Insulation under upvc window

[Loofah]

The areas under and around most of our upvc windows get really cold. I've assumed it's just the way it is but there are a couple that get condensation (granted one is a bathroom) just a couple of inches from the window for the width of the frame.
In the pic it would be covering the sliver of tile but no further. My question is should there be any insulation at that point of is this just the way it is? It's a cavity wall built a few years ago.

 

[Swwils]

Yes there should be insulation, often left out.

It looks like your windows are set too far forward in the reveal, so if this is a typical cavity construction your tiles are touching the outer brickwork.

If this is the case then nothing you can do but insulate the reveals, or bring the window back so they are 30mm over the cavity closer.

 

[Loofah]

Full depth of the tiled area is 270mm and I believe it's a standard construction. If I understand you then I'd have to lift the tiles and insulate underneath then replace? I guess the installers have relied on the wall cavity insulation which was a foam board cut roughly to size which must have left gaps.

 

[Swwils]

Would only be able to tell from a photo outside showing where the window is placed.

Basically if you decide to have your windows very flush with the outside brickwork then you need to have insulated reveals normally.

If you don't want to insulate the reveals then you need to pull the window back so it's at least 30mm over the cavity. Often this is misquoted to be 30mm away from the front of the brickwork which is no longer correct.

So if you imagine on a 100mm of brick and a 70mm thick uPVC frame you end up with a chance that the internal finishes are attached to outside brickwork if the frame is only 30mm away from the brick face - this ignores all the insulation in the junction.

 

[Loofah]

Pic is easy enough This is the same window but all are fitted in the same manner -

 

[Loofah]

I think I understand you. Basically the window is fitted so far forward (toward the outside) that the bit of tiled sill that is getting condensation on it is sitting over a poorly insulated gap which is the wall cavity and that gap should have been properly insulated.

 

[Swwils]

The gap should be insulated but also it should not be possible for an internal finish to touch this outer brickwork. Yours almost definitely is.

So you either need to bring the window in, or insulate the entire reveals, including the gap. This would give you say 20mm of insulation thickness before your internal finish touches this block work. Since it spans the gap.

 

[Loofah]

Thanks. This is pretty standard for the builder I used, it's a constant stream of finding things like this

 

[Swwils]

Brick sill is a tricky detail to get right without preformed elements.

I also cant see any weeps or effective drainage for the window. It has some face drains and its hard to tell but the underside concealed drain has been sealed up inside?

Hopefully this window doesn't see much driven rain?

 

[Loofah]

Not sure what I'm looking for to be honest. There's holes from the inside that drain out the front which you have seen but I can't see any other drainage.

 

[Loofah]

I did some reading up to get better informed. Here's a link to read in case someone else needs it https://www.revealdoorsandwindows.c...d-secret-drained-aluminium-doors-and-windows/

I get the comment on driving rain now! Thankfully it's pretty sheltered

 

[Loofah]

If I drill through the brickwork just under the outside sill would I be able to foam fill the underside of the window? Seems the simplest way of insulating it

 

[Swwils]

No it won't resolve the issue. You need to either insulate the reveals or move the window AND do what you are suggesting which is to fix the insulation in the cavity.

 

[Loofah]

Understood. That's a pain!
Thanks for your help