I am looking to get as much head room as possible in a small toilet / shower room. The plans call for 100mm or insulation between the joists and 50mm bellow on my vented tiled roof. As it's quite a small space I was wondering if I used vacuum insulation panels between the joists is it possible to do away with the under joist insulation all together? Thanks
VIP insulation and joists
- Thread starter TKH
- Start date
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What do you mean by vacuum insulated panels? Got a link? This is a loft convertion presumably? And you mean rafters right?
Hello thanks for the reply. Yes sorry yes it is the rafters in a loft conversion. What I was looking at was this http://www.kingspaninsulation.co.uk/Products/Optim-R/Optim-R/Overview.aspx
The shows is unfortunately next to a wall only about 190 ~193 cm tall. The ceiling high does increase to 220 ~ 223 cm but sadly that has to be the entrance side. So just thought if I could gain those 5cm back it would make a massive difference to the feel and user friendliness of the room.
The shows is unfortunately next to a wall only about 190 ~193 cm tall. The ceiling high does increase to 220 ~ 223 cm but sadly that has to be the entrance side. So just thought if I could gain those 5cm back it would make a massive difference to the feel and user friendliness of the room.
In the low area, fill the space between the rafters, then put 10-20mm of spacetherm, then plasterboard. Taper to 50mm over the other part of the room, with conventional insulation.
You can buy spacetherm on ebay and it's easy to use. Those VIP panels are much more exotic, and I've never seen anyone suggest using them between joists or rafters.
You can buy spacetherm on ebay and it's easy to use. Those VIP panels are much more exotic, and I've never seen anyone suggest using them between joists or rafters.
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The issue is not so much the amount of insulation, but the elimination of the thermal bridge that the rafters will create if there was no underside insulation. This is more of an issue in bathrooms.
On the basis that the inspector will not check the insulation and less insulation for a small area is not an issue, then it would be possible to reduce the amount of underside insulation.
10mm of standard foil backed insulation would do. Not standard polystyrene though.
Whether that Spacetherm product is any better for the given thickness, you'll need to check.
On the basis that the inspector will not check the insulation and less insulation for a small area is not an issue, then it would be possible to reduce the amount of underside insulation.
10mm of standard foil backed insulation would do. Not standard polystyrene though.
Whether that Spacetherm product is any better for the given thickness, you'll need to check.
The insulation level (ultimately - thickness) only has to be 'reasonable'. You could argue that in such a small space, it would be reasonable to reduce the insulation thickness locally.
Spacetherm is roughly twice as good as mineral wool for any given thickness. It's massively more expensive though.
One of the more practical products made from it is this:
http://www.phstore.co.uk/PDF/Proctor/Proctors - Spacetherm CBS - Datasheet.pdf
http://www.phstore.co.uk/index.php?route=product/product_grouped&product_id=1552
It's a "cold bridge strip", i.e. a narrow strip that you can fix over a joist/rafter. Could be useful here.
One of the more practical products made from it is this:
http://www.phstore.co.uk/PDF/Proctor/Proctors - Spacetherm CBS - Datasheet.pdf
http://www.phstore.co.uk/index.php?route=product/product_grouped&product_id=1552
It's a "cold bridge strip", i.e. a narrow strip that you can fix over a joist/rafter. Could be useful here.
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