# Fitting a double glazing unit



## AndyBoyd (21 Aug 2007)

I have a door at the back of my bathroom that leads out onto the flat roof above the kitchen, the glass in this door is the only glass in the house that is not double glazed.

Now looking at the rebate the glass sits in, there is room to swap it out for a double panel

My question is how does one fit a double glased unit?

There seesm to be a sealant around the outside - is this sealant on both sides of the glass?

Does one fit the wood strips that hold it in directly on the glass (hence pushing on the glass unit) or does one use the sealant layer as a cushion.

What is the best clearance to leave between the glass and the size of the frame (width and height clearance)

I see special sealant for this in my local DIY uit that I must use I guess

Any advice as ever much appreciated


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## JFC (21 Aug 2007)

A nice bead of mastic , push the glass in , mastic again and fit the beads . If it's a timber door pin the beads to the door if plastic i think they use rubber gaskets and the beads clip into a rebate but i dont do plastic .


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## OLD (21 Aug 2007)

The unit should rest on plastic spacers about 2mm the glass man will supply it gives a even spacing around the unit. Units can be made up in various thicknesses to fit for replacement work only.


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## AndyT (21 Aug 2007)

Have a look at the Window Man ( http://www.thewindowman.co.uk/windowwood.htm ) and his 'free e-book' on adapting standard wooden frames to take double glazed units. The key point is to design in a way of keeping the sealing strip between the panes dry.


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## AndyBoyd (21 Aug 2007)

Super thanks everyone


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## llangatwgnedd (21 Aug 2007)

Shomai Andy.
Make sure the beading will be internal, use non setting putty on hardwood frames, or Plumbers Mate on painted wood and the unit to sit on rubber spacers to all allow expansion and contraction which is the biggest failing of DG units as the upvc fitter uses plastic wedges to pin up the wobbly upvc transoms, and down the road comes misted units.

Oh, and the beadings can go on dry with no putty.

Cheers


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## JFC (21 Aug 2007)

Yup forgot to mention the 2mm gap  Plumbers mate goes rock hard doesn't it ?


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## Max Power (21 Aug 2007)

Andy,
under no circumstances use putty.The oil in it will break down the seal in the unit, you should use butyl compound, which is similar in appearance to brown putty but is safe to use. Firstly measure the depth of available rebate after allowing for glazing beads .This will enable the manufacturer to calculate the cavity of the unit ie 4-12-4. The 12 being cavity and the 4s being the two glass panes.Obviously you will require toughened safety glass for a door.
Measure the overall aperture and deduct approx 8mm from the width and height this will be your size. fitting is pretty much as per a standard pane ie packers at the bottom ,bed it into the butyl compound fit your glazing beads clean off, then stand back and admire.


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## JFC (21 Aug 2007)

16 mm cavity to comply with uk regs , just mastic the thing in mate . I've never had a call back !


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## JFC (21 Aug 2007)

PS if you want to make it more work read the instructions on the back of the mastic tube before you cut the top of . I find a 7.3* cut on the nozzle gives a perfect bead of mastic .


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## Andy Pullen (22 Aug 2007)

I thought it was a 12mm spacer for the unit if it is filled with argon or 16mm if not. I also understood that because most glass goes into plastic windows these days, that the sealant they use on the actual unit can also be butyl and hence be broken down by butyl mastic used to install it in timber windows so best to use silicon made for glazing and wooden beads. Could be wrong though


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## Andy Pullen (22 Aug 2007)

And dont forget that for a door and surrounding glass it has to be toughened but they generally let the spacer regs go because the rebates aren't generally deep enough. Ask your local glass supplier.:wink:


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## Modernist (22 Aug 2007)

I'd leave a little more than 2mm gap unless you are sure the frame is absolutely square. By the time the glazier has allowed a little slip between the panes and added (roughly) plenty of black tape you will need it. Work out where the metal separator will be in relation to the moulding or bead. You don't want the metal bit or black tape showing round the edge.

I use a glazing silicone around the outside rebate and pin in the inner beads dry. In my case the loose beads are on the inside but if yours arn't I would be inclined to use silicone both sides. 

Be sure to use a dedicated glazing silicone some are definitely not suitable.


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## Dibs-h (24 Aug 2007)

Andy

As others have mentioned it may need to be toughned glass, especially if the glazed area is below a certain height from the floor. For windows it is or was till recently around 82 cm.

With respect to measurements - I've always measured height and width (measure both the height on both sides and the width on both sides - incase it is really out of square) and deducted 6mm from both measurements if things aren't drastically out of square.


Glass - if you are having units made up, get whatever you fancy, argon filled, coated, etc. U values ranging from 1.9 down to 1.3. Even Self cleaning if you are inclined - and it really does work. Although with Self cleaning glass the bedding sealants are phenominally expensive - trust me I know! Find someone who actually makes the units - a damn sight cheaper!

It might be an idea to go for toughened on one side and laminated on the other - you may want to check that the door will take the additional weight - IG units are not light weight!

With respect to fitting - prime the rebate with some quick drying varnish or similar and.. sod it can't be bothered to write it out. Be much easier point you to something with pictures - much easier to follow,

http://www.hodgsonsealants.com/technica ... lector.php

You need to be selecting either option B5 or B6, column 2 (fully bedded, non drained system). Then select "method statement" - very easy and straight forward.

Ignore the bit about glazing shovels - absolutely useless! Much easier with those suction cup things! Glazing\location blocks - Wickes do them in a mixed pack, green ad brown - <£5, get a couple of packs.

Butyl tape - use "Jumbo Strip" by Hodgsons, and the sealant should be something like Everbuild 450.

You may need to ring Hodgsons sale dept up and find out who buys Jumbo Strip off them, that is local to you.

Note of caution - you will need to trim excess tape off. On the inside of the door, trim it flush, and on the outside, trim it to the same angle as the bead. BUT do NOT use a straight edge knife or stanley blade - use a curved one. Running a straight blade along the glass will ultimately introduce thermal stresses and lead to unit failure, with it either shattering or cracking - I've had both!

Use Brass or SS pins to pin the beading in place.

Any questions - let me know. If you are having problems with the Jumbo strip - let me know how much you need (perimeter of unit\opening x 2 plus a bit extra) and I'll see what I can do.


Dibs


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## RogerS (25 Aug 2007)

What exactly is a 'drained and ventilated frame'?


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## RogerS (25 Aug 2007)

AndyT":5xzdws5x said:


> Have a look at the Window Man ( http://www.thewindowman.co.uk/windowwood.htm ) and his 'free e-book' on adapting standard wooden frames to take double glazed units. The key point is to design in a way of keeping the sealing strip between the panes dry.



Andy...do you have a link to his 'free e-book' as I'm unable to find it.

Thanks

Roger


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## Jake (25 Aug 2007)

Roger Sinden":3todr5rz said:


> What exactly is a 'drained and ventilated frame'?



I think that is where the bottom glazing bead has weepholes routed into its base, so that air can get in under the unit (supported on plastic packers) and water can get out.

But I'm guessing.


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## AndyT (27 Aug 2007)

Roger Sinden":2m4d7u5a said:


> AndyT":2m4d7u5a said:
> 
> 
> > Have a look at the Window Man ( http://www.thewindowman.co.uk/windowwood.htm ) and his 'free e-book' on adapting standard wooden frames to take double glazed units. The key point is to design in a way of keeping the sealing strip between the panes dry.
> ...



It's over on the right hand side of the page - http://www.thewindowman.co.uk/wood_drainage_files/wooden_windows_drainage_new.pdf.

And Jake is spot on with the drained and ventilated design.


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## RogerS (27 Aug 2007)

Thanks Andy...that's really timely and very useful.

Roger


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## JFC (27 Aug 2007)

Ahhhh weep holes , the perfect conditions for rot to start .


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## RogerS (27 Aug 2007)

JFC":2kcphnw4 said:


> Ahhhh weep holes , the perfect conditions for rot to start .



Between a rock and a hard place then ? Rotten windows or misted up double glazing units. I know..the perfect solution...uPVC :wink:


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