Removing sealed units

[cdbe]

Hi, I need to reglaze an old externally glazed upvc window, it has an internal rubber gasket - do I remove this first or the beading? Also, any way to measure for the new units in-situ from inside as it's on the first floor?

Thanks

Thanks

 

[crank39]

Measure plastic to plastic and ADD 30mm but this can be hit and miss and you're taking a risk, if you measure from the outside then measure from the bead joint and DEDUCT 10mm, if you can't get up to measure from outside how do you propose to change the glass?

Remove internal gasket first then external beads next

 

[cdbe]

Thanks, I can get up but would rather not drag the ladders out twice if I could avoid it, however by the sounds of it I think I'd be better doing that than making an expensive mistake!

 

[crank39]

Play it safe

 

[God]

Face of spacer To spacer + 23mm

 

[Gazman16]

Face of spacer To spacer + 23mm

Thats what I do, Although when making units I was taught 24mm for PVC and 25mm for aluminum windows

Then of course you also need the thickness of the unit. Without a £30 set of calipers that will reach around the frames you would have to take the unit out to check

 

[crank39]

Is that how you measure your thickness Gaz, I use a merlin but I'm a snob I guess

Also how do you measure from the inner face of the spacer when its buried 6mm behind the rebate, surely its still a guess

Next time you measure for a unit measure from the bead side and deduct 10mm as normal then pop round the other side and measure plastic to plastic and add 30mm and i bet that gets you close to your first measurement, from experience 24mm is still a bit slack

 

[Gazman16]

That was how we made the units. So 12mm perimeter edge seal for PVC windows and 12.5mm on Ali.
You can see the internal face of the spacer so even if it is a slight guesstimate my sizes still work out within 2mm of the old one overall. Usually bang on though.

My old company had a Merlin but got a unit size wrong once so I never really trusted them since. Was a really sunny glairy day so possibly I just read it wrong.
I got a £30 caliper and its never done me wrong in 10 years that Ive been on my own.

 

[crank39]

Fair comment, I've had mine 15 years and never got one wrong with it

 

[cdbe]

So I measured the two units today -

Plastic to plastic.............Actual.........Diff
1592-------------------------------1623------------31
1020-------------------------------1045------------25
943----------------------------------969-------------26
438----------------------------------463-------------25

Thickness I'd got by measuring in to the glass from a straight edge inside and out then doing the sum - this was dead right at 20mm.

The units are a very tight fit - about 2mm gap which seams tight to me but they've been in 20+ years with no problems. Across the centre of the large one there's no gap (no lintel at the moment so the soldier course is bearing onto it - the new unit will have to perform the same function for the time being).