If you leave all the windows as simple large single glazed panels in your bus you will come into big problems with insulation down the line. During winters it will be freezing and in summer it will be boiling. (I can testify to this as my last campervan had no insulation and full length windows down each side of the bus – had temperatures in central Spain in the bus of 60 degrees and got Pneumonia living in the bus in an English Winter!) In your design stage you need to decide which ones you want to keep and which to frame and insulate over, to reduce the heat loss/gain. You can pair the considerations for heat gain with possibly adding an awning, so you can park with one side facing the sun and then shield with a large awning perhaps!?
Anyway, back to the framing! So in total we used about 30 pieces of 2.4 metres 2 x 1 inch pine for the framing of the bus for GBP 3 each, which came to a total of about GBP 90. We used the 2inch side lying flat against the frame work with the 1nch side sticking out. be aware that this meant our outer layer of insulation would have to fit into 1 inch. (Also note that different Builders Merchants will stock differing thicknesses of 2 x 1. Some may be 38mm x 19mm and some 40 x 21mm. Make sure you buy all timber from the same place!) You will need a really good drill for this as drilling into bus steel framing is a nightmare, we lost many drill bits and screws in our battle of man against steel!
We decided to keep 2 large windows in the lounge / Kitchen area along with one small sliding window above the kitchen for ventilation. We also kept one window in the bedroom along with the top windows of the back entry doors. We looked into the cost of buying window tints and it would have come to GBP 120! So, we experimented spray painting a piece of glass with Black Painters Touch Spray paint and that seemed to work very well, and we opted for this method instead. You need to spray very light gradual layers to avoid dripping, be warned from the inside of the bus it will look messy, but as ours already had tint on the windows from the outside, it completely blacked out the windows and the glass gave them a lovely high gloss sheen. As we are building frames over the inside of the windows it didn’t matter that the final spray wasn’t perfect on the inside.
Essential Equipment for this stage: Painters Touch Black Spray Paint (we used about 4/5 cans), Masking Tape, Wide Roll of Plastic, Big sheets of old cardboard for masking out areas/parts of the bus
We decided it would get confusing to measure and cut each piece of wood in advance of installing, so we just measured and cut the wood as we went. You want to put in enough framing to support your wall cladding effectively, so be sure to add extra framing in areas that are going to support more weight. (EG: if you are putting a cupboard on the wall or its where a bathroom wall will be). This stage certainly takes a lot longer than planned, especially if you are drilling into thick box-steel members. For this you will need a decent quality corded drill (don’t use the hammer setting as this will blunt the drill bits). You will want to invest in some quality Cobalt drill bits. We dipped our drill bits into grinder Diamond Oil to make the drill bits last longer, and we still went through about 15 of them (cost around $25 just in drill bits). When cutting your lengths of wood to size (we mainly used 2 x 1’s) for this framing, if you can measure and cut them accurately so that they need a gentle tap into place, it saves having to hold them whilst attaching them and makes for stronger framing. This isn’t necessary just frees up a hand for drilling and screwing in.
Once you have the correct length of wood, decide where you are going to drill into the frame, avoiding welded joints, and then drill through the wood. Use a countersink drill attachment to sink the holes and this will make sure that your screws sit level at the end.
Once the wood is drilled and countersunk, then put in place a drill through the frame slowly and dipping the bit in some oil between each drill. Also give the drill bit time to cool now and then. Use correct length metal self-tapping screws to screw into the frame.
(TIP: make sure you buy the correct length metal self-tappers and make sure that you buy the correct drill width that matches your screws, as too small a drill bit will mean screws wont self-tap and too big will mean screws are too loose in the hole.)
Put up the frame verticals and then screw in horizontal lengths and different heights so that you can access the screwing in of the horizontal lengths. We used 30 lengths of 2×1’s and despite the cost we were a little concerned about the unnecessary weight. We therefore didn’t add as many struts as some people have, but decided we would settle for slightly flexible walls in parts over added weight.
Essential Equipment for this stage: Electric Drill and steel drill bit, Screws for Steel)