Raising attic floor to improve insulation

[Greenbean]

Hi , I'm a v amateur diyer living in a standard 90s bungalow - looking to raise attic floor to allow for 300mm insulation . Currently have around 100mm under existing chipboard. My plan is to place 2x9 timber batten at right angles to existing joints and raise the existing chipboard . Because of the way the chip board has been placed , I will need to place at least 8-10 4m lengths of the 2x9 timber .

Just wondering , is there any issue with increasing the weight of the extra timber on the existing joists ? The existing joist are in excellent condition

Should I remove old insulation, fill the space between joists to 200mm and place another layer of 100mm going the other direction? Or should I just leave the old insulation and run 200mm layer at right angles to joists ?

Thanks

 

[DannyBoyD]

IANAB (I Am Not A builder).

Leave the existing insulation & add the new stuff over it. I don't know that you need 2" x 9" timber to support flooring chipboard; I think you could get away with smaller battens. How much are you storing in the attic?

 

[Greenbean]

IANAB (I Am Not A builder).

Leave the existing insulation & add the new stuff over it. I don't know that you need 2" x 9" timber to support flooring chipboard; I think you could get away with smaller battens. How much are you storing in the attic?

Just need 8-9 inches to allow for the height of insulation - to avoid compressing it .
Attic will be only for storing decorations , luggage cases etc

 

[Pinoy adventure]

Some say leave the old stuff there but for the sake of an extra €100/€200 I’d remove it.
300mm is plenty so depending on the sizes of current timbers ?