Hello everyone,

My semi detached house loft has a loose fill material and has been floored
with normal woodchip flooring. I was thinking of upgrading the insulation
but rather than lift the flooring I thought I would put the insulation onto
the inside of the roof. Is this a good idea and what type of insulation
should I use? I envisaged using glass fibre rolls but how would I keep it in
place?
All suggestions welcome, Jackie

"Jackie" wrote in message
.uk...
Hello everyone,

My semi detached house loft has a loose fill material and has been floored
with normal woodchip flooring. I was thinking of upgrading the insulation
but rather than lift the flooring I thought I would put the insulation
onto the inside of the roof. Is this a good idea and what type of
insulation should I use? I envisaged using glass fibre rolls but how would
I keep it in place?
All suggestions welcome, Jackie

sorry I meant chipboard

Jackie wrote:

My semi detached house loft has a loose fill material and has been floored
with normal woodchip flooring. I was thinking of upgrading the insulation
but rather than lift the flooring I thought I would put the insulation onto
the inside of the roof. Is this a good idea and what type of insulation

Whether it is a good idea or not will depend on a few things...

The roof timbers need ventilation to ensure they stay dry and free from
rot. If you stick a layer of insulation under them you can potentially
cut off the air flow to them, and in time cause more serious problems.

The way round this is usually by arranging for some air flow behind the
insulation using either a breathable under tile felt, or soffit and
ridge vents.

should I use? I envisaged using glass fibre rolls but how would I keep it in
place?

One way is with a rigid PIR foam insulation board. Well known trade
names include Celotex and Kingspan, but there are plenty of other brands
that make the same stuff - often cheaper. This can be wedged into place
between rafters, and screwed to the underside of them.

There are some pictures he

http://www.internode.co.uk/loft/insulating.htm


--
Cheers,

John.

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

John Rumm wrote:
Jackie wrote:

My semi detached house loft has a loose fill material and has been
floored with normal woodchip flooring. I was thinking of upgrading the
insulation but rather than lift the flooring I thought I would put the
insulation onto the inside of the roof. Is this a good idea and what
type of insulation

Whether it is a good idea or not will depend on a few things...

The roof timbers need ventilation to ensure they stay dry and free from
rot. If you stick a layer of insulation under them you can potentially
cut off the air flow to them, and in time cause more serious problems.

The way round this is usually by arranging for some air flow behind the
insulation using either a breathable under tile felt, or soffit and
ridge vents.

One way is with a rigid PIR foam insulation board. Well known trade
names include Celotex and Kingspan, but there are plenty of other brands
that make the same stuff - often cheaper. This can be wedged into place
between rafters, and screwed to the underside of them.

There are some pictures he

http://www.internode.co.uk/loft/insulating.htm

Also have look at this Kingspan brochure, which has lots of diagrams
related to what John wrote above:
http://www.insulation.kingspan.com/n.../extras/UG.pdf

And as I mentioned in a reply to another post a few hours ago, the place
to buy cheap insulation board from is:
http://www.secondsandco.co.uk/

David

wrote:

I have a low pitched roof boarded out for storage. It only has 50mm of
fibreglass insulation. I don't want to insulate the rafters as it will reduce
the headroom, and will be difficult to ventilate. I could get 90mm kingspan
(or equivalent) under the boarding (floor) between the (ceiling) joists,
possibly supplemented with 50mm above the joists. Are there any pitfalls in
this approach?

It will work... Remember that the better insulated it is, the colder it
will get. That means you will need to take more care preventing any
tanks/pipes from freezing (that will apply pretty much to any insulation
you fit).

The solid panels obviously need to be cut to fit (which is the advantage
of the fibreglass stuff - you can stick that in quite quickly), the ones
over the joists however can just be screwed down in a few places and
then the boards laid directly on them (it is quite tough in compression)


--
Cheers,

John.

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

In message , John
Rumm writes
wrote:

I have a low pitched roof boarded out for storage. It only has 50mm of
fibreglass insulation. I don't want to insulate the rafters as it will reduce
the headroom, and will be difficult to ventilate. I could get 90mm kingspan
(or equivalent) under the boarding (floor) between the (ceiling) joists,
possibly supplemented with 50mm above the joists. Are there any pitfalls in
this approach?

It will work... Remember that the better insulated it is, the colder it
will get. That means you will need to take more care preventing any
tanks/pipes from freezing (that will apply pretty much to any
insulation you fit).

The solid panels obviously need to be cut to fit (which is the
advantage of the fibreglass stuff - you can stick that in quite
quickly), the ones over the joists however can just be screwed down in
a few places and then the boards laid directly on them (it is quite
tough in compression)



I only have one layer of (off the top of my head around 40-50mm)
fibreglass loft insulation. I've boarded half the loft (screws, so can
be moved), and I'm thinking about improving the insulation, both because
the house gets bloody cold upstairs in winter and also because of fuel
costs. Does anybody have any links that point to the relative efficiency
of insulation methods. I will be going for the floor insulation as I
also don't want to lose headroom, and would like to know how my rough
and ready current fibreglass compares against the above boarding, and
also how a floored loft (standard shed loft chipboard) compares against
non-floored (hey even chipboard must insulate to some extent!). A quick
google didn't find any straightforward links.

--
Mike Buckley
RD350LC2
http://www.toastyhamster.org
BONY#38

mike. buckley wrote:

I only have one layer of (off the top of my head around 40-50mm)
fibreglass loft insulation. I've boarded half the loft (screws, so can
be moved), and I'm thinking about improving the insulation, both because
the house gets bloody cold upstairs in winter and also because of fuel
costs. Does anybody have any links that point to the relative efficiency
of insulation methods. I will be going for the floor insulation as I

Good load of figures in this document:

http://www.sheffins.co.uk/building_r...FULL%20DOC.pdf

for the fibreglass stuff:

http://www.isowool.com/pdfs/Loft%20Insulation.pdf

(note they are showing figures for two layers of (thicker) wool that you
have)

also don't want to lose headroom, and would like to know how my rough
and ready current fibreglass compares against the above boarding, and
also how a floored loft (standard shed loft chipboard) compares against
non-floored (hey even chipboard must insulate to some extent!). A quick
google didn't find any straightforward links.

Adding flooring to an uninsulated loft will help (more by virtue of ther
trapped layer of air than the chipboard itself), however compared to a
real insualting product the chipboard iteself is relatively insignificant.

--
Cheers,

John.

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

In message , John
Rumm writes

Good load of figures in this document:

http://www.sheffins.co.uk/building_r...FULL%20DOC.pdf

for the fibreglass stuff:

http://www.isowool.com/pdfs/Loft%20Insulation.pdf

(note they are showing figures for two layers of (thicker) wool that
you have)


That's interesting thanks.

I've had a look in my loft and I seem to have variable joist widths
(3400-3700mm), but I reckon I'll be able to cram better insulation in
than I currently have. The property (1938 semi) has been re-roofed at
some point, and a lot of debri has been left over the plaster which the
current fibreglass rolls are sitting on.

I had a look in one of the sheds at lunch and they had 150mm, 170mm and
200mm rolls, but when they are wrapped up they feel nothing like that
size! I think I'll probably get a couple of rolls and see how it goes,
the site above assumes double layer over the joists, but I want to put
chipboard down, so that's not an option for me. Hopefully with the more
modern foil backed fibreglass I'll get better insulation than the
current fairly haphazard fibreglass.

--
Mike Buckley

Mike Buckley wrote:

I had a look in one of the sheds at lunch and they had 150mm, 170mm and
200mm rolls, but when they are wrapped up they feel nothing like that
size! I think I'll probably get a couple of rolls and see how it goes,
the site above assumes double layer over the joists, but I want to put
chipboard down, so that's not an option for me. Hopefully with the more

You could fill between the joists with the fibreglass, but then lay a
ridgid panel right over the joists and put the chipboard down on that.
(a bit like you make flat roofs these days).

modern foil backed fibreglass I'll get better insulation than the
current fairly haphazard fibreglass.

Much of the stuff is not foil backed (unless you explicitly go looking
fot it!). There not not much point compressing more into the joist space
than fits normally, since it is the trapped air that does a fair amount
of the insulating)


--
Cheers,

John.

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

In message , John
Rumm writes
Mike Buckley wrote:

I had a look in one of the sheds at lunch and they had 150mm, 170mm
and 200mm rolls, but when they are wrapped up they feel nothing like
that size! I think I'll probably get a couple of rolls and see how it
goes, the site above assumes double layer over the joists, but I want
to put chipboard down, so that's not an option for me. Hopefully with


You could fill between the joists with the fibreglass, but then lay a
ridgid panel right over the joists and put the chipboard down on that.
(a bit like you make flat roofs these days).
Hmm, need some long screws to secure it all - but that sounds a good
idea.

modern foil backed fibreglass I'll get better insulation than the
current fairly haphazard fibreglass.

Much of the stuff is not foil backed (unless you explicitly go looking
fot it!). There not not much point compressing more into the joist
space than fits normally, since it is the trapped air that does a fair
amount of the insulating)
I just randomly looked at the first stuff I came to in the shed, it was
foil backed and plastic wrapped, which you just lay down in the joist
space and cut the ends as necessary. The rest of the stuff was about 3
miles up on the top shelf, so I could see neither price nor quality.
Trip to a builders merchant methinks.

Thanks for the advice.

--
Mike Buckley