Anyone know where I can buy 50 mm loft insulation roll?

[stuffandnonsense]

Am insulating loft (as cold loft), ripping out the old tissue-thin insulation first as it is full of mouse crap and rubbish. Am having problems finding suitable (and cheap) first-level insulation to go between the ceiling joists before rolling thicker stuff over the top. Two problems:
- non-standard size at mostly 41 cm gaps (width of gap, not joist centres) with a few 33 cm at the middle.
- depth is not suited to the current standard sizes - they're only 50 mm deep, and I can't find loft roll (e.g. Knauf) at this thickness.
Can't afford the expensive loft boards that I could cut to fit. And even the semi-rigid rafter roll mineral stuff seems to be a factor of 10 more expensive.

Does anyone have any suggestions? Looking for a solution I can buy in person in the north-east or buy online and have home-delivered. Thanks

 

[PrenticeBoyofDerry]

Is the loft floor boarded out?
Is that why you need 50mm?
Because if it's not boarded out, you can get any thickness down.

 

[stuffandnonsense]

Hmm - I thought it was best to infill the gaps between joists, then lay crossways over the top. Surely if I just lay a 200mm layer over the joists, it will leave voids for convection currents to take my precious heat away? This is the reason I planned to do it myself rather than pay £100 for someone to throw some rolls on top in an hour.

 

[PrenticeBoyofDerry]

Your only going to get rollbatt @ standard sizes of 100, 150, 170, 200mm.
If you have the time you could strip the layers down to 50mm.
But I would lay the 100mm down in between joist and fill in any gaps in before layering over top.
You can get rigid boards and slabs @ 50mm.

 

[stuffandnonsense]

Have been looking around, and I see plenty of cavity/acoustic insulation at 50 mm thick (e.g. Rockwool, costs around £2/m2 + vat). Anyone know if this would do the job I'm looking for, or is there some reason not to use batts for insulating the floor in a loft?

 

[freddiemercurystwin]

Jeez, just buy 100mm, lay a layer between the joists squash it in the thinner gaps or cut it a bit thinner, lay another layer perpendicular across the top, then another. You're thinking too much!

 

[mointainwalker]

The acoustic stuff is the same material. You will however pay a lot more for it pro rata because :

a) The manufacturers always try to increase their margins on new products
b) Being "acoustic" it probably won't benefit from any subsidies from the energy companies.