Loft insulation
 

Part of our previously mentioned 17th century Norfolk cottage is a much more
recently built single storey annexe. It has a steeply pitched roof (to
match the rest of the property) and access to this roof space by a small
door in one of the bedrooms. It is wonderful storage space.

The floor timbers are standard 4" x 2" with the standard (then) 4" of
glassfibre insulation. It is loosely floored with moderately thin, but
adequate planks (the previous owner worked for Boulton and Paul and seems to
have access to an inexhaustible supply of timber).

I want to screw down these planks and make the floor more stable - but -
what should I do for insulation? Do I raise each floor timber so I can put
say 2" more insulation under the floor? Do I cram in 2" more insulation to
the existing space? How should this situation be approached - given that
funds are quite tight and I'm not really looking to spend much. I suspect
some sort of compromise will be the answer - but what?

TIA

Keith

Loft insulation
 

Keith Dunbar wrote:

I want to screw down these planks and make the floor more stable - but -
what should I do for insulation? Do I raise each floor timber so I can put
say 2" more insulation under the floor? Do I cram in 2" more insulation to
the existing space? How should this situation be approached - given that
funds are quite tight and I'm not really looking to spend much. I suspect
some sort of compromise will be the answer - but what?

Cheap answer is just screw down what you have. Better answer would be
PIR foam boards say 50mm thick laid over the joists, and the boards
screwed through them. The boards would probably cost £10 - £12 or so
each though (for a 2440x1220mm one).


--
Cheers,

John.

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

Loft insulation
 

"John Rumm" wrote in message
...
Keith Dunbar wrote:

I want to screw down these planks and make the floor more stable - but -
what should I do for insulation? Do I raise each floor timber so I can
put say 2" more insulation under the floor? Do I cram in 2" more
insulation to the existing space? How should this situation be
approached - given that funds are quite tight and I'm not really looking
to spend much. I suspect some sort of compromise will be the answer -
but what?

Cheap answer is just screw down what you have. Better answer would be PIR
foam boards say 50mm thick laid over the joists, and the boards screwed
through them. The boards would probably cost £10 - £12 or so each though
(for a 2440x1220mm one).


Right. Sounds promising, and not too expensive - given that I would only
need to put the PIR foam boards where I want to have flooring (I'm going to
put 8' x 4' sheets of chipboard on 2" x 1" timbers between rafters for the
bulk of my storage).

Two questions.
What exactly are PIR foam boards?
How does 50 mm PIR foam board compare with 4" glassfibre as insulation?

Keith

Loft insulation
 

Keith Dunbar wrote:

Right. Sounds promising, and not too expensive - given that I would only
need to put the PIR foam boards where I want to have flooring (I'm going to
put 8' x 4' sheets of chipboard on 2" x 1" timbers between rafters for the
bulk of my storage).

With rafters being the sloping bits, I am having trouble visualising this...

Two questions.
What exactly are PIR foam boards?

Polyisocyanurate foam. Common trade names are Celotex, Ecotherm,
Kingspan etc. Its a rigid foam with foil covering on each face.

How does 50 mm PIR foam board compare with 4" glassfibre as insulation?

If you take a rough estimate as it being twice as effective for a given
thickness, then the two would be comparable.


--
Cheers,

John.

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

Loft insulation
 

"John Rumm" wrote in message
...
Keith Dunbar wrote:

Right. Sounds promising, and not too expensive - given that I would only
need to put the PIR foam boards where I want to have flooring (I'm going
to put 8' x 4' sheets of chipboard on 2" x 1" timbers between rafters for
the bulk of my storage).

With rafters being the sloping bits, I am having trouble visualising
this...


You must forgive my ignorance of the names of all the funny bits of roofs
.....
(maximise screen to view this best)

|
| | | |
| | | |
| | | |
| | |
|
| | |
|
| oooooooooo | | ooooooooo |
| | | |
| |
| | | |
| |
| | | |
| |


There is just about room for a 4' width of chipboard at "ooooooooo"

Where would I be best (i.e. cheapest) going to for this PIR board? How
strong is it?
Can one stand on it? I would need lots of quite long screws to fix the
flooring to the joists.
Is there any reason why I should need to. Could I create a sort of raft of
flooring above the PIR?

Thanks so much for your help.

Keith

Loft insulation
 

On Tue, 31 Jul 2007 04:27:02 GMT, "Keith Dunbar"
wrote:


"John Rumm" wrote in message
...
Keith Dunbar wrote:

Right. Sounds promising, and not too expensive - given that I would only
need to put the PIR foam boards where I want to have flooring (I'm going
to put 8' x 4' sheets of chipboard on 2" x 1" timbers between rafters for
the bulk of my storage).

With rafters being the sloping bits, I am having trouble visualising
this...


You must forgive my ignorance of the names of all the funny bits of roofs
....
(maximise screen to view this best)

|
| | | |
| | | |
| | | |
| | |
|
| | |
|
| oooooooooo | | ooooooooo |
| | | |
| |
| | | |
| |
| | | |
| |


There is just about room for a 4' width of chipboard at "ooooooooo"

Where would I be best (i.e. cheapest) going to for this PIR board? How
strong is it?
Can one stand on it? I would need lots of quite long screws to fix the
flooring to the joists.
Is there any reason why I should need to. Could I create a sort of raft of
flooring above the PIR?

Thanks so much for your help.

Keith

Keep an eye on ebay eg:
http://cgi.ebay.co.uk/Celotex-Kingsp...QQcmdZViewItem

If you stand on it you leave a slight indentation of your foot but
with plywood covering it you wouldnt because your weight is spread.

As for screwing it down I'd suck it and see. I think that the weight
of the plywood and the friction would keep it in place. Maybe use a
marker pen to indicate werethe joists are incase you want to at a
later date. If you are planning on cutting everything up to small
pieces tto get it through a small hatch then maybe it should be
screwed down.

Loft insulation
 

Keith Dunbar wrote:

You must forgive my ignorance of the names of all the funny bits of roofs
....
(maximise screen to view this best)

THese pictures only really work if you use a non proportional (e.g.
courier) font to draw them and view them....


|
| | | |
| | | |
| | | |
| | |
|
| | |
|
| oooooooooo | | ooooooooo |
| | | |
| |
| | | |
| |
| | | |
| |


There is just about room for a 4' width of chipboard at "ooooooooo"

Where would I be best (i.e. cheapest) going to for this PIR board?

A specialist insulation provider probably. One of the outfits that can
supply "seconds" would be good for this application.

How strong is it?

Fairly stiff - stronger that expanded polystyrene for example.

Can one stand on it?

If it is laid flat on the floor then yes. If you are laying it across
joists then I would not stand over the centre of the span unless it had
a board over the top.

I would need lots of quite long screws to fix the
flooring to the joists.

Probably.

Is there any reason why I should need to. Could I create a sort of raft of
flooring above the PIR?

If you have a reasonable area of it, and the covering will remain in one
lump without fixing then a raft would work.


--
Cheers,

John.

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

Loft insulation
 

"John Rumm" wrote in message
...
Keith Dunbar wrote:

You must forgive my ignorance of the names of all the funny bits of roofs
....
(maximise screen to view this best)

THese pictures only really work if you use a non proportional (e.g.
courier) font to draw them and view them....


|
| | | |
| | | |
| | | |
| | | |
| | | |
| oooooooooo | | ooooooooo |
| | | | |
|
| | | |
| |
| | |
| | |


There is just about room for a 4' width of chipboard at "ooooooooo"

Where would I be best (i.e. cheapest) going to for this PIR board?

A specialist insulation provider probably. One of the outfits that can
supply "seconds" would be good for this application.

How strong is it?

Fairly stiff - stronger that expanded polystyrene for example.

Can one stand on it?

If it is laid flat on the floor then yes. If you are laying it across
joists then I would not stand over the centre of the span unless it had a
board over the top.

I would need lots of quite long screws to fix the flooring to the joists.

Probably.

Is there any reason why I should need to. Could I create a sort of raft
of flooring above the PIR?

If you have a reasonable area of it, and the covering will remain in one
lump without fixing then a raft would work.



Just out of interest, what is the current requirement for loft insulation -
in inches of glassfibre?

Keith

Loft insulation
 

On 30 Jul, 19:37, "Keith Dunbar" wrote:
Part of our previously mentioned 17th century Norfolk cottage is a much more
recently built single storey annexe. It has a steeply pitched roof (to
match the rest of the property) and access to this roof space by a small
door in one of the bedrooms. It is wonderful storage space.

The floor timbers are standard 4" x 2" with the standard (then) 4" of
glassfibre insulation. It is loosely floored with moderately thin, but
adequate planks (the previous owner worked for Boulton and Paul and seems to
have access to an inexhaustible supply of timber).

I want to screw down these planks and make the floor more stable - but -
what should I do for insulation? Do I raise each floor timber so I can put
say 2" more insulation under the floor? Do I cram in 2" more insulation to
the existing space? How should this situation be approached - given that
funds are quite tight and I'm not really looking to spend much. I suspect
some sort of compromise will be the answer - but what?

TIA

Keith

Dear Keith
Have you considered that 4" joinst as ceiling joists may be adequate
but as floor joists particularly storage will not be? If the span is
much more than about 10 foot you are risking deformation unless all
you are storing is light boxing.
If it is heavy storage you will need to put in stronger joists of
deeper section to avoid defection
if you just want to insulatate - the suggestions made to date are
fine.
Chris

Loft insulation
 

Loft insulation
 

wrote in message
oups.com...
On 30 Jul, 19:37, "Keith Dunbar" wrote:
Part of our previously mentioned 17th century Norfolk cottage is a much
more
recently built single storey annexe. It has a steeply pitched roof (to
match the rest of the property) and access to this roof space by a small
door in one of the bedrooms. It is wonderful storage space.

The floor timbers are standard 4" x 2" with the standard (then) 4" of
glassfibre insulation. It is loosely floored with moderately thin, but
adequate planks (the previous owner worked for Boulton and Paul and seems
to
have access to an inexhaustible supply of timber).

I want to screw down these planks and make the floor more stable - but -
what should I do for insulation? Do I raise each floor timber so I can
put
say 2" more insulation under the floor? Do I cram in 2" more insulation
to
the existing space? How should this situation be approached - given that
funds are quite tight and I'm not really looking to spend much. I
suspect
some sort of compromise will be the answer - but what?

TIA

Keith

Dear Keith
Have you considered that 4" joinst as ceiling joists may be adequate
but as floor joists particularly storage will not be? If the span is
much more than about 10 foot you are risking deformation unless all
you are storing is light boxing.
If it is heavy storage you will need to put in stronger joists of
deeper section to avoid defection
if you just want to insulatate - the suggestions made to date are
fine.
Chris

Don't the trusses that I tried to depict in an earlier post support the
ceiling/floor joists - aren't they effectively hanging from them?

Keith