Spray foam insulation

tom1ie wrote: »

Is it worth getting the rafters sprayed also?

No. The insulation on the attic floor defines your thermal envelope and the rafters are outside this so no impact.

Cavity could be pumped provided it is not in one of the defined hi exposure areas.

tom1ie wrote: »

Grand.
1. So if I wanted to improve heat retention in the house I would increase the depth of this insulation.

2. What’s your view on getting the cavity’s in the external walls sprayed even though I have the inside slabbed? Is this outside the thermal envelope also?
Thanks.

1. No, not necessarily. What's your air tightness like?
2. Is it certified for this application? No certification, no dice.

tom1ie wrote: »

I presume it’s a massive deep retrofit type job to get a building like mine air tight?

Depends really but not necessarily once you know (or have been shown) where for example the top 3 issues are. If 2 of these can be easily addressed and the 3rd maybe later when improving something else then real improvements are possible without breaking the bank. There is generally also more than one way to airtighten a building and measures can always be incorporated when doing other works / improvements.

listermint wrote: »

Tbf though, moving the ventilation into the rafter space via approved card system and baffles . And then turning the attic space into a warm room does have an impact on the thermal envelope of the house.

Saying it has no impact isn't true.

I was describing the impact within the existing thermal envelope i.e. the room(s) below the insulated attic floor. No mention was made by the OP of turning the attic into a habitable space which I think you are proposing if I understand your post correctly.

Also, there is a myth out there that sprayfoam deals with airtightness as well as insulation and many '000s of euro have been spent in error by homeowners in these types of situations thinking they will have a warm attic by sprayfoaming the rafters.

MicktheMan wrote: »

I was describing the impact within the existing thermal envelope i.e. the room(s) below the insulated attic floor. No mention was made by the OP of turning the attic into a habitable space which I think you are proposing if I understand your post correctly.

Also, there is a myth out there that sprayfoam deals with airtightness as well as insulation and many '000s of euro have been spent in error by homeowners in these types of situations thinking they will have a warm attic by sprayfoaming the rafters.

So true

tom1ie wrote: »

Hi all
I’m thinking of getting spray foam insulation done in the attic.
I already have about 2 rolls thick (400mm?) of earth wool insulation in the attic.
Is it worth getting the rafters sprayed also?
Does the spray go all the way to the wall plate and block off the ventilation to the roof?
I have installed 50mm insulated plasterboard on all the external walls, would it be worth getting the walls pumped with spray foam also?

It’s a 1966 semi detached brick built 4 bed.

Thanks all.

I'm in a similar situation. Our upstairs rooms adjoin the unoccupied attic (dormer), those room are alway much colder even with heat on. I was considering replacing all the fibreglass insulation on the dwarf walls with kingspan fitted between the studs. Not a small or cheap job but yesterday i received my FLIR One thermal imaging camera & surveyed the rooms upstairs & basically the dwarf wall is quite well insulated with a few cold spots that need to be remedied.

The major heat sink was the sloping section from the top of the dwarf wall to the dormer ceiling. This was measuring 5.5'C last night when I checked. That sloping section runs the whole length of the upstairs on both sides about 30sqm of heat sink. It's difficult to access this section which might explain why there is only expanded polystyrene (aeroboard:rolleyes:) for the first 30cm on the lower side.
Check out the picture.

So now i got to spray foam this section & i'm in the market for a competitive professional vendor with all the required certificates - any recommendations appreciated.

the quickest answer is to ask them perhaps there are cables in the area ?

dathi wrote: »

the quickest answer is to ask them perhaps there are cables in the area ?

Thanks Dathi, no mention of cables or any other good reason other than its faster. Sigh.

In the wind wrote: »

I just challenged it & he said he done it that way because it was faster.
I rejected that as a good reason because I don't care about fast, I care about correct.
He then changed tack & said the space was too tight.
I challenged that with the fact that a different space they just completed correctly was even tighter.
He then acknowledged that they were shortcutting & would rework the whole lot correctly.

In a sense they should be thankful that I spotted this before they had started to spray as the rework could have been a lot more.
The boss just turned up coincidentally & I brought it to his attention & he said it was completely wrong & that they had to rework the whole lot.

It pays to keep an eye on workers & quality of work & understand the standards. I hope this is helpful to others in future.

so they're just tidying up there now. It makes quite a mess but a cleanable mess.

-I completed a full inspection & found about a dozen spots of poor coverage / no coverage & they went in and fixed it up.

-Fibreglass insulation needs to be rolled back into place where it was pushed aside for access.

-Excess carding material needs to be removed from the attic as it is a fire hazard & looks like crap.

- several monster cans cleaned up - it is hot stuffy work - I don't envy they guys but they were masked up.

- the hardened foams crumbs & dust are all over the place but they're vacuuming that up now.

-Plenty of wall & door scrapes from working in the area, I'll assess that when the place is cleared out. A little care here would have prevented this.

- I noticed a chimney stack that is not sprayed is already sweating in the attic space so that needs to be dealt with intelligently. Sigh.


Now lets see how the house feels tonight...

Yep I'm pleased with the result. The job seems to be working well & the house is warmer & quieter for sure. You will need to monitor the work as it proceeds & I recommend holding back 10% payment for a month or so until you have had time to complete inspection & to allow time for you to find issues or damage.

I do need to throw an eye on the chimney that was sweating , in fact I'll do it this evening.