Now that I am working in the 'back bedroom' I am becoming more keenly awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening window and the frame (it's not 'pulling to' fully). That I will take a look at shortly. But the one I want to ask about is a gap between the uPVC frame and the window cill.

This gap is pretty narrow but I think is where the cold air is coming in (from the cavity?). The inside of the frame has a hollow 'lip', about 2" wide by 1/2" deep, the lipped edge of which is supposed to be in contact with the top of the cill; but it is a few mm clear.

I can apply some sealant but because it is basically a crack, with nothing behind, I am dubious that this will be a reliable seal. The nuclear option is trying to squirt some expanding foam into volume behind the lip, but I really don't want to try that. Is there anything else I can do to improve my chances of sealing this gap?

Thanks, J^n

On Monday, 25 January 2021 at 14:58:27 UTC, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening window and the frame (it's not 'pulling to' fully). That I will take a look at shortly. But the one I want to ask about is a gap between the uPVC frame and the window cill.

This gap is pretty narrow but I think is where the cold air is coming in (from the cavity?). The inside of the frame has a hollow 'lip', about 2" wide by 1/2" deep, the lipped edge of which is supposed to be in contact with the top of the cill; but it is a few mm clear.

I can apply some sealant but because it is basically a crack, with nothing behind, I am dubious that this will be a reliable seal. The nuclear option is trying to squirt some expanding foam into volume behind the lip, but I really don't want to try that. Is there anything else I can do to improve my chances of sealing this gap?

Thanks, J^n


Go to your local DG material supplier and ask for a capping strip these come in various widths and the double glazers use them to cover any unsightly gaps usually between frame and reveal where plaster gets damaged removing old frames. I have a couple in precisely the same situation as yours.

The strips are normally secured with double sided tapes and finished off with a thin fillet of silicone the same supplier should be able to give the right tape which needs to be the foam backed type not the sellotape thin stuff.

Richard

It happens that Tricky Dicky formulated :
The strips are normally secured with double sided tapes and finished off with
a thin fillet of silicone the same supplier should be able to give the right
tape which needs to be the foam backed type not the sellotape thin stuff.

Eurocell - They have an online presence and lots of local outlets.

On Monday, January 25, 2021 at 3:10:59 PM UTC, Tricky Dicky wrote:
On Monday, 25 January 2021 at 14:58:27 UTC, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening window and the frame (it's not 'pulling to' fully). That I will take a look at shortly. But the one I want to ask about is a gap between the uPVC frame and the window cill.

This gap is pretty narrow but I think is where the cold air is coming in (from the cavity?). The inside of the frame has a hollow 'lip', about 2" wide by 1/2" deep, the lipped edge of which is supposed to be in contact with the top of the cill; but it is a few mm clear.

I can apply some sealant but because it is basically a crack, with nothing behind, I am dubious that this will be a reliable seal. The nuclear option is trying to squirt some expanding foam into volume behind the lip, but I really don't want to try that. Is there anything else I can do to improve my chances of sealing this gap?

Thanks, J^n
Go to your local DG material supplier and ask for a capping strip these come in various widths and the double glazers use them to cover any unsightly gaps usually between frame and reveal where plaster gets damaged removing old frames. I have a couple in precisely the same situation as yours.

The strips are normally secured with double sided tapes and finished off with a thin fillet of silicone the same supplier should be able to give the right tape which needs to be the foam backed type not the sellotape thin stuff.

Hmm - it is probably the very same 'capping strip' that I am referring to as the 'lip'. I suspect it was applied when these frames were retro-fitted to the property (before my time here).

My 'capping strip' seems to be solidly fixed to the main window frame. I am not sure how it is fixed - glue, perhaps.

I suppose I could either experiment with removing that where it joins the window, and/or putting a larger capping strip over the current one. I can see where there used to be a fillet of silicone which is no longer present. It's either just disintegrated or shifting window cill etc. has caused it to fail.

Food for thought, thanks.

J^n

On Monday, 25 January 2021 at 15:45:40 UTC, jkn wrote:
On Monday, January 25, 2021 at 3:10:59 PM UTC, Tricky Dicky wrote:
On Monday, 25 January 2021 at 14:58:27 UTC, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening window and the frame (it's not 'pulling to' fully). That I will take a look at shortly. But the one I want to ask about is a gap between the uPVC frame and the window cill.

This gap is pretty narrow but I think is where the cold air is coming in (from the cavity?). The inside of the frame has a hollow 'lip', about 2" wide by 1/2" deep, the lipped edge of which is supposed to be in contact with the top of the cill; but it is a few mm clear.

I can apply some sealant but because it is basically a crack, with nothing behind, I am dubious that this will be a reliable seal. The nuclear option is trying to squirt some expanding foam into volume behind the lip, but I really don't want to try that. Is there anything else I can do to improve my chances of sealing this gap?

Thanks, J^n
Go to your local DG material supplier and ask for a capping strip these come in various widths and the double glazers use them to cover any unsightly gaps usually between frame and reveal where plaster gets damaged removing old frames. I have a couple in precisely the same situation as yours.

The strips are normally secured with double sided tapes and finished off with a thin fillet of silicone the same supplier should be able to give the right tape which needs to be the foam backed type not the sellotape thin stuff.
Hmm - it is probably the very same 'capping strip' that I am referring to as the 'lip'. I suspect it was applied when these frames were retro-fitted to the property (before my time here).

My 'capping strip' seems to be solidly fixed to the main window frame. I am not sure how it is fixed - glue, perhaps.

I suppose I could either experiment with removing that where it joins the window, and/or putting a larger capping strip over the current one. I can see where there used to be a fillet of silicone which is no longer present. It's either just disintegrated or shifting window cill etc. has caused it to fail.

Food for thought, thanks.



J^n

I think you will find it is double sided tape not glue simply easier and quicker for the installers to do it that way no waiting for glue to set. It is surprising how well it sticks it was certainly the case with our windows. We had some old uPVC windows replaced that had too narrow an air gap with external beads which still used the old wooden interior cills with a wooden fillet strip to span the gap. The new windows had a covering cill (actually fascia board) siliconed over the top of the wooden cill a capping strip was used to fill the gap. How did I know it was taped on? A roofer put his foot through the bedroom ceiling and a falling piece of PB put a large dent in my brand new cill which subsequently was replaced.

Richard

On 25/01/2021 14:58, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly
awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening
window and the frame (it's not 'pulling to' fully). That I will take
a look at shortly. But the one I want to ask about is a gap between
the uPVC frame and the window cill.

The simplest temporary solution to possibly both of these is a length of
shrink wrap tubing which is soft enough to push into position and
pliable enough to make a reasonable seal. Temporary fix try cardboard.

You can get P or W profile soft foam tape with a sticky back for making
good an opening window seal. Easier than tweaking hinges in mid winter.

This gap is pretty narrow but I think is where the cold air is coming
in (from the cavity?). The inside of the frame has a hollow 'lip',
about 2" wide by 1/2" deep, the lipped edge of which is supposed to
be in contact with the top of the cill; but it is a few mm clear.

It is rather hard to visualise the profile you want to fill. But a first
try with a piece of folded paper will quickly establish if that is where
the cold draft is coming from.

I can apply some sealant but because it is basically a crack, with
nothing behind, I am dubious that this will be a reliable seal. The
nuclear option is trying to squirt some expanding foam into volume
behind the lip, but I really don't want to try that. Is there
anything else I can do to improve my chances of sealing this gap?

Sealant is usually well behaved for gaps narrower than about 5mm. Much
beyond that you might find that it is unwilling to bridge the gap.

--
Regards,
Martin Brown

Hi Martin
(you are not *the* Martin Brown, late of University of York, by any chance?

On Monday, January 25, 2021 at 4:16:41 PM UTC, Martin Brown wrote:
On 25/01/2021 14:58, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly
awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening
window and the frame (it's not 'pulling to' fully). That I will take
a look at shortly. But the one I want to ask about is a gap between
the uPVC frame and the window cill.
The simplest temporary solution to possibly both of these is a length of
shrink wrap tubing which is soft enough to push into position and
pliable enough to make a reasonable seal. Temporary fix try cardboard.

I confess that I have been considering cardboard, as you say for a temporary
fix, myself...


You can get P or W profile soft foam tape with a sticky back for making
good an opening window seal. Easier than tweaking hinges in mid winter.
This gap is pretty narrow but I think is where the cold air is coming
in (from the cavity?). The inside of the frame has a hollow 'lip',
about 2" wide by 1/2" deep, the lipped edge of which is supposed to
be in contact with the top of the cill; but it is a few mm clear.
It is rather hard to visualise the profile you want to fill. But a first
try with a piece of folded paper will quickly establish if that is where
the cold draft is coming from.

The profile is a bit like an 'el', or hockey stick shape - mostly flat with a small
lip at the end. I am pretty sure a goodly proportion of the draught is coming from there.

I can apply some sealant but because it is basically a crack, with
nothing behind, I am dubious that this will be a reliable seal. The
nuclear option is trying to squirt some expanding foam into volume
behind the lip, but I really don't want to try that. Is there
anything else I can do to improve my chances of sealing this gap?

Sealant is usually well behaved for gaps narrower than about 5mm. Much
beyond that you might find that it is unwilling to bridge the gap.

Yeah. I am thinking that I could use two applications of sealant; one to be
pushed back mostly 'inside' the gap. Then when it has dried it will form
a rear surface for the second application to be pressed against, if that makes sense...

J^n

On 25/01/2021 16:13, Tricky Dicky wrote:
On Monday, 25 January 2021 at 15:45:40 UTC, jkn wrote:
On Monday, January 25, 2021 at 3:10:59 PM UTC, Tricky Dicky wrote:
On Monday, 25 January 2021 at 14:58:27 UTC, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening window and the frame (it's not 'pulling to' fully). That I will take a look at shortly. But the one I want to ask about is a gap between the uPVC frame and the window cill.

This gap is pretty narrow but I think is where the cold air is coming in (from the cavity?). The inside of the frame has a hollow 'lip', about 2" wide by 1/2" deep, the lipped edge of which is supposed to be in contact with the top of the cill; but it is a few mm clear.

I can apply some sealant but because it is basically a crack, with nothing behind, I am dubious that this will be a reliable seal. The nuclear option is trying to squirt some expanding foam into volume behind the lip, but I really don't want to try that. Is there anything else I can do to improve my chances of sealing this gap?

Thanks, J^n
Go to your local DG material supplier and ask for a capping strip these come in various widths and the double glazers use them to cover any unsightly gaps usually between frame and reveal where plaster gets damaged removing old frames. I have a couple in precisely the same situation as yours.

The strips are normally secured with double sided tapes and finished off with a thin fillet of silicone the same supplier should be able to give the right tape which needs to be the foam backed type not the sellotape thin stuff.
Hmm - it is probably the very same 'capping strip' that I am referring to as the 'lip'. I suspect it was applied when these frames were retro-fitted to the property (before my time here).

My 'capping strip' seems to be solidly fixed to the main window frame. I am not sure how it is fixed - glue, perhaps.

I suppose I could either experiment with removing that where it joins the window, and/or putting a larger capping strip over the current one. I can see where there used to be a fillet of silicone which is no longer present. It's either just disintegrated or shifting window cill etc. has caused it to fail.

Food for thought, thanks.



J^n

I think you will find it is double sided tape not glue simply easier and quicker for the installers to do it that way no waiting for glue to set. It is surprising how well it sticks it was certainly the case with our windows. We had some old uPVC windows replaced that had too narrow an air gap with external beads which still used the old wooden interior cills with a wooden fillet strip to span the gap. The new windows had a covering cill (actually fascia board) siliconed over the top of the wooden cill a capping strip was used to fill the gap. How did I know it was taped on? A roofer put his foot through the bedroom ceiling and a falling piece of PB put a large dent in my brand new cill which subsequently was replaced.

Richard


I watched a local firm replace windows over the road. They glued the
trim strips on with superglue, then ran a bead of clear mastic at the
junction between trip strip and brickwork. This covers the 5mm gap
and hides any old paint splashes.

The internal trip strips are just to hide any damage they might have
done to the plaster removing the old window. Quick'n'Dirty.

I watched Anglian do a similar 1970's property further down the
road and they used expanding foam in the gap between frame and
window reveal, then removed the excess and then fitted the
trim strips. the expanding foam stops air leakage around the
frame which is what the OP can detect.

He could just run some white silicone into the gap and smooth
it off.

On 25 Jan 2021 at 17:12:59 GMT, "jkn" wrote:

Hi Martin
(you are not *the* Martin Brown, late of University of York, by any
chance?

On Monday, January 25, 2021 at 4:16:41 PM UTC, Martin Brown wrote:
On 25/01/2021 14:58, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly
awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening
window and the frame (it's not 'pulling to' fully). That I will take
a look at shortly. But the one I want to ask about is a gap between
the uPVC frame and the window cill.
The simplest temporary solution to possibly both of these is a length of
shrink wrap tubing which is soft enough to push into position and
pliable enough to make a reasonable seal. Temporary fix try cardboard.

I confess that I have been considering cardboard, as you say for a temporary
fix, myself...


You can get P or W profile soft foam tape with a sticky back for making
good an opening window seal. Easier than tweaking hinges in mid winter.
This gap is pretty narrow but I think is where the cold air is coming
in (from the cavity?). The inside of the frame has a hollow 'lip',
about 2" wide by 1/2" deep, the lipped edge of which is supposed to
be in contact with the top of the cill; but it is a few mm clear.
It is rather hard to visualise the profile you want to fill. But a first
try with a piece of folded paper will quickly establish if that is where
the cold draft is coming from.

The profile is a bit like an 'el', or hockey stick shape - mostly flat with a
small
lip at the end. I am pretty sure a goodly proportion of the draught is coming
from there.

I can apply some sealant but because it is basically a crack, with
nothing behind, I am dubious that this will be a reliable seal. The
nuclear option is trying to squirt some expanding foam into volume
behind the lip, but I really don't want to try that. Is there
anything else I can do to improve my chances of sealing this gap?

Sealant is usually well behaved for gaps narrower than about 5mm. Much
beyond that you might find that it is unwilling to bridge the gap.

Yeah. I am thinking that I could use two applications of sealant; one to be
pushed back mostly 'inside' the gap. Then when it has dried it will form
a rear surface for the second application to be pressed against, if that
makes sense...

J^n

I'd be inclined to use low expansion foam, then sealant over that. Sealant on
top of dried sealant doesn't sound ideal.

--
Cheers, Rob

On Monday, January 25, 2021 at 6:46:43 PM UTC, RJH wrote:
On 25 Jan 2021 at 17:12:59 GMT, "jkn" wrote:

Hi Martin
(you are not *the* Martin Brown, late of University of York, by any
chance?

On Monday, January 25, 2021 at 4:16:41 PM UTC, Martin Brown wrote:
On 25/01/2021 14:58, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly
awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening
window and the frame (it's not 'pulling to' fully). That I will take
a look at shortly. But the one I want to ask about is a gap between
the uPVC frame and the window cill.
The simplest temporary solution to possibly both of these is a length of
shrink wrap tubing which is soft enough to push into position and
pliable enough to make a reasonable seal. Temporary fix try cardboard.

I confess that I have been considering cardboard, as you say for a temporary
fix, myself...


You can get P or W profile soft foam tape with a sticky back for making
good an opening window seal. Easier than tweaking hinges in mid winter.
This gap is pretty narrow but I think is where the cold air is coming
in (from the cavity?). The inside of the frame has a hollow 'lip',
about 2" wide by 1/2" deep, the lipped edge of which is supposed to
be in contact with the top of the cill; but it is a few mm clear.
It is rather hard to visualise the profile you want to fill. But a first
try with a piece of folded paper will quickly establish if that is where
the cold draft is coming from.

The profile is a bit like an 'el', or hockey stick shape - mostly flat with a
small
lip at the end. I am pretty sure a goodly proportion of the draught is coming
from there.

I can apply some sealant but because it is basically a crack, with
nothing behind, I am dubious that this will be a reliable seal. The
nuclear option is trying to squirt some expanding foam into volume
behind the lip, but I really don't want to try that. Is there
anything else I can do to improve my chances of sealing this gap?

Sealant is usually well behaved for gaps narrower than about 5mm. Much
beyond that you might find that it is unwilling to bridge the gap.

Yeah. I am thinking that I could use two applications of sealant; one to be
pushed back mostly 'inside' the gap. Then when it has dried it will form
a rear surface for the second application to be pressed against, if that
makes sense...

J^n
I'd be inclined to use low expansion foam, then sealant over that. Sealant on
top of dried sealant doesn't sound ideal.

I do have a proper expansion foam gun ... is low expansion foam a very different
thing than the 'normal' stuff? I have never knowingly used the former.

Would it be feasible to squeeze the tube down to 5mm or so to get the foam into the
hollow area under the capping strip? It does seem that this would give a more
'structural' solution than just sealant alone.

I am in the process of cutting away the old sealant BTW, so it won't be sealant on
sealant.

Thanks, J^n

Is the upvc just a hollow U shape and bends when you put pressure on it, if
so then I agree its going to be hard to fill it. If it seems pretty solid
then sealant will work, indeed may be the only way. At least its relatively
easy to get rid of if it fails.

One might have supposed whoever fitted it would have spotted this and put
something in there to start with before finally fixing the frame in.

Its quite a common problem I've seen all sorts of things done, even a piece
of wood screwed to the front flat face of the upvc with some kind of filler
under it, but that depends on how extreme you want to get and whether you
really want to have to paint it.
Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"jkn" wrote in message
...
Now that I am working in the 'back bedroom' I am becoming more keenly awar
of the draughts in there...

There seem to be two main causes. One is a gap between the opening window
and the frame (it's not 'pulling to' fully). That I will take a look at
shortly. But the one I want to ask about is a gap between the uPVC frame and
the window cill.

This gap is pretty narrow but I think is where the cold air is coming in
(from the cavity?). The inside of the frame has a hollow 'lip', about 2"
wide by 1/2" deep, the lipped edge of which is supposed to be in contact
with the top of the cill; but it is a few mm clear.

I can apply some sealant but because it is basically a crack, with nothing
behind, I am dubious that this will be a reliable seal. The nuclear option
is trying to squirt some expanding foam into volume behind the lip, but I
really don't want to try that. Is there anything else I can do to improve my
chances of sealing this gap?

Thanks, J^n

I've seen a video on YouTube about expanding foam tape which is nothing to do with expanding foam as found in a can!

It's foam tape which is supplied in a flattened form and expands when you release it from the roll - used to seal the variable gap under a skirting board in the video I saw

A bit of an update - with a bit of judicious poking around I have determined that the capping strip ('45mm bull nose, perhaps) *is* probably superglued
to the frame - I was prying at the wrong bit! I think with gentle application of a mallet & bolster chisel I can probably knock it off quite easily.

So that will make sealing it a lot easier - I can use low-expansion foam in any gap, then refit the capping strip as if from new (or even buy as new strip, gasp)

I've also realised that the gap in the window is where the rods stuck open some years ago, and I just fitted an espag handle 'temporarily'. That might be a real pain to fix, and it is on the first floor, sigh...

Anyway, thanks for all the thoughts and suggestions

J^n

On 25 Jan 2021 at 19:57:13 GMT, "jkn" wrote:

On Monday, January 25, 2021 at 6:46:43 PM UTC, RJH wrote:
On 25 Jan 2021 at 17:12:59 GMT, "jkn" wrote:

Hi Martin
(you are not *the* Martin Brown, late of University of York, by any
chance?

On Monday, January 25, 2021 at 4:16:41 PM UTC, Martin Brown wrote:
On 25/01/2021 14:58, jkn wrote:
Now that I am working in the 'back bedroom' I am becoming more keenly
awar of the draughts in there...

There seem to be two main causes. One is a gap between the opening
window and the frame (it's not 'pulling to' fully). That I will take
a look at shortly. But the one I want to ask about is a gap between
the uPVC frame and the window cill.
The simplest temporary solution to possibly both of these is a length of
shrink wrap tubing which is soft enough to push into position and
pliable enough to make a reasonable seal. Temporary fix try cardboard.

I confess that I have been considering cardboard, as you say for a
temporary
fix, myself...


You can get P or W profile soft foam tape with a sticky back for making
good an opening window seal. Easier than tweaking hinges in mid winter.
This gap is pretty narrow but I think is where the cold air is coming
in (from the cavity?). The inside of the frame has a hollow 'lip',
about 2" wide by 1/2" deep, the lipped edge of which is supposed to
be in contact with the top of the cill; but it is a few mm clear.
It is rather hard to visualise the profile you want to fill. But a first
try with a piece of folded paper will quickly establish if that is where
the cold draft is coming from.

The profile is a bit like an 'el', or hockey stick shape - mostly flat
with a
small
lip at the end. I am pretty sure a goodly proportion of the draught is
coming
from there.

I can apply some sealant but because it is basically a crack, with
nothing behind, I am dubious that this will be a reliable seal. The
nuclear option is trying to squirt some expanding foam into volume
behind the lip, but I really don't want to try that. Is there
anything else I can do to improve my chances of sealing this gap?

Sealant is usually well behaved for gaps narrower than about 5mm. Much
beyond that you might find that it is unwilling to bridge the gap.

Yeah. I am thinking that I could use two applications of sealant; one to
be
pushed back mostly 'inside' the gap. Then when it has dried it will form
a rear surface for the second application to be pressed against, if that
makes sense...

J^n
I'd be inclined to use low expansion foam, then sealant over that. Sealant
on
top of dried sealant doesn't sound ideal.

I do have a proper expansion foam gun ... is low expansion foam a very
different
thing than the 'normal' stuff? I have never knowingly used the former.

I've got some of the Screwfix own brand cheapie in the gun right now, and it's
what I'd call 'high expansion'. The lower expansion is easier to control I
find. But I've just done a round of filling (foam into cavities/gaps then fine
filler or caulk on top) and it's gone OK - just need to be sure the flow is
just right for the gap you're filling.


Would it be feasible to squeeze the tube down to 5mm or so to get the foam
into the
hollow area under the capping strip? It does seem that this would give a more
'structural' solution than just sealant alone.

Don't see why not. Maybe try a small area first?


--
Cheers, Rob