Pitched Roof and Cold Attic insulation

Domicio

Hi, my house is always cold and I'm trying everything that I can before investing on an EWI. Checking the attic that has 300mm insulation and air ventilation tiles, I found a space between the external wall and the attic floor area is not insulated at all (as per photos above).

Is it right or it's missing insulation?

I can't reach the area as it gets really tight so if anything needs to be done, it would need to be done through the roof.

Any advise is highly appreciated.

Thanks

listermint

That's your wall plate (timber) . Beyond that there should be no insulation but before that (your side) of the image there should be insulation above the ceiling up to that wall plate. You should also leave a gap between the membrane and the insulation try not to have the membrane pushed right up against the pitched underside of the roof membrane. This is for airflow. You want airflow above the insulation but not below it. I.e between insulation and ceiling.

Domicio

Thanks a million for taking the time to explain it to me.

10-10-20

Figure 6a on page 8 shows this detail:

https://www.kingspan.com/content/dam/kingspan/kil/products/thermapitch-tp10-gb-and-ireland/kingspan-thermapitch-tp10-brochure-en-ie.pdf

The black object marked as "Proprietary eaves ventilator" is where listermint is mentioning where there needs to be a ventilation gap.

The one item of insulation that you appear to be missing is the small amount which runs up from the cavity closer (see image 5a) to the "wall plate". The wall plate is that piece of wood with the nail lying on it in the second photo. So the guidance that he gave is that insulation could/should be fitted as per the image at "Flexible insulation material tightly packed to block cold bridge and retard air infiltration", but maintaining the air channel as mentioned.

chooseusername

https://www.boards.ie/discussion/comment/121383517#Comment_121383517

" try not to have the membrane insulation pushed right up against the pitched underside of the roof membrane"

I was a bit cunfused, is this what you intended?

Also, my understanding is the loft insulation should extend beyond the wall-plate to the cavity closer, while maintaining a ventilation gap between it and the roof membrane.

listermint

https://www.boards.ie/discussion/comment/121383796#Comment_121383796

Correct and correct.

TimHorton

https://www.boards.ie/discussion/2058323097/pitched-roof-and-cold-attic-insulation

I started on the same Journey about 1 year a go, I corrected the Attic Insulation as per posts above and then added 100mm Insulation to the inside on all External Walls in 4 Bedrooms with Vapour Control etc, Now the rooms (especially the 2 north facing gable end rooms with 2 external walls in each room) have been transformed from cold uninviting rooms to warm cosy and comfortable. I DIY'ed for about 3 to 4 K , EWI is very expensive.

Mr321

https://www.boards.ie/discussion/comment/121384107#Comment_121384107

Good to hear some feedback on the EWI

whizbang

I DIY'ed for about 3 to 4 K ?? thats an awful lot!

Whats absolutely critical is that gap between the plasterboard and the wallplate. pack tightly here.

Major PITA gettin in there..

whizbang

Is that 1st pic the top of the wall - 9" solid ? with wall plate on top?

Be careful about pushing fibre insulation into contact with the back of the fascia/soffit. It will wick up moisture up into attic.

TimHorton

https://www.boards.ie/discussion/comment/121386525#Comment_121386525

That was not just the Attic detail , That cost includes internal insulation with 100mm polyiso/vapour control layer/timber batten/foil backed plasterboard in 4 Bedrooms & EnSuite. Window Boards removed and all 4 window reveals insulated and taped with Air Tightness Membrane/Tape and new Window Boards...Rooms are now very comfortable and easy to heat - I have also added Smart TRV Valves to keep rooms at 20/21 degrees during the evening.

Domicio

https://www.boards.ie/discussion/comment/121383616#Comment_121383616

Any suggestions of a reliable company in Dublin that would this kind of job? Thanks

gandalfio

Would spray foam insulation be suitable in this instance?

listermint

https://www.boards.ie/discussion/comment/121388641#Comment_121388641

No. And I'd recommend steering clear of it. It's causing a bit of a stir for mortgage approvals at the moment. Engineer sign offs etc .visibility of roof structure.

loyatemu

https://www.boards.ie/discussion/comment/121387026#Comment_121387026

did you strip back the walls before adding the insulated boards, or just add them on top of the existing plaster? How much total space did you lose off each wall?

TimHorton

https://www.boards.ie/discussion/comment/121392659#Comment_121392659

Left Walls as they were.

Added the following and lost 142.5 mm on external Walls., Rooms were on the larger side so not a major deal, especially in rooms with only 1 external wall.

100 mm Insulation Board

Vapour Control Layer

30 mm Timber Batten - For Service Cavity

12.5 MM Foile Backed Plasterboard

Outside Temp was down to 4 Degrees Last night and occupied bedrooms stayed at just under 20 degrees all night - Heating was turned off at 9.30 PM!

Gamechanger - Rooms are warm comfortable and take very little to heat

See my approach (Insualtion/Vapour Control/Timber Batten), Airtight Tape on Insulation sheets, and all openings (Plumbing and Electric) sealed with Airtight connections.