Framing the New Roof

With the outer walls of the second storey complete, our contractors start building the new roof over the extension. This has three sloping elevations and will need to be cut in to the existing roof.

The first job is to set the wall plates. These are timbers on top of the new walls onto which the rafters will sit. A couple of slates are removed from the existing roof where the new walls abut so that the existing wall plate can be exposed. The new wall plates are then bedded in sand and cement mortar on top of the walls and are joined at the corners with halving joints.

A row of slates is removed from the old roof in line with the centre of the section using a tool called a slate ripper. This is a very simple but effective tool. It has a long flat iron with backward facing slots on the end of a slightly wider head. This is fed up under the slates and the slots hooked round the nails holding them in place. A sharp downward pull shears the nail releasing the slate without breaking it. Removing this row of slates up the roof makes it easier to climb up the roof on the battens and access the point where the new ridge will tie in. The weather at the moment is perfect for cutting in the new roof but, as always, you need to be prepared. That’s why the builders are only removing the bare minimum of the old roof covering for the moment.

The new ridge timber is cut and joined to the existing roof timbers where the centre line meets the hip and the other end is left untrimmed for the moment. The position of the last whole rafter before the rear sloping section on the extension roof is marked on the wall plate and these rafters are cut and fitted. The new ridge is trimmed back to these. Next, some awkward angles are calculated and marked so that the hip timber on either side can be cut and fixed where the ridge and final rafters meet.

With these main timbers in place, you can see the outline shape of the new section in full and the carpenter starts work on cutting and fixing the intermediate rafters. You can see in the pictures how the ends of the rafters are cut over the wall plate with what is called a birds mouth joint. You can also see how the ends of the rafters are left untrimmed. These will be cut back later. All the full length rafters spanning between the wall plate and the ridge timber are fixed first. Then, the rafters spanning between the wall plate and the hip timbers of the new section are cut in.

Finally, to complete the main timber work, the rafters between the ridge and the valley on one side are cut in. Slates in this area are removed so that the valley timber can be fitted and the new rafters can be tied in to this. As you can see, the angles on the ends of these are a little more complex. The weather has also changed a bit so a tarpaulin is set in place over the top section so that if it starts hammering down, the exposed roof area can be protected. The valley is lined on either side with a wide section of timber. Before the roof slates are laid at this junction, the timber will be dressed with lead to form a watertight valley beneath the slates.

The next job is to set the ceiling joists for the new room below. These span between the rafters where they sit on the wall plate and are cut and fixed in position. It doesn’t take long before these are all in place and work can start on finishing off the ends of the rafters.

A builders line is used across the rafters where they will need to be trimmed. The line is stretched between the rafter ends on the existing roof and the external corner of the new roof so that cut lines can be marked on all of the new rafters. A vertical line is marked on each at this point. Similarly, the horizontal level for trimming the ends is marked out. The rafters are trimmed along these marks with a circular saw making light work of the job.

With all these cut back and perfectly aligned, the new plastic fascias and soffits can be installed. The fascias are cut to length with mitred corners. These fascias are plastic finished in black to match the black painted ones on the main house. The beauty of these plastic sections is that they require no maintenance. This is particularly helpful as painting soffits and fascias is a cumbersome and awkward job. The back of the fascia section has a rebated slot into which the soffit sections will sit. The white plastic soffit section is then cut to length – also with mitres for the corners, and fixed in place.

The timber frame for the new roof is now complete and the builders are ready to start the roof covering tomorrow.

If you live in the Hertfordshire area and are looking for a professional building contractor, you can get in touch with G L Smith and Sons via their website: http://www.glsmithandsons.co.uk/