Insulating a boarded loft?

[stillfrazzled]

Was due to have my loft insulated today - deal through my local council.

However, I had my first good look at the loft this weekend (we've only been here a few months and haven't had a proper loft ladder put in yet) and realised it was entirely boarded.

Company confirmed that all they were planning to do was lay insulation on the boards, rendering it basically useless for storage, so I postponed.

We need the storage space, but also need the insulation. Don't have lots of money.

Any hints/recommendations from MNers more clued up than me?

Can you lift the boards and insulate under them?

I don't think you can lift boards and insulate underneath, or not via one of the council offers anyway, because the recommended depth of insulation is more than the depth of the rafters on which the boards will be resting. No point in insulating to recommended depth, then squashing the insulation down to put boards back, as this makes the insulation useless.

Drat, I'd feared that. So do people with boarded lofts just not have insulation?

We have the Aluminium foil backed insulation boards that are thin enough to fit under the boards and between the rafters -- in places where we want the boards. And elsewhere (low rafters) we have the standard 25-30cm of rockwool. It's a reasonable compromise that gives us a lot of storage space.

Celotex.

No easy answer. What alardi said is the best compromise. We have done the same but taking up boards in the loft can be really hard work.

alardi, I might slightly love you . Can you put them on the top of existing boards ?

we've got insulation below the boards (not sure how deep though) and then a HUGE layer of boxes and clutter acting as insulation on top of the boards...

You can't walk around on them, Frazzled, if that's what U mean. You need to lift existing boards & put the Celotex underneath... I guess you could install yet more boards over Celotex on existing boards, but you'd lose height in the loft space..

There are several options here. Beyond a standard foil faced insulation board, there are other phenolic faced insulation boards which are higher performance and will help you achieve a better U value. Celotex, Kingspan, extrathem etc.. all offer a full range of foil faced PU boards so you can guarantee that you can acheive the required u value by insulating under the floorboards. However, because of the COLD BRIDGING effect of the joists, you now need to insulate over the joists before replacing your floorboards which can be a PITA.

IMO your best option would be to (fit to the eaves instead of the floor) use a multifoil such as YBS Superquilt or TRI ISO 10 which is super stuff, easy to use and very thin. Downside is that some LAs don't approve of multifoils so the best bet is to talk to YBS first and they will advise

www.ybsinsulation.com/products_roof_superquilt.htm