer thats gonna be bricked in by muppets on sh't rates on a newbuild site...
ive had french doors 25mil to nothing and the reverse on the other jamb...
usual scenario, brick to brick, 3 measurements, take the smallest and deduct 10 mil...
nowt worse than having to get the plane out when youre on price...
Chris W
Well-Known Member
dodgy mate BUT you do raise a point.. internal measure is a must... just to check it aint been dabbed, reveal linered etc...
then your into knock-ons etc or the worst one has got to be an internal window board 80mm higher than the external brickwork... and it gets missed... looks bloody awful and god help you if its internal bead...
board off, plaster comes with it (if your not careful, theres a trick to that i find)
or slightly less annoying but equally scabby looking is the trickle vent fixed to the head rail as opposed to the sash and buried in a dabbed head....
99% of that game is knowing what NOT to do... the actual fixing off, glazing and trimming is childs play...
you wouldnt believe some of the things ive seen lads do on council contracts... more like a demolition job than owt else :RpS_laugh:
theres more to the game than people realise and most of it is in the surveying... knowing how to rip out properly is a must too... fitting on price is down to technique, teamwork and just plain brute force and ignorance.. :rolleyes)
you ever get on any blocks of flats bubbles? on the mastclimbers? theyre a right buzz... :RpS_biggrin:
then your into knock-ons etc or the worst one has got to be an internal window board 80mm higher than the external brickwork... and it gets missed... looks bloody awful and god help you if its internal bead...
board off, plaster comes with it (if your not careful, theres a trick to that i find)
or slightly less annoying but equally scabby looking is the trickle vent fixed to the head rail as opposed to the sash and buried in a dabbed head....
99% of that game is knowing what NOT to do... the actual fixing off, glazing and trimming is childs play...
you wouldnt believe some of the things ive seen lads do on council contracts... more like a demolition job than owt else :RpS_laugh:
theres more to the game than people realise and most of it is in the surveying... knowing how to rip out properly is a must too... fitting on price is down to technique, teamwork and just plain brute force and ignorance.. :rolleyes)
you ever get on any blocks of flats bubbles? on the mastclimbers? theyre a right buzz... :RpS_biggrin:
Chris W
Well-Known Member
ones i did were gloucester and manchester (levenshulme)...
we got one lad, crack shot with a bit of old gobbo, and an alotment over the way...
he's getting the cold frames bang on every time from 10 floors up and 60 yards away...
gardeners are coming round every morning goin 'bloody kids!!! you aint got any more of them sashes have you lads?'...
(pullin off 180 spinners and stackin em intact in the skip, gardeners went through loads of em for us) :RpS_laugh:
knocked a mini crowbar under a cill to wedge a kitchen window up prior to fixing once..
hopped over the balcony and into the kitchen to drill it off... completely forgot about the bloody crowbar...
now theres about an 18" gap between the mastclimber and the building... and the labourers are sweeping up on the ground... were 8 floors up...
the crowbar missed one of em by about 6 inches and bounced back up 5 floors or so...
lad comes up the lift, comes in the flat still white as a f'ckin sheet with me crowbar in his hand.. just gives it me, turns round and buggers off without sayin a word!!!
later in the pub the phrase was 'me arse was twitchin like a rabbits nose for the next hour'... :-0
we got one lad, crack shot with a bit of old gobbo, and an alotment over the way...
he's getting the cold frames bang on every time from 10 floors up and 60 yards away...
gardeners are coming round every morning goin 'bloody kids!!! you aint got any more of them sashes have you lads?'...
(pullin off 180 spinners and stackin em intact in the skip, gardeners went through loads of em for us) :RpS_laugh:
knocked a mini crowbar under a cill to wedge a kitchen window up prior to fixing once..
hopped over the balcony and into the kitchen to drill it off... completely forgot about the bloody crowbar...
now theres about an 18" gap between the mastclimber and the building... and the labourers are sweeping up on the ground... were 8 floors up...
the crowbar missed one of em by about 6 inches and bounced back up 5 floors or so...
lad comes up the lift, comes in the flat still white as a f'ckin sheet with me crowbar in his hand.. just gives it me, turns round and buggers off without sayin a word!!!
later in the pub the phrase was 'me arse was twitchin like a rabbits nose for the next hour'... :-0
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