Mass timber’s profile is rising but many architects and engineers are still unfamiliar with how it can be integrated into their designs.

Over-engineered solutions can lead to complications, resulting in wasted time, unnecessary costs and heightened execution risks.

Design efficiency starts by emphasizing repetition and standardization in sections and connections, says Pierre-Yves Leroux, sales representative and technical adviser with Art Massif, a mass timber glulam manufacturer based in Saint-Jean-Port-Joli, about 80 kilometres southwest of Quebec City.

Leroux, who presented a webinar, hosted by Woodworks Atlantic, covered structural optimization methods, moisture protection as well as anchor and connection details that can result in cost and time savings.

He says one of the keys to success is retaining a mass timber manufacturer early in the design process to validate spans, assembly feasibility and installation logistics.

Using a 3D model to ensure fit across disciplines, including mechanical, steel and envelope designs is critical, Leroux says, adding mockups and testing of critical path connections allow for reserve time in the schedule, if required.

“With too many sections and beam references, you increase your designing time for screw and steel connections. It increases the time for ordering the material, fabricating it and co-ordinating it with our supplier and it also increases the risk of error at installation.”

Among the challenges with long spans, he adds, are shipping complications to site, increased risk of damage and excessive deflection and tolerance issues with other members.

Leroux says Art Massif has developed a prefabrication process for glulam timber decking planks with attached plywood and a temporary membrane that reduces the time/risk of exposure of the structure to the elements. It can also eliminate up to 60 per cent of the installation time.

The prefabricated decking panel system was used on the roofs of two 27,000-square-foot middle schools in Quebec, cutting installation time by four to five weeks over a conventional installation.

He adds the decking can be manufactured in a variety of thicknesses.

For the 13,800 square foot theatre at the Hudson Valley Shakespeare Campus in the Hudson Valley, New York, Art Massif specified a slim 1.5” decking that provides design flexibility on the “signature project.”


The decking can be manufactured in a variety of thicknesses.
  
The curved glulam beams offer “sweeping shapes” to the structure, he says.

“The panelization of the GLT decking on glulam is a very interesting solution to use for an optimized decking system on a large surface.”

While engineering design is often established by the time Art Massif enters the picture, in some cases such as the Shakespeare theatre job, the manufacturer was involved in a design assist capacity.

Leroux says another important factor early in a project is to design a structure with moisture protection in mind. Roof overhangs, elevated column bases, the elimination of drill hole perforations and moisture protection during concrete pours can eliminate headaches later on.

In its plant a waterproof wax is applied to the non-visible end grain of all elements to prevent moisture infiltration, Leroux says, adding the co-ordination of design work with the general contractor and subs such as roofing membrane and steel suppliers is important early on.

As for anchoring points, rather than go with the most common method of cast-in-place steel rods, a preferred option is chemical anchors that allow for precise positioning onsite and can withstand gravity loads, he adds.
  
Source: canada.constructconnect.com