As I mentioned in another thread, I have a garage with a corrugated thin
metal roof which suffers badly from condensation. Has anyone any experience
with spray-on foam insulation on such a roof, either professionally applied
or DIY? For a DIY product see for example,
http://www.spray-insulation.co.uk/ .

I've also thought about lining the roof with a thin polystyrene veneer such
as Warmaline (but would it follow the corrugations?) or using Celotex sheets
(which would create lots of air gaps) but I've been told that the foam is
the most effective way of stopping the problem.

If anyone's tried it, or has any thoughts, I'd be grateful for any info.

In message , Bert
Coules writes
As I mentioned in another thread, I have a garage with a corrugated
thin metal roof which suffers badly from condensation. Has anyone any
experience with spray-on foam insulation on such a roof, either
professionally applied or DIY? For a DIY product see for example,
http://www.spray-insulation.co.uk/ .

I've also thought about lining the roof with a thin polystyrene veneer
such as Warmaline (but would it follow the corrugations?) or using
Celotex sheets (which would create lots of air gaps) but I've been told
that the foam is the most effective way of stopping the problem.

Sheet steel roofing is available with a layer of *felt* attached to the
underside. I don't understand the mechanism but it may just retain the
condensation; allowing it to evaporate when the sun comes out.

If anyone's tried it, or has any thoughts, I'd be grateful for any info.

I've not tried it but I have heard that a fine mesh net fitted close to
the underside and trapping a layer of air can work. I think moisture in
the trapped air layer condenses but because convection is interrupted
further moisture can't reach the cold surface.

I would be surprised if your concrete slabs are not tongue and groove
and even more surprised if someone does not suggest the angle grinder
solution:-)

regards






--
Tim Lamb

Tim Lamb wrote:

Sheet steel roofing is available with a layer of *felt* attached to the
underside. I don't understand the mechanism but it may just retain the
condensation; allowing it to evaporate when the sun comes out.

Thanks for that. I'm not sure I'd be too happy about having a large expanse
of water-soaked felt just above my head...

I've not tried it but I have heard that a fine mesh net fitted close to
the underside and trapping a layer of air can work.

That's intriguing. There's enough headroom - just - to hang a Celotex or
similar ceiling below the metal roof making no contact at all with it
(except perhaps for however it was fixed). Possibly that might be the best
solution. I imagine it would also be necessary to seal off the ends of the
roof, which at the moment are just open to the air, through the troughs in
the corrugations.

I would be surprised if your concrete slabs are not tongue and groove...

This ought to be in the other thread I suppose, but judicious probing with
knife and drill into the mastic seals between the panels has revealed plain
(and not particularly close-filling in places) butt joints.

...the angle grinder solution:-)

Could still be the way, if the bolts won't budge.

Bert

Owain wrote:

Have a look at anti-condensation coatings used in shipping containers.

Thanks for that. As with the spray foam there seems to be a divide between
DIY products and professionally applied solutions. A quick search hasn't
turned up much in favour of the DIY paints, though that might simply reflect
the fact that people are usually more apt to complain than to praise.

Here's what seems to be a typical DIY product, Johnstones Anti-Condensation
Paint: http://tinyurl.com/69vrf8e . Has anyone here used it, or something
like it?

Bert

"Bert Coules" wrote in message
o.uk...
As I mentioned in another thread, I have a garage with a corrugated
thin
metal roof which suffers badly from condensation. Has anyone any
experience
with spray-on foam insulation on such a roof, either professionally
applied
or DIY? For a DIY product see for example,
http://www.spray-insulation.co.uk/ .

I've also thought about lining the roof with a thin polystyrene
veneer such
as Warmaline (but would it follow the corrugations?) or using
Celotex sheets
(which would create lots of air gaps) but I've been told that the
foam is
the most effective way of stopping the problem.

If anyone's tried it, or has any thoughts, I'd be grateful for any
info.






I had the roof (fibre reinforced corugated cement sheets) of my 2000
sq foot barn sprayed as I was using it as a workshop. I had 100mm
sprayed on the ceiling and 75mm sprayed on the walls which I then
lined with 18mm osb3 board. It has been entirely satisfactory. Mind
you it cost a fortune. Took four 205 litre drums of the foam and two
blokes 3 days.

AWEM

Andrew Mawson wrote:

I had the roof (fibre reinforced corugated cement sheets) of my 2000
sq foot barn sprayed as I was using it as a workshop... Mind
you it cost a fortune.

My garage roof is a tad more modest at 140 sq ft. Within the DIY
possibility-band, I'd have thought. Good to know it worked for you; thanks.

Bert

"Bert Coules" wrote in message
o.uk...

As I mentioned in another thread, I have a garage with a corrugated thin
metal roof which suffers badly from condensation. Has anyone any experience
with spray-on foam insulation on such a roof, either professionally applied
or DIY? For a DIY product see for example,
http://www.spray-insulation.co.uk/ .

I've also thought about lining the roof with a thin polystyrene veneer such
as Warmaline (but would it follow the corrugations?) or using Celotex sheets
(which would create lots of air gaps) but I've been told that the foam is
the most effective way of stopping the problem.

If anyone's tried it, or has any thoughts, I'd be grateful for any info.

---------------

I can vouch for the 'felt' coated sheeting. I have had it on a building with
a roof cover of approximately 30ft x 20ft for the last five years and I have
never yet seen any sign of condensation or damp on it and never a drip -
excellent in my experience. It's a very thin layer of this stuff - not
exactly felt - applied to the underside of the sheets that apparently traps
condensation and allows it to evaporate when the conditions change. It does
appear to work.

Neil

"It was im" wrote:

I can vouch for the 'felt' coated sheeting. I have had it on a building
with a roof cover of approximately 30ft x 20ft for the last five years and
I have never yet seen any sign of condensation or damp on it and never a
drip - excellent in my experience.

Neil, do you know if it's possible to apply this material (or have it
applied) to an existing plain metal roof? I must do some more searching.

Thanks very much.

Bert

I'm not sure I'd be too happy about having a large expanse of water-soaked
felt just above my head...

Tim, I'm sorry, that was an over-hasty response. Searching around, I've
discovered a custom-made felt-like membrane called Drip Stop which is
specifically designed to hold water as condensation develops and then let it
evaporate later. Clearly, this is exactly the material which you were
referring to. Unfortunately, it doesn't seem to be available as a separate
product for application to an existing roof, but only (as you also said)
prebonded to manufactured panels. Pity.

Bert

John Rumm wrote:

it sounds like a reasonable proposition for
a basically sound garage roof with not much in the way of wood about.

Yes, I agree. Not particularly cheap, though, (although if it's as
effective as they claim, that wouldn't be a major consideration) especially
once you take into account that the corrugations in the sheet metal increase
the surface area to be covered by a considerable factor.

I'm trying to find out if the water-retaining feltish membrane which Tim
Lamb mentioned can be obtained for DIY application to an existing roof. No
luck yet, though.

Bert

On 07/06/11 10:57, Bert Coules wrote:
As I mentioned in another thread, I have a garage with a corrugated thin
metal roof which suffers badly from condensation. Has anyone any
experience with spray-on foam insulation on such a roof, either
professionally applied or DIY? For a DIY product see for example,
http://www.spray-insulation.co.uk/ .

I've also thought about lining the roof with a thin polystyrene veneer
such as Warmaline (but would it follow the corrugations?) or using
Celotex sheets (which would create lots of air gaps) but I've been told
that the foam is the most effective way of stopping the problem.

If anyone's tried it, or has any thoughts, I'd be grateful for any info.





Perhaps a celotex or kingspan seconds roof under the corrugated
(where the corrugations above the kingspan are open to the air outside
amd thus ventilated and any leaks would drain out)
and the kingspan is sealed with foam like pinkgrip
so warm moist air wont get up there to condense,

[g]

George wrote:

Perhaps a celotex or kingspan seconds roof under the corrugated
(where the corrugations above the kingspan are open to the air outside
amd thus ventilated and any leaks would drain out)
and the kingspan is sealed with foam like pinkgrip
so warm moist air wont get up there to condense,

I have wondered about something like that. Would it be sufficient, do you
think, to attach the Celotex directly to the underside of the roof (which
would leave lots of individual air gaps but put the false ceiling in
intermittent contact with the real one) or should it be suspended a little
below (which would leave one overall air gap and no direct contact at all)?

Bert

On 08/06/11 22:31, Bert Coules wrote:
George wrote:

Perhaps a celotex or kingspan seconds roof under the corrugated
(where the corrugations above the kingspan are open to the air outside
amd thus ventilated and any leaks would drain out)
and the kingspan is sealed with foam like pinkgrip
so warm moist air wont get up there to condense,

I have wondered about something like that. Would it be sufficient, do
you think, to attach the Celotex directly to the underside of the roof
(which would leave lots of individual air gaps but put the false ceiling
in intermittent contact with the real one) or should it be suspended a
little below (which would leave one overall air gap and no direct
contact at all)?

Bert
perhaps if you glued battens to the metal
with pinkgrip foam or similar,
then screwed into the battens
you wouldnt puncture the roof!
[g]

George,

perhaps if you glued battens to the metal
with pinkgrip foam or similar,
then screwed into the battens
you wouldnt puncture the roof!

Thanks, but I'm not worried about puncturing the roof (Celotex even in large
sheets, is surely light enough to be glued to the metal sheeting). I just
wonder if a complete air gap would be more effective than a partial one.

Bert

In article , Bert
Coules writes
George,

perhaps if you glued battens to the metal
with pinkgrip foam or similar,
then screwed into the battens
you wouldnt puncture the roof!

Thanks, but I'm not worried about puncturing the roof (Celotex even in large
sheets, is surely light enough to be glued to the metal sheeting). I just
wonder if a complete air gap would be more effective than a partial one.

The safest bet would certainly be to stand the celotex off (under) the
roofing a tad as any water from future leaks couldn't be held in contact
with the sheeting by contact with the celotex, encouraging rust. You
could easily achieve this with a few thin pads of something stuck to the
sheets of celotex before it goes up. Side nailing into rafters would be
a common way to pin the sheets up and if you leave a slight gap then
foam could be used to seal them up and fix them in place, saving foil
taping. I'd say making the lower face of the insulation air tight to the
room was pretty important to avoid any hint of damp air reaching the
cold sheets. I reckon that seconds of 2" celotex would be about 1/3 -
1/2 the price of foaming.
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

In message , fred writes
In article , Bert
Coules writes
George,

perhaps if you glued battens to the metal
with pinkgrip foam or similar,
then screwed into the battens
you wouldnt puncture the roof!

Thanks, but I'm not worried about puncturing the roof (Celotex even in large
sheets, is surely light enough to be glued to the metal sheeting). I just
wonder if a complete air gap would be more effective than a partial one.

The safest bet would certainly be to stand the celotex off (under) the
roofing a tad as any water from future leaks couldn't be held in
contact with the sheeting by contact with the celotex, encouraging
rust. You could easily achieve this with a few thin pads of something
stuck to the sheets of celotex before it goes up. Side nailing into
rafters would be a common way to pin the sheets up and if you leave a
slight gap then foam could be used to seal them up and fix them in
place, saving foil taping. I'd say making the lower face of the
insulation air tight to the room was pretty important to avoid any hint
of damp air reaching the cold sheets. I reckon that seconds of 2"
celotex would be about 1/3 - 1/2 the price of foaming.

My experience of anything glued to the underside of metal exposed to
sunshine is that, eventually, the glue fails. Witness droopy sound
insulation in my tractor cabs:-(

regards

--
Tim Lamb

John Rumm wrote:

Although a flat panel of insulation just below the exiting roof would not
need to cover the extended "as the roof undulates" distance. Could you
afford to lose say 50mm of height?

Yes, just - and I think that what you suggest is emerging as the favourite
solution, especially given that I was planning on lining the walls too,
which would create a more-or-less completely sealed box within the original
garage structure.

Many thanks for the thoughts.

Bert

Fred wrote:

The safest bet would certainly be to stand the celotex off (under) the
roofing a tad...

Thanks for that. As you might see from my earlier reply to John Rumm, this
is definitely emerging as the favourite approach.

I reckon that seconds of 2" celotex would be about 1/3 - 1/2 the price of
foaming.

I've bought Celotex seconds in the past but I can't now remember the source.
I'll do some searching around.

Bert

Tim Lamb wrote:

My experience of anything glued to the underside of metal exposed to
sunshine is that, eventually, the glue fails.

Thanks for the warning. I think securing to the rafters and to new
battening along the sides is probably the way to go.

Bert

John Rumm wrote:

I've bought Celotex seconds in the past but I can't now remember the
source. I'll do some searching around.

One oft seen recommendation is:
http://www.secondsandco.co.uk/

Thanks for that. I found the place where I bought from previously: A&A
Insulation Services in Pontypridd: http://www.aandainsulationservices.com/ .
They've just quoted me £15 each for 2400x1200x50mm Celotex, plus £30
delivery; I'll compare that with Seconds and Co.

Out of interest, I just checked Wickes: their price is £27.98 for singles
(not seconds, of course) reducing to £19.98 each for ten or more.

Bert