Timber condition reporting and resistographic testing.

Once a property is taken over and works are being planned, we carry out investigations to determine the condition of the timbers in the structure. We use non invasive surveying techniques where required and resistographic drill exploration where necessary to produce a report document. We produce the information necessary for the design team to make their decisions in an informed manner and reduce the risks inherent in the renovation and conservation of historic buildings.

Typical truss report

Building Name Main Goods Depot
Building Type Open storage area
Inspection Date 25.09.2018
Building Age 1854
Usage History unused for some time
Truss Description Queen post truss with iron connections
Truss Span 13.50m to 13.70m

 

Inspection notes

Truss number 1
Deflection Yes
Breaks no
Splits no
Cracking yes along eastern principal rafter and straining beam
Rot yes along straining beam and western bearing end
Insect Damage yes weevil attack noted
Moisture Content 18% where covered
Movement in joints yes in queen posts and strut connections
Metal tension bars corrosion present
Metal stirrup connectors corrosion present
Overall rating Poor
Comment
  • This truss is in poor condition with excessive water and timber damage present in the straining beam
  • The bearing end on the western side is excessively wet
  • The strut to principal rafter connections have disengaged so the member is no longer in compressions
  • The truss is currently in failure

Scientific testing procedures for determining wooden building elements suitability for restoration.

Timber is often misdiagnosed as being unfit for purpose. This is because of non-informed condition reporting. There may be a crack evident on the side of a beam or moisture present but no investigation into how deep the crack goes or what damage if any has the water done to the beam. This results in a lot of works being carried out for replacement, the resulting costs and loss of original fabric can be quite extensive. 

We survey the building elements to determine the strength that remains insitu. This allows the structural engineer to make an informed decision to repair or leave alone the structural element. We primarily use our experience to report on the visual defects but where less obvious defects arise, or certainty is needed we use resistographic testing to map the timber elements across the structural plain and thereby determine the remaining strength relative to other samples taken.