Measuring up for replacement windows

[Onoff]

I've put in two new build windows, two replacement windows and 3 doors, all upvc. The windows were new and the doors all secondhand.

 

Limited experience then but I'd go for Compriband or Illbrück equivalent tape every time over foam. If I had to use foam then Illbrück FM330 over anything else. 

 

I'd really urge you to watch White Gold about how not to fit "double glazing". It's on Netflix. 

[Mike]

22 hours ago, Novice Becky said:

I think I'll go for 10mm all round (so 20mm on each dimension) as I want to use Compriband (or equivalent) and airtightness tape

 

Personally I allow 7.5mm on every side, so 15mm on the width and height. That gives enough tolerance if the brickwork or windows are a few mm out, while also allowing enough space for Compriband / foam.

 

I use Compriband on the outside then, when it's expanded, apply Illbrück FM330 foam from the inside (a small initial foaming to avoid displacing the Compriband). To do that you'd need to leaving a gap between the window and the paster wide enough to insert the nozzle of the foam gun.

 

Note that Compriband, if installed correctly, is rated water tight to 600 pascals - that's a wind speed of around 70mph. In the case of a timber frame I'd add a lead tray below the sill to divert any rain that gets past the Compriband to the outside.

[Novice Becky]

@CrofterReally encouraging to hear that your windows worked out. Recip saw noted - I've been wondering about how I'll get the old ones out! Once I've ordered there'll be no going back and I'll have 8 weeks to swot up on how to do it.

 

@Gone WestGood to hear that other people had a first time for installing windows. I'll make sure I have plenty of help - also need to find a friend with Netflix to watch White Gold suggested by @Onoff.

 

@Mike @nod I like how there's always more than one way to do anything on this forum and you have to use your own judgement. I'll have a final think through my fitting tolerance. Having seen other people's windows I'm not too scared now - I don't have rendering to deal with and I have a 1.5m steel ruler. Tremco and Illbruck products are very popular on this site so I'll go with them. I have FM330 if I need it - just need to practise getting the quantities right (been a little over-enthusiastic in the past!)

[Novice Becky]

1 hour ago, Mike said:

Note that Compriband, if installed correctly, is rated water tight to 600 pascals - that's a wind speed of around 70mph. In the case of a timber frame I'd add a lead tray below the sill to divert any rain that gets past the Compriband to the outside.

Thanks. This is really useful to know in case I do other windows (I did get a leak at the top of my expert fitted windows a few years ago) but once I've fitted these windows I'm having the failed CWI insulation sucked out and replaced with EPS beads and THEN I can finally convert the side passage into a sort of shed/store so I don't think water ingress will be an issue for me.

[craig]

On 23/02/2024 at 15:56, Novice Becky said:

Hope it's ok to pick up this old discussion or am I supposed to start a new one? I'm measuring for replacement windows and I've been putting it off as I can't find anyone to install only (I supply) ... looks like I'll have to learn how to DIY and rope in some friends. It's just two windows down the side of my 1960s bungalow (plus a composite front door - on another discussion). I replaced all the other windows 15 years ago.  I think I'm going for timber frame, triple glazed from Russell Timber. They're good value and look pretty similar to my other (expensive) windows.

 

QUESTION: when measuring do people take off 10mm all round, so subtract 20mm from both the height and width?

There's no rendering, just brick, so I've measured from brick-to-brick on the width and on the height I did from mortar under the brick at the top to the bottom of the sill (see photos). I'll use the smallest measurements.

 @nod sounds like you've done this lots. Any advice?

 

Or any recommendations of builders/window fitters near J9 of M25? FENSA installers won't do it. Local builder quoted £1750 to fit 2 small windows and a composite front door (I supply windows and compriband and air-tightness tape). Sounded a lot to me.

 

Thanks for helping

Where are you based? I can recommend some installers that will install only for you (location dependent), if you’re stuck.

Edited February 26 by craig

[Novice Becky]

2 hours ago, craig said:

Where are you based? I can recommend some installers that will install only for you (location dependent), if you’re stuck.

Thank you. We're 5 mins from Junction 9 of M25 (Surrey)

[craig]

Dropped you a message with number for installer, he’ll help ya and it won’t be £1,750 👍
 

Have you ordered yet? Speak with him on measurements, I’d be lookibg for 5mm all around on a brick opening like you have tbh. That’s enough for a 3 to 5mm Compriband or a nice mastic bead. 

Edited February 26 by craig