Hi,

When we moved, the surveyors report said the windows had not been
finished properly. It seems that the glazing company screwed the
frames into holes in the wall and left it at that. There is no sealant
along the sides.

From what I gather, the windows were fitted circa 1981 by a company
now out of business, so I can't get them to finish the job!

OTOH nothing terrible seems to have happened in the thirty years they
have been "unfinished" but I was thinking about running some sealant
down the sides to keep rain out. I am very confused by all the
different tubes available. I have found tubes labeled "high modulus
silicone suitable for brickwork and upvc" and tubes labeled "low
modulus silicone suitable for brickwork and upvc" as well as special
glazing silicone labeled "suitable for brickwork and upvc". What are a
high and low modulus and what are they good/bad for?

Since all these tubes say they can be used on brick and upvc, does
this mean any would be suitable, or is one better than the others?
Should I use the specific glazing one?

If you have seen my recent thread about insulating a room, I knocked
off the old plaster in one room and there is a gap around the window
where I can see all the way outside! So I am thinking of using foam to
fill this space.

That will be easy in the room where I have demolished the wall but I
don't want to have to demolish the walls in the other rooms. What is
the best way to fill around the frames in the other rooms, without
disturbing the inside? I was thinking of using foam from outside but
taking care not to have it overflow onto the brickwork. What's the
best way to do this? Inject foam every foot or so?

TIA

Fred
wibbled on Wednesday 21 April 2010 09:21


That will be easy in the room where I have demolished the wall but I
don't want to have to demolish the walls in the other rooms. What is
the best way to fill around the frames in the other rooms, without
disturbing the inside? I was thinking of using foam from outside but
taking care not to have it overflow onto the brickwork. What's the
best way to do this? Inject foam every foot or so?

TIA

Hi fred,

When I installed my new windows, I only had a 1/4" gap to inject from the
outside. It is possible to get foam in there without too much ado.

Masking tape on the frames right up to the edge if you don't want to deal
with cleaning any mishaps off. Masking tape on the bricks if possible. I
couldn't - had rustic (herringbone deep surface pattern) LBCs.

Try to move the gun nozzle along at such a speed, with slow injection of
foam so that the immediate expansion of the foam lies 1/4" or so below the
surface of the frame. Foam is less sticky in the secondary expansion phase
so although parts may extrude out, leave them until dry. They mostly come
clean off.

After a day or two, use a razor sharp blade to trim any extrusion off and
finish with frame sealant over the top.

If any does get onto the bricks, leave until dry and use a bronze wire
brush, fine wire, to brush it off.

Injecting from outside is sufficient to seal against any draughts or water
ingress.

However, if the frames are securely screwed into the wall and the gap is
small, just use frame sealant. It is after all what the did in the old days
before foam.

Cheers

Tim

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

On Wed, 21 Apr 2010 11:14:34 +0100, Tim Watts wrote:

Masking tape on the frames right up to the edge if you don't want to deal
with cleaning any mishaps off. Masking tape on the bricks if possible. I
couldn't - had rustic (herringbone deep surface pattern) LBCs.

Try to move the gun nozzle along at such a speed, with slow injection of
foam so that the immediate expansion of the foam lies 1/4" or so below the
surface of the frame. Foam is less sticky in the secondary expansion phase
so although parts may extrude out, leave them until dry. They mostly come
clean off.

I have a similarly patterned brick, so it's important to keep anything
out of the grooves. I shall try the masking tape, if it will hold.

I have put foam around the window I have access to from inside and it
didn't expand explosively, so I must be getting used to applying
gentle pressure to the trigger at last I even had to put a second
layer in.

After a day or two, use a razor sharp blade to trim any extrusion off and
finish with frame sealant over the top.

If any does get onto the bricks, leave until dry and use a bronze wire
brush, fine wire, to brush it off.

Injecting from outside is sufficient to seal against any draughts or water
ingress.

However, if the frames are securely screwed into the wall and the gap is
small, just use frame sealant. It is after all what the did in the old days
before foam.

When was foam invented? I thought I had lazy installers at first but
perhaps it wasn't used in the early 1980s?

Thanks again.

Fred wrote:

OTOH nothing terrible seems to have happened in the thirty years
they have been "unfinished" but I was thinking about running some
sealant down the sides to keep rain out. I am very confused by all
the different tubes available. I have found tubes labeled "high
modulus silicone suitable for brickwork and upvc" and tubes labeled
"low modulus silicone suitable for brickwork and upvc" as well as
special glazing silicone labeled "suitable for brickwork and upvc".
What are a high and low modulus and what are they good/bad for?

For our purposes, modulus = stretchiness. So high modulus for sealing
gaps which flex and move (bathtubs, light door-frames), low modulus for more
stable gaps. For keeping rain out of the gaps above, it really doesn't
matter - any decent brand of silicone sealant will do it well enough.

In article , Steve Walker
writes
Fred wrote:

OTOH nothing terrible seems to have happened in the thirty years
they have been "unfinished" but I was thinking about running some
sealant down the sides to keep rain out. I am very confused by all
the different tubes available. I have found tubes labeled "high
modulus silicone suitable for brickwork and upvc" and tubes labeled
"low modulus silicone suitable for brickwork and upvc" as well as
special glazing silicone labeled "suitable for brickwork and upvc".
What are a high and low modulus and what are they good/bad for?

For our purposes, modulus = stretchiness. So high modulus for sealing
gaps which flex and move (bathtubs, light door-frames), low modulus for more
stable gaps. For keeping rain out of the gaps above, it really doesn't
matter - any decent brand of silicone sealant will do it well enough.

Think you have that the wrong way up, high mod is stiffer than low mod,
counter intuitive but true nonetheless.

As I think Tim has said, foaming the gap will give a good robust and
mostly airtight base and surface sealing with an _acrylic_ frame sealant
will give the o/p the option of painting over later. For the o/p,
acrylic sealants hide under many descriptions but anything that is
specified as paintable will be acrylic or a modified (paintable)
silicone and will be suitable.
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

On Wed, 21 Apr 2010 21:55:46 +0100, fred wrote:

Think you have that the wrong way up, high mod is stiffer than low mod,
counter intuitive but true nonetheless.

As I think Tim has said, foaming the gap will give a good robust and
mostly airtight base and surface sealing with an _acrylic_ frame sealant
will give the o/p the option of painting over later. For the o/p,
acrylic sealants hide under many descriptions but anything that is
specified as paintable will be acrylic or a modified (paintable)
silicone and will be suitable.

Thanks, the stiffness definition makes sense, so you choose the
sealant's modulus depending on the amount of movement in the joint.

I vaguely remember Young's modulus in physics, is that all part of the
same thing?

I am sealing around a upvc window, so there shouldn't be any movement
unless the frame expands and contracts in the sun/shade. I will be
sealing the gap between brick and upvc so I don't think that
"over-paintability" is something that is necessary for me.

Thanks again.

PS I'm not a fan of DOGS either; what's the real reason for them: to
prevent you recording their programmes?

In article , Fred

Thanks, the stiffness definition makes sense, so you choose the
sealant's modulus depending on the amount of movement in the joint.

I vaguely remember Young's modulus in physics, is that all part of the
same thing?

Pass, I looked it up at one time to work out why it appeared to be the
wrong way up and forgot the reason but remembered the practical part.

I am sealing around a upvc window, so there shouldn't be any movement
unless the frame expands and contracts in the sun/shade. I will be
sealing the gap between brick and upvc so I don't think that
"over-paintability" is something that is necessary for me.

I agree that you have what should be a low movement situation so high
modulus should do fine. It has the added benefit of being more robust
too, increased flexibility has its disadvantages. The acrylic frame
sealants are more robust still but are perhaps less flexible.

In response to your question about the before foam days, I think things
were made to closer tolerances and sticky mastic was used in place of
silicone. Going back further, my C1900 sash windows in sandstone
openings were bedded in a plaster like facing of about 20mm deep to make
up the irregular gap between window and stone (a bit like foam today)
which was weathered with mastic mortar. Nowadays, when these need
repaired the average tradesman packs the gap with highly moisture
resistant newspaper, spreads on mastic mortar and scarpers.

PS I'm not a fan of DOGS either; what's the real reason for them: to
prevent you recording their programmes?

I think content protection is the real reason although many falsehoods
are spread to justify their presence. The brand identity one I think is
the least convincing, I chose channels by content and don't have any
problem identifying which channel I am viewing. The info button is
always there for the hard of thinking or remembering. If they absolutely
must have them then C4, E4 et al seem to have a more acceptable delivery
with translucent logos that sit in the corner of the widescreen picture
rather than floating at what would be the corner of a cropped 4:3 frame.
For me the ultimate insult (in this context) is a solid white logo on
dark or night-time scenes such as with Five or Five USA, with wildly
contracting logo colours such as those on BBC3 and ITV2,3,4 coming a
close second.

Anyway, a positive outcome of my distaste for intrusive logos is that I
am watching less television and getting more done elsewhere.

Good luck with the windows.
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********