I've been following various threads here over the months about
insulating lofts, but none of them quite seem to answer my question.

I've already got Rockwool type material laid between the ceiling joists,
which gives a nominal four inches, this is now in the process of being
boarded over for a combination of storage and a hobby area. However,
partly to increase the overall insulation, and partly to reduce the
extremes of temperature in the loft, I want to insulate the underside of
the roof. My idea is to fasten some form of sheet material to the
underside to the roof joists (4x2s), with a flat section at the top
(overall I've got about 8ft of headroom in the main area), thus leaving
an air gap above it.

Now the question is, what would the panel recommend that I use ?. A
Kingspan type material looks good (but there appear to be several
grades), as it weighs very little (so little extra weight on the
timbers), and the foil finish should reflect some of the light, but are
there better alternatives ?


TIA

Adrian
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On Mar 4, 2:09 pm, Adrian Simpson wrote:
I've been following various threads here over the months about
insulating lofts, but none of them quite seem to answer my question.

I've already got Rockwool type material laid between the ceiling joists,
which gives a nominal four inches, this is now in the process of being
boarded over for a combination of storage and a hobby area. However,
partly to increase the overall insulation, and partly to reduce the
extremes of temperature in the loft, I want to insulate the underside of
the roof. My idea is to fasten some form of sheet material to the
underside to the roof joists (4x2s), with a flat section at the top
(overall I've got about 8ft of headroom in the main area), thus leaving
an air gap above it.

Now the question is, what would the panel recommend that I use ?. A
Kingspan type material looks good (but there appear to be several
grades), as it weighs very little (so little extra weight on the
timbers), and the foil finish should reflect some of the light, but are
there better alternatives ?

Since the roof space needs a lot of venting, you will need to have the
eaves open all the time. Therefore insulating the roof is going to be
a waste of time.

A huge amount of moisture rises from the living quarters into the
void. Sealing it will cause too much condensation to build up in the
attic.

Weatherlawyer wrote:

I've been following various threads here over the months about
insulating lofts, but none of them quite seem to answer my question.

Since the roof space needs a lot of venting, you will need to have the
eaves open all the time. Therefore insulating the roof is going to be
a waste of time.

A huge amount of moisture rises from the living quarters into the
void. Sealing it will cause too much condensation to build up in the
attic.

I have a slightly different query -
I'd like to improve the insulation in a roof-space
where there is no flooring, just joists,
and I am wondering if there is a simple way of blowing insulating material
into the space?
(There is some fibre-glass insulation between the joists now,
but it rather thin.)


--
Timothy Murphy
e-mail (80k only): tim /at/ birdsnest.maths.tcd.ie
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland

Adrian Simpson wrote:
I've been following various threads here over the months about
insulating lofts, but none of them quite seem to answer my question.

I've already got Rockwool type material laid between the ceiling joists,
which gives a nominal four inches, this is now in the process of being
boarded over for a combination of storage and a hobby area. However,
partly to increase the overall insulation, and partly to reduce the
extremes of temperature in the loft, I want to insulate the underside of
the roof. My idea is to fasten some form of sheet material to the
underside to the roof joists (4x2s), with a flat section at the top
(overall I've got about 8ft of headroom in the main area), thus leaving
an air gap above it.

Now the question is, what would the panel recommend that I use ?. A
Kingspan type material looks good (but there appear to be several
grades), as it weighs very little (so little extra weight on the
timbers), and the foil finish should reflect some of the light, but are
there better alternatives ?


TIA

Adrian

50mm celotex between the joists should leave you the required 50mm gap
between it and the roof tiles. Easy to cut with a handsaw, but a bit pricey

Many years ago - 14 I recall - I did my loft. I used 2 inch 8 ft x 4
ft polystyrene panels which I cut with a hot wire cutter - car battery
and a bit of wire - into strips that fitted snugly between 4 x 2
joists, leaving a 2 inch air gap above to the roofing felt. Below I
used the blue membrane to seal followed by plasterboard. It has been
fine. No doubt if I was doing it again there are better materials on
the market such as the kingspan.

Timothy Murphy wrote:
Weatherlawyer wrote:

I've been following various threads here over the months about
insulating lofts, but none of them quite seem to answer my question.

Since the roof space needs a lot of venting, you will need to have the
eaves open all the time. Therefore insulating the roof is going to be
a waste of time.

A huge amount of moisture rises from the living quarters into the
void. Sealing it will cause too much condensation to build up in the
attic.

I have a slightly different query -
I'd like to improve the insulation in a roof-space
where there is no flooring, just joists,
and I am wondering if there is a simple way of blowing insulating material
into the space?

Sure, if you don't mind it continuing to blow about every time there's a
breeze.


(There is some fibre-glass insulation between the joists now,
but it rather thin.)



Can't get much easier than rolling out some extra fibreglass, or get
someone in for £200-£300.

In article ,
Stuart Noble writes:

Sure, if you don't mind it continuing to blow about every time there's a
breeze.

In the recent gales we had, all the gardens around me were left
with large wet clumps of fibreglass insulation dotted around.
No idea whose house it came from.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article .com,
"Weatherlawyer" writes:

Since the roof space needs a lot of venting, you will need to have the
eaves open all the time. Therefore insulating the roof is going to be
a waste of time.

A huge amount of moisture rises from the living quarters into the
void.

Not unless you've got lots of holes through the ceiling,
badly fitting loft hatch, etc, in which case repair them.
Air/Moisture transfer through plasterboard itself is
insignificant.

Sealing it will cause too much condensation to build up in the
attic.

The attic won't be cold anymore.

You will need to ventilate on the cold side of the new insulation.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
Stuart Noble writes:

50mm celotex between the joists should leave you the required 50mm gap
between it and the roof tiles. Easy to cut with a handsaw, but a bit pricey

Since this isn't needed for any Building Control regulatory reasons,
you could pick up seconds from ebay or the like. A friend did this
a couple of years ago, and got it much cheaper. Might want to check
it's fire resistant though.

If you don't mind losing an inch or so, 25mm sheets fixed under the
rafters would give continuous runs. Could combine that with 25 or
50mm between rafters as Stuart says.

BTW, I found the bread knife was best for cutting it!

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Mar 4, 3:26 pm, wrote:
Many years ago - 14 I recall - I did my loft. I used 2 inch 8 ft x 4
ft polystyrene panels which I cut with a hot wire cutter - car battery
and a bit of wire - into strips that fitted snugly between 4 x 2
joists, leaving a 2 inch air gap above to the roofing felt. Below I
used the blue membrane to seal followed by plasterboard. It has been
fine. No doubt if I was doing it again there are better materials on
the market such as the kingspan.

Your health hazard is a major fire risk too.

On 04 Mar 2007 16:53:42 GMT, (Andrew
Gabriel) wrote:

In article .com,
"Weatherlawyer" writes:

Since the roof space needs a lot of venting, you will need to have the
eaves open all the time. Therefore insulating the roof is going to be
a waste of time.

A huge amount of moisture rises from the living quarters into the
void.

Not unless you've got lots of holes through the ceiling,
badly fitting loft hatch, etc, in which case repair them.
Air/Moisture transfer through plasterboard itself is
insignificant.

Thats only correct if the plasterboard is moisture resisting ie with
aluminium foil on the reverse side.

Andrew Gabriel wrote:
In article ,
Stuart Noble writes:
50mm celotex between the joists should leave you the required 50mm gap
between it and the roof tiles. Easy to cut with a handsaw, but a bit pricey

Since this isn't needed for any Building Control regulatory reasons,
you could pick up seconds from ebay or the like. A friend did this
a couple of years ago, and got it much cheaper. Might want to check
it's fire resistant though.

If you don't mind losing an inch or so, 25mm sheets fixed under the
rafters would give continuous runs. Could combine that with 25 or
50mm between rafters as Stuart says.

BTW, I found the bread knife was best for cutting it!


I didn't want to jeopardise the lunchtime sandwiches:-)
An old handsaw worked well for me

In article ,
FKruger writes:
On 04 Mar 2007 16:53:42 GMT, (Andrew
Gabriel) wrote:

In article .com,
"Weatherlawyer" writes:
A huge amount of moisture rises from the living quarters into the
void.

Not unless you've got lots of holes through the ceiling,
badly fitting loft hatch, etc, in which case repair them.
Air/Moisture transfer through plasterboard itself is
insignificant.

Thats only correct if the plasterboard is moisture resisting ie with
aluminium foil on the reverse side.

No, it's true regardless. The amount of air which will permeate
a sheet of plasterboard is completely insignificant compared with
any tiny amount of loft ventilation. Moisture gets into lofts
in air through cracks, oversized pipework/cable holes, badly
fitting loft hatches, recessed downlighter holes, etc.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article .com,
Weatherlawyer writes
On Mar 4, 2:09 pm, Adrian Simpson wrote:
I've been following various threads here over the months about
insulating lofts, but none of them quite seem to answer my question.

I've already got Rockwool type material laid between the ceiling joists,
which gives a nominal four inches, this is now in the process of being
boarded over for a combination of storage and a hobby area. However,
partly to increase the overall insulation, and partly to reduce the
extremes of temperature in the loft, I want to insulate the underside of
the roof. My idea is to fasten some form of sheet material to the
underside to the roof joists (4x2s), with a flat section at the top
(overall I've got about 8ft of headroom in the main area), thus leaving
an air gap above it.

Now the question is, what would the panel recommend that I use ?. A
Kingspan type material looks good (but there appear to be several
grades), as it weighs very little (so little extra weight on the
timbers), and the foil finish should reflect some of the light, but are
there better alternatives ?

Since the roof space needs a lot of venting, you will need to have the
eaves open all the time. Therefore insulating the roof is going to be
a waste of time.

A huge amount of moisture rises from the living quarters into the
void. Sealing it will cause too much condensation to build up in the
attic.


The roof space is a "L" shape, with vented soffits on the two longs
sides (the short sides come down to a flat roof), with a gable at one
end, and the party wall at the other, so there is currently some
ventilation from the gable (a gap big enough to get your hand through).
The section running across to the party wall has plenty of height, hence
the idea of placing the insulation on the underside of the timber,
rather than in the gap (makes it easier to do as well)

The existing ceiling is the original 1939 plaster board, so how moisture
proof that is I don't know. There are very few holes in it, apart from
where the cables for the light fittings go through, the only others are
the ducting from the bathroom, and the hatch itself, which is a fairly
good fit (although some draught strip to help it seal would be no bad
thing).

I don't think insulating the roof is entirely a waste of time though.
Bearing in mind the main reason for doing it to allow it to be used for
a hobby room, in the summer it gets very hot up there, I would hope the
insulation will do something to help regulate that, and in the winter, I
think with the aid of a small fan heater, it will be moderately
bearable.

Comments about the fire risk (particularly with polystyrene) elsewhere
in the thread are noted.


Adrian
--
To Reply :
replace "news" with "adrian" and "nospam" with "ffoil"
Sorry for the rigmarole, If I want spam, I'll go to the shops
Every time someone says "I don't believe in trolls", another one dies.

Stuart Noble wrote:

Andrew Gabriel wrote:

In article ,
Stuart Noble writes:

50mm celotex between the joists should leave you the required 50mm
gap between it and the roof tiles. Easy to cut with a handsaw, but a
bit pricey


Since this isn't needed for any Building Control regulatory reasons,
you could pick up seconds from ebay or the like. A friend did this
a couple of years ago, and got it much cheaper. Might want to check
it's fire resistant though.

If you don't mind losing an inch or so, 25mm sheets fixed under the
rafters would give continuous runs. Could combine that with 25 or
50mm between rafters as Stuart says.

BTW, I found the bread knife was best for cutting it!


I didn't want to jeopardise the lunchtime sandwiches:-)
An old handsaw worked well for me

I was told that using an electric carving knife was the quickest and
easiest way.

Dave

Dave wrote:
Stuart Noble wrote:

Andrew Gabriel wrote:

In article ,
Stuart Noble writes:

50mm celotex between the joists should leave you the required 50mm
gap between it and the roof tiles. Easy to cut with a handsaw, but a
bit pricey


Since this isn't needed for any Building Control regulatory reasons,
you could pick up seconds from ebay or the like. A friend did this
a couple of years ago, and got it much cheaper. Might want to check
it's fire resistant though.

If you don't mind losing an inch or so, 25mm sheets fixed under the
rafters would give continuous runs. Could combine that with 25 or
50mm between rafters as Stuart says.

BTW, I found the bread knife was best for cutting it!


I didn't want to jeopardise the lunchtime sandwiches:-)
An old handsaw worked well for me

I was told that using an electric carving knife was the quickest and
easiest way.

Dave

Anything with teeth cuts it really quickly, and it's easy to shave a few
mm off too. Put another way, it's not like trying to cut foam rubber

Stuart Noble wrote:
Dave wrote:
Stuart Noble wrote:

Andrew Gabriel wrote:

In article ,
Stuart Noble writes:

50mm celotex between the joists should leave you the required 50mm
gap between it and the roof tiles. Easy to cut with a handsaw, but
a bit pricey


Since this isn't needed for any Building Control regulatory reasons,
you could pick up seconds from ebay or the like. A friend did this
a couple of years ago, and got it much cheaper. Might want to check
it's fire resistant though.

If you don't mind losing an inch or so, 25mm sheets fixed under the
rafters would give continuous runs. Could combine that with 25 or
50mm between rafters as Stuart says.

BTW, I found the bread knife was best for cutting it!


I didn't want to jeopardise the lunchtime sandwiches:-)
An old handsaw worked well for me
I was told that using an electric carving knife was the quickest and
easiest way.
Dave

Anything with teeth cuts it really quickly, and it's easy to shave a
few mm off too. Put another way, it's not like trying to cut foam rubber


An old hardpoint saw with the set ground off the sides of the teeth
works pretty well. It cuts straight and fast, but with a very narrow
kerf more like a knife.


--
Ian White

"Weatherlawyer" wrote in message
oups.com...
On Mar 4, 3:26 pm, wrote:
Many years ago - 14 I recall - I did my loft. I used 2 inch 8 ft x 4
ft polystyrene panels which I cut with a hot wire cutter - car battery
and a bit of wire - into strips that fitted snugly between 4 x 2
joists, leaving a 2 inch air gap above to the roofing felt. Below I
used the blue membrane to seal followed by plasterboard. It has been
fine. No doubt if I was doing it again there are better materials on
the market such as the kingspan.

Your health hazard is a major fire risk too.


Anyone use this?


http://www.spray-insulation.co.uk/DIY.htm


Seems a tad expensive but I wonder if it would be suitable to use between
the joists as I can then board the loft isntead of either squishing
the -now- glassfibre or getting some Kingspan

Thoughts?

Cheers

Richard

On Tue, 06 Mar 2007 18:00:05 GMT, "r.bartlett"
wrote:


"Weatherlawyer" wrote in message
roups.com...
On Mar 4, 3:26 pm, wrote:
Many years ago - 14 I recall - I did my loft. I used 2 inch 8 ft x 4
ft polystyrene panels which I cut with a hot wire cutter - car battery
and a bit of wire - into strips that fitted snugly between 4 x 2
joists, leaving a 2 inch air gap above to the roofing felt. Below I
used the blue membrane to seal followed by plasterboard. It has been
fine. No doubt if I was doing it again there are better materials on
the market such as the kingspan.

Your health hazard is a major fire risk too.


Anyone use this?


http://www.spray-insulation.co.uk/DIY.htm


Seems a tad expensive but I wonder if it would be suitable to use between
the joists as I can then board the loft isntead of either squishing
the -now- glassfibre or getting some Kingspan

Thoughts?

Cheers

Richard



This is a really good idea. Not.

All of the application illustrations show examples where controlling
the thickness of the sprayed gunk doesn't matter.

You would have real fun cutting it back in order to board over the
top.

It's probably a job better left to the professionals - apparently they
are going to regulate its use.....


--

..andy