Hello,

I have a garage constructed of a single brick skin with a leaky roof
(see flat roof post). I am thinking about insulating it with some
Kingspan or Celotex. Would a 50mm thick sheet be sufficient if I fix
it to all three walls and the ceiling or should I use a thicker sheet?
Or is it a waste of time, after all, the fourth wall is not a wall at
all but a door. Is any saving made by the Kingspan on three walls
going to be lost due to heat loss through the door?

Do I have to leave a gap between the kingspan and the brick? I thought
I read on this group that I should leave an air gap? Would a gap of
one or two inches be sufficient? Is this just to stop condensation on
the bricks?

I presume an air gap alone is not sufficient and that the gap requires
to be ventilated? Would having it open at the eaves be sufficient?

If I cover the Kingspan with plywood, would 12mm ply be sufficient to
withstand knocks and would it support shelves, or would I be best to
use 18mm?

Thanks.

Stephen wrote:

If I cover the Kingspan with plywood, would 12mm ply be sufficient to
withstand knocks and would it support shelves, or would I be best to
use 18mm?

I did my workshop (similar construction to your garage by the sounds of
it) with 50mm foil faced PIR foam, and 12mm ply lining. I used a
combination of squirty foam, and some 5 & 1/4" screws through the lot
into holes drilled into the brick / blockwork - you only need about 4
screws per sheet. No air gaps required. The result is plenty strong
enough to take shelves or anything else you want to mount.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Stephen wrote:
Hello,

I have a garage constructed of a single brick skin with a leaky roof
(see flat roof post). I am thinking about insulating it with some
Kingspan or Celotex. Would a 50mm thick sheet be sufficient if I fix
it to all three walls and the ceiling or should I use a thicker sheet?
Or is it a waste of time, after all, the fourth wall is not a wall at
all but a door. Is any saving made by the Kingspan on three walls
going to be lost due to heat loss through the door?

Do I have to leave a gap between the kingspan and the brick? I thought
I read on this group that I should leave an air gap? Would a gap of
one or two inches be sufficient? Is this just to stop condensation on
the bricks?

I presume an air gap alone is not sufficient and that the gap requires
to be ventilated? Would having it open at the eaves be sufficient?

If I cover the Kingspan with plywood, would 12mm ply be sufficient to
withstand knocks and would it support shelves, or would I be best to
use 18mm?

Thanks.

I did my garage/workshop by covering the walls with DPM plastic
sheeting, fixing 2x2 treated battens vertically with 1400 gaps, 8x4
sheets of 50mm polystyrene in the gaps and then 8x4 18mm shuttering ply
screwed to the battens (I trimmed the polystyrene slightly so it was
narrower than the ply). The thicker ply means I can screw almost
anything to it, almost any where.
I cut thinner celotex to fit the panels in the steel doors and stuck
them directly to the steel. A rubber wiping strip on the bottom of the
doors and some bits of rubber up the sides stop most of the draft.
I also cut polystyrene to fit between the rafters and just wedged them
in (but you need to fix your leaks first!).
I also put the boiler and DHW tank in the back of the garage, together
with a small radiator to heat the work area when needed.

So far it's been through one or two winters and has been successful

Dave

On 23 Apr, 14:59, Stephen wrote:
Hello,

I have a garage constructed of a single brick skin with a leaky roof
(see flat roof post). I am thinking about insulating it with some
Kingspan or Celotex. Would a 50mm thick sheet be sufficient if I fix
it to all three walls and the ceiling or should I use a thicker sheet?
Or is it a waste of time, after all, the fourth wall is not a wall at
all but a door. Is any saving made by the Kingspan on three walls
going to be lost due to heat loss through the door?

Do I have to leave a gap between the kingspan and the brick? I thought
I read on this group that I should leave an air gap? Would a gap of
one or two inches be sufficient? Is this just to stop condensation on
the bricks?

I presume an air gap alone is not sufficient and that the gap requires
to be ventilated? Would having it open at the eaves be sufficient?

If I cover the Kingspan with plywood, would 12mm ply be sufficient to
withstand knocks and would it support shelves, or would I be best to
use 18mm?

Thanks.

If you are converting a garage, please do make sure that you have a
good emergency exit - not an up-and-over door. My father didn't and
he died.

Rob

On Thu, 23 Apr 2009 15:21:33 +0100, John Rumm
wrote:

I did my workshop (similar construction to your garage by the sounds of
it) with 50mm foil faced PIR foam, and 12mm ply lining. I used a
combination of squirty foam, and some 5 & 1/4" screws through the lot
into holes drilled into the brick / blockwork - you only need about 4
screws per sheet. No air gaps required. The result is plenty strong
enough to take shelves or anything else you want to mount.

Thanks. I was confused about the air gap. I understand you need an air
gap when you insulate a loft space because there are timbers that need
ventilation but there are no timbers when insulating the garage walls,
so I wasn't sure if one was needed. I doubt I'll ever get the car in
there - there's too much junk in the way - but if I could lose the air
gap and use 12mm ply instead of 18mm, then that would maximise the
space. Thanks again.

On Thu, 23 Apr 2009 15:35:50 +0100, NoSpam
wrote:

I did my garage/workshop by covering the walls with DPM plastic
sheeting, fixing 2x2 treated battens vertically with 1400 gaps, 8x4
sheets of 50mm polystyrene in the gaps and then 8x4 18mm shuttering ply
screwed to the battens (I trimmed the polystyrene slightly so it was
narrower than the ply). The thicker ply means I can screw almost
anything to it, almost any where.

Sorry, I am bit unsure why did you need to use DPM?

I notice you used polystyrene rather than kingspan/celotex. I thought
realise that polystyrene is very much cheaper than celotex but I
thought it was a much poorer insulator? 50mm of polystyrene would be
equivalent to how much celotex? I won't have the advantage of a boiler
and water tank, so I wonder whether I might notice the difference?
Should I pay more for the celotex?

Polystyrene is also more flammable, so is that another good reason not
to use it?

John seems to be able to screw anything to the 12mm ply he used, so I
hope to use 12mm rather than 18mm, just to help keep the cost down. Do
you think that would work as well as your 18mm ply?

Thanks again.

On Thu, 23 Apr 2009 12:36:11 -0700 (PDT), Rob G
wrote:

If you are converting a garage, please do make sure that you have a
good emergency exit - not an up-and-over door. My father didn't and
he died.

I am very sorry to hear this.

I am not converting it as such, it was a garage before and will be a
garage after, just hopefully it won't get as cold so that the tins
won't freeze and the metal things won't get covered in condensation
and rust.

Stephen wrote:
On Thu, 23 Apr 2009 15:21:33 +0100, John Rumm
wrote:

I did my workshop (similar construction to your garage by the sounds of
it) with 50mm foil faced PIR foam, and 12mm ply lining. I used a
combination of squirty foam, and some 5 & 1/4" screws through the lot
into holes drilled into the brick / blockwork - you only need about 4
screws per sheet. No air gaps required. The result is plenty strong
enough to take shelves or anything else you want to mount.

Thanks. I was confused about the air gap. I understand you need an air
gap when you insulate a loft space because there are timbers that need
ventilation but there are no timbers when insulating the garage walls,

Yup, in a loft you not only have the timbers, but also the possibility
of water ingress should a tile slip or break. A garage wall is a much
simpler proposition.

so I wasn't sure if one was needed. I doubt I'll ever get the car in
there - there's too much junk in the way - but if I could lose the air

Yup, know that feeling!

gap and use 12mm ply instead of 18mm, then that would maximise the
space. Thanks again.

12mm seems adequate for quite reasonable loads. Give a paint with some
light coloured emulsion as well and it makes the whole space much
lighter and more inviting.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Stephen wrote:
On Thu, 23 Apr 2009 15:35:50 +0100, NoSpam
wrote:

I did my garage/workshop by covering the walls with DPM plastic
sheeting, fixing 2x2 treated battens vertically with 1400 gaps, 8x4
sheets of 50mm polystyrene in the gaps and then 8x4 18mm shuttering ply
screwed to the battens (I trimmed the polystyrene slightly so it was
narrower than the ply). The thicker ply means I can screw almost
anything to it, almost any where.

Sorry, I am bit unsure why did you need to use DPM?

To reduce the moisture entering the workshop


I notice you used polystyrene rather than kingspan/celotex. I thought
realise that polystyrene is very much cheaper than celotex but I
thought it was a much poorer insulator? 50mm of polystyrene would be
equivalent to how much celotex? I won't have the advantage of a boiler
and water tank, so I wonder whether I might notice the difference?
Should I pay more for the celotex?

You need to get the thermal conductivity figures and do the sums to
decide whether the cost is worth the performance. I stumbled over a pea
processing factory that was being dismantled so the polystyrene sheets
were free.

Polystyrene is also more flammable, so is that another good reason not
to use it?

I tested it and it appeared to have a flame retardent in it, it burnt
slightly but then went out. It's down to cost-benefit again

John seems to be able to screw anything to the 12mm ply he used, so I
hope to use 12mm rather than 18mm, just to help keep the cost down. Do
you think that would work as well as your 18mm ply?

Obviously it depends what you might want to fix to it and how it will be
fixed to the wall.

Thanks again.

On Sun, 26 Apr 2009 10:46:22 +0100, NoSpam
wrote:

John seems to be able to screw anything to the 12mm ply he used, so I
hope to use 12mm rather than 18mm, just to help keep the cost down. Do
you think that would work as well as your 18mm ply?

Obviously it depends what you might want to fix to it and how it will be
fixed to the wall.

Shelves, shelves, and more shelves!

On Sun, 26 Apr 2009 10:46:22 +0100, NoSpam
wrote:

I notice you used polystyrene rather than kingspan/celotex. I thought
realise that polystyrene is very much cheaper than celotex but I
thought it was a much poorer insulator? 50mm of polystyrene would be
equivalent to how much celotex? I won't have the advantage of a boiler
and water tank, so I wonder whether I might notice the difference?
Should I pay more for the celotex?

You need to get the thermal conductivity figures and do the sums to
decide whether the cost is worth the performance. I stumbled over a pea
processing factory that was being dismantled so the polystyrene sheets
were free.

I thought that would be a simple exercise so I went away to look for a
web site listing u values. I've now got a headache!

I've seen sheets of polystrene, kingspan, and celotex for sale in
places like Wickes and B&Q. You would think they might include
u-values in the product descriptions on their web sites but they
don't.

I visited the celotex and kingspan websites and became bewildered with
the variety of sheets they sell.

I think 50mm polystyrene has a u-value of 0.48 W/m^2K but I wasn't
sure what the difference was between expanded, blown, and extruded
polystyrenes.

I think, but I'm really not sure, that 50mm celotex has a u-value of
0.30 W/m^2K and 25mm has a u-value of 0.45 W/m^2K, in which case
celotex packs as much insulation into half the thickness.

Does 50mm Kingspan have a u-value of 0.28 W/m^2K? None of the web ites
I found made it simple to look these figures up.

I suppose I'll have to go away and work out what this all means. I
need to work out the area of my wall but then what? Select a
temperature difference and from that I can calculate a heating
requirement?

I'm confused!

In message , Stephen
writes
On Sun, 26 Apr 2009 10:46:22 +0100, NoSpam
wrote:

I notice you used polystyrene rather than kingspan/celotex. I thought
realise that polystyrene is very much cheaper than celotex but I
thought it was a much poorer insulator? 50mm of polystyrene would be
equivalent to how much celotex? I won't have the advantage of a boiler
and water tank, so I wonder whether I might notice the difference?
Should I pay more for the celotex?

You need to get the thermal conductivity figures and do the sums to
decide whether the cost is worth the performance. I stumbled over a pea
processing factory that was being dismantled so the polystyrene sheets
were free.

I thought that would be a simple exercise so I went away to look for a
web site listing u values. I've now got a headache!

The Celotex site has a calculator. You need to sign up and then remove
most of your security but it will give a printed result suitable for
presenting to building control.

regards

--
Tim Lamb

Stephen wrote:

I thought that would be a simple exercise so I went away to look for a
web site listing u values. I've now got a headache!

Any use:

http://wiki.diyfaq.org.uk/index.php?title=Heat_loss





--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Apr 26, 10:36*pm, Stephen wrote:

I've seen sheets of polystrene, kingspan, and celotex for sale in
places like Wickes and B&Q.

You'll probably get more for your money he

http://www.secondsandco.co.uk/

They've been mentioned on here several times, and I've used them and
found them fine.