Spray foam loft insulation

**sniper-sam** · 24th February 2015, 23:06

With the impending arrival of our wee baby we are considering getting this done. The upstairs in our house is always considerably colder than downstairs.
my rough calculation going on the price per sq metre is £1300. Now the first thing, the guy told me to measure the length and the width of the house and that will give me the sq m that I need, is this correct?

and now more importantly, has anybody got this done and what are your thoughts, there are some horror stories on www about people getting rot because the roof can't breath etc. the guy on the phone told me that the installers leave a 50mm gap between the roof lining and the foam itself to allow the wood to breath and to prevent sweating etc.

any info good or bad would be much appreciated. This would be our biggest outgoing in terms of home improvement since moving here 6 years so want to get the decision right. Plus if it is a lemon of an idea I'd rather know as the £1300 could definately be better spent on baby stuff.....

**benny.c** · 24th February 2015, 23:20

I assume you can't or don't want to insulate between the ceiling joists which would be much cheaper? If insulating between the rafters I would go for a rigid board like Kingspan rather than the sprayed option. To get a decent depth of insulation and maintain an air gap under the sarking felt though, you may have to fit battens depending on the depth of your existing rafters. There's also a bubble wrap type product that can reduce the overall depth required but it needs to be used together with a board insulation to get somewhere near current regs.

Insulating at rafter level means you are heating the loft to some extent whereas at ceiling level you are only heating habitable rooms.

**sniper-sam** · 24th February 2015, 23:24

There's insulation already down between the ceiling joists, standard stuff that you find in all houses. Nothing of course between the roof joists which is were the foam comes in. Now I know that the roof joists can be insulated with other product, like the normal roll out stuff etc but this foam apparently makes it 100% sealed.
Whatever happens I don't want to be doing anything myself. Have enough on at the minute without adding the to the list.

**itsgotournameonit** · 24th February 2015, 23:32

Sam. What has made you think of the spray rather than traditional "Knauf" loft Insulation ? Your calculation is correct BTW.

How big is the loft based on your measurements ? Top up insulation is about £20.00 for 11 meters square.

**benny.c** · 24th February 2015, 23:39

What depth of ceiling insulation do you have at the moment? To achieve current building regs you need around 300mm, which is cheap to install (but not that great for loft storage). If your ceiling is well insulated and you minimise air leakage through the loft hatch, light fittings etc then there is no need to make the loft space itself air tight.

In the construction industry, sprayed solutions are hardly ever used for roof insulation where other options are available. My main worry would be the semi-permanent nature I suppose. It may well make your roof space more air tight (not always a good thing) but you'll be heating a space you don't use, which isn't ideal.

Rolled mineral wool type insulation isn't suitable for insulating between rafters as it doesn't have a good enough U-Value for that kind of depth. A rigid board is required.

**sniper-sam** · 24th February 2015, 23:42

Saw an ad on TV. That's about the reason lol.
problem with top up insulation is we have stuff down on part of the floor and o way am I starting to lift it all about. Insulating the actual roof seems like the best option as it a blank canvas essentially, completely clear and easy to access.

**itsgotournameonit** · 24th February 2015, 23:45

Originally Posted by benny.c

What depth of ceiling insulation do you have at the moment? To achieve current building regs you need around 300mm, which is cheap to install (but not that great for loft storage). If your ceiling is well insulated and you minimise air leakage through the loft hatch, light fittings etc then there is no need to make the loft space itself air tight.

In the construction industry, sprayed solutions are hardly ever used for roof insulation where other options are available. My main worry would be the semi-permanent nature I suppose. It may well make your roof space more air tight (not always a good thing) but you'll be heating a space you don't use, which isn't ideal.

Rolled mineral wool type insulation isn't suitable for insulating between rafters as it doesn't have a good enough U-Value for that kind of depth. A rigid board is required.

Yep have to agree that I have never heard of a sprayed solution used for insulation.Are you thinking that it would be best to use Celotex ?

**sniper-sam** · 24th February 2015, 23:45

Benny not sure what the depth is but it defiantly doesn't come up ove true too of the rafter.
Cant remember the terminology but the guy did say it was pouris, gts sprayed on 1mm thick and expands to 100mm.

**rsykes2000** · 24th February 2015, 23:47

I read this recently and it put me right off the idea. Don't listen to the salesman... http://forums.moneysavingexpert.com/....php?t=5171597

**benny.c** · 24th February 2015, 23:53

Originally Posted by sniper-sam

Saw an ad on TV. That's about the reason lol.
problem with top up insulation is we have stuff down on part of the floor and o way am I starting to lift it all about. Insulating the actual roof seems like the best option as it a blank canvas essentially, completely clear and easy to access.

Fair enough, but by insulating at rafter level you are heating an area the size of your whole first floor that you don't live in. If the primary concern is making your first floor warmer, then reducing the heat loss through the ceiling should be your first port of call. You wouldn't heat your garage, so why heat your loft?

If insulating at rafter level, I'd still go for a board rather than a sprayed solution. It's proven to work and provided the correct air gaps are maintained, there will never be any rot problems.

Originally Posted by sniper-sam

Benny not sure what the depth is but it defiantly doesn't come up ove true too of the rafter.
Cant remember the terminology but the guy did say it was pouris, gts sprayed on 1mm thick and expands to 100mm.

You can't have much ceiling insulation as ceiling joists aren't that deep usually.

I've been to seminars on the sprayed stuff (I'm an architect) so I'm familiar with it, but I don't know anyone that would specify it over Kingspan, Celotex etc given the choice. I believe its popular in Canada though!

**sniper-sam** · 25th February 2015, 00:02

Yeah be my I'm starting to have doubts now to be honest. Can't find any positives anywhere.
i presume companies can come up and insulate the roof with these boards? Like I've already stated no matter what happens I don't want to be part of it.

- - - Updated - - -

Originally Posted by rsykes2000

I read this recently and it put me right off the idea. Don't listen to the salesman... http://forums.moneysavingexpert.com/....php?t=5171597

Thanks for that, although some technics described in this thread are different to what ive been quoted it still doesn't sit well with me.

**benny.c** · 25th February 2015, 00:14

Originally Posted by sniper-sam

Yeah be my I'm starting to have doubts now to be honest. Can't find any positives anywhere.
i presume companies can come up and insulate the roof with these boards? Like I've already stated no matter what happens I don't want to be part of it.

Yes, a decent small builder will be capable of installing boards and any additional timber.

**mountmusic** · 25th February 2015, 01:12

£1300 per square metre seems shockingly expensive for something that is of limited benefit.

I had an additional 200cm of insulation installed in my loft in November. Total cost to supply and lay 65 square metres was £365 and, if I had wanted, they would have supplied a raised wooden storage platform for £25 per square metre.

**Kingstepper** · 25th February 2015, 01:55

Originally Posted by mountmusic

£1300 per square metre seems shockingly expensive for something that is of limited benefit.

I had an additional 200cm of insulation installed in my loft in November. Total cost to supply and lay 65 square metres was £365 and, if I had wanted, they would have supplied a raised wooden storage platform for £25 per square metre.

£1300 is the total price!

Originally Posted by sniper-sam

Now the first thing, the guy told me to measure the length and the width of the house and that will give me the sq m that I need, is this correct?

Will only the area if the roof is flat.

**sniper-sam** · 25th February 2015, 09:21

The more I think about it and the more I read the comments on here, I do value opinion a lot on this forum, the more I'm thinking against it.
there is an area on either side of the central walkway so to speak in our loft that is completely free of anything so putting down more insulation across the ceiling beams would be very easy to so and I'd imagine that this would atleast give us some benefit. It's a start anyway and as much as I don't want toshi should be something I could do relatively quickly.

**Jeremy67** · 25th February 2015, 09:30

Any difficult to remove system is a bad idea as is any system that might cause a lack of ventilation. I would avoid any goo based insulation system and do it properly with either more mat style insulation or a sheet based system.

**ralphy** · 25th February 2015, 09:50

My principle concern over spray foam loft insulation is that you are insulating the entire loft whereas you really want to preserve heat in the living accommodation. The loft is dead space and so without good insulation above the top floor ceilings you will be paying to heat an area that you don’t want/need to. I’d prefer to be able to see the roof joists and felt than to have them hidden away by covering: any problems can then be identified and dealt with before they become a major issue.

R

**o u t a t i m e** · 25th February 2015, 10:50

I got it done a couple of years ago. My main concern was the mess they left behind. That stuff can (and did) stain walls and floorboards where they were sloppy with it. The holes also weren't refilled properly and you can see the unevenness in some areas. If you get it done, make sure you get someone really good and tell them to take the time to do it well!

**Paddy** · 25th February 2015, 11:53

Insulation Rule Number One is install a vapour barrier on the hot side. If you don't do this, vapour will condense after passing through to the cool side. It'll pass through plaster, plasterboard, block and brickwork. This is not something the government has been making clear when persuading people to insulate, and is storing up all sorts of rotting-rafter problems for the future.
You can insulate under the rafters and have a warm roof space, which is probably unnecessary, expensive, but easier, or insulate over the ceilings and have a cold roof space, but either way, you'll need a vapour barrier on the warm side.
This weekend I lifted up 100mm of existing insulation in about a third of our loft, put down a vapour barrier, then replaced the insulation and added 200mm more. Not a pleasant job, but the increased level of water daily in the dehumidifier indicates the improvement. Prior to this, it would drip from the eaves on one gable end, and you could see mould and rot starting on gable and valley rafters. You can buy a 2.5m x 20m roll of vapour barrier from Wickes for about £20, so it doesn't add a big cost.

**MB2** · 25th February 2015, 12:16

I wondered about this some years ago because I was losing tiles from my non-insulated (or membraned) slate Victorian roof.

Advice from a roofer (who had no vested interest) was to avoid. His main concerns were -

1 Roof had been designed a certain way based on the materials used so considered (unlike a membrane) it was an unintended sealing in of the joists etc.

2 (his main concern) When the roof is finally replaced it will make the task much harder and more expensive.

You used to be able to get beaded insulation so if loft has been boarded would a possibility be drilling a hole between the joists and filling with loose fill insulation if don't want to take it all up again?

**kultschar** · 17th February 2023, 01:44

Big thread bump but only search which showed similar topic

Just had a building surveyor report on a 3 year old house and it flagged up the roof has been insulated with Spray foam insulation and not to proceed unless it is removed by vendor and replaced with suitable insulation. Pretty gutted as its been a long hunt and I was confident a new modern house would have had no red flags.

A quick google and I can see the points he makes about timber rot as well as mortgages / banks not touching with a barge pole and also it could be difficult to sell-on in future.

I am guessing this stuff is extremely difficult to remove and will destroy the felt / tiles underneath?

Finally I'm baffled a modern new build house would of used this stuff due to the above warnings which seems to be all over the internet????

**hogthrob** · 17th February 2023, 10:06

If there are companies that do it, there must be plenty of people that blindly believe salesmen.

**oldoakknives** · 17th February 2023, 10:25

Originally Posted by sniper-sam

With the impending arrival of our wee baby we are considering getting this done. The upstairs in our house is always considerably colder than downstairs.
my rough calculation going on the price per sq metre is £1300. Now the first thing, the guy told me to measure the length and the width of the house and that will give me the sq m that I need, is this correct?

and now more importantly, has anybody got this done and what are your thoughts, there are some horror stories on www about people getting rot because the roof can't breath etc. the guy on the phone told me that the installers leave a 50mm gap between the roof lining and the foam itself to allow the wood to breath and to prevent sweating etc.

any info good or bad would be much appreciated. This would be our biggest outgoing in terms of home improvement since moving here 6 years so want to get the decision right. Plus if it is a lemon of an idea I'd rather know as the £1300 could definately be better spent on baby stuff.....

Sounds like a great way to ensure any future work required to the roof is as difficult as possible. And if they leave a gap to allow the wood to breathe the best answer is not to do it and let the roof breathe. Just get the loft properly insulated above the ceilings.

**Mike2500** · 17th February 2023, 12:30

Not wishing not add a spanner in the works here but I understood from a mortgage advisor that most banks will not give a mortgage on a property if it has spray foam insulation. More often than not a new roof is required!!

This may not affect you right now but if you were to sell your property and your buyer needs a mortgage, it could make the property unattractive to potential buyers so it might be worth thinking about.

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**kultschar** · 17th February 2023, 12:44

Originally Posted by Mike2500

Not wishing not add a spanner in the works here but I understood from a mortgage advisor that most banks will not give a mortgage on a property if it has spray foam insulation. More often than not a new roof is required!!

This may not affect you right now but if you were to sell your property and your buyer needs a mortgage, it could make the property unattractive to potential buyers so it might be worth thinking about.

Sent from my iPhone using TZ-UK mobile app

Yes I believe that is the case.

Property I have looked at has been flagged up with it and Surveyor recommends vendor removes it before exchange. I guess they will be reluctant to do this initially.

Can't find too much on removal process - a few companies show before and after pics but I guess won't show examples / cases of damage to felt / roof

**Mike2500** · 17th February 2023, 13:38

I believe removal process is not simple and also relatively expensive for what is being done. Not sure how the cost would compare to a new roof either.
Sorry to present not great news!

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**Chris_in_the_UK** · 17th February 2023, 13:42

Avoid it (seriously).

https://hoa.org.uk/advice/guides-for...of-insulation/

**alanm_3** · 17th February 2023, 16:00

Listened to a R4 broadcast about this and as usual both sides blamed each other. The manufacturers and the registered contractors all say that they prepare a pre and post application report and say that the surveyors and consequently the lenders are lazy and don’t trust them. The surveyors take the opposite view that there are too many non-legit companies doing it without any pre-spray checks that consequently hide issues in the roof and joists.
They both called for regulation to avoid the very issues discussed here.

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**xxnick1975** · 17th February 2023, 17:55

Seems very odd on such a new house. Was this installed retrospectively by the vendor, or was it part of the original spec? If retro, why? New builds are generally very well insulated from the get go.

Also is this house part of a larger development? Maybe it's a more modern product/building system and doesn't have issues?

But when all said and done that's unusually strong advice from the surveyor, so certainly worth heeding!

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**Michael 38** · 17th February 2023, 19:07

My mum had it done on her house about 40 years ago as it never had a membrane and snow used to come under the tiles if the wind was in the right direction she never had any problems with it

**awright101** · 17th February 2023, 19:33

Mortgage valuers don’t like it and report the property as unsuitable. For that reason alone I would avoid unless the vendor is prepared to go to the expense of having it removed.

**hansblix2001** · 17th February 2023, 20:13

Originally Posted by sniper-sam

With the impending arrival of our wee baby we are considering getting this done. The upstairs in our house is always considerably colder than downstairs.
my rough calculation going on the price per sq metre is £1300. Now the first thing, the guy told me to measure the length and the width of the house and that will give me the sq m that I need, is this correct?

and now more importantly, has anybody got this done and what are your thoughts, there are some horror stories on www about people getting rot because the roof can't breath etc. the guy on the phone told me that the installers leave a 50mm gap between the roof lining and the foam itself to allow the wood to breath and to prevent sweating etc.

any info good or bad would be much appreciated. This would be our biggest outgoing in terms of home improvement since moving here 6 years so want to get the decision right. Plus if it is a lemon of an idea I'd rather know as the £1300 could definately be better spent on baby stuff.....

Please please don’t do this.

Our house had this s**t sprayed on the roof when we first looked at it. It was picked up by our surveyor and our bank’s surveyor. The bank refused to lend us anything because of it (they, along with various other lenders we spoke with, say it eventually rots the roof as moisture can’t escape and is a massive red flag).

We had to spend £10,000 to remove it before we could get a mortgage and it added a massive amount of stress to the process.

I don’t care what anyone says about the positives, just don’t do it.

**hansblix2001** · 17th February 2023, 20:19

Originally Posted by kultschar

Big thread bump but only search which showed similar topic

Just had a building surveyor report on a 3 year old house and it flagged up the roof has been insulated with Spray foam insulation and not to proceed unless it is removed by vendor and replaced with suitable insulation. Pretty gutted as its been a long hunt and I was confident a new modern house would have had no red flags.

A quick google and I can see the points he makes about timber rot as well as mortgages / banks not touching with a barge pole and also it could be difficult to sell-on in future.

I am guessing this stuff is extremely difficult to remove and will destroy the felt / tiles underneath?

Finally I'm baffled a modern new build house would of used this stuff due to the above warnings which seems to be all over the internet????

Just saw this was a bump and I replied to the wrong person!

Most people get talked into it by pushy sales people. It’s a total con and not worth the hassle.

We basically had to get a new roof, the stuff is massively messy and difficult to remove - it took our roofer a week and an enormous skip. There’s still bits of it in our loft despite it being removed.

If you get it done, be prepared to remove it if you want to sell the place, unless someone is paying entirely in cash.

**kultschar** · 17th February 2023, 20:30

Originally Posted by xxnick1975

Seems very odd on such a new house. Was this installed retrospectively by the vendor, or was it part of the original spec? If retro, why? New builds are generally very well insulated from the get go.

Also is this house part of a larger development? Maybe it's a more modern product/building system and doesn't have issues?

But when all said and done that's unusually strong advice from the surveyor, so certainly worth heeding!

Sent from my M2101K6G using Tapatalk

It is indeed strange. Was it maybe deemed ok to use 4 years ago and only recently been seen in a bad light? Surveyor is calling me next week to go through the report so I can find out more then regardless.

The house is a very modern one off job. Even if removable by the vendors I am unsure if certain sections are possible. The house is a H shape so the two ends/wings of the H are high pitched roofs with vaulted ceilings therefore no loft and presumably no room for access - I am not sure if these roof types have insulation in general. If they do (guess they must do) then I guess it would be impossible to remove without ripping off roof or ceiling.

The middle section is accessible and is an actual loft where the sprayed Insulation has been found.

**Gruntfuttock** · 17th February 2023, 21:13

A house on our estate has a ‘to be sold by auction’ sign outside. Intriged by this we looked up the house on the estate agents site. Details included a note that the previous buyer pulled out due to not being able to get a mortgage once the spray foam roof insulation had been spotted at survey time.

**demonloop** · 17th February 2023, 22:08

We’re in the process of selling our house and the buyers lender had a survey done. It was one of the first questions asked. Checked the loft and made sure we didn’t have it installed

**walkerwek1958** · 18th February 2023, 11:18

Definitely a bad idea, apart from the risk of encouraging rot the logic is somewhat flawed.

Far more sensible to ensure the loft insulation is as good as it can be, that’ll minimise heat transfer into the loft space. If the loft space isn’t much warmer than the outside temperature there’s no advantage in minimising heat losses from the loft.

**kace** · 18th February 2023, 14:20

Originally Posted by Michael 38

My mum had it done on her house about 40 years ago as it never had a membrane and snow used to come under the tiles if the wind was in the right direction she never had any problems with it

My dad had it done on our family home a good 25years ago for similar reasons. Last time I looked up there it all looked fine.

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