Cold Reveal

[Onoff]

This is where I am with the bathroom window reveal:

 

 

Cast your minds back:

 

The generic 2G window is fixed in the outer leaf of a traditional cavity wall.

 

This is the original window. Tbh it's in very good condition but (only 'cos of this place ) I'm beginning to question it's insulating properties! 

 

The fitting was atrocious. Huge gaps all round, as in near 1" at the top.

 

 

 

Similar underneath. The gaps were just covered up with upvc trim.

 

So I Soudal foamed all 4 sides:

 

 

The cavity closers appear to be sheet steel:

 

 

In the 60mm cavity I foam gunned in 50mm chunk of eps:

 

 

Then cut flush and tidied everything to a level with a skin of mortar.

 

 

I lined all 4 sides with overlapping dpm attached by spray adhesive:

 

 

Then Sikaflexed 27mm insulated pb to all 4 sides. Note a good thick line against the window that the insulated pb pushed up against.

 

 

 

 

So why, no when I stand near the window reveal does that area feel "cold"? Not a draught per se though a thermal imaging camera might tell a different story. It's just like the whole of the reveal feels like a cooler area of air.

 

Going to check the fan light rubber seals for a start.

 

Am i maybe just feeling it as the walls either side have a vcl and are filled with pir

 

Cheers

[dpmiller]

It's the glass.

[newhome]

+1 I would say the glass too. 

[Oz07]

the window is going to be a cold area. Fair play though you've done a cracking job of the reveals. What's the dpm for don't you think this will affect bonding of the plasterboard to substrate

[ToughButterCup]

9 hours ago, Onoff said:

[...]

So why, no when I stand near the window reveal does that area feel "cold"? Not a draught per se though a thermal imaging camera might tell a different story. It's just like the whole of the reveal feels like a cooler area of air.

[...]

 

Isn't that the phenomenon which causes many to fit a radiator directly under a window?

There'll be a descending column of relatively cool air being delivered to SWMBO's feet. And, since wimmin are generally freeeeezing all year round, you'll be told about how extra cold the bathroom is (because, at the time of the complaint, her feet will be both wet and uncovered)

 

Solution: shower with slippers on. Simples!

[MikeGrahamT21]

I would say definitely the main cause is the glass, perhaps consider changing the glazing unit for the highest spec double with warm edge spacers you can get, or you may be able to change the beading and fit a 36mm triple in (depending on the frame make).

 

Another thing which I have found on our windows, is where they are located in the wall build up. I've found if they are an inch in from the edge of the external brick, our frames are a full 7-8 degrees colder than the ones which are set in around 2.5inch, basically like they used to do in the olden days when people weren't too bothered about deep sills.

[Onoff]

4 hours ago, Oz07 said:

the window is going to be a cold area. Fair play though you've done a cracking job of the reveals. What's the dpm for don't you think this will affect bonding of the plasterboard to substrate

 

I worried over that too but no, its as solid as a rock. Backed up anyway by the line of pb screws that attach the insulated pb at the top, bottom and sides into the stud frame then the rear of the pb is stuck to the window frame with EBT.

 

The dpm was lightly scuffed up a bit first with wet 'n dry and cleaned with Multisolve. Spray adhesive on the old (gloss?) painted reveals and dpm then stuck and smoothed out. Lines of EBT on the face of the dpm and the "pir" side of the pb stuck to that, braced to let dry. Idea was as a vcl and draught proofing measure. Tbh that has worked as has the vcl over the studwork wall pre the Aqua Panel and mrpb. All this though focuses the cold spots like the empty wall drain trap and bfo square of cold glass!

 

It's funny as I grew up when "double glazing" came in (White Gold on Netflix is worth a watch btw). Back then early adopters were seen as proper posh! Tbh it probably wasn't that good and the fitting left a lot to be desired. Fitters on a price, super quick at putting them in and no foam or Compriband. All the DG windows here are "gappy" like that except the two I've personally put in and the window above I've addressed.

 

 

 

 

[Onoff]

7 minutes ago, MikeGrahamT21 said:

I would say definitely the main cause is the glass, perhaps consider changing the glazing unit for the highest spec double with warm edge spacers you can get, or you may be able to change the beading and fit a 36mm triple in (depending on the frame make).

 

Another thing which I have found on our windows, is where they are located in the wall build up. I've found if they are an inch in from the edge of the external brick, our frames are a full 7-8 degrees colder than the ones which are set in around 2.5inch, basically like they used to do in the olden days when people weren't too bothered about deep sills.

 

I WAS going to take the window out and set it back in further a little while ago. "THEY" all said not to on here! 

 

Replacement glass is an option. I use a local guy. Offers nitrogen filled too I think. Just a pitta to take out the beads, measure, wait for him to make it etc. Thinking easier if going to all that trouble to get a 3G one and set it back in further.

Edited October 26, 2018 by Onoff

[Onoff]

1 hour ago, recoveringacademic said:

 

Isn't that the phenomenon which causes many to fit a radiator directly under a window?

There'll be a descending column of relatively cool air being delivered to SWMBO's feet. And, since wimmin are generally freeeeezing all year round, you'll be told about how extra cold the bathroom is (because, at the time of the complaint, her feet will be both wet and uncovered)

 

Solution: shower with slippers on. Simples!

 

There'll be a blind and the window will be right above the towel rail at least. Not forgetting virtually directly underneath the body dryer!

[MikeGrahamT21]

24 minutes ago, Onoff said:

 

I WAS going to take the window out and set it back in further a little while ago. "THEY" all said not to on here! 

 

Replacement glass is an option. I use a local guy. Offers nitrogen filled too I think. Just a pitta to take out the beads, measure, wait for him to make it etc. Thinking easier if going to all that trouble to get a 3G one and set it back in further.

 

I'd be interested to know the reasons why people say not to move it further in. The idea is to have the window form part of the insulation layer as i'm sure you know, if its mounted only an inch in from outside, you will always get some of the outer layer masonry showing through on the inside. Not sure if you have one, but this is easily measured with an IR non-contact thermometer, and as every building differs, you may be able to move it less, but choose a very cold day, with the heating on inside, i was amazed how moving ours in 5cm would make such a difference, the temperature gradient is very steep.

 

Other option is to build an outer 'frame' to surround the window and brickwork for a small area, and put some 20mm PIR inside it, then clad with something which looks really nice

[Ed Davies]

42 minutes ago, Onoff said:

Offers nitrogen filled too I think.

Roughly 78% nitrogen, 22% other gasses including small quantities of dihydrogen monoxide?

[Onoff]

17 minutes ago, MikeGrahamT21 said:

 

I'd be interested to know the reasons why people say not to move it further in. The idea is to have the window form part of the insulation layer as i'm sure you know, if its mounted only an inch in from outside, you will always get some of the outer layer masonry showing through on the inside. Not sure if you have one, but this is easily measured with an IR non-contact thermometer, and as every building differs, you may be able to move it less, but choose a very cold day, with the heating on inside, i was amazed how moving ours in 5cm would make such a difference, the temperature gradient is very steep.

 

Other option is to build an outer 'frame' to surround the window and brickwork for a small area, and put some 20mm PIR inside it, then clad with something which looks really nice

 

One future option is EWI but I only want to do that if I can get pp to change from a hip end roof to gables. Then the whole gable end would be well insulated bringing this window inside the new thermal envelope. Just looking for my IR thermometer now as it happens...

[Onoff]

2 minutes ago, Ed Davies said:

Roughly 78% nitrogen, 22% other gasses including small quantities of dihydrogen monoxide?

 

Don't know, not much on his website. Guessing just does 28mm DG. That's what the two I've fitted latterly are, these just to replace a couple of wooden  originals.

 

http://www.collinshomeimprovements.co.uk/

[ProDave]

26 minutes ago, MikeGrahamT21 said:

 

I'd be interested to know the reasons why people say not to move it further in. The idea is to have the window form part of the insulation layer as i'm sure you know, if its mounted only an inch in from outside, you will always get some of the outer layer masonry showing through on the inside. Not sure if you have one, but this is easily measured with an IR non-contact thermometer, and as every building differs, you may be able to move it less, but choose a very cold day, with the heating on inside, i was amazed how moving ours in 5cm would make such a difference, the temperature gradient is very steep.

 

Other option is to build an outer 'frame' to surround the window and brickwork for a small area, and put some 20mm PIR inside it, then clad with something which looks really nice

Normal priactice up here with a timber framed house, is the window (plus it's fire stop) forms the cavity closer so window partly into timber frame partly into blockwork skin.

[MikeGrahamT21]

8 minutes ago, Onoff said:

 

One future option is EWI but I only want to do that if I can get pp to change from a hip end roof to gables. Then the whole gable end would be well insulated bringing this window inside the new thermal envelope. Just looking for my IR thermometer now as it happens...

 

Yeah an EWI wrap around is another option if you are going down that route, i'm still undecided on EWI due to cost.

[Onoff]

17 minutes ago, MikeGrahamT21 said:

 

Yeah an EWI wrap around is another option if you are going down that route, i'm still undecided on EWI due to cost.

 

@oranjeboom just did it as a retrofit on an existing bungalow so I'll be picking his brain. He's pretty close to me too