The loft room has to be supported above the rooms below. The new structure doesn't put any weight on any part of the original structure apart from the brick walls. The whole thing sits on steel beams inserted into the walls at either end.
The roof originally took all of its support from the walls. There are two wooden beams which go from side to side, but apart from those, if the two sides of the roof were not tied together, the whole thing would fall flat on top of the house.
The beams will now also support some of the roof weight. The drawing doesn't really seem to show how big the beams actually are...
The beams originally turned up early in the week. They were so big and so heavy that the team decided that it was just too dangerous to manhandle them into the loft space.
The lorry collected the beams and took them away. They were then sawn in half (well, about 60:40 actually) and then returned with a splicing kit.
The crane lifts the cut beams into the loft through the front side of the roof.
These beams weigh about 56kg per metre.
A short section of beam heads upwards. The only lifting points are steel hooks around the ends of the beam, nothing else to secure it.
Looping the chain around the bean and using the hook to lock the loop... Why doesn't it slide out?
I start moving away from the window at this point.
Now the long section goes up.
Meanwhile, the team inside the loft are manhandling the beams into their final position.
Do these beams really have to be so big? The architect says that they span a gap that is more than 6m wide, and so the building rules specify the size of the beam. But to me they look like they could take the weight of the whole house, let alone the loft.
The builder agrees. He thinks he would use this sort of beam to jack up a whole house from underneath.
I've seen smaller wooden beams in houses that are hundreds of years old...
The beams sit in holes in the brick wall. The roof will be supported by studs rising vertically from the steels.
The two parts of the beam are spliced together using plates and bolts. I remember studying this when I was at university. It's all about forces of stress, shear, friction and stiction.
I think we're building the Forth Bridge here.
