I've tried to find a thread on the forum about spray pu insulation without success. Does anyone have experience of it regarding cost and insulation values compared to PIR?

I'm planning to insert 140 mm PIR into my open panel timber frame walls. But i have so many studs at varying centres that i'm considering alternatives.

Look at @PeterStarck's blog. He used icynene.

Other suppliers: Isothane, Walltite.

 

Generally pretty expensive.

 

Consider cellulose?

Are you looking at a DIY basis or getting a contractor in? 

3 hours ago, Onoff said:

Look at @PeterStarck's blog. He used icynene.

I'll check it out...

2 hours ago, gravelld said:

Other suppliers: Isothane, Walltite.

 

Generally pretty expensive.

 

Consider cellulose?

Is cellulose sprayed onto open panels?

47 minutes ago, Alexphd1 said:

Are you looking at a DIY basis or getting a contractor in? 

Contractor. I'd need to compare price of contractor with time saved cutting PIR, and therefore labour costs.

£30m2 @ 300mm thick is a number which sticks in my mind. Can't remember U value. You get a pretty good air tightness compared to hand cutting rigid insulation. 

Some figures here:

 

 

I think it could/would be a very good solution for on site timber frame build. It is possible to do a DIY (we are doing it) but you need a lot of m2 to make costs/work add up.

Edited November 8, 20187 yr by Alexphd1

13 hours ago, Blob the Builder said:

Is cellulose sprayed onto open panels?

 

Yes, you can wet spray cellulose to open panels fairly easily.  Doesn't seem to have caught on here, but it's used elsewhere:

 

 

I've used DIY spray PU foam to help a friend insulate the inside of a steel boat hull years ago.  Not that difficult, but it does require a fair bit of practice to judge the expansion level.  It's pretty temperature sensitive we found, so that when we were getting to the end of the job, when the interior had warmed up a fair bit, the foam started to expand a bit more and we needed to speed up the application rate.  Even then we had to cut off loads of excess foam, we had dozens of sackfuls of trimmings where we'd cut the foam back to get it level with the battens that the lining was screwed to.

IN both Thermal and accoustic terms, how effective is wet cellulose as in the video above, compared to say rockwool slabs. I had always thought on using rockwool slabs for the filling in the stud walls upstairs to reduce sound transmission, amongst other systems on top. Would cellulose be as effective in that instance?

Our house uses dry blown cellulose, but should be much the same in terms of acoustic performance to the wet sprayed stuff, I should think.  It is exceptionally good as acoustic insulation, especially when you consider that we have no masonry construction at all.  The house is eerily quiet, especially at night, and any slight external noise that does get in seems to be via the windows and doors.

 

I would imagine that if used to fill internal walls cellulose would out-perform rockwool as acoustic insulation by a fair bit.  I think the only problem may be finding someone with the kit to install it, although it doesn't look to be a particularly hard job to do.

Thermally there is not a lot of difference, 40mm of cellulose has about the same insulating effect as 35mm Rockwool slabs. (Thermal conductivities of 0.04 and 0.035/0.034 respectively)

Righteeeo, so actually if your external walls and ceilings are well insulated, shouldn't make much of a difference thermally one method to the next, but acoustics is where there may be a decent difference.

 

I know if sort of oversimplifies if a bit, but given that it seems to be recycled paper for the most part, can the process of recycling and blowing in, be done on site by the same machine? And I assume there are no issue with it sitting around electrical cables/pipes etc?

9 minutes ago, Big Neil said:

Righteeeo, so actually if your external walls and ceilings are well insulated, shouldn't make much of a difference thermally one method to the next, but acoustics is where there may be a decent difference.

 

I know if sort of oversimplifies if a bit, but given that it seems to be recycled paper for the most part, can the process of recycling and blowing in, be done on site by the same machine? And I assume there are no issue with it sitting around electrical cables/pipes etc?

 

The process of making Warmcel is a bit more involved than just shredding old newspaper.  The paper is shredded, then sort of fluffed into fibres, then treated with borax, then dried, before it's ready to be used.  From the look of the stuff I'd say that it may well be a wet process used to break it up into fibres, as it is a fairly uniform grey colour, with just hints that it was once newspapers.  I doubt that you could get the right sort of control of the final product by trying to make it on site, from old newspapers, especially as there is probably a fair bit of testing done at each stage to make sure that the product meets the specification.

As I have said before elsewhere I am a bit dissapointed at noise levels between floors in my new build and we have 100mm rockwall between ceiling and floor, if I were to do it again I would either double board the ceiling, use sound block plaster board or use top hat sound insulation rails. With regard sound transference through stud walls it has been said that “mass” is good, I.e. solid stuff, I packed all my plaster board off cuts in the void as well as rockwall and I am pleased with the result.

Is there any merit to having some sort of hybrid in any situation, so lets imagine in the floor of the loft for a minute. Lets say a layer of EPS then a load of cellulose, sandwiched by maybe a sheet of PIR. Or any combination frankly, they were just the first three which came to mind?

Interesting or scaremongering?