Replacement windows in cavity.

[Jonno35]

Hi everyone, looking for a little advice on fitting some windows if poss.
I've fitted quite a few windows in the past (I'm actually time served as a bench joiner in previous career....but mainly on the manufacturing side), UPVC and timber but always been able to get solid fixings before.
Mother in wants some new hardwood windows which I've been asked to fit. Looking at the old windows they sit in the cavity and are pushed up tight to the inside of the outer brick skin, and then pointed in with trowel mastic.
The new windows are not made yet so there is a choice of making them the exact size of the opening or again slightly wider and try and wriggle into the cavity.
Anyone know the best way of fitting these, usually I would drill straight through the rebate in the frame with frame fixings but in this case it would be into fresh air.

Two options I've considered are:

Can I use something like 1" steel straps cut into 6 or 7" lengths, screw to outside of the window (straps pointing in), offer the window in and then fasten these to inside reveals (the straps would be lined over with ply or such anyways as the old lining is shot)?
Also using this method I imagine it would be better for the windows to be actual size of opening rather than trying to get into cavity and tight against outer skin.

Other option I considered would be to try and wriggle windows into cavity and up against outer skin of brick on the sides, wedge against outer skin and then foam where possible. Rebuild lining against new frame effectively trapping it?

I feel the first option might be the way but would love some input on this.
Thanks.

 

[The Bullet]

the new windows should come with fixing clips that will hammer in to the side of the frame, which you can then screw through to fix to the ingos, then cover with trimming.

However i prefer to cut timber blocks and hammer into the cavity and fix through the frame. If you do this put some damp proof between the timber block and outside brick or any moisture could penetrate through the wood and reach the inside brick.

 

[Pinnacle69]

what about installing insulated cavity closers first ? its another option and easy

 

[Jonno35]

Thanks fellas, like the idea of the timber wedges and then screw into it, that would allow me have the frames the same size as the opening instead of larger and trying to wriggle into the cavity.
I will take a look at the insulated cavitity closers as well though, never used em before.

Also, what about sealing between brick and frame, used allsorts before, trowel mastic, pointed with sand/cement. Fitted some oak windows a couple years ago and used brown polysulphide frame sealent.....that was quickest but was a bit of a pain to get out of the tube in an even bead....the stuff felt like it needed heating up to become softer.
Have things moved on any or is polysulphide still the norm? For what it's worth the frames will be Utile or Sapele so I suppose it would need to be a red/mahogany kind of colour (only ever used brown and white before).

Thanks again folks.

 

[Pinnacle69]

i usually seal in clear neutral cure silicone then quadrant over the top, nice neat finish dont see any ugly sealant

 

[Jonno35]

i usually seal in clear neutral cure silicone then quadrant over the top, nice neat finish dont see any ugly sealant

That's a good shout Pinnacle. Biggest issue with the polysulphide I found was getting a nice even bead on the brickwork/stone against the frame. Water with a bit of fairly liquid helped but still not brill.
Think I'll try the quadrant if I can find some in Utile/Sapele.

 

[Pinnacle69]

cavity closers can be found at eurocell by the way ten quid ish for a 5m lenth im sure theres a branch near you and they deliver

 

[Jonno35]

cavity closers can be found at eurocell by the way ten quid ish for a 5m lenth im sure theres a branch near you and they deliver

Cheers matey.

 

[Jonno35]

Pinnacle, do you find the cavity closers ok for fixing into with biggish hardwood frames, looks like they would be ideal for UPVC? Or do you use a few straps as well?

The two front frames are 1830mm high and 1220mm wide, toughened glass in the bottom and are 3" section (thick).

Cheers again.

 

[Pinnacle69]

to be honest a few straps wouldnt do any harm you can get different size closers dependent on cavity size to stop any lateral movement in the cavity and yes with 70mm upvc it does work well which is my main field to be honest and i tend to overdo it with the "spax" fixings !! i prefer to put a lot in, head and cill aswell, plus hardwood windows are more rigid and you are re-doing the reveals which will also hold them in . as long as the cavity closers are tight in the cavity you will not have a problem plus it has an insulation value and they are pvc so no dpc needed either cheers

 

[Jonno35]

to be honest a few straps wouldnt do any harm you can get different size closers dependent on cavity size to stop any lateral movement in the cavity and yes with 70mm upvc it does work well which is my main field to be honest and i tend to overdo it with the "spax" fixings !! i prefer to put a lot in, head and cill aswell, plus hardwood windows are more rigid and you are re-doing the reveals which will also hold them in . as long as the cavity closers are tight in the cavity you will not have a problem plus it has an insulation value and they are pvc so no dpc needed either cheers

Sounds ideal. I assume using the closers that you have would to have the windows made to more or less exact size of the opening, rather than a little wider....and then trying to get into the cavity a little and tight up the inside of the face brick/otside skin? Looks like the closers come flush with edge of inner and outer skin so getting into the cavity a little wouldn't be an option (not that that would be a problem).

 

[Pinnacle69]

thats correct they sit more or less flush with brick work so give yourself 5-10mm for clearance when plumbing up quadrants will hide the edges as well good luck i think it will look superb

 

[Jonno35]

thats correct they sit more or less flush with brick work so give yourself 5-10mm for clearance when plumbing up quadrants will hide the edges as well good luck i think it will look superb

Cheers mate, I'll let you know how it goes....top advice.

 

[stevethejoiner]

Hi,
Securing timber blocks in the cavity for your fixing points will work, we used this method for open cavity fixed frames years ago when installing hardwood frames with ali insert windows, this was prior to uPVC.
But be warned !!!
Property with cavity fixed frames will possible be quite old so the cement or even lime mortar joints and pointing could now be quite soft and weak. I recal blowing the cavity (pushing the cavity apart) You want to get the fixing blocks a nice tight fit, but a fraction too tight and you end up repointing.

Personally I would use insullated cavity closures. Dont make the hardwood frames oversize and try springing them into the cavity, your end up knocking the life out of them trying to get them to fit. Then end up knocking them out and planing wood away and banging in again. Just make them about 5mm smaller than brick reveal and use the strap method, fixing internally in the plaster reveal.
Can you move the frames just a fraction forward of the cavity, so the front edge is properly covering the brick edge, this will make pointing or mastic jointing easier. You can run a quadrant around the inside to make up the difference for moving the frames forward.
And when you make the frames, why not run a small rebate up the outside of jambs and do traditional vertical cement cut pointing line. The rebate will hold the cement pointing into the frame and stop it dropping out in the future. If the frames are not being painted you will need to oil/seal the hardwood first to stop the cement staining the wood.
With the correct ratio of water in the mix (not too wet) you can apply the pointing quite heavy onto the brick face pushing it into the wood rebate. Leave about 25mm of pointing onto the brick face, and dont worry how straight its vertical line is, as when you complete all the pointing up one side, you simply cut it off straight with the side of the trowel or float, as long as its not too wet, it will not stick or stain the bicks and the uneven excess drops off. If you like this idea, you may want too start another thread for vertical pointing tips. I am sure a bricky would advise you on that.

 

[Pinnacle69]

one more thing dont forget you will need a bigger cill 180mm instead of standard 150mm cheers