Summary
• Simpson Strong-Tie recently launched a glulam connector catalogue.
• It has developed a concealed beam hanger for use with glulam.
• CLT requires the use of connectors of commensurate size and strength.
• The use of good connectors at junctions between floors, walls and roofs will help builders meet airtightness and thermal efficiency targets
The construction sector has had a tough time but it seems we may now be seeing the first real forward movement of the new build housing market, as well as commercial projects. It is early days, with many hurdles to cross before we can say it is a recovery, but there seem to be positive strides happening.
At the forefront is timber – an adaptable construction material, flexible when necessary, but also strong and rigid when engineered into beams, posts and joists.
Whether it is timber frame houses, or glulam structures for supermarkets, or cross-laminated timber (CLT) panels in new school buildings, timber is leading the way.
Connecting timber structures together has developed from the mortice and tenon or dowelled joints, to specifically designed and engineered metal connectors which help the installer to produce an accurate, strong connection every time, and provide a known load-bearing capacity, which aids building designers.
Connector suppliers are always looking at ways to improve existing connector products but also at developing new connectors for the ever-changing timber construction industry. For example, we recently launched a glulam connector catalogue, aimed at supplying the products that the glulam companies require off-the-shelf, rather than having to design and manufacture each one from scratch.
Glulam is used as much for its aesthetic appearance as its strength, so many of our glulam connectors have been designed to be hidden when used, such as the TU concealed beam hanger. The concealed nature of the hanger does not impact its load-carrying capacity.
Size and strength considerations
CLT is becoming more common in the UK, particularly in new school and college buildings and, like glulam, it requires different connectors from general housing. Although most are more standard products from our range, such as angles and screws, they are of a size and strength commensurate with the impressive dimensions of the material. We have worked with the CLT companies to produce a range of connectors to suit their building methods and timescales, giving them the product and delivery service when they need it.
Regulation is also playing a major part in shaping the timber construction market. Two things stand out in this area: the Code for Sustainable Homes (CSH) and the Eurocode 5 (EC5) regulations.
The CSH is set to continue, in some form, through the next four to five years, continuing the emphasis on improving the efficiency of our new homes. The code affects all types of housing construction, be it timber frame, masonry, SIPs, insulated concrete form, or steel frame and each method has its answer to the new levels of U-values, airtightness and thermal efficiency demanded.
Timber frame has taken the Fabric First approach, using the fabric of the building to meet the new and increasing demands of the CSH going forward. One of the key areas, using a Fabric First approach, is the junctions between the walls of the building at foundation level, floor level, roof level and where panels abut each other. Fixing at these junctions using products designed to do the job will make the whole build more efficient in meeting the regulations and more cost-effective overall.
Impact of EC5
The EC5 design code came into force in April 2010 and although the UK building industry is yet to use it on a day-to-day basis, it will start to have an impact on how we build over the coming years.
Designing and building in accordance with the new Eurocodes has and will present many challenges throughout the industry. However, by conforming to these new standards it will provide a common approach to achieve the same goal. And having a common approach allows us to develop specific details to meet the ever-increasing demands of the standards.
What does the future hold? Fifteen years ago we saw the first of the engineered I-joists arrive in the UK and people said they would never catch on. Now they are dominant on the vast majority of national housebuilders’ sites. Today we are seeing a number of new factory-made building systems, like SIPs and cold-formed steel, growing their share of the market.
Timber frame is a factory-made product and we can see these methods, along with hybrid wall and roof systems, meeting the demands of the ever-tightening regulations and tolerances of the future. Add in the on-site skill shortages we currently have and factory-based systems tick a lot of the boxes. Timber, in all its forms, is leading the way.
These new building systems provide the next challenge for companies such as ours to design and engineer new connectors to help them create safer structures, economically.
