UPVC Window Cill Installation

[pertinky]

Hey guys,

Back with another summer of diy adventures!

I've built a little dwarf wall for a porch and I've got all the windows and door ready to fit....

I was wondering how to go about installing the cill on to the dwarf wall?

Seems some suggest floating it, others fixing it. I've got it all cut and ready to go!

At what point should I then put some frame sealant/silicone around the internal and external joints? As I understand the aim is to keep any water from getting underneath the cill. Obviously if I go down the fixing route I will need to seal any fixings that penetrate this.

 

[Gazman16]

Assuming the window is fixed on both sides top and bottom fixings are generally a bad idea as they can cause leaks.
Unless it is a very wide window that is.

 

[pertinky]

Assuming the window is fixed on both sides top and bottom fixings are generally a bad idea as they can cause leaks.
Unless it is a very wide window that is.

L shape dwarf wall so window (approx 1.3m) corner post window (approx 450mm) frame coupler door

That was pretty much my concern. Thought, if I start with the side window then there will literally be fixings on each side and nothing in between - seems too few to me.

Maybe if I fix the cill and ensure its sealed then fixings on the side should be sufficient and dont fix the top

 

[Gazman16]

I would go without a fixing to start with (you can add one later if needs be).

You could bed the cill down on a good line of silicone, Its amazing how firm that will be when it goes off.

If you do find you need to add a fixing at a later date then pre-drill through inside section (you don't want to breach the drainage channels) Countersink a bit, then hammer drill, then blow through the hole to remove dust and swalf, then pump some silicone in the hole and finally fix your screw.