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Roof Trusses & Joists UK

How to Build Roof Trusses

Below we provide you with an insight on how to build roof trusses. A roof truss is a type of built-up structural member that can be used in place of a single girder or beam. Trusses are made from multiple straight timbers arranged in triangles. This design allows a truss to span a very long distance without intermediate support; they are preferable to large, heavy girders because of their low cost and easy implementation.


A Fink Roof Truss showing Top Chords, Bottom Chords and Webs.

The process of making or ‘building’ a roof truss all begins with the design. Our software enables us to design projects ranging from the very small to the very large and can incorporate multiple types of roof trusses with varying spans and truss shape configurations.

Refer to our design page for more detail on the full process

The best material for building trusses is stress graded TR26 grade timber which is exclusive to the Trussed Rafter Industry. You can find out more about why it’s all that we use on our timber page.

Our designs will ensure that the trusses are capable of withstanding the expected loading for your structure, roof and is adequately supported at its bearing points. These calculations are suitable to provide for building control and negate the necessity of a structural engineer.

The roof truss will have a horizontal bottom chord (sometimes called a tie) and two angled top chords that follow the roof line in a duo shaped roof structure. The top and bottom chords are connected by "web" members, which will be positioned to form triangles. Triangulation provides the basis for the strongest possible structure for supporting weight.

Once we have designed your roof trusses to British Standards and/or European Standards, dimension are sent to the Depauw saw and each timber is cut to its required length and angle. Once the angle is cut, each end is marked so that the shape of the truss can be fitted together on our pressing tables.

We have invested in top of the range, state of the art machinery, which allows us to facilitate very high volumes of timber cutting with ease. This is a vital part of our process which allows us to maintain our 5 day delivery nationwide service all year round.

This is an image of our Depauw 16 axis, 4 blade computerised saw.

Our experienced sawyers make sure that our timbers are cut to the exact length that our production managers instruct them to produce. After they are marked and stacked, the timber is then moved onto the pressing department.

The pressing process is an extremely important stage in the manufacture of a roof truss. All timbers are fitted together and metal connectors are fixed on both sides. It is a common misconception that the metal plate connectors are able to be simply hammered to fix down on site.

In fact, each plate is designed by the engineer to take into account the deflection and the movement in each joint and considers whether the member will be in compression or in tension. Each plate, whilst only small, takes into account the loading for the roof which is loaded with tiles, snow fall, tanks, plasterboard, light storage and for people standing in the roof – it all adds up!

This image shows the truss pressing table with timbers slotted together, ready for the metal connector plates to be placed over each joint.

Minera Roof Trusses use a gantry system in the optimum position for producing our vast quantities of roof trusses. It is a hydraulic press and it is repeatedly exposed to tremendous pressure. For this reason, our hydraulic presses are extremely robust. The maximum press power is between 23 and 50 tons – A stark contrast to the metal plates being hammered into place.

Please note - the metal plates must never be removed or repositioned when onsite. Hammering has been disproved as an effective method by British Standards as it damages the galvanised metal teeth and causes the teeth to roll. By using a hydraulic press, the plates are able to enter the timber in one swift movement.

This is one of our 23 - 50 Ton hydraulic presses being used to fix the metal connector plate into each joint of the trussed rafter.

This procedure is then repeated on the next trussed rafter until the quantity required is reached. The process is repeated for the next truss configuration until each structure is completed for our customer’s order.




Read more information about our Roof Trusses on the following pages

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