The body was insulated from the factory, but that was 1980's rock-wool which is not exactly the best thing available and is also an itchy fluffy pain in the everything to work with. We decided to pull it out and replace with 25mm Celotex which is more insulating (about twice as insulating in fact) and less horrible. The ambulance was obviously never designed to be a camper originally so the walls are only ~30mm thick and the steel frame makes quite a thermal bridge - not much we can do about that but we'll just have to turn the heating up!

Anyway, after removing lots of drive rivets / scrivets that hold the wall and roof panels on - there were some we couldn't remove, the bottom section is “proper” riveted to the steel frame where it meets the floor and frankly we didn't feel like dismantling the entire back body so we went for what we could get, which was ~90% of the total amount of insulation in the rear body.

In the end it only took us a couple of sheets of 25mm Celotex so cost next to nothing.

A few shots of work in progress:

Ceiling before:

Ceiling naked:

Ceiling after:

The gaps are for the lights - that will be addressed in Mk2.

While we had the panels down we gave them a good scrub, far easier when they're on the floor than back on the ceiling!

While we had the panels down I took the opportunity for some future-proofing by inserting rivnuts in all the holes that were once-upon-a-time used to attach interior fittings. This meant that we had ready attachment points for future things without having to take panels off or try to guess where body struts were.

There were a few things we couldn't practically do anything about: The back doors are full of rockwool too, but the construction does not lend itself to easy disassembly. The doors are riveted together, as two interlocked shells over a steel frame, so we'd have to drill lots of rivets out to get them apart.

The rear windows are single-glazed, not a lot we can do about that although we did add curtains (more on those in a minute)

The cab itself is a standard Land Rover cab, not very insulated and not really lending itself to insulating. The previous owner had fitted Wright Offroad mats which make a fair difference to the floor, and we made some foil thermal blinds, more on those in a minute too.