Although this property was quite a decent size (four bedrooms with en-suite bathrooms) the customer wanted to add one more bedroom for the oldest son - teenagers always need a little more privacy. There was a large unused attic space, which could be converted into a bedroom.
The tricky thing on this conversion was the roof structure. Firstly, it was a trussed roof, meaning - none of the existing structural timbers were suitable for holding a roof if some of these timbers were removed. Also, this was a detached house - no party walls available to hold the structural steel beams. The arrangement was to install four heavy load floor steel beams, spanning over 8 meters. On the two of these beams a cranked roof frame with purlins was to be constructed. This frame would hold the whole roof structure, transferring the load onto the two floor beams.
Floor beams installation was a bit tricky: the eaves space was sloping at almost 45 degrees and we had to install the steels by placing them on top of the external house walls - they had to go right to the very end of the eaves. The first floor ceilings were flush with the top of these structural walls. And the ceiling joists were running across the steel beams position. The only solution was to firstly chamfer at 45 degrees the ends of the beams - so they fit under the roof right to the very end. Secondly, the ceiling joists had to be cut out to make room for steel beams. We had to then prop up the ceilings on the floor below, so they don't come down during the installation. We managed to complete this most important part of structural works in less than a week. Then we doubled up the roof joists - to make them strong enough to support the roof weight and installed a cranked steel frame. The rest of the works was as usual - insulation placed in, partitions, stairs installed, electrical and central heating installations, drylining and finishing.
The structural works had a major impact on the costs of this project - only the steel prefabrication had cost over £6000, when normally on a terraced house it costs no more than £1500. The end result - big room, around 24 square meters, with ceiling height of 2.6 meters. Finishing is basic there but it hides a lot of structural work.
Below - images of how we progressed on this loft conversion.