Keep old 1cm fibreboard on roof or remove when re-tiling?

[SilverSaloon]

Hi

I am planning to re-slate my roof.

Currently under the slate there is an old sheet membrane that will need replacing, but there is also under that a sort of 1cm fibre board.

Is it worth me keeping this, basically as extra insulation rather than taking it all away and putting standard breathable roofing felt + the slate?

I am also planning a loft conversion in the near future too. Am I better with just breathable membrane here or as its going to be insulated on the inside between the rafters should I also keep the fibre board in place too.

Its old but its all extra protection that is already in place + essentially "free"

thanks for any advice.

 

[freddiemercurystwin]

If it were me, and I could stretch to it, I would fit continuous ridge vents as well as the breathable membrane, occasional condensation can be an issue in lofty's, even when they have a breathable membrane. They can only let so much moisture out.

Removing the fibre board is a no-brainer.

 

[Alastairreid]

What do you have on your roof slates or tiles?

If slated how are the slates fixed? is the roof battened.

Do you have fibre board between the rafters?

 

[SilverSaloon]

What do you have on your roof slates or tiles?

If slated how are the slates fixed? is the roof battened.

Do you have fibre board between the rafters?

It is currently tiles but was originally slate (is 1850's cottage). I want to put it back to slate.

currently you have the rafters, then batterns, then the fibre board, then more batterns which the tiles hook onto.