Glueing uPVC sill to existing timber sills

[wbmkk]

What is the best product to stick down uPVC sills which are being fitted directly ontop of the existing timber sills? Is silicon the best or a no nail type mastic ?

Secondly, what is fitted to the ends ? Are there special end pieces or isi
It just acase of. Urging a setup of uPVC trim and sticking it to the sill ends.

 

[TheGayOwl]

I would use either silicone or gripfill etc.

Not sure as to whether solvent free adhesive should be used as it is uPVC and may react, but I have for many years used both the above with no problems.

Some sills you can get end caps for, though I normally prefer to just try and get it looking nice n neat without them. I prefer the uPVC sills to only protrude out from the wall by 10-25mm so can usually get a decent finish. This sometimes requires cutting away the original timber sill though.

 

[Drhuid]

Greetings
I have soft wood windows which are beginning to rot at the cill.
I am thinking of trimming out the front of the cill, curing any damp, and then adding a new cill, either hardwood or UPVC along the front. I would screw the new cill in from the leading edge to secure it against frame sealant.
What is best and easiest to work with,, hardwood or UPVC?
Thanks

 

[crank39]

What is the best product to stick down uPVC sills which are being fitted directly ontop of the existing timber sills? Is silicon the best or a no nail type mastic ?

Secondly, what is fitted to the ends ? Are there special end pieces or isi
It just acase of. Urging a setup of uPVC trim and sticking it to the sill ends.

Low modulus neutral curing silicone will by far give the best results, will dry elastic so will allow for a bit of expansion and contraction, with the no nails/grip fill adhesives they all dry rock hard so a sharp knock or expansion /contraction then the glue will just pop off the pvc, either way just rough up the underside with a stanley blade to give the silicone a key.

End caps are available from the building plastics supplier where the boards came from, these just trim to size and super glue on, use glue with an activator, saves standing there for 10 mins waiting for it to grab