insulating rafter's

[diycooper]

Going to be starting a diy loft conversion for storage soon so would like some advice.

My rafter are 75mm so wa thinking of leaving a 25mm gap then fitting 50mm kingspan between rafters then boarding with foil backed plasterboard. Is this the best way to go ?

 

[diycooper]

Anyone ?

 

[freddiemercurystwin]

Maybe if you said thanks once in a while ......

 

[diycooper]

Maybe if you said thanks once in a while ......

You know what freddy I didnt realize I wasnt, I use to always say thanks . I reallly do appreciate all the help I get or got ha off this site

 

[diycooper]

Take it Im not going to get any answers here then.

 

[freddiemercurystwin]

I wasn't asking for a thanks earlier (so feel free to cancel it), just making an observation given your past posting history, no matter.

Do you have felt under the tiles?

If you wish to insulate at rafter level unless you have either a breathable membrane of no felt at all beneath the tiles you will need to fit continuous ridge vents and ensure your eaves ventilation allows airflow up the gap between the insulation and the underside of the felt which needs to be 50mm by the way.

If you don't ensure the timbers are ventilated, condensation will occur and eventually the timbers will rot

 

[diycooper]

I wasn't asking for a thanks earlier (so feel free to cancel it), just making an observation given your past posting history, no matter.

Do you have felt under the tiles?

If you wish to insulate at rafter level unless you have either a breathable membrane of no felt at all beneath the tiles you will need to fit continuous ridge vents and ensure your eaves ventilation allows airflow up the gap between the insulation and the underside of the felt which needs to be 50mm by the way.

If you don't ensure the timbers are ventilated, condensation will occur and eventually the timbers will rot

Yes I have felt which is not breathable, the rafter's are 75mm, will 50mm kingspan be ok with a 25mm gap if I do not insulate underneath the big 9 x 2 eaves?