Do I need to board over Celotex being used for storage in loft?

The simple answer is - if you aren't going to damage it you don't need to protect it.

So just sliding a cardboard box over it - no problem. Things which will rip the foil and tear the foam - better to protect it.

Tim W

There are some boards already on the joists so it will be supported.

Would hardboard be sufficient to protect the insulation? I don't think I'd be storing anything that would be likely to get through that.

is there some special tape for sticking sheets of insulation together? I'd be using 8 * 4 sheets but would have to cut them into 8 * 2 sheets to get through the loft hatch.

The centre area of my loft was already boarded with a mixture of materials that had accumulated over the years.

I then covered this with two layers of Knauf space board insulation,(1200 mm x 500 mm x 50 mm) with the joints staggered.

As I needed to hold everything down, and the insulation will dent from point loads such as bony knees and storage box feet, I covered it with hardboard (full sheets cut across into 500 mm strips {plus off cuts} at B&Q) and screwed it all down to the boarding using M6 x 120 mm woodscrews which were on offer at CPC.

I was very pleased that the installation went exactly as planned. I did drill pilot holes, but the screws would probably have self-drilled.

The only slight problem, which became apparent after a few weeks, is that (despite the fact that the hardboard spent some of the autumn stored in the caravan, until I could get the job done) the sheets have expanded slightly and bowed a little. I haven't been up there recently to see if the summer weather has shrunk them back.

Chris