Thank you all for suggestions. As the doors are roller type I think it is agreed the only practical solution is to hang something against the doors, so back to either duvet, curtain or a foil screen.

Location: Sunny Devon

Hi Nick

what are the measurements of the door?

Location: Dover, Kent

Ok so a serious suggestion.... in some commertial workshops they have a curtain of 8" wide vertical strips of heavy plastic which you can just walk through or drive a car through.

The foil backed insulation is called Cellatex or similar. Unfortunately Nicks doors roll up at the top, so you cant add any significant thicknes to them. It would work well to insulate the roof, although in effective thickness' it is quite expensive.

The gold and silver "space blanket" plastic film stuck to the inside of the door would stop the drafts through the door itself.

Is it feasible to make vertical window blinds this sort of size? they would provide a secondary barrier to the cold, and could be drawn open to allow access.

Perhaps panels could be made using rigid foam insulation such as Recticel and attached to the doors when closed. It comes in in 8'x4' sheets. Quite expensive but very effective.
The problem would be were to put them when the doors are opened. If only one door is usually used the loose panel could stand up behind one of the other doors.

Location: Melrose, Roxburghshire

Have been into Keyline building supplies this morning Celulite sheets @ 25mm thick x 8'x4' are £8.50 +vat and weigh very little. I am working on cutting them to fit the anels on the inside of the door

Location: Oakley ,Hants

Just an idea: cut them narrower and tape them into a folding screen?

The idea I'm taking from the above discussion for myself is curtains. That could either be second hand "real curtains" or old duvets or cheap sleeping bags but the idea of a rail and hoops and tie backs is such an obvious one for an insulating and draft proof screen that can be quickly and easily moved out the way.

This is the stuff I use in my workshop to separate warm room from the big cold one which has a large exterior metal door. I can work in there with the engine running if necessary and still have a hot spot to retreat to.

I think the picture is turned through 90* so you'll have to lie on your side to view it !

Location: Ripon

The ultimate solution but unfortunately the most expensive would be to replace the current roller doors with insulated ones.

Location: Oxfordshire

Decided to go the route of insulation board, three sheets per door duck taped so they can form a screen elsewhere when not in use. Derek those sheets are very cheap I can only find Celotex at about £20 per sheet. Do you know if Keyline only local to you or nationwide?

Location: Sunny Devon

Nick,

I've just Googled Celotex and found some cheaper than your £20 and in your County - Roofingsuperstore in Estover, Plymouth. Sheet size 1200 x 2400 x 25mm for £12.90 including vat.

I've also Googled Keyline Builders Merchants and they apparently have branches in Rockbeare, Exeter and Plympton, Plymouth and Newham Industrial Estate, Truro in Cornwall.

https://www.roofingsuperstore.co.uk/product/insulation-2/pitched-roof-insulation/celotex/celotex-tb3025-zero-odp-rigid-insulation-board-25mm-x-1200mm-x-2400mm.html

http://www.keyline.co.uk/store-finder

Jeff.

Location: Almost but not quite, the far North East of England

Thank you, investigating the very best price today.

Location: Sunny Devon

I have found Celotex for £12.87 inc. Vat at RGB which is only 4 miles away. I will post results when I have fitted them

Location: Sunny Devon

Found a much cheaper solution - going to be 34C here today!

Tony.

Location: Malvern, Melbourne, Australia