What are Truss Clips?
Truss clips are metal components designed to securely fix trusses to wall plates to resist wind uplift on the truss and avoid any damage to the truss caused by skew nailing. The calculations we provide that you are able to use to pass Building regulations account for the use of truss clips. Please note that our calculations do not allow for skew nailing as a method of fixing.
What is Skew Nailing?
Skew Nailing is a method of ‘fixing’ that is often used by roof installers, but the method of Skew Nailing, is not recommended. There are no mandatory regulations that require the use of truss clips for a secure fixing. Nevertheless, the British Standards and the Trussed Rafter Association strongly advise the use of truss clips. It is best practice to use truss clips because it is impossible to apply proof calculations to a pair of skew nails. Skew nailing can often cause damage to the nail plate on the eaves joint at the time of fixing. If you decide to use skew nailing to fix your roof trusses, building regulation officers may fail your truss installation.
What size are Truss Clips?
We have two sizes of truss clips – 38mm and 50mm. The truss clip that we provide for your order depends on the size of timber used to make your trusses. All truss clips are included within your quote and are not an additional cost after order.
How much do Truss Clips cost?
As discussed above, truss clips are a minimal but essential cost. At 34p per truss clip and the potential risk to invalidate your designs if not used, it really is a no brainer to use your truss clips when installing your roof trusses.
How to fit Truss Clips?
There are two truss clips used per truss, one on either side where the truss is fixed to the wall plate. It is common practice to install the truss clip on the inside of the wall plate but can also be fitted on the outside of the wall plate depending on the truss heel detail.
Truss clips must not be fitted horizontally onto the wall plate – please refer to our diagram below.
Please ensure that you nail into all the holes available on the face of the truss clip. There are two holes on one side of the ceiling chord fixing and three holes on the other side. There are then seven holes on the bottom of the truss clip which attaches to the wall plate. It is important to utiliize all available holes within the truss clip, some roof installers only use up to four of the thirteen holes that are available. Please note our calculations account for all holes having been used to properly secure the truss clip to the truss and wall plate.
Are there any alternatives to Truss Clips?
When securing more than a single truss then the use of framing anchors is required. This is because truss clips are limited to 38mm or 50mm in size. If dealing with a 2 ply, 3 ply or 4ply trusses then framing anchors can be positioned either side of the truss at both ends of the wall plate. 2 ply, 3 ply and 4 ply trusses are where two, three or four trusses are bolted together to add strength in cases where trusses are required to carry additional weight loading. Similarly to truss clips, framing anchors provide proof calculations for secure fixing which skew nailing cannot do. They’re only 4p more (38p per framing anchor in total) than truss clips (34p) but of course there are four in total needed per truss for secure fixing and so slightly more costly overall.
If you have chosen a raised tie truss or scissor truss then we highly recommend the use of Slide shoes (sometimes referred to as Glide Shoes depending on the supplier) in place of truss clips or framing anchors.
Slide shoes are fitted (like truss clips and framing anchors) at the wall plate of the truss and allow a restricted amount of horizontal movement. Standard truss design has the ceiling chord directly coming out from the wall plate. The raised tie and scissor truss designs allow for a higher ceiling chord, this allows for more space from the wall plate, which is where the truss sits. This can lead to deflection in the rafter and forces an outward movement from the wall plate. Please be aware that when using truss clips on larger raised tie or scissor trusses there is potential for damage to be caused to the supporting wall, due to the horizontal force the trusses could exert on the wallplate. The Slide Shoe greatly minimizes the potential for structural damage through allowing for slight movement.
Although Slide Shoes are slightly more costly than truss clips, the advantages that they bring to ensuring the structural integrity of your property for the long run makes them a very worthwhile and what we consider an essential investment for your build.
Slide shoes are available in more sizes than a truss clip which allows for them to be used on single and multiple ply trusses.
*please note that all costings are accurate as of February 2020 and are subject to change without notice.
In mainland UK on trussed rafters and engineering joists.
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