The upstairs external walls of our house have a narrow cavity - too
narrow to be filled when we had cavity wall insulation downstairs.

I'm about to redo the bathroom and I'm considering beefing up the
insulation with Kingspan under plasterboard.

I've got some sheets of Kingspan left over from a previous job so I
don't particularly want to buy the ready-bonded Kingspan/plasterboard
combo. Because it's a small, I don't want to lose a lot of floor area
building stud walls, battening or dot and dabbing.

Is there a cheap, easy way to do this that doesn't lose an inch or two
of room space? A suitable cartridge adhesive or hammer in fixings
maybe?

The end result will be tiled over.

On Monday, 17 September 2012 10:57:09 UTC+1, mike wrote:
I'm about to redo the bathroom and I'm considering beefing up the
insulation with Kingspan under plasterboard.

Same here. Celotex's web site has some nice illustrated constructional suggestions.

OTOH, I read all their suggestions carefully, then ignored them. I'm using half the thickness, with cold bridges around my studs. It means I lose about 2" on the room, not 5".

On Monday, September 17, 2012 10:57:09 AM UTC+1, mike wrote:
Because it's a small, I don't want to lose a lot of floor area
building stud walls, battening or dot and dabbing.


Why would studs reduce the floor area? You could use studs that are the same thickness as your Kingspan. wedge the kingspan between them and tape over the joins and studs (vapour barrier), then plasterboard.

Robert

On Monday, 17 September 2012 12:05:45 UTC+1, RobertL wrote:
Why would studs reduce the floor area?

The "official" line is that studs are cold bridges. So you need two layers of board and studs, with the studs crossed. You also need to size the thickness, such that single layer board thickness under the studs is still adequate. This turns into quite a thick package.

On 17/09/12 12:12, Andy Dingley wrote:
On Monday, 17 September 2012 12:05:45 UTC+1, RobertL wrote:
Why would studs reduce the floor area?

The "official" line is that studs are cold bridges. So you need two layers of board and studs, with the studs crossed. You also need to size the thickness, such that single layer board thickness under the studs is still adequate. This turns into quite a thick package.


dont use studs, stck it with dryfix
http://www.youtube.com/watch?v=WHJ2Iy60BWI
?

[george]

On Mon, 17 Sep 2012 02:57:09 -0700 (PDT), mike
wrote:

Is there a cheap, easy way to do this that doesn't lose an inch or two
of room space? A suitable cartridge adhesive or hammer in fixings
maybe?

Expanding foam used as a criss-cross pattern and a line around the
edge. You can get low-expansion ones, but the ordinary one does fine.
Just brace the board against the wall for up to an hour until the foam
hardens off.

mike wrote:

The upstairs external walls of our house have a narrow cavity - too
narrow to be filled when we had cavity wall insulation downstairs.

I'm about to redo the bathroom and I'm considering beefing up the
insulation with Kingspan under plasterboard.

I've got some sheets of Kingspan left over from a previous job so I
don't particularly want to buy the ready-bonded Kingspan/plasterboard
combo. Because it's a small, I don't want to lose a lot of floor area
building stud walls, battening or dot and dabbing.

Is there a cheap, easy way to do this that doesn't lose an inch or two
of room space? A suitable cartridge adhesive or hammer in fixings
maybe?

The end result will be tiled over.

You could screw teh Kingspan to the wall - use 30mm (IIRC) disc washers -
somthing like:

http://www.astra247.com/8476/Heating...-Plastic-(Bag-
of-100-Washers)/100-Plastic-Washers-per-Bag/

Or nail in fixings:

http://www.pureadhesion.co.uk/marmox...b-plug-fixing-
dowels-110mm.html


However you may need fixings at fairly close intervals (perhaps every 30cm
in a grid which is a lot).


Or you can foam bond it to the wall with a PU foam made for the job - a low
expansion type, eg:

http://www.toolstation.com/shop/p60449

Ditto plasterboard.


Personally I would use the foam above with a few screw fixings - every 2' or
so, and "marmox" washers. The screws will keep the board in place while the
foam sets - it is low expansion but it still does expand. I've used that
particular product and it is very very sticky - do not get on carpet, in
hair etc. What gets on cloth never comes off.

Do the same for the PB - use the foam and a few long drywall screws into
wall behind the Kingspan. You could just use teh foam, but the setting time
is about 15-30 minutes so you'd need to prop everything until that time has
elapsed.


--
Tim Watts

On 17 Sep, 12:12, Andy Dingley wrote:
On Monday, 17 September 2012 12:05:45 UTC+1, RobertL *wrote:
Why would studs reduce the floor area?

The "official" line is that studs are cold bridges. *So you need two layers of board and studs, with the studs crossed. You also need to size the thickness, such that single layer board thickness under the studs is still adequate. *This turns into quite a thick package.

The cold bridging is probably not a deal breaker. The advantage of
studs is that (assuming you remember where they are) you have
something behind the plasterboard to fix into (for cupboards, shelves,
radiators, etc.). Easier than trying to fix to a wall through 2 inches
of Kingspan.

Cheers
Richard

On Sep 17, 2:00*pm, Tim Watts wrote:
mike wrote:
The upstairs external walls of our house have a narrow cavity - too
narrow to be filled when we had cavity wall insulation downstairs.

I'm about to redo the bathroom and I'm considering beefing up the
insulation with Kingspan under plasterboard.

I've got some sheets of Kingspan left over from a previous job so I
don't particularly want to buy the ready-bonded Kingspan/plasterboard
combo. *Because it's a small, I don't want to lose a lot of floor area
building stud walls, battening or dot and dabbing.

Is there a cheap, easy way to do this that doesn't lose an inch or two
of room space? *A suitable cartridge adhesive or hammer in fixings
maybe?

The end result will be tiled over.

You could screw teh Kingspan to the wall - use 30mm (IIRC) disc washers -
somthing like:

http://www.astra247.com/8476/Heating...al-or-Plastic-...
of-100-Washers)/100-Plastic-Washers-per-Bag/

Or nail in fixings:

http://www.pureadhesion.co.uk/marmox...b-plug-fixing-
dowels-110mm.html

However you may need fixings at fairly close intervals (perhaps every 30cm
in a grid which is a lot).

Or you can foam bond it to the wall with a PU foam made for the job - a low
expansion type, eg:

http://www.toolstation.com/shop/p60449

Ditto plasterboard.

Personally I would use the foam above with a few screw fixings - every 2' or
so, and "marmox" washers. The screws will keep the board in place while the
foam sets - it is low expansion but it still does expand. I've used that
particular product and it is very very sticky - do not get on carpet, in
hair etc. What gets on cloth never comes off.

Do the same for the PB - use the foam and a few long drywall screws into
wall behind the Kingspan. You could just use teh foam, but the setting time
is about 15-30 minutes so you'd need to prop everything until that time has
elapsed.


I applied kingspan with fixing foam and screws/big washers. I
plastered straight onto it using lots of PVA (on surface and in
plaster), no plasterboard at all. (Scrim on joints)
Been OK for five years.

Thanks for all the replies. The dryfix or low-expansion foam with
some of those whack-in fixings sound like just the thing.