Loft insulation

[gemius]

As a retired carpenter/site manager I've known a bit about insulation in a roof but I've been retired 10 years, things move on and I no longer have any contacts in the trade.
In a weak moment I agreed to have a survey done of my roof. The salesman, who insisted he wasn't a salesman, but pulled every sales trick in the book to get me to sign up, made a few points which I would like an opinion on.
He was selling spray insulation between the rafters to create what we used to call a warm roof. He said that the building regs had changed and this is what was being used in all houses now. Is that true?
He rubbished fibre glass because it takes up moisture and will draw heat up from below. That was never mentioned in my day when we were putting a foot of fibre glass in roofs.
I have no quarrel with the product but my roof has a good layer of insulation at joists level
so what do you think the advantage would be to have the rafters done and the crucial question how much would you expect to pay.

 

[foxhole]

He was talking b o l l o c k s.

 

[paulrockliffe]

The advantage of the spray insulation is that he can send his partner roofing company round in 10 years time to quote for the new roof after all your rafters have rotten through.

 

[SFK]

It gets me very upset when I see this being marketed in lobby of the DIY sheds.

No advantage whatsoever. And no price is cheap enough. DO NOT DO IT.

In addition to above comments, I have seen houses that have used spray insulation as being difficult to sell.
You cannot check the rafters for rot, the foam is stuck on all the slate tiles so nightmare for surveyor to check for issues, and difficult for future roofers to fix.

Also, standard loft insulation is cheap and effective:
https://www.wickes.co.uk/search?text=loft+insulation

SFK

 

[gemius]

Thank you all. Looks like I stirred you up a bit!
There was no chance of me signing up on the spot but I wasn't 100% sure what the situation was as I did do a few warm roofs using a sheet material and I think they made a good job and wouldn't have had the issues you indicate.
I agree with everything you said so thanks for that. The next time I'm tempted by this sort of harassment I'll give myself a good talking to.

 

[Leofric]

I doubt whether the principles of thermal insulation etc in houses have changed that much since you were a site manager 10 years ago

 

[gemius]

No I don't think the rules have changed. Prevent any warm air from entering the roof space and ensure adequate ventilation across the space. Do that and you won't go far wrong.

 

[Leofric]

No I don't think the rules have changed. Prevent any warm air from entering the roof space and ensure adequate ventilation across the space. Do that and you won't go far wrong.

- and about 300mm of mineral wool quilt insulation at joist level of course.