My dad mentioned today that they have had their loft insulated. My first thought was they’d finally got around to topping up the existing fibreglass insulation. No, turns out that’s all been removed and the underside of roof (not between the joists) has been spray foamed. The whole roof void is now sealed, all soffit vents covered. I asked if there was a vapour barrier and my dad said no, it’s breathable apparently (open cell foam then I guess?)

All sounds absolutely bonkers and unnecessary to me. Firstly, they now have to heat the roof space to stop heat escaping from the rooms below. Secondly the lack of vapour barrier seems wrong. What will stop vapour condensing inside the insulation?

After Googling I can see that this stuff is not good news at all. It could completely devalue the house to £0, rot the rafters and be far more expensive to remove than install.

Is this stuff always bad news? I get the feeling they’ve been sold this by someone. My dad said things like the the old insulation gets damp and breaks down over time. I don’t think either are true. Also it was apparently cheaper than replacing/topping up the existing mineral wool/fibreglass. I don’t believe that…

It could be all OK, but I know this industry is full of shysters.

Generally the roof needs to be designed from scratch to use that sort of spray foam insulation, or extensively tweaked. Or, as you say, you’ll get damp/rot and the roof will need replacing.

Obviously i’d get an expert opinion.

Generally, it’s a scam. For example:

https://www.herefordshire.gov.uk/news/article/1232/spray-scam-hits-herefordshire-residents

Yeah, rip that out and get rid of it.

I’d be nervous but o understand there are types that are breathable so dampness isn’t necessarily and issue. You’ll need to find out more about the product used

https://www.massfoamsystems.co.uk/
Icynene, I’ve read a good review of that from someone that installed it in 2009.

Even if it’s a great product, the application is key. Why seal up the roof space? It’s designed to be vented and cold.

At best it seems they’ve been sold a hyped-up product, resulting in a completely over-engineered solution. At worst they’ve made their home worthless.

breathable so dampness isn’t necessarily and issue

My understanding of dew point in a wall/roof is… you have warm damp air one side of the insulation, cold dry on the other. The warm air passes through the insulation. At some point it will reach a point where the water in the air condenses, due to the changing temperature. You don’t want this point to be the inside of the roof or joists. Breathability makes no difference.

One solution is a vapour barrier to stop the moist air

It’s a total con that will require a complete reroof to fix, even then it’s a complete nightmare to get rid of. It also makes houses unmortgageable.

Is spray foam the new gig for the asphalt driveway pikeys?
Assume this was a Knock on the door offer of service rather than through a building envelope business?

It is a really bad idea because it creates a barrier for moisture to leave the house. The house will be prone to damp, unless you have a mechanical ventilation system that covers the whole living area and as described above, it causes the timbers to rot as moisture they absorb can’t evaporate into the loft space.

Ads for this stuff pop on on Facebook quite often – I usually go in and ask if I can see their BBA certificate. My comment is always deleted and then I’m blocked.

No BBA certificate – don’t use it.

BBA certificate

Do we at this point mention that most of the flammable cladding on high rise buildings had BBA?

Assume this was a Knock on the door offer of service

Yup, seems it all stemmed from a cold call.

Who is best to advise on this, i.e. essentially to have a look and condemn it?

Do we at this point mention that most of the flammable cladding on high rise buildings had BBA?

BBA certificates are specific to a particular application.  Just because it has an Agrement Certificate for one application doesn’t mean it is suitable for another.  Half the issue with the issue with the usage of insulation in high-rise rain screen cladding seems to be down to someone extrapolating one set of test results into an entirely different situation where conditions are hugely different.

I’ve used spray foam in the past but it was in a specific situation where on balance it was the best solution.  It needs to be used very carefully for the reasons already mentioned.

Who is best to advise on this, i.e. essentially to have a look and condemn it?

You could try either a local authority building control officer or a private building control officer.  There will be a fee but having a piece of paper saying that it doesn’t comply with building regulations (or the Scottish equivalent) would be a huge benefit claiming back what they have charged and costs for making good.  Plenty of RICS surveyors or chartered architects do expert witness work of this type but building control would be my first call

After Googling I can see that this stuff is not good news at all. It could completely devalue the house to £0, rot the rafters and be far more expensive to remove than install.

I’ve had to look into this stuff myself, here are a few things I’ve found out (open to debate obvs)…

– I dunno about devaluing the house to £0, but it’s unlikely a lender will offer a mortgage
– A man who removes it for a living told me he’s yet to actually find any rotten rafters beneath it
– Some house owners choose to cut it away so the fronts of the rafters are exposed, in order to monitor it
– It doesn’t mean a new roof is needed, but it will cost thousands to get it professionally removed

I remember seeing this stuff causing similar problems on Watchdog back in the late 90s I’d hoped they’d pretty much banned this practice apart from where absolutely/specifically required

Good luck in finding a cost effective resolution.

Just get the loft well ventilated and reinsulate above the ceilings and then forget all about it.
If the tiles are in good condition should be fine, not great but i wouldn’t lose sleep over it.

Building Regulations require any additional insulation work to be sufficient to bring the insulation up to current standards. It’s unlikely that the sprayed foam does that, and very unlikely that the installer will have had it inspected for compliance. Is it in England/Wales or Scotland?

Obviously this is just from third person perspective, but recently doing some work for a estate agents and the person who ran the office asked me if I knew anything about spray foam loft insulation as they had a property where no mortgage lender would lend due it being used. It was a new thing for them to come across and they had lost a string of potential buyers over it.

Is it in England/Wales or Scotland?

England. I emailed my parent’s local building control but they didn’t seem that interested. Perhaps because it’s Friday afternoon or perhaps because most building control offices are thin on technical knowledge for anything that’s not belt and braces, traditional builds.

– I dunno about devaluing the house to £0, but it’s unlikely a lender will offer a mortgage
– A man who removes it for a living told me he’s yet to actually find any rotten rafters beneath it
– Some house owners choose to cut it away so the fronts of the rafters are exposed, in order to monitor it

I think the problem is you cannot ever fully inspect the rafters (without removing the foam) to know if they are rotten or not. Hence the surveyor will highlight that and the lender won’t lend on the house. Exposing the fronts of the rafters surely just creates a cold bridge, on which condensation will form?

What will stop vapour condensing inside the insulation?

Logically no, because the air is now above the dew point. The coldest, wettest air in the house will sink so the loft space should be dry? To get condensation you’d need a barrier that was conductive to heat.

The problem I’d imagine is any moisture that gets through the tiles is now trapped above it, whereas previously it was being dried out by the warm dry air in the loft.

IANAExpert, but did have our wall cavities done recently with the blown in fibre stuff so I’ve been taking insulation horror stories with a pinch of salt.

Just get the loft well ventilated and reinsulate above the ceilings and then forget all about it.

Short term this is probably the best way forward. However if they need to release equity or downsize it looks like it’s going to be a nightmare.

The coldest, wettest air in the house will sink so the loft space should be dry?

Cold air will sink, but humid air is less dense than dry air (because water vapour is less dense than oxygen or nitrogen). Warm air not only rises, but has more capacity for moisture. If the roof is not well insulated, the temperature of the inside surface is low enough to cool the warm moist air and condense the moisture.

Building Regulations require any additional insulation work to be sufficient to bring the insulation up to current standards. It’s unlikely that the sprayed foam does that, and very unlikely that the installer will have had it inspected for compliance

I’ve just been wondering about this. Would it not be my parent’s responsibility, not the installer, to meet the regs? Unless the installer was doing some sort of self certification?

Would it not be my parent’s responsibility, not the installer, to meet the regs?

That’s an interesting question. The Building Regulations are mostly written in the form “The building shall be…” which avoids allocating responsibility. I’ve had a quick look at them and at the Building Act under which they are made, and there are more references to “the person carrying out the work” than to “the owner”. So I would think it’s the installer – but I’m a retired civil/structural engineer, not a lawyer.

Most construction law does recognise that the customer will not be in a position to know enough technical detail to be responsible, and puts the onus on the person providing the service (which is why the Government’s attempts to put the cost of fixing flammable cladding onto the leaseholders have been met with such uproar).

I’ve been in contact with some surveyors and they have provided useful information.

Another nugget from my parents, the company advised that they will return in 6 months to do a “humidity” check. I’m pretty sure you can’t just spot check humidity? You would monitor indoor, outdoor and roof space humidity over a period, say a week. Then expect the loft humidity to stay between the indoor and outdoor levels, not exceeding the outdoor level.

or perhaps because most building control offices are thin on technical knowledge for anything that’s not belt and braces, traditional builds.

Or they’ve been cut to the bone by successive cuts to LA funding and simply don’t have the resources needed…..

Another nugget from my parents, the company advised that they will return in 6 months to do a “humidity” check.

Last cowboy building co my folks dealt with had ceased trading twice in the 6 months between finishing the (botched) building work and the first signs of damp…

Still the same vans, employees, boss, phone number and shit building practices though.

@footflaps

Or they’ve been cut to the bone by successive cuts to LA funding and simply don’t have the resources needed…..

Yes, same result really. In larger cities they tend to have a good breadth of knowledge, mainly because they can have more people/resources and opportunities to be exposed to new things. In more rural and suburban locations they have to deal with the same technical breadth but with fewer people/resources.

I would honestly just take it out and cut the losses on the cost of installing it. Are they actually using the loft as a habitable space? If not, pretty much everything about the product is worse than a traditional setup with insulation only laid on top of the first floor ceiling and the roof left uninsulated and well ventilated.

I would honestly just take it out and cut the losses on the cost of installing it

This is what I want them to do in the end. But they’ve been sold the product and I get the impression it wasn’t cheap, so been gathering some information from various sources to help to them understand why it’s such a bad idea. Also if there is enough evidence showing faults or mis-selling then we can pursue the installer (good luck with that I hear you say!)

If anyone needs detailed insight of the current situation with spray foam loft insulation, then this is worth watching

It’s primarily for mortgage advisors but is very informative.

My tuppence… Nearly 2 years ago I viewed a house on behalf of my MIL (relocating darn sarf) in a neighbouring village. It had been on the market for something like a year with a couple of sales falling through. I asked why this was and it turned out the vendor had let it out for years and had that insulated spray foam done about 20 years ago… potential buyers had been told by their lenders that they would not be allowed to complete their purchase unless the roof was replaced. Said vendor was adamant they were making a fuss and refused to have it done for months. Finally, she realised she had to replace the roof so she did, I then made her an offer and it was job done.

Slight thread de-rail, but I’m just about to complete on a house whos attic looks like this..
The surveyor didn’t make much mention of the insulation directly under the roof tiles, presumably it’s ok as it has vents in it?

He did mention the regualar insulation on the ‘floor’ of teh attic was a little thin and could do to be a bit thicker…does that mean I can just buy a few rolls of the appropriate stuff and just plonk it on top of the existing stuff?

https://photos.app.goo.gl/ndbnPX7c42jtPPpA6

That’s not insulation it’s just the waterproof membrane under the tiles.

I’ve found out which product was used. It does not have a current BBA certificate (it was withdrawn in 2019). Are there any implications of this? Does this actually mean anything in this situation?

BBA seems to demonstrate a product is of a certain quality, but I’m not sure the lack of BBA cert means it does not comply with building regulations, for example.

That’s not insulation it’s just the waterproof membrane under the tiles.

Is there insulation over this and under tiles? Unusual in UK, but not unheard of and common on continent.

Are there any implications of this? Does this actually mean anything in this situation?

Implications for you, likely none.
Implications for the company is that they wont get specified on larger jobs.