Attic insulation

funkey_monkey

I want to increase insulation in the attic of our 70's bungalow. It currently has mineral wool only between the joists. Can I place insulation boards on top of the joists or must I stick with the same type of insulation?

Padre_Pio

You can, but it's probably cheaper and easier to add more wool across the joists.

Is there a reason you want to go for the boards?

funkey_monkey

No. I thought it might be easier to just put the flooring boards back down on top of them and maybe would have a better u-value for same depth.

Padre_Pio

Yes your right, you just need to make sure there's no air gap between the wool and the board, while trying not to squash the wool too much.

Those click in flooring boards are expensive, you can use half inch ply instead. The rigid PIR gives a decent backing to it, and screws into the joist stop it flexing.

Biker1

https://www.boards.ie/discussion/2058354103/attic-insulation

If you use mineral wool in the majority of the area and use 150mm EPS backed plywood for the area you need for storage. Cheapest option.

funkey_monkey

https://www.boards.ie/discussion/comment/122208890#Comment_122208890

The attic is already floored with chipboard so I have to lift it first and then put it down on top of the raised insulation.

I thought I could get away with thinner insulation board and just set the chip board on top. Otherwise I'll have to use those risers and the mineral wool which would require a lot more work to secure and tidy up the edges.