Upgrading loft insulation, what else to do a proper job? Information, help, tips and advice on cavity walls, ceilings and lofts etc....

[GNorthy]

Hi,

I'm planning to update the insulation in our loft. The house is from ~year 2000 and only has 100mm currently.

I've done quite a bit of reading about do's and don'ts, but still have a few questions.

We have vented soffits, so I know I need to keep airflow through them and around the loft above the insulation. II've not been right into the eves yet, but there's triangular shaped polystyrene pieces in the corners, my guess is these allow airflow? There's a few missing, and I've not seen them for sale anywhere. I've seen the corrugated black plastic ones, should I replace missing ones with the black ones?

While I'm up there, I'd like to do a proper job. I'm planning to seal all the lights, pipes etc. I was going to use 'loft lids' on the lights with silicone. Should I just use expanding foam on any pipes?
Is there anything else that would be good to seal? Tops of interior walls? Anything to seal on exterior walls?

That brings me onto another question. Do I add insulation between the last joist and the exterior wall? Any worries about damp or ventilation here?

I'm kind of looking to do the best job I can that doesn't need touching again ever or for a long time. So any other tips/ideas are also appreciated.

Thanks,

G

[stoneyboy]

Hi gnorthy
You must maintain a ventilation path above the insulation at eaves level, pick whichever method is easiest. Take the insulation right into the eaves and onto any wall plate or you may get mould growing in the corners of the rooms below. Don’t forget to insulate the loft hatch.
If you have downlighters and you’re going to fit loft lids make sure you have led bulbs. If they are halogen leave the area above clear for cooling.
Regards S

[GNorthy]

Hi Stoneyboy,

Thanks for the reply.

Yes all LED here :-)

Thanks for the heads up about taking the insulation right onto the wallplate.

What about between the last joist and the wall? Do I need to poke some insulation down that gap and then the next cross layer, start touching the wall?

What did you think to my ideas about sealing things? There's a few pipes which I imagine should be sealed. Are there any other things that should be done for draughts?

Many thanks,

G

[stoneyboy]

Hi gnorthy,
Yes plug any gaps next to the last joist.
Holes around pipes can be difficult to seal but expanding foam is ideal - use a fire grade.
Regards S