Natural slate comes from Wales, Brazil, China, Spain and varies in quality, colour, texture and thickness. Clay tiles are handmade or machine-made and often smaller, taking longer to lay. Before being nailed into place, the roofer spends time organising the tile batches so that when hung the roof looks uniform. Manmade roof tiles are made of concrete or fibre-cement and mimic the look of slate and clay. Large format tiles that interlock are quicker and easier to lay than nailing. Plain tiles are small and rectangular and must be laid double-lapped, which takes longer.

What roof type for my extension??

Planning permission for an extension or garden room is highly likely to mean using the same roof tiles as the main house. Pay careful attention to ensure there is a tie-in without causing problems later on where roofs meet. In the case of a new house, a gable roof – two sloping planes that meet at the top – is one of the simplest roof shapes to construct. A complex design with multiple intersecting roofs requires more carpentry skill and tile cuts to put together. Make sure you find someone with proven experience.

• Flat roof
• Gable roof
• Pitched roof
• Green roof

Specialist roofers

Green roofs planted with sedum and wildflowers make a lovely focal point from upstairs windows and attract insects and bees. The design could also help resolve a planning requirement for the building to blend into the countryside. Green roofs are mostly flat but there are products that work on pitches between 10-45°. The lighter, extensive and semi-extensive green roofs suit sheds, garages and garden rooms better. Use Intensive weighty roofs in larger projects. A biosolar green roof integrates solar panels for the joint benefit of harnessing energy and creating biodiversity. See here for a list of approved green roof companies: www.greenrooforganisation.org/gro-members.

Listed buildings require listed building consent before any work can begin and this includes the roof. Projects of this type are sensitive, involving repairs to preserve an existing roof or fitting new in a sympathetic way. Find a list of National Heritage Roofing Contractors National Federation for Roofing Contractors (NFRC): www.nfrc.co.uk/find-a-heritage-roofer.

Flat roofs are covered with reinforced bitumen membrane, single-ply membrane (polymer-based materials) or liquid membrane (rubber-based). See below for advice on where to find recommended companies.

Finding a reputable tradesperson for you roof extension

Ask friends, family, neighbours. Also ask for recommendations from other trades, especially carpenters and bricklayers, who work alongside roofers. It’s always helpful if you find a team who know each other and get on well. Your local builders’ merchant may be able to suggest local companies. Or search for members of the NFRC at www.nfrc.co.uk, the Confederation of Roofing Contractors at www.corc.co.uk and Trusted Traders – endorsed by Which? – at https://trustedtraders.which.co.uk/popular/roofers/.