Attic floor insulation

MrBumBum

This is a topic I know NOTHING about so would appreciate if any advice could be phrased in such a way a child could understand it.

Recently bought and moved into a 23 Yr old C3 rated house. Got a BER after Solar PV install and windows and door upgrade. House went to a B3.

On the BER suggested improvements it mentioned attic insulation.

The rafters are full of the rock wool stuff, if I was to change anything what's the best course of action?

- shove it to the side and squeeze more in

- lay more on top of it

-pull it all out and buy thicker newer stuff

Maybe about 1/3rd of the attic floored so doing the whole lot probably isn't really an option.

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Cheers

Lumen

Roll another layer over the top at 90 degrees.

mulbot

Yea double layer the rock wall, 90' over the bottom layer

Citroen2cv

Get the second layer under the wiring.

MrBumBum

Cheers lads. Just to make sure I'm picking this up right - you're saying lay more insulation crossways over the existing stuff, as in the rafters would be completely buried?

Alkers

https://www.boards.ie/discussion/comment/122751769#Comment_122751769

Thats exactly it, if you want to floor any of the attic you can get legs which poke through the new layer of insulation and attach to the rafters.

What depth of insulation do you have currently?

You should end up with 300mm

MrBumBum

Dunno the current depth Alkers.

Cheers lads, like I said, it's a topic I know nothing about. Laying the insulation the other way was something I didn't even consider.

I find the house holds a bit less heat than I'd expect it to, hopefully if I do this it'll make a difference.

conor_mc

This will give you the idea re raising the flooring with loft stilts. Definitely agree with the other recommendations, lay out an additional layer above the existing stuff at 90 degrees. Your heating bill will notice the difference for sure!

https://www.youtube.com/watch?v=9w1mumxL0_8

MrBumBum

Thanks for your help lads. I have been educating myself on this the last few days.

It seems I have a bit of "pattern staining" or "ghosting" on the ceiling, I'd imagine another layer of insulation in the other direction over the joists would help?

Going to follow your advice anyway. As previously mentioned I dont know a whole lot about it.

Would something like this do the job?

https://www.chadwicks.ie/all-products/building/insulation-1/insulation-loft/knauf-earthwool-loft-roll-150mm-combi-9-18m2-21460.html

Calahonda52

I find the house holds a bit less heat than I'd expect it to, hopefully if I do this it'll make a difference.

You need to address uncontrolled ventilation first:

..

Please post pictures of this

showing location vis a vie the external walls

It seems I have a bit of "pattern staining" or "ghosting" on the ceiling.

Power cables cannot be buried under 150 mm insulation, especially elec shower, elec cooker .

They are designed to be air cooled

can be sleeved by splitting black flexible conduit longitudinally and taping up again every so often with good quality tape

GreeBo

https://www.boards.ie/discussion/2058377176/attic-floor-insulation

Are the rafters literally "full" with existing insulation, as in up to their tops?
If so then laying at 90* is exactly what you want to do. If not then you might want to top up first, depending on how high the existing insulation is compared to the rafters.

Check the insulation around the edges of the roof, you need to make sure that air isnt getting in underneath the insulation, but also ensure that you dont pile insulation up right against the roof or you will block the attic ventilation.
If you google "rafter tray" you will see what you need to use to continue ventilation and also increase the insulation.