Before work could begin on the flat roof, a ring beam needed to be formed using plywood, reinforced with steel and filled with concrete. To make the building structurally sound. Another course of block was added to bring the height of the ceilings up on the inside.
Now the walls are strengthened and to height, the framework for the new flat roof can begin. Firstly the overlong Ridge beam is set in place with the correct fall built beneath it. One inch per foot in this case. The rafters are cut to size and spaced on 16 inch centres, catching all edges of the plywood sheathing.
The timber bridging(or blocking) is spaced at 4 feet on centre catching the other edge of the plywood whilst preventing the rafters from twisting. A small space has been left between the ridge beam and plywood for the circulation of air after the ceiling is in place.
The ridge beam was placed square from the front of the structure, exactly where the partition wall was to divide the rooms. With the old structure being way off square, the back half of the roof is cut to the angle it runs on. The new partition wall offers more strength to the flat roof.
The flat roof covering, begins with a bitumen primer, then a 3mm torch on, roll out bitumen felt. Followed by a 5mm torch on, roll out bitumen felt finished in mineral. A choice of mineral colours are available. Done properly this finish can last up to thirty years with a small amount of maintenance. Other flat roof coverings such as epdm and fibreglass can be used.
This is where the overlong ridge beam comes into play. Extending over the front door by 4 feet reaching the property boundary. The extended roof here serves a few purposes. Firstly, a cover over the door entrance, secondly the roof helps square the garden area, enclosing the garden nicely! Thirdly, serves as short term storage in the event of showers as such.