DIY Foam spray insulation

[Arnold9801]

I’d be interested to know if anyone has done their own ceiling spray foam insulation?

 

We are currently doing a large dorma new build. The roofers haven’t long finished the slating and the scaffolding came down today. The fitting of the windows is next but I’m thinking of spray foam insulation on the underside of the roof between the rafters myselfI’ve just watched some YouTube’s on spray foaming yourself and as I’m doing most of the build I’m  considering doing this as well as opposed to getting a team in to do it.

 

Ive seen that the materials are readily available for it here in the UK.

 

Would appreciate your advice.

 

Arnold9801

[Iceverge]

@Arnold9801.

 

@Gone West sprayfoamed his original house with icynene via a contractor. IIRC it worked well but there was a lot of waste.  

 

When I priced it for our own house it was quite expensive. If done incorrectly it can shrink and leave gaps. My preference would be for mineral wool or ideally blown cellulose behind a membrane. 

 

What is your current roof buildup? What kind of roofing membrane did you use? Do you have any photos? 

 

 

[SteamyTea]

7 hours ago, Iceverge said:

If done incorrectly it can shrink and leave gaps

Even if done correctly this can be an issue.

PUs can shrink for over a year, it is why your furniture cushions seem overly tight in the covers when new, we built long term shrinkage in.

[JohnMo]

Our roof was done in Icynene, the contractor heats it up to a high temperature before application.  Our roof is about 270m2 and it took two days to apply and cut back, the was 10 large bags of waste.

 

There is two ways to fill, fully fill, where they over fill and cut back, with huge amounts of waste.  Or fill and cut back the high spots, we had some areas where the insulation is about 5 to 10mm below flush, which worked for us.  Not cheap, but if i paying a contractor to install anything else, labour cost could have been huge.  We have Posi rafters and I wanted all areas filled.

 

Our roof after application of Icynene, was exposed for about a month prior to vcl was installed and no shrinkage seen

[SteamyTea]

1 minute ago, JohnMo said:

the contractor heats it up to a high temperature before application

Yes, it is often forgotten.

[JohnMo]

Forgot to mention all surfaces have to below a set moisture content, prior to applying, we had to wait 3 months after finishing the roof 

[Gone West]

@Arnold9801 This gives you a flavour of what to expect with Icynene. We did our our whole house in 2014 and had it sprayed to a depth of 350mm which was more than twice the depth they had ever done before. As already said the walls have to be warm so a job for the summer.

 

 

 

 

 

 

 

Edited November 26, 2021 by Gone West

[Nickfromwales]

On a job now where a basement ceiling has been sprayed, and a very mixed bag from one set of installers to another.

First crew must have been smoking something potent, and left a horrific mess in their wake. Company then sent two great guys who took one look and swore a LOT, then arranged to come back and ‘rectify’…….

Latest combo of closed and open cell saw the open cell left a good 4-6” below the level where the PB’s will be affixed, where it just expanded beyond the 8,000 gaps that the second team tried to spot-fill from the first crews train-wreck, with the closed cell a lot better where it doesn’t expand like crazy as the open cell does. 
So;

Question : Why would this company say that if the foam is cut back ( or compressed ) they would void any warranty? Has anyone else got a copy of their contract who could read the small print and reply here please? It is clear that every example I’ve seen, plus the images above, have had / needed cutting back to at least some degree. Did all the above end up voiding their warranties? TIA. 

Edited November 26, 2021 by Nickfromwales

[SteamyTea]

55 minutes ago, Nickfromwales said:

Why would this company say that if the foam is cut back ( or compressed

If you compress it, the thermal resistance will reduce.

Cant see a problem with cutting back, except it may change moisture absorption.

 

I have always like the idea of spraying in a foam, but having worked in the industry, I would make sure that sprayers also fully cleaned up.

[Nickfromwales]

19 minutes ago, SteamyTea said:

If you compress it, the thermal resistance will reduce.

Cant see a problem with cutting back, except it may change moisture absorption.

 

I have always like the idea of spraying in a foam, but having worked in the industry, I would make sure that sprayers also fully cleaned up.

This first lot left it like a war zone.

Instruction from the lady in charge “push up anything protruding and board over it”. Small print says cutting or compressing voids the warranty. Ffs. 18mm plywood would struggle to pull all this up, let alone fecking plasterboard!!!!

I think I may call them back to demonstrate the fitting of the first plasterboard…….”such fun” ?. 

Their work here is not yet done ?

[A_L]

1 hour ago, Nickfromwales said:

Why would this company say that if the foam is cut back ( or compressed ) they would void any warranty?

 

Because it would alter the physical properties of the install. Particularly they sell it on air-tightness, removal of the 'skin' that forms could significantly affect this. The thermal resistance would also be affected by this, it may also affect the vapour resistivity although this fairly low anyway, probably not critical.

[Nickfromwales]

39 minutes ago, A_L said:

 

Because it would alter the physical properties of the install. Particularly they sell it on air-tightness, removal of the 'skin' that forms could significantly affect this. The thermal resistance would also be affected by this, it may also affect the vapour resistivity although this fairly low anyway, probably not critical.

Thanks.
Property is already airtight to ( provisional ) 0.8 ACH, and this retrospective layer of foam is for insulation qualities only. A sheet membrane or Passive Purple liquid membrane will be employed, if / where necessary, to complete the airtight detailing ( as required ). 

Cutting back would only reduce the thickness to the specified ~200mm, and would thus negate any compression? 
Open cell is, by name, open cell, so why the issue with cutting it and exposing its ‘innards’ ?  All images above show cut foam  

Edited November 26, 2021 by Nickfromwales

[JohnMo]

BBA Cert for Icynene states.

 

"Once cured, if required the product is trimmed flat using a saw and covered with lining board."  So no issue trimming, as stated it is an open cell product.

 

[Arnold9801]

Thanks for your replies. Where can you get the flexi saw blade from?
 

[markc]

5 hours ago, Arnold9801 said:

Thanks for your replies. Where can you get the flexi saw blade from?
 

Why flexi saw? You want the trimmed area flat and level with the rafters or studs.

bow saw blade with a bolt at each end to make holding easier for awkward areas but you can do pretty much everything with an ordinary wood saw … if need be bend the blade near handle to crank the handle away from wall …. But then you end up doing some cuts uphill because the saw becomes handed.

[Gone West]

8 hours ago, Arnold9801 said:

Thanks for your replies. Where can you get the flexi saw blade from?
 

I borrowed one from the Icynene installers. Amazon had one, but no longer in stock.

https://www.amazon.co.uk/Spray-Foam-Insulation-Saw-29/dp/B00G2G0XT4

Sorry a quick search but couldn't find any.

[scottishjohn]

a lot of mortgage companies and surveyors will give you a bad report  with foam infill ,as they cannot inspect the roof ,so assume you are hiding rotten beams etc

 and as it is an area where there could be condensation 

i would go for CLOSED CELL foam -not   open cell.

CLOSED CELL IS A WATER PROOF BARRIER 

and can be used for tanking basements on outside ,which they do in the states

 closed  cellis what they use for buoyancy in canoes ,and lifebouys   lining shipping containers when they make thnm into an office etc --no condensation that can travel through the foam -like it can with open cell

 

 it is dearer then open cell -but you can buy DIY units  also insulation is similar To PIR-better than open cell

 quite commonly used in barn conversions to seal up old lime mortar walls  before  wood frame kit 

 40-50mm is all you need to seal it upand also get all the drafts   ,then fill up to rafter depth with mineral bats  or something --that will cut down costs

Edited November 27, 2021 by scottishjohn