Historically the majority of repairs to structural timbers have been carried out using traditional methods involving either the use of steel plates and bolts or a variety of timber scarf joints.
Although many of these traditional repairs have been subject to engineering calculation and design, it has to be assumed that the majority of repairs have been based on experience and good judgement.
A major reason for this assumption is that very few contractors in the building conservation industry have their own in-house qualified structural engineers.
For the same reason most structural repairs involving a resin component will not have been subject to qualified engineering design.
The effects of legislation and a greater awareness of contractual responsibilities are leading to increased levels of engineering involvement in the building conservation industry.
Regardless of the repair method adopted there will often be a legal requirement to provide structural calculations.
In the case of upgrading a structure, e.g. increasing the floor loading from domestic to commercial capacity, structural calculations will always be required, hence a structural engineer will be involved from the outset.
There are three levels of procedure in arriving at a practicable, well-engineered design for the repair or upgrading of structural timbers - collating information, relaying information to a central point and joint assessment.