Attic Insulation

Sparky1972

I am looking to get the Attic insulated and have a few quotes on spray foam on the roof up to the Apex. One company use Icynene and tell me they can spray directly onto the membrane whereas the other company say they will install a breathable membrane first of which they will then spray onto.. Not sure why the Icynene say they don't need a breather and spray directly to roof. anyone have any information on which is correct and best?
Also I am reading online that if you have spray foam insulation in Attic roof, that banks take a negative view of it and will not lend mortgages or equity release - Is this really the case?
Hard to get reliable information on this stuff.. Appreciate the advice..

TheBoyConor

I wouldn't touch that spray foam. Not a hope.

Any places I've seen it done looked like a right dirty mess. And it hides everything behind it.

I'd be concerned that it could bring about rot in the timbers as it seals everything in pretty good. If I went to look at a house that had a spray foam in the attic I'd be wondering what sort of horrors it is hiding .

Calahonda52

there are two types of spray foam.
One is closed cell and the other is open cell.
You can research the important differences.
One is better as an insulator than the other, and therefore more expensive.
The reality is that there is no way, pre installation of knowing which one you are getting.
in relation to the inserting of a breathable membrane, I don't believe that is what they suggest as this would require removing the slates and replacing the existing.
I think what they are suggesting is that the will install ventilation baffles, which, if done properly, will leave a ventilation space, all the way around, tying into your ventilated eaves. If done properly.

Spraying onto the existing, even if a breathable membrane is not something I would recommend.

I cant comment on the banks issue: having spent 20 years in finance, there wont be a equity release exception, they will either lend or not.

What I do know is that early work in this area was based on ignorance of the science and done by fly by night operators, driving white vans, with no trade markings, working on a cash basis for the slimely suited sales person.

I have seen several cases where after 12-15 years, the roof rafters rotted at the rafter wall plate junction where the birds mouth is, and the roof slowly collapsed.
.
In all cases, the roofing felt was the original black bituminous felt and the foam was open cell.

I agree with TBC above except on the neatness, it can be made neat but is rarely done.

I have used it for internal walls and when it is trimmed off and slabbed over it works well.

In these cases, it was open cell and I knew what I was getting.

The fundamental issue for me with this stuff is that
The reality is that there is no way, pre installation, of knowing which one you are getting.

Lumen

Presumably you want a warm roof because you want a warm attic, i.e. want to bring it into the building envelope?

Cos if you're going to vapour barrier and slab over the foam on the underside and have a non-breathable felt flush to the top side, the openness of the foam isn't going to make a blind bit of difference.

Calahonda52

Lumen wrote: »

Presumably you want a warm roof because you want a warm attic, i.e. want to bring it into the building envelope?

Cos if you're going to vapour barrier and slab over the foam on the underside and have a non-breathable felt flush to the top side, the openness of the foam isn't going to make a blind bit of difference.

It does matter because there is a big difference in U value and cost between open and closed.

In addition, there is need for signifiant detailing at the eaves which cant be done without stripping part of the roof off

Sparky1972

So the net conclusion from all of this is run a mile from spray foam and stick with more traditional methods..

Lumen

Calahonda52 wrote: »

It does matter because there is a big difference in U value and cost between open and closed.

In addition, there is need for signifiant detailing at the eaves which cant be done without stripping part of the roof off

I just meant that neither will keep the timbers dry if they're packed between impermeable materials.

TheBoyConor

I would stay clear of it tbh. It depends too much on being done properly to rule out the possibility of hidden dry rot down the line.
Things being done properly is something which I don't see too often from most Irish contractors.

Yellow_Fern

New builds are a bit different but on retrofits attic insulation takes very careful detailed work with use of thermal cameras to check for gaps but generally people tend to happy or unaware they have gappy jobs. I would see spray foam as a quick fix and quick fixes are rarely the best choice.

Muahahaha

Lumen wrote: »

Presumably you want a warm roof because you want a warm attic, i.e. want to bring it into the building envelope?

Cos if you're going to vapour barrier and slab over the foam on the underside and have a non-breathable felt flush to the top side, the openness of the foam isn't going to make a blind bit of difference.

If not spray foam what is the best way to bring the attic into the building envelope? Ive the problem of a bedroom in the attic with crawl spaces both sides of it. Was freezing last winter so thinking of sorting it soon and had a couple of spray foam companies out to quote a few months back, approx 1,500 was the quote

Another company mentioned something about a 'warm roof' involving taking it all apart and insultaing that way but at big cost, c.5k if I remember correctly and out of my budget.

Is there any middle ground, I had thought spray foam was the way to go but this thread has me reviewing that. If I were to go spray foam are there companies out there that are NSAI certified or is there any way a layman can know that the job is going to be done to a good standard. It even worries me that you could be sold open cell but they are actually using the cheaper closed cell, its pretty frustrating to think you could spend a fair wedge of cash and the job might deteriorate the building over time.

Lumen

Muahahaha wrote: »

are there companies out there that are NSAI certified

The NSAI certifies neither companies nor products but products used in specific applications with a certain conditions being met.

You should ask the supplier for details of the NSAI certification, find the original certs on the NSAI website and check that the application is covered and conditions can be met.

There are many cases of suppliers pushing certified products for uncertified applications. They typically sketch over the details and then waffle when pressed.

You will also find BBA certification, but you need to similarly check the details.

This is cowboy central.

Tilikum17

What’s are people’s thoughts on ecobead? If that the same as the foam, or better?

Yellow_Fern

Tilikum17 wrote: »

What’s are people’s thoughts on ecobead? If that the same as the foam, or better?

I think that is very common in walls in new builds. Is that used in attic retrofits?

Tilikum17

Yellow_Fern wrote: »

I think that is very common in walls in new builds. Is that used in attic retrofits?

We’ve just bought a house that has an E rating in the country side. So I want to pump plenty of money into insulating it.

When I say countryside, it’s 10min drive from my old house in the city.

Muahahaha

Lumen wrote: »

The NSAI certifies neither companies nor products but products used in specific applications with a certain conditions being met.

You should ask the supplier for details of the NSAI certification, find the original certs on the NSAI website and check that the application is covered and conditions can be met.

There are many cases of suppliers pushing certified products for uncertified applications. They typically sketch over the details and then waffle when pressed.

You will also find BBA certification, but you need to similarly check the details.

This is cowboy central.

Yeah thats the bit that worries me. If you know of a company you can recommend please PM me. Seems to be a minefield out there

Calahonda52

IIRC, this thread stared with spray foam.
my comments above are underscored by this post by lumen on certs.
you just don't know.

Yellow_Fern

Tilikum17 wrote: »

We’ve just bought a house that has an E rating in the country side. So I want to pump plenty of money into insulating it.

When I say countryside, it’s 10min drive from my old house in the city.

Get a airtightness test, then when it gets cold get a thermal test and let them tailor a solution to the structure of your house. Irish houses are handmade and they vary so much so it is impossible to say what is best for house. Generally speaking external wall insulation is a lot better than pumping the walls but I am generalising. There are traditional houses that should not be given this insulation.

BryanF

Yellow_Fern wrote: »

Generally speaking external wall insulation is a lot better than pumping the walls but I am generalising.

generally speaking, it’s best to pump block/cavity/block walls, before considering external wall insulation