With no attic space above, you obviously can't lay rolls of loft insulation above a vaulted ceiling so in order to keep the heat in we would have to insulate between the rafters using PIR boards (i.e., Celotex).
We'd already done some of the insulation several months ago. This is what the main bedroom looked like before any insulation had been fitted - note the wobbly Celotex 'Tower of Doom' that we employed in order to reach the highest bits of the roof (bah, scaffold towers are for wimps).
In order to allow air to continue circulating between the rafters, Alan put up several battens that would act as spacers.
The battens stop the insulation from getting pushed up too high and preserve a 50mm air gap.
We cut 150mm thick Celotex to fit snugly between the rafters. This type of insulation is roughly twice as efficient as conventional loft roll (so 150mm Celotex insulates as efficiently as around 300mm thick mineral wool).
Cutting and fitting thick Celotex throws up lots of horrible dust.
The only drawback with the 'Tower of Doom' was that it would get progressively lower with each sheet of Celotex we used, so we decided we better get all the high bits out of the way first.
The roof timbers have lots of supports holding everything together so several insulation boards needed awkward shapes cut out of them in order to fit perfectly.
Getting there.
Once we'd finished fitting the Celotex panels, we taped up all the gaps using aluminium tape and temporarily fixed some lengths of batten across them to stop any falling out.
We also insulated the steel frame that runs around the feature window and Alan made up some battens that sit within the Celotex in order to provide some solid fixing points for the heavy Fermacell board that will go on later.
Several months later... we added long lengths of batten to the vaulted ceiling which we would use to attach our plasterboard.
In between these lengths of batten, we also fitted a second layer of 25mm Celotex sheets. Despite being relatively thin, these sheets hugely increase the u-value (insulation efficiency) of the ceiling by helping to eliminate cold bridging as well as acting as an additional air seal over all any small gaps.
The second layer of Celotex going on.
Working out the u-value you need is relatively easy thanks to several calculators available online. Alan planned the insulation requirements of the vaulted ceiling so that it would match the insulation in the rest of the house. Mainly to keep the building inspectors happy - though it also seemed a good idea to maintain the same level of insulation throughout the house.
Onto the other side - before the double layer of insulation...
...and after.
The site manager deep in concentration.
Finally we were ready to begin boarding. That ceiling looked an awful lot higher once we started trying to haul a 28kg sheet of plasterboard up into place. It's at this point that you really hope that metal cable on the winch doesn't snap!
Yet again, the panel lifter comes to the rescue. There's just no way we could have lifted these into place by hand. As an extra safety measure Alan screwed some small battens under the plasterboard to ensure it didn't slip off the lifter.
Manoeuvring the plasterboard carefully into position over the battens.
Naturally we couldn't proceed with work until the site inspector had completed his extensive surveys.
We cut the tapered edge off the boards at the very top edge where it meets the central beam to save having to fill that later.
We were relieved to get the last of the 'high' boards installed.
A slight change of plan. We were going to keep these little alcoves on either side of the room but the lack of fixing points coupled with metal plates and bolts sticking out in all the wrong places, meant it would be much easier to board straight across.
Alan rigged up a wooden framework to secure the board...
... then we filled in the area with some more Celotex...
...and finally boarded straight across.
Same thing on the other side. Framework was carefully fitted so it lined up with all the existing angles...
...extra supports were added...
...and finally the plasterboard could be screwed into place.
Ta-da!
Bedroom ceiling finished. So much work went on behind that plasterboard!
While we worked on the bedroom ceiling, the site manager continued to conduct more important surveys throughout the house. Here he is rigorously inspecting the structural integrity of the window sills.
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