Attic insulation

me4many · 04-01-2026 08:34PM #1

I will be putting down a layer of insulation at right angles to what's there at the moment (between the joists) .

It's really hard to get right down to the eaves and still leave a gap over the insulation. I noticed that the air flows very freely from where the felt overlaps about a quarter way up the roof. I'm wondering how important it is to have a gap at the eaves.

Any info appreciated.

Thanks.

billbond4 · 04-01-2026 09:01PM

Very important.

If you block it up, you will have moist air trapped in your attic, and it will condense on the insulation making it wet and that will transfer through to the ceiling below.

I learnt that the hard way, as I blocked up mine, so last summer I removed the insulation at the eaves and now hardly any condensation in the attic now.

monseiur · 04-01-2026 09:19PM

Make a simple box with plywood and place over each vent in soffit Fit insulation firmly around it to keep them in place Job done ! Be sure to make boxes bigger than size of actual vent. To help pin point the location of vents get someone to shine a high power torch up thru vent from outside.

DBK1 · 04-01-2026 09:25PM

https://www.telfords.ie/continous-rafter-tray-600mm-x-6m-392817?srsltid=AfmBOoqGNERM1MpkIiqXW0FoFDvoQuvZXU5ORyjnpGuZ8bi5fVDrCAtv

Something like that should solve your problem.

DublinDilbert · 04-01-2026 10:03PM

use a better insulation at the eves, so you don’t need as much. It is very important to insulate the wall plate and maintain air flow. Rockwool is very good and keeps its shape. I cut 100mm Rockwool at a 45 degree angle and push it into the eves, this covers the wall plate and still allows air flow.

billbond4 · 05-01-2026 04:39PM

@DublinDilbert +
I did something similar, got a roll of Reflective membrane Silver Bubble insulation roll i.e.

https://www.diy.ie/departments/ybs-reflective-membrane-silver-bubble-insulation-roll-l-7-5m-w-0-6m-t-3-5mm/5060078160421_BQ.prd?storeId=1374

and cut it into roughly 60cm pieces, then folded it over and taped it,
so I have a 20cm wide piece of insulation that I can put on wall plate, thats nice and thin so its keeps the airflow.
From looking below with a thermal camera that sorted some coldspots for me

Attic insulation

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