2017-08-06: Bench bed and cladding test

We’ve been busy on various jobs since I last wrote, mostly trying to get some basic components built in prototype form for we can take the van on a short trip and test some things out.

Almost every design/build problem in the van is a chicken and egg problem. And we tie ourselves in knots trying to decide which part to commit to, so that we can move on. The interaction of furniture, cladding, and electrical supply is one such problem.

Since we had to start somewhere, we took the passenger side of the van as a low risk first step.

Bench bed

I started by building a simple bed frame. It’s mostly self supporting, with the legs nearest the wall bolted to the van body using rivnuts.

Bench/bed frame

I set the frontmost legs back from he edge of the bench so that, when seated, you can swing your legs back. The front and sides will be panelled with ply, as will the top. For now, we have a piece of MDF on top to use as a test. The front edge of the bench has a 2cm lip which will form the middle (longitudinal) support for the bed. The other half of the bed will be removable, with one edgeand resting on this lip, and the far side resting on a lip on cabinets (still to be built) on the other side of the van.

Structure of the bench largely complete

Cladding

Once the bench was complete, we spent many hours figuring out how the cladding could work. The van walls are curved, and flexible plywood could conform to the curve, but there are very few places where it could be pinned back to the walls, risking it flapping around, unsupported, or ‘drumming’ when on the move. So we decided to build a flat frame for the middle section of the wall, onto which one large sheet of flat ply can be fastened.

To clad that section, we re-used some of the 5mm plywood that was in the van when we bought it , cutting out holes for the task lights and USB sockets. It feels pretty solid, so we’ll see how it works on our trip in a couple of weeks.

One wall section insulated, with electrical supply, and framing up ready for cladding

Wood selection for framing and cladding: do the math

I’m evaluating different materials for cladding the walls of the van, and for building frames and panels for furniture (bed, kitchen units, etc.)

Commercial outfitters here in the UK use materials I find unappealing, whereas DIY convertors often stick to what they can find in the out-of-town DIY store. I’d like to weigh up – literally – the pros and cons of a few approaches that are in scope for me.

Absolute weights

Weight is a key factor, not least because of the payload limit of the van. But also efficiency, handling and sizing. I consulted a few sources to find out the weight of different wood types. The excellent Collins Complete Woodworker’s Manual gives ‘average dried weight’ for a range of hard and soft woods. (This is just a selection of woods that are available to me, and might be appropriate.)

Soft woods

  • Sitka and Norway spruce — 450 kg/m3
  • Pines (White, Ponderosa, Yellow) — 420 – 480 kg/m3

To verify, I weighed some 44mm square batons I bought from Wickes (the same product is also available at B&Q). It’s usually labelled as ‘whitewood’ or  spruce. It worked out at 423 kg/m3.

Hard woods

  • European beech — 720 kg/m3
  • American white ash — 670 kg/m3
  • American white oak — 770 kg/m3

Plywood

My local timber merchant also stocks lovely BB Grade Birch Plywood, and they gave me the specs for a couple of thicknesses:

  • 12 mm 8×4 sheet — 25.25kg (707 kg/m3)
  • 9 mm 8×4 sheet — 19.50kg (728 kg/m3)
  • 6 mm — extrapolated: 749 kg/m3
  • 18 mm — extrapolated: 665 kg/m3

These are the woods and panel materials that are available to me (discounting the crap I don’t want to touch).

Wall cladding

Many DIYers seem to go for either cheap plywood faced with car felt, or wooden cladding boards, made from spruce or maybe pine.

I like a wooden finish, but those cladding boards are either thin or heavy. Here’s a typical review of some 8mm spruce cladding (just labelled ‘softwood’) from a DIY store:

At least 20% of these poor quality timbers where so warped, bent or sub standard that they could not be used for the project. They are only finish sanded on one side witch means that you cant switch boards around to hide knots and holes where knots where.

Large chunks where often taken out of the tounges or groves making them incredibly hard to fit together. Every single piece is labled with an incredibly sticky label that is impossible to peel off on the face side of the board making for a enfuriating few hours of peeling and scrubbing.

This chimes with my experience too. You could go for thicker boards, but then you’re looking at some serious weight. To clad an 8′ x 4′ area with 14 mm softwood cladding would weigh about 18.8 kg. The same area in 6 mm birch ply (which has a lovely finish) would weigh about 13.4 kg.

There are other factors of course, (how well does the cladding conform to the curves of the van, does it need to bear weight or hold a screw), but the weight and aesthetics certainly point to the thin 6 mm ply as a good option.

Furniture framing

I’ve made lots of furniture out of stud timbers and that 44mm section whitewood. It’s fine, and in certain orientations and thicknesses, adequately strong.

But I’m interested in using something that cuts more cleanly, is stronger and has some flex for the construction of cabinet and bed frames. Ash looks promising here. I need to do some practical experiments – and more research, but the weight difference doesn’t look too bad, especially when you consider you could get away with smaller cross-sections of wood for many applications in the van.

Bed ideas

Common formats include two facing bench seats with a removable table in between, or a permanent raised bed in the back of the van with lots of storage underneath. I’m more interested in a slide out bed design that only needs one bench to work (plenty of seating for 2 people) and lets you maintain a walk through floor plan.