The ice hockey arena in Winnipeg was built in the early 1970s using glulam beams to form the large free span ceiling over the ice rink and stadium seating. Glulam is a popular choice for cost effective solutions to spanning large areas as it is stronger than pure timber and has predictable mechanical properties.
Winnipeg’s location in the Canadian Prairies gives it a humid continental climate. Summers have frequent thunderstorms, winters are significantly colder and drier, and spring and fall are in between the two. Snow occasionally lasts six months of the year. Temperatures do occasionally drop below −40°C. Most years do, however, see several nights with lows dropping to −30 °C. In the summer temperatures exceed 30 °C.
The combination of the low humidity and low temperature is not conducive to dry rot but there are still issues where poor design leads to problems with timber structures.
In this case the glulam beams were located inappropriately into steel shoes which had been bolted to the concrete foundations. Falling rain had drained into the space at the intersection between the beams and the top of the metal shoe edge, thus capturing moisture between the inside of the metal shoe and its inserted glulam foot, similar to timber sitting in a bucket of water!
The timber had absorbed the moisture through both the sides and end grain of the steel encased glulam lamellae.
The steel shoe encapsulated timber created the ideal environment for localised rot to occur during the moist and warmer climatic periods.
The loading from the weight of the roof and any snow was transmitted from the glulam to the shoe. Once the bearing or connection was lost as a result of the decay then the structural integrity of the building was compromised.
The photographs below show the damage to the timber evident above the shoe. Once the exterior timbers were removed the rot in the foot of the glulam beam was evident.
Following the removal of the damaged timber, holes were drilled into the glue laminated foot of the beam to receive stainless steel shear rebar rods. The rods had been bonded into the glulam using Rotafix Structural Adhesive (RSA) which was developed specifically for exterior applications where moisture was present in the components that were to to be bonded.
To prevent further wet rot attack and to facilitate the forming of a new bearing of the exact shape of the shoe Rotafix recommended casting a new foot in TG6 Timber Grout to seal the end grain of the to-be-connected timber and to prevent further decay. This gave a higher structural strength and would not be affected by any extremes of moisture and temperature.
Temporary shuttering was attached to the glulam beam and secured tightly to the exterior of the steel shoe. A small grout entry at the top of the shuttering provided access for Rotafix TG6 Timber Grout to be poured into the shoe and shuttering.
TG6 Timber Grout is a two-part aggregate filled fire resistant pourable grout, designed to de-aerate during installation and prior to curing, ensuring a void free constant density cured material. This product is fire rated to 1 hr. thus providing added structural assurance.
Once the TG6 Timber Grout cured it was mechanically dressed in line with the rest of the glulam beam and shoe assembly, followed by over-coating to give a structural repair without compromising the aesthetics of the building.
For existing or new projects a variation of shoe to foot design is available from Rotafix. We design the foot shoe connection for individual projects with the aid of your dimensioned sketches. Please contact our technical department for further information.
Rotafix are able to provide comprehensive training and support for contractors carrying out structural repairs for most building restoration projects.
For further information about the Resiwood system of repair, using TG6 Timber Grout or design assistance with any new build or refurbishment projects, please contact us on +44 (0)1639 730481 where one of our technical team will be happy to assist.