The insulation was supposedly improperly installed. There, saved you a click.
this post was submitted on 12 Aug 2024
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Important info not in title or body of post: Mortgage companies are worried that spray foam can cause condensation which damages timbers.
Just to clarify further: Condensation management as part of insulation is half the battle, but frequently overlooked.
The problem comes where cold surfaces meet warm air, and what happens to the moisture in the air at that point.
The spray foam seals the timber in a way that it cannot be accessed from the inside, but generally a membrane in not installed on top of the wood. So warm air can still get through.
If my room is full of lovely 21 degree air, and the outside is zero, then if that air is able to get to a nice cold roof truss, it will be dropping a lot of evaporated water on the truss.
And if that wood can't get sufficient airflow to dry out, it'll get damp. And eventually rot.
Meanwhile, you can't even get to the truss to look at it, because it's covered in foam.
So the mortgaging companies are (very understandably) staying away from that potential hot potato.
You could have a house that looks absolutely fine, until the trusses start collapsing.
The ways we work around it are either ventilation (having the roof itself still vented to the outside), vapour sealing (stopping warm air from getting to the insulation), or using ventilation that breathes (water/vapour can move through it, allowing it to dry out naturally).
Can someone explain why spray foam seems to be the go-to for US construction? Is it different types of wood/treated vs untreated?
"At the root of the problem are cowboy traders (unlicensed tradesman/contractor) who apply the foam without a full survey or appropriate expertise – but because of lenders’ caution, this is affecting other homeowners who had similar work." also "because surveyors are unable to inspect the roof timbers behind the layers [for moisture], mortgage lenders tend to issue blanket refusals on properties where any foam is present." Maybe in the U.S. we just use wood moisture meters to check for moisture?
My impression is that homes in the US tend to have more wood involved in their construction generally, so it seems plausible to me that US construction methods may be more experienced with ways of managing wood moisture
Sounds like the foam is the issue, which may be down to the shade tree handy man they hired being unlicensed or uninsured to perform insulating. If a person isn't a dedicated HVAC worker who has day-to-day experience with insulation types and how to properly apply them, then the work may be causing more harm than good.
If the insurance and mortgage companies have a list of guidelines needed for insulation installation, it makes sense that folks need to follow them to continue using their services. Spraying any old foam into nooks and crannies is a fine way of hiding problems.
The problem with this style of foam application, is that you cannot get to the wood to check the moisture content, without ripping down the foam (or probing through it, exacerbating any problem).
So there isn't a way to test. And as there have been problems, the lenders won't take the risk on any more.
I was thinking the meters with the metal probes that go through yeah. Wasn't aware that could exacerbate the issue.
I looked into spray foam insulation but not only were there lots of risks, but it was more expensive than traditional warm roof insulation with PIR boards or similar. I do think people should research what they put in their own homes as it wasn't hard to find information that ruled out spray foam insulation fairly quickly.
Having said that, there is clearly some sort of regulatory gap here as not being able to mortgage your home is a very serious consequence of a relatively small and seemingly innocuous home improvement decision.
When I first moved into my house I needed to improve the insulation as the existing stuff wasn't sufficient. I reached out to a spray foam company who sent a salesman around. The guy was incredibly pushy and didn't care about the minor details. When I was saying it was too much he called his manager up on the phone and was talking to her like she was a piece of shit that he'd trodden in. I reached a point and asked him to leave. About 15 minutes after he'd left the manager called me back directly sounding like she'd been crying, asking for feedback on the guy. Even after I said it was a terrible experience she continued to try and sell the service to me! It was probably some terrible double-act to get sales.
It left a bad taste, I got the feeling it was a terrible cowboy operation and they were claiming to be one of the major players in the UK. Seeing this and over time reading people's experiences really makes me feel like I dodged a bullet by not getting foam spray insulation. It all sounded too good to be true.
The other problem is at some point you are going to want to remove and redo it. How are you supposed to do that with spray insulation?
I am not a construction expert, so check your sources on this.
My understanding is that, for new construction, spray foam is most often used in areas that aren't likely going to be damaged by condensation, such as against concrete, or metal. I had looked into spray foam for my home, because my home was built in the early 80s--before building codes existed in my area--and there's no cladding on the house and just fiberglass bats between the studs. Because there's no cladding, there's much more air incursion through the bats, esp. since the interior walls are lapped wood paneling rather than wall board. Spray foam would have been a total air barrier, but it would end up being applied directly to the inside of the exterior siding, which would be a nightmare when siding needs to be replaced, and would probably cause moisture issues.
The best solution appears to be to use 3" EPS foam cut to fit between the studs, and then use spray foam to fill any gap between the studs and the EPS. That still allows an air gap between the foam and the exterior siding so that moisture can evaporate.
In the case that's being cited here, I'm not sure why they opted for spray foam over EPS or fiberglass bats. If their home is well sealed, then bats should have been perfectly sufficient, although they have a lower R-value per inch than EPS. Oh, and the difference between polyisocyanurate and EPS/XPS is about R1.5/inch, but that difference drops to about R.25/inch after a decade. That meanst that you don't gain much in the long term when you use faced polyisocyanurate board. I'm not sure what blowing agents are used for polyiso; it might be more environmentally friendly to manufacture.