After the ridge beam was up we started putting up the rafters. These are not solid wooden beams but are beams manufactured from a type of hardboard and plywood. The particular ones we are using are 400mm deep and the top and bottom are 60mm wide by 40mm and they are in the shape of a I and are therefore ‘i’ beams. There are advantages and disadvantages to them. The main advantage is that they are very light and strong for there length and in our case because they are 400mm deep we will be able to slip small conventional bales down between them to act as our roof insulation.
The main disadvantages are that they need ‘stiffeners’ or plywood nailed on to them at points where they are supported and that they must not get wet. We therefore not only have the straw bales which must not get wet but also the rafters – a bit of a problem if one is trying to do the job in the middle of an English winter!
We are therefore going to the trouble, after putting up a number of rafters, of screwing on battens across those rafters, stretching poly-tunnel plastic across them and then screwing more battens on top again to secure the plastic and stop it blowing away. Later, once all the rafters are in place, we will have to remove a section of the battens and plastic at a time, put in the bales, a layer of clay render and and then put on the permanent tin roof. This is quite a bit of work but cheaper than putting up a temporary scaffold roof – we had quotes of between £5,000 to £7000 to do this.
The pictures below show you some of the process.
The beams carried up the ladder and being put in place.
The ‘I’ beam is also put up from the other side.
We soon realised there is an easier way than sawing by hand!
Because of the shape of the building the rafters from each side did not meet in a straight line but at a bit of an angle. This made it difficult to cut correctly on the ground beforehand, so we found that cutting the two beams together with the chain saw was the easiest and quickest way of doing it.
The saw struggled going through the hardboard, which is extremely hard! It was therefore easier, having cut the top first to then push the saw through the hardboard at the bottom, cut through the bottom plywood and then cut up through the hardboard in as straight a line as possible!
It then remained to screw the beams in place and together.
The bottom of the beam is attached to a beam fixed to the roof plate, although here to a beam over the future firewood store. This is done using a special metal connector which has a pitch which can be varied. It is first nailed in place and the beam then nailed to it.
Here a wwoofer from France is measuring the 48cm to nail on the next one. The distance is determined by the size of the small bales which we will later put up between the rafters for insulation.
Tablehurst Straw House 