Like someone else who posted here recently, I have a bit of second floor
which slightly overhangs the rest of the building (essentially in front
of the front door, making a covered but open porch area). I have
seriously considered a boiling oil hatch, but think I might leave that
for another day.

Currently I just have the joists there. I need to insulate it, and
cover it up, so what I was planning to do was:
- Screw some kingspan to the underside of the joists, to ensure the
joists don't act as a cold bridge.
- Screw some ply under the kingspan to cover it.
- Add some additional insulation between the joists, above the kingspan.

In fact I have a bunch of plasterboard backed kingspan offcuts that I
might use here, so would attach it plasterboard side up (so plasterboard
side faces upwards).

Does this sound like a sensible approach?

Piers

"Piers" wrote in message
...
Like someone else who posted here recently, I have a bit of second floor
which slightly overhangs the rest of the building (essentially in front of
the front door, making a covered but open porch area). I have seriously
considered a boiling oil hatch, but think I might leave that for another
day.

Currently I just have the joists there. I need to insulate it, and cover
it up, so what I was planning to do was:
- Screw some kingspan to the underside of the joists, to ensure the joists
don't act as a cold bridge.
- Screw some ply under the kingspan to cover it.
- Add some additional insulation between the joists, above the kingspan.

In fact I have a bunch of plasterboard backed kingspan offcuts that I
might use here, so would attach it plasterboard side up (so plasterboard
side faces upwards).

Does this sound like a sensible approach?

It needs insulating.
Important too that there are no gaps.
Leave a space and fill with canned foam.

In article ,
Piers writes:
Like someone else who posted here recently, I have a bit of second floor
which slightly overhangs the rest of the building (essentially in front
of the front door, making a covered but open porch area). I have
seriously considered a boiling oil hatch, but think I might leave that
for another day.

Currently I just have the joists there. I need to insulate it, and
cover it up, so what I was planning to do was:
- Screw some kingspan to the underside of the joists, to ensure the
joists don't act as a cold bridge.
- Screw some ply under the kingspan to cover it.
- Add some additional insulation between the joists, above the kingspan.

In fact I have a bunch of plasterboard backed kingspan offcuts that I
might use here, so would attach it plasterboard side up (so plasterboard
side faces upwards).

Does this sound like a sensible approach?

I lifted the floorboards above my porch, and laid fibreglass loft
insulation on top of the porch ceiling, but it sounds like you don't
have a porch ceiling? If so, do you want the timbers to still be
visible (are they part of the building style/design)? How deep are
they?

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

[Default] On Sat, 03 Aug 2013 10:48:18 +0100, a certain chimpanzee,
Piers , randomly hit the keyboard and wrote:

Like someone else who posted here recently, I have a bit of second floor
which slightly overhangs the rest of the building

- Screw some kingspan to the underside of the joists, to ensure the
joists don't act as a cold bridge.

Insulation and soffits with a low vapour permeability (e.g., rockwool)
are recommended for exposed floors. The use of impermeable materials
can hold water, especially from leaks or spills. Thermal bridging
through the joists is likely to be low; it's more likely to occur in
the walls if they carry up above the bottom of the joists - the outer
leaf suddenly becomes an inner leaf.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have I strayed"?

On 04/08/2013 20:35, Hugo Nebula wrote:
[Default] On Sat, 03 Aug 2013 10:48:18 +0100, a certain chimpanzee,
Piers , randomly hit the keyboard and wrote:

Like someone else who posted here recently, I have a bit of second floor
which slightly overhangs the rest of the building

- Screw some kingspan to the underside of the joists, to ensure the
joists don't act as a cold bridge.

Insulation and soffits with a low vapour permeability (e.g., rockwool)
are recommended for exposed floors. The use of impermeable materials
can hold water, especially from leaks or spills. Thermal bridging
through the joists is likely to be low; it's more likely to occur in
the walls if they carry up above the bottom of the joists - the outer
leaf suddenly becomes an inner leaf.


Useful comments - thanks. I'd already planned on treating the
external-internal wall as an external wall for its entire height. But
yes, it seems like i should use something permable for insulation and
then to cover.