What are roof trusses?

A roof truss is an engineered, structural framework of triangulated timbers that provides support for a roof. A roof formed using trusses can use up to 40% less timber than a traditional roof – this makes them highly cost effective.

Roof trusses are prefabricated, which saves time on-site when it comes to installing them.

How do roof trusses work?

Roof trusses act much like a lid on a box. They work by transferring the weight of the roof to the load bearing walls of the house.

How are trusses measured?

Trusses are measured using span and pitch. Additional measurements will be required when needing to match an existing roof.

While there are plenty of online tutorials showing you how to do this, it’s best to leave this to an experienced truss designer. This way, all factors of the build will be taken into consideration and trusses will be designed and specified to suit.

House roof | Elliotts
How many roof trusses do I need?

The number of trusses required for a roof depends completely on the design. However, typical roof truss spacing means that they are usually 400mm (16 inches) or 600mm (24 inches) from centre – this means from the centre of one truss to the centre or the next truss.

What are trusses made of?

Our trusses are made from TR26. This is a strong, specialist engineering grade of timber for trussed rafters.

Are trusses and rafters the same?

While both trusses and rafters effectively do the same job, there are some differences which make trusses more suitable for modern builds.

Trusses are delivered to site as a full structural component – saving labour time and costs when it comes to installation. Rafters are known as a ‘cut roof’ single component which need to be assembled on-site.

Trusses can spread the weight of a roof across a number of triangulated struts and braces, whereas Rafters have 2 main outer beams which provide the support.

Trusses v rafters | Elliotts
Can trusses be cut/altered?

No. As an engineered product built for purpose, any moderations could affect the structural integrity of the truss.

What are attic trusses?

An attic truss is a type of roof truss that has an open space at the bottom to accommodate a living space and is designed to allow for domestic floor loadings.

By opting for attic trusses, you can future-proof your property by having the option of extending your living space into the roof if required.

We can accommodate various designs based on your requirements.

How do I match an existing roof?

If you are building a double-storey extension, you will need to match your existing roof in with the new roof on the extension. This requires the following measurements:

  • Overall span (Wall to Wall)
  • Bottom Chord Length (If different than the Wall-to-Wall Span)
  • Overhang Length
  • Heel Height
  • Peak Height
  • Pitch/Slope of Roof

Need to match an existing roof? We can come to site to measure and provide accurately-measured trusses.

Matching an exisiting roof
Can I get trusses with no overhang?

Yes. We are seeing more buildings being designed without truss overhang to create a contemporary, minimalist look.

Trusses can be manufactured without the overhang.

No overhang roof
What truss profile is best for my build?

This all depends on your designs and requirements. Profiles will be designed to dissipate the roof load across various struts and braces in a way that works best for the build.

Talk to us about trusses

Still have some questions about trusses? Would you like a quote for your next projects?

Fill out the form with your requirements and one of our engineered timber team will come back to you.



Please note: we only supply trusses to locations in the South of England.

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