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    • CommentAuthorfinnian
    • CommentTimeJan 21st 2017
    I've built a workshop which I've made some wooden opening windows for. These have a rebate to accommodate double glazed insulated units. I'm planning on using neutral curing silicone to seal the units on the weather side (since I haven't put in slots for aquamac type seals).

    What is the procedure for installing the glazing, and the frames/sashes? Do I screw the frames to the wall studs first, use foam (or compressible band) to fill the gap, then install the sashes? Or do I put everything together first, and then lift the whole lot into place?
    • CommentAuthortony
    • CommentTimeJan 21st 2017
    You have to. Be extremely careful with silicone as the oil in it can soak into the stuff that they use to seal the units together and wreck them.

    Mine are all done with silicone and this is standard practice in Europe but rare here.

    Think about drained rebates as these are fail safe.
    • CommentAuthorGotanewlife
    • CommentTimeJan 21st 2017 edited
    Posted By: tonyMine are all done with silicone and this is standard practice in Europe but rare here.
    You mean the black 'stuff' sealing the 2 (or 3) panes of glass is silicone-based in yours and hence mine (as I am in Italy) - I have not come accross this issue before and it is alarming!!! Are you sure about using silicone based pane sealing goo in Europe - I am dubious, never seen it mentioned, never appear to be any difference in the big manufacturers UK vs EU websites, etc. I certainly wasn't 'really' careful when I did my retro fit DG units into my old wood windows - careful but not 'certain because the DG units will fail if not' careful.

    Finnian - clearly if you can manage the whole units made up then it makes certain that you don't warp the frame putting it in but above a fairly small size this is going to become much more difficult. If it were me I would have confidence that I wasn't going to warp thew frames and fit them before the glass. If you can afford the expanding tape and you have made gaps of the correct size and regular enough to use the tape then do so as the tape is more likely to be airtight over a longer period of time than expanding foam and of course you stop any possibility of warping the frames through over-use of expanding foam. (and it is cleaner!!!).
    • CommentAuthorblacksmith
    • CommentTimeJan 21st 2017
    Not sure on the size of your windows but mine I put in (eventually) using neutral curing, low modulus silicone sealant. This is correct for glazing double-glazed units.

    I made a huge mistake with my first attempt and it made me want to weep. Having ordered my glazing I asked a carpenter friend what he used to glaze his with and pointed me to what he used - sure enough it stated that it was suitable for glazing. After spending the best part of the day installing the six panels on the ground floor I felt that I had achieved something. I will never know what compelled me to look at the product website that evening but glad I did as in the technical download it stated, alongside it's suitability for glazed units it said 'not suitable for thermal/ double-glazed units'. Pity it did not say this on the packaging.

    It took me another whole day to remove the just installed glazing and then another five days to remove all traces of the silicone from the units and frames, tenacious stuff.

    Lesson learned - carry out your own due diligence and certainly ask whatever manufacturer of product available for it's suitability. Everyone I did contact said neutral curing, low modulus.

    My frames were a bit large to glaze and fit so installed and screwed to main frame packed out first, glazed and then foamed where needed. If the image comes out you will get an idea.

    best of luck.
    • CommentAuthorjfb
    • CommentTimeJan 21st 2017
    if you are going to use expanding foam make sure you brace the frames to stop them warping.
    Some foams expand less (soudal do one) and are better for the job.
    • CommentAuthorfinnian
    • CommentTimeJan 22nd 2017
    OK, thanks all: sounds like the main thing is to make sure that everything stays nice and flat so it all fits together once installed, and the foam doesn't warp the frames. And to use the right silicone...

    Think it should be pretty straightforward to add some drainage to the rebates.
    I think what Tony is on about above is that the silicon sealant will/can attack the black goo used to construct the DG units. If the DG units come with sticky metallised tape on the edges should be no problem, if you can see the black goo then best to keep the silicon off that (or uses acrylic sealant, but that not so good).

    A drain in the rebate is good/needed and put spacers under the DG units to keep them off the wood. This will help stop the DG units failing due to moisture ingress.

    If the frames + glass are manageable I would install as a unit, otherwise frames first then glass and try to borrow a couple of glaziers suction cups (e.g. http://www.ggrglass.co.uk/suction-cups/ ) because they make life so much easier.
    • CommentAuthorblacksmith
    • CommentTimeJan 23rd 2017
    RE: silicone attacking black separator bar and seal.

    In mid Wales here in UK I have only ever seen one glazed unit with a metallised edge tape, all others are simply sealed in black gaffer tape. Personally I have bought from three different suppliers and they all come with a gaffer tape edge seal over the glass.

    Certain types of silicone will readily attack this seal, I had the misfortune to use a High Modulus Acetoxy silicone as recommended in the first instance - see above. Even though stated as suitable for glazing it was not correct for double glazing. It is easily to identify when your using it (High Modulus Acetoxy ) as it gives of a strong vinegary ordure.

    The low modulus type does not have this smell. It is safe to bed double glazed units into and does not attack the seal, some folks remove the gaffer seal and bed directly onto the silicone and then fill around the void edges, finishing with the glazing bead pushed against the silicone - then trimmed off when cured. This, so long as it's done thoroughly creates a weatherproof seal. Not so much with a drained rebate I imagine but then I have not attempted this - something to have a look at.
    • CommentAuthorfinnian
    • CommentTimeJun 4th 2017
    Just like to say that putting these units in with neutral curing silicone worked well: no obvious problems. The units were wrapped in gaffa-type tape, as suggested above! I used some little wood spacers to keep the silicone bed depth to 3mm.

    Thanks all for the advice.

    Standard plastic unit hinges seem to work well.

    Rebates were 'drained' with a few drill holes to external side, and spacers used to keep the unit off the bottom of the rebate. We'll see how well they last. Will need to figure out what to treat them with.
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