Spray foam insulation vs cellusose in dormer attic

ixiathor

hi,

We have a bungalow with a converted dormer attic, done about 5 years ago. The builder who did the attic conversion did a really poor job on the insulation - a mix of Xtratherm rigid insulation between the joists (lots of gaps, not sealed) and some fibreglass/rockwool held in place by plastic sheeting and no insulation above the flat part of the ceiling at all. As a result, the attic rooms are very cold.

We have about 6 inches of normal fibreglass roll insuation on the attic floor. Things are made worse by lots of downlighters (in place when we bought the house).

I've got 3 quotes - two from spray foam insulation firms and one from a pumped cellulose.

Both spray foam insulators propose spraying from the wall plates up to the existing rigid instulation and some of the other gap areas, as best possible, creating an air-tight sealed attic to a large extent. One of these is IAB approved. Costs are high (big area) and dependent on depth of insulation applied. Both are open-cell foam.

The cellulose installer proposes pumping 4-12 inches on top of the existing insulation (covering the downlighters with pots) - to include the attic ceiling area and insulating the attic stud walls with 100mm of "loft wool". They will also insulate the access hatch doors. Price is about half of the cheapest foam insulation option.

Seeking advice / experiences of use of either types of insulation and results ...

thanks

Ix.

Radonman

Just be careful with the spray on foam insulation, from what i hear you need a vapour control layer to be installed too to avoid condensation. Also id remove the pots from the down lighter and replace them with certified down lighter mini or maxi boxes as you can air seal these and put insulation around them (available in hardware shops - Cork builders providers for definite). hope this helps

Macspower

The open cell spray foam will not cause any condensation or dampness of any sort... provided it is certified by the NSAI and has the Agrement cert and it is installed by a reputable installer.

Depending on your application it may require vents cards fitted between the felt and the foam but this is not normal on retrofits.

Done correctly the foam is a lifetime job. The celulose however is not.. Get certified U values for both and comepare the products..

I am a bit biased as I am a spray foam installer but what I say above is fact. Please be carefull of who does the job and get references and look for the certification. The certified products should be no more expensive than the non certified ones..

soldsold

Macspower wrote: »

Done correctly the foam is a lifetime job. The celulose however is not.

I am a bit biased as I am a spray foam installer.

a bit biased? Can you back up these sweeping statements with any data or reports?

Macspower

soldsold wrote: »

a bit biased? Can you back up these sweeping statements with any data or reports?

Absolutely, Our foam has the NSAI Irish Agrement cert and both ourselves and the foam manufacturer offer a written lifetime guarantee on our foam and work.

But don't take my word for it. take the word of the NSAI. they have carried out stringent testing on the product. Our IRISH AGRÉMENT BOARD
CERTIFICATE NO. 10/0354 says it all really..

I'm not sure if I'm allowed to post a copy here or a link to our cert that explains all .I don't want to blatently advertise on a public forum as boards.ie have been good to me over the years and I never abuse the forum..

Perhaps a mod can verify if I can post a copy here in the public interest...

Basically if a company can't provide you with an IAB cert then they cannot back up their claims. There are many companies out there using uncertified products and some are using products that are pure petroleum based and only suited to agri work but some contractors are spraying this uncertified foam into domestic houses.. some will also try and pass different Q marks as certification.. but this has nothing to do with product testing. just a Q mark for the company like a kind of ISO thing...

Beware and ask and research the product before you book anyone to do work for you is my advice... I would expect and encourage a potential customer to check us out before they let us do work on what is potentially one of the most important decisions they will ever make.

While as you correctly pointed out I am biased towards foam I still think I am in a good position to advise people here on what to do before getting work done... I don't want to seem like I'm advertising but done correctly Spray Foam outclasses traditional insulation in so many ways.

muffler

Macspower, PM any links you may have to whoever wants them.

Cheers

soldsold

I'd certainly agree that spray insulation gets over some pitfalls of normal shoved in insulation alright, namely airtightness and gaps in the insulation. For me, I'm getting my rafters pumped with cellulose next week, as the rafters depth can be full filled as its a breathable roof with softboard on top, density is 65kg/m2 so should help prevent overheating in summer, and Ive used airtightness tape and completing blower door tests at the moment, so Ive worked around the airtightness and gap issues.

I'd love to think that spray insulation was risk free, and with continuous ventilation it probably is (my roof is a warm roof so no wind blowing around in it which is another advantage), but as its pretty new or at least hasnt scaled up in Ireland compared to other forms of insulation, I'll wait and see how it performs

IAB certification certainly helps though, as you say there are a lot of foams out there that are uncertified. Sorry for going off topic on this, hope the thread gets back on track now...

moan 77

Could I get a pm from macspower with all or any info as i'm on the spray road at the moment.

sas

Macspower wrote: »

Done correctly the foam is a lifetime job. The celulose however is not..

Can you elaborate on why the cellulose isn't a life time job?

ei.sdraob

sas wrote: »

Can you elaborate on why the cellulose isn't a life time job?

Doesnt cellulose compress over time? also heard rodents like the stuff...

soldsold

ei.sdraob wrote: »

Doesnt cellulose compress over time?

I assume by "compress" you mean slump in the rafters and leave a gap at the top. The cellulose designed for rafter fill doesnt slump from any research Ive done on it, discussions on other forums from people who had it installed etc. Im getting mine filled to 65kg/m3 so there is really no way something so tightly packed in could compress.

ei.sdraob wrote: »

also heard rodents like the stuff...

Not according to google...

http://www.google.ie/search?sourceid=chrome&ie=UTF-8&q=mice+in+cellulose