Home I Profile I Projects I Sketchbook I Architecture


Models and tools

Barn Conversion, Wales

  

In most traditional buildings with sloping roofs the ceiling beams and joists play a vital, if unappreciated, role in preventing the roof structure from spreading. Removing the ceiling at the top floor of a house is often seen as a way of enhancing the existing or newly-created space but how this is achieved requires careful consideration to maintain the stability of the remaining structure.

At a barn in Wales the desire to create a large space up to the underside of the roof involved the removal of one of the timber trusses.  New deep rafters were designed to span between a ridge beam and the eaves but a way had to be found to avoid forces from the roof pushing out the top of the walls. The solution was to clad the rafters with plywood so that each pitch of the roof acts as an inclined beam tied at the ends to a stiff structure that transfers the loads into the foundations.

The simple models shown here were load-tested to confirm how the roof acted with and without these stiff end restraints and communicate the principles of our design to the client, architect and builder.

 

St. Giles Church - repair to the decayed end of a timber beam

As part of our appraisal of a church tower roof we found that one of the main timber roof beams had a significant decay at one end.

The solution of a timber scarf joint was discarded to avoid temporary support work and a steel splice repair was adopted with steel channels fixed either side of the existing timber.

Instead of the conventional method of bolting the channels through the timber we developed an alternative detail to clamp the splice in place using top and bottom steel sections to avoid the need to drill through the existing timber.

Unfortunately the contractor installed the steel sections the wrong way around. This simple model demonstrated to the architect and the builder the difference between the splice being correctly installed, as shown on our drawings, and what had been built.

Steel sections incorrectly installed by the contractor
photo showing splice incorrectly installed

Model demonstrating the failure of incorrectly installed supports
  

Load test on the splice as correctly installed