Whether you're building 100 new homes, a porch or an extension which requires matching to an existing roof, Perran Trusses are able design and manufacture the many types of roof trusses to meet your specific requirements. You can read our installation guide here. Roof trusses, or trussed rafters as they are sometimes referred to, are used in the majority of new housing in the UK and Ireland and are increasingly being used in commercial and industrial settings. So why are trusses so popular? Firstly, a trussed roof is a fully engineered structure delivering a practical and versatile roofing solution.