In this vlog I continue putting the soft loft insulation into the campervan’s nooks and crannies plus I begin cutting the insulation boards to shape.
For the large and easily accessible sections of the van such as the roof and much of the side walls, I could use Celotex PIR (polyisocyanurate) board for insulation. This is some of the best stuff you can buy in terms of its heat retention, with a lambda value of 0.022. Only aerogel can beat it (at 0.014!) but it’s about ten times as expensive for less than twice the performance.
The difficulty with Celotex is that it’s a stiff board that can only be shaped with a knife so you have to cut it, painstakingly, to fit the van. Once you start you realise just how “not square” a lot of the van really is. Where you imagine it’ll be a quick job to cut out a piece to size, in reality you end up shaping corners, sloping edges and trimming out bits here and there to accommodate the various bits of metal that stick out along the van sides. It’s not hard, just time consuming.
The way I worked was to use large scraps of cardboard to make up templates by trial and error and then cut the board against those templates and trim them to final size.
For those parts that would simply be too awkward or impossible to push a rigid board into, then something like loft insulation can be ideal. It only has half the insulating value of Celotex and you absolutely mustn’t compress it else it loses its insulating properties (it’s the air gaps between the fibres that make it work so if it’s squashed, you lose those gaps) but it’s very easy to stuff into corners and up the load-bearing struts of the van.
It can also be cut with a bit of effort (I found part-tearing it with one hand while the other cut with scissors worked well) and so you can make little bits of it to fit into the awkward areas of the van.
The insulation I used is a recycled plastic made by “Diall” and purchased from B&Q. It comes in 18m rolls and I ended up using just under three rolls once I’d stuffed everywhere I could think of. This was rather more than I’d expected but it’s amazing how it gets used up. The Celotex sheets were also bought from B&Q for convenience.
Many people have queried why not use spray foam to insulate the van. It can go everywhere including the awkward spaces, has great insulating properties and forms an integral vapour barrier. It has much to commend it and some van builders do indeed go down this route however you have to do an awful lot of tedious masking off to stop the spray sticking to bits you don’t want it to such as any wiring. It’s not ideal in tight spots because it can expand to the point where it deforms the metal, and it’s also pretty much impossible to remove later in case you need access. I wouldn’t have wanted to pay for it to be done so I’d have done it myself and that’s messy and requires quite warm ambient temperatures, which weren’t the case at the time of me doing this.