Like any product on the market, it’s only as good as the materials used to build it. The same is true for roof trusses. While we’ve discussed the types and family of roof trusses, we’ve never spoken about the individual parts that go into making our roof trusses.
Here are the main material parts of a truss.
Chords
Chords are the main members in a roof truss, these are large pieces of timber. They can be made from various types of wood, but the decision is normally dependant on budget. You could choose a hardwood or softwood option, if you are interested in pricing you can use the Timber Merchant’s calculator.
The most important aspect when purchasing wood that will be eventually used for chords is that you source them from an accredited body.
Locally, in South Africa, these are suppliers with South African Bureau of Standards (SABS) and South African Technical Auditing Services (SATAS) certifications.
We feel like it should go without saying it, but if standards aren’t maintained there are bound to be failures. If there are any doubts about the quality of wood you’re purchasing, you can reach out to ITC SA and enquire.
Then again, all structural timber grown in, or imported into South Africa, needs to adhere to the South African-based ISO 17065 accredited Product Certification Body.
As a normal consumer, you can inspect the pieces of timber by eye.
What you’re looking for is how many times the length has been joined together, or how many splice points it has. A splice point will be joined by a metal plate. If the piece is riddled with joins and splice points it’s normally considered not to be as strong as a single span. Then again, as the calculator we mentioned earlier will show you, full-length wood is expensive.
We highly doubt you’ll see gaps in the timber between the joins (they look like zig-zags in the wood) but if there are gaps we’d suggest returning the wood to the supplier.
Nail Plate / Gusset Plate
Trusses are designed to shift weight loads (the weight of the roofing on the truss) through the timbers via angles down into the walls, which then transfer the weight into the foundations. Right, now that we’ve explained that, those angles or mitre cuts need to be joined together, and this is done through gusset plates.
While some roofs might be nailed together with long “roofing nails”, we strongly recommend you use plates. They are normally galvanised, so weathering isn’t a problem and these plates can bear more weight compared to a bunch of nails. For an experiment, nail two pieces of wood together, even when a nail is driven in deeply, you can still pull it apart.
The main reason why plates can hold more weight is that the forces at work are spread evenly over the surface. It should also be mentioned that they’re not hard to install and if you are building a truss on your own, don’t cut corners and rely on wood glue and nails to hold your roof together.
Wall Plates
Making sure your truss is attached to the wall is important for obvious reasons.
Selecting the best quality will help ensure that your truss stays in place. This would mean reviewing the guage of the steel bracket (width), the types of fasteners (like solid steel rods and bolts), wall plugs and screws, and that they are all galvanised.
If you’re still uncertain about the parts you’ll need, we can help, just drop us a message.
