Under many of my windows, behind the radiator, the plaster has a hair
line crack. This is a standard wall with proper plaster, not plaster board.

I recently redecorated a room, raked out the crack filled with polyfilla
and the cracked returned within months.

The cracks never get big so it doesn't seem to be structural movement.
May be it is heat expansion.

So I hit on the idea of caulking the crack instead of filling. It is
mainly hidden behind the radiator so a minor imperfection doesn't notice.

Was this a sensible idea of will the emulsion paint crack on top of the
caulk. I just read the caulk tube and it explicitly says not to do this (.

Nick Wrote in message:
Under many of my windows, behind the radiator, the plaster has a hair
line crack. This is a standard wall with proper plaster, not plaster board.

I recently redecorated a room, raked out the crack filled with polyfilla
and the cracked returned within months.

The cracks never get big so it doesn't seem to be structural movement.
May be it is heat expansion.

So I hit on the idea of caulking the crack instead of filling. It is
mainly hidden behind the radiator so a minor imperfection doesn't notice.

Was this a sensible idea of will the emulsion paint crack on top of the
caulk. I just read the caulk tube and it explicitly says not to do this (.


Differential expansion, will always be liable to show cracks.

Could fit a trim to the edge of the windowsill to hide it, then
forget about it..
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

In article ,
Nick wrote:
So I hit on the idea of caulking the crack instead of filling. It is
mainly hidden behind the radiator so a minor imperfection doesn't notice.

Was this a sensible idea of will the emulsion paint crack on top of the
caulk. I just read the caulk tube and it explicitly says not to do this (.

Not paint over decorator's caulk? Not much point in it, then, I'd say. ;-)

My problem was cracks in the ceiling between sheets of plasterboard fitted
and skimmed in the mists of time. Polyfilla was useless - but a good caulk
has worked beautifully. But took several layers to get a good level
surface.

--
*Why isn't there mouse-flavoured cat food?

Dave Plowman London SW
To e-mail, change noise into sound.

I'kd not worry, they are just covering themselves I think. Most of the walls
in a nearby public building have this problem behind the radiators.
Didnt they used to glue some naff looking alluminium stuff over the wall to
hide it all?
Brian

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

Blind user, so no pictures please!
"Nick" wrote in message
news
Under many of my windows, behind the radiator, the plaster has a hair line
crack. This is a standard wall with proper plaster, not plaster board.

I recently redecorated a room, raked out the crack filled with polyfilla
and the cracked returned within months.

The cracks never get big so it doesn't seem to be structural movement. May
be it is heat expansion.

So I hit on the idea of caulking the crack instead of filling. It is
mainly hidden behind the radiator so a minor imperfection doesn't notice.

Was this a sensible idea of will the emulsion paint crack on top of the
caulk. I just read the caulk tube and it explicitly says not to do this
(.

Nick wrote:

Under many of my windows, behind the radiator, the plaster has a hair
line crack. This is a standard wall with proper plaster, not plaster board.

I recently redecorated a room, raked out the crack filled with polyfilla
and the cracked returned within months.

What I find works for such cracks, is to rake them out to between 5 and
10mm wide and deep, fill them level with one of those "one strike"
nanosphere fillers, when it's dried, it will in my experience still be
"a bit squidgy" so firmly tamp the filler into the crack, then re-fill
the resultant 1 or 2mm recess with a sandable filler.

Providing you haven't got any actual movement going on in the wall, that
will hold.

Brian Gaff submitted this idea :
I'kd not worry, they are just covering themselves I think. Most of the walls
in a nearby public building have this problem behind the radiators.
Didnt they used to glue some naff looking alluminium stuff over the wall to
hide it all?

No, the idea of the foil, is to try to reflect heat from the radiator
back into the room - rather than the radiator warming up the wall which
would lose heat to the outdoors.

In article ,
Harry Bloomfield wrote:
Brian Gaff submitted this idea :
I'kd not worry, they are just covering themselves I think. Most of the
walls in a nearby public building have this problem behind the
radiators. Didnt they used to glue some naff looking alluminium stuff
over the wall to hide it all?

No, the idea of the foil, is to try to reflect heat from the radiator
back into the room - rather than the radiator warming up the wall which
would lose heat to the outdoors.

What about the air rising from the rad meeting that cold wall? With
central heating rads it's convection which does most of the heating - not
radiation.

--
*Suicidal twin kills sister by mistake.

Dave Plowman London SW
To e-mail, change noise into sound.

on 29/04/2017, Dave Plowman (News) supposed :
What about the air rising from the rad meeting that cold wall? With
central heating rads it's convection which does most of the heating - not
radiation.

Yes I know, but that fact doesn't stop people selling them, nor people
buying them assuming they must work.

In message , "Dave Plowman (News)"
writes

What about the air rising from the rad meeting that cold wall? With
central heating rads it's convection which does most of the heating - not
radiation.

So should we really refer to them as convectors instead of radiators?
--
Graeme

Graeme explained :
So should we really refer to them as convectors instead of radiators?

Really, yes. They warm the air which flows past them by convection air
currents. Cool air comes in at the bottom, then collects warmth as it
rises past the radiator. The warmed air will warm the wall behind the
radiator to some extent, but alloy foil alone will not prevent that -
insulation of the wall will, so thin polystyrene sheet would be much
more effective.

In message , Harry Bloomfield
writes

The warmed air will warm the wall behind the radiator to some extent,
but alloy foil alone will not prevent that - insulation of the wall
will, so thin polystyrene sheet would be much more effective.

Yes, I have vaguely thought about a sheet of thin 3 ply behind the rad,
just with slots to hang over the brackets. Polystyrene glued to the
ply, and possibly foil glued to the polystyrene.
--
Graeme

Graeme Wrote in message:
In message , Harry Bloomfield
writes

The warmed air will warm the wall behind the radiator to some extent,
but alloy foil alone will not prevent that - insulation of the wall
will, so thin polystyrene sheet would be much more effective.

Yes, I have vaguely thought about a sheet of thin 3 ply behind the rad,
just with slots to hang over the brackets. Polystyrene glued to the
ply, and possibly foil glued to the polystyrene.

Just take the rad off & stick it all to the wall?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

In message , jim
writes
Graeme Wrote in message:

Yes, I have vaguely thought about a sheet of thin 3 ply behind the rad,
just with slots to hang over the brackets. Polystyrene glued to the
ply, and possibly foil glued to the polystyrene.

Just take the rad off & stick it all to the wall?

I am never very brave when it comes to plumbing stuff, although it all
sounds easy in theory. Turn off valves, loosen joints, catch water in
old ice cream container, job done. Hmm...

--
Graeme

In article ,
Graeme wrote:
In message , Harry Bloomfield
writes

The warmed air will warm the wall behind the radiator to some extent,
but alloy foil alone will not prevent that - insulation of the wall
will, so thin polystyrene sheet would be much more effective.

Yes, I have vaguely thought about a sheet of thin 3 ply behind the rad,
just with slots to hang over the brackets. Polystyrene glued to the
ply, and possibly foil glued to the polystyrene.

I'd love to see some test figures on how this sort of thing performs.
Given the large wall area as opposed to the bit behind the rad. My gut
feeling is you wouldn't be able to measure any difference.
If it was worthwhile, would be easy enough to make a rad which included
insulation to the rear.

--
*Heart attacks... God's revenge for eating his animal friends

Dave Plowman London SW
To e-mail, change noise into sound.

In message , "Dave Plowman (News)"
writes
In article ,
Graeme wrote:

Yes, I have vaguely thought about a sheet of thin 3 ply behind the rad,
just with slots to hang over the brackets. Polystyrene glued to the
ply, and possibly foil glued to the polystyrene.

I'd love to see some test figures on how this sort of thing performs.
Given the large wall area as opposed to the bit behind the rad. My gut
feeling is you wouldn't be able to measure any difference.

I tend to agree, which is why it is a vague thought. Given that a
radiator is really a convector, as discussed, is that much heat really
radiating out into or through the wall? The heat is mainly going
upwards, not outwards.
--
Graeme

Graeme wrote:
In message , "Dave Plowman (News)"
writes
In article ,
Graeme wrote:

Yes, I have vaguely thought about a sheet of thin 3 ply behind the rad,
just with slots to hang over the brackets. Polystyrene glued to the
ply, and possibly foil glued to the polystyrene.

I'd love to see some test figures on how this sort of thing performs.
Given the large wall area as opposed to the bit behind the rad. My gut
feeling is you wouldn't be able to measure any difference.

I tend to agree, which is why it is a vague thought. Given that a
radiator is really a convector, as discussed, is that much heat really
radiating out into or through the wall? The heat is mainly going
upwards, not outwards.

There is some heat loss through the wall behind the radiator which is
at a higher temperature than the rest of the wall. Using a foam/foil pad
will reduce this to some extent, however IMO it is not worth doing as
the dust build up will reduce the reflectivity of the foil after a few
months.

In article ,
Capitol wrote:
Graeme wrote:
In message , "Dave Plowman (News)"
writes
In article ,
Graeme wrote:

Yes, I have vaguely thought about a sheet of thinF 3 ply behind the
rad, just with slots to hang over the brackets. Polystyrene glued to
the ply, and possibly foil glued to the polystyrene.

I'd love to see some test figures on how this sort of thing performs.
Given the large wall area as opposed to the bit behind the rad. My gut
feeling is you wouldn't be able to measure any difference.

I tend to agree, which is why it is a vague thought. Given that a
radiator is really a convector, as discussed, is that much heat really
radiating out into or through the wall? The heat is mainly going
upwards, not outwards.

There is some heat loss through the wall behind the radiator which is
at a higher temperature than the rest of the wall. Using a foam/foil pad
will reduce this to some extent, however IMO it is not worth doing as
the dust build up will reduce the reflectivity of the foil after a few
months.

When I wallpapered the room, I removed the radiator and stuck baking foil
on the wall behind the radiator before repapering.

--
from KT24 in Surrey, England

"Capitol" wrote in message
news
Graeme wrote:
In message , "Dave Plowman (News)"
writes
In article ,
Graeme wrote:

Yes, I have vaguely thought about a sheet of thin 3 ply behind the rad,
just with slots to hang over the brackets. Polystyrene glued to the
ply, and possibly foil glued to the polystyrene.

I'd love to see some test figures on how this sort of thing performs.
Given the large wall area as opposed to the bit behind the rad. My gut
feeling is you wouldn't be able to measure any difference.

I tend to agree, which is why it is a vague thought. Given that a
radiator is really a convector, as discussed, is that much heat really
radiating out into or through the wall? The heat is mainly going
upwards, not outwards.

There is some heat loss through the wall behind the radiator which is at a
higher temperature than the rest of the wall. Using a foam/foil pad will
reduce this to some extent, however IMO it is not worth doing as the dust
build up will reduce the reflectivity of the foil after a few months.

Not true of foam. Still not worth doing tho, too small an area to matter.

On 28/04/2017 15:01, Dave Plowman (News) wrote:

Not paint over decorator's caulk? Not much point in it, then, I'd say. ;-)

My problem was cracks in the ceiling between sheets of plasterboard fitted
and skimmed in the mists of time. Polyfilla was useless - but a good caulk
has worked beautifully. But took several layers to get a good level
surface.


I finally did two layers of caulk before painting. There is still a
slight indent where the caulk shrank.

Anyway the experiment is on.

I noticed that every window with a radiator below has cracked vertically
behind the radiator, none of the windows without a radiator has such a
crack. Also the walls with radiators on but no window haven't cracked.
Well one wall that has a radiator both sides has cracked but I
pollyfilled it years ago and the crack never came back.

It seems there is something special about the combination of window and
radiator.

On 28/04/2017 17:55, Andy Burns wrote:

What I find works for such cracks, is to rake them out to between 5 and
10mm wide and deep, fill them level with one of those "one strike"
nanosphere fillers, when it's dried, it will in my experience still be
"a bit squidgy" so firmly tamp the filler into the crack, then re-fill
the resultant 1 or 2mm recess with a sandable filler.

Providing you haven't got any actual movement going on in the wall, that
will hold.

This will be my next strategy if the caulk fails.

Thanks.

In article ,
Nick wrote:
My problem was cracks in the ceiling between sheets of plasterboard fitted
and skimmed in the mists of time. Polyfilla was useless - but a good caulk
has worked beautifully. But took several layers to get a good level
surface.


I finally did two layers of caulk before painting. There is still a
slight indent where the caulk shrank.

Yes. As I said can take several goes to get it flat. But worth the effort,
since none of the cracks here have opened up again. As they did with any
of the regular fillers I tried before.

If only someone could produce a flexible grippy filler that didn't shrink.
;-)

--
*Dancing is a perpendicular expression of a horizontal desire *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman wrote:

If only someone could produce a flexible grippy filler that didn't shrink.

That's why I mentioned the one-strike stuff, the only thing is it
doesn't produce a plaster-smooth finish and doesn't take sanding well,
hence topping it off with something else.

replying to Nick, Dain1 wrote:
If you heat a wall up, then cool it off, then heat it up....eventually, with
all the expansion and contraction, it will crack. Because we live in rabbit
hutches someone had the bright idea of making slim rads that could be bolted
to the wall - so the walls crack.

--
for full context, visit https://www.homeownershub.com/uk-diy...r-1205324-.htm

On Monday, 8 January 2018 18:44:07 UTC, Dain1 wrote:
replying to Nick, Dain1 wrote:
If you heat a wall up, then cool it off, then heat it up....eventually, with
all the expansion and contraction, it will crack. Because we live in rabbit
hutches someone had the bright idea of making slim rads that could be bolted
to the wall - so the walls crack.

I expect it's been sorted since it was asked 8 months ago. Get yourself a sensible portal to this place.
http://wiki.diyfaq.org.uk/index.php/...up_access_tips


NT

On Sunday, 30 April 2017 02:03:51 UTC+1, Graeme wrote:
In message , Harry Bloomfield
writes

The warmed air will warm the wall behind the radiator to some extent,
but alloy foil alone will not prevent that - insulation of the wall
will, so thin polystyrene sheet would be much more effective.

Yes, I have vaguely thought about a sheet of thin 3 ply behind the rad,
just with slots to hang over the brackets. Polystyrene glued to the
ply, and possibly foil glued to the polystyrene.
--
Graeme

Proper insulators/reflectors can be bought for the purpose.
EG:-
https://www.toolstation.com/shop/p27...AurDEA Lw_wcB