Should you hire a roofer or a builder?

Anything that keeps rain out of the top of the house is roofing. Replacing slipped or cracked tiles, re-covering a slope, relaying slates, renewing a flat-roof membrane, dressing lead around a chimney or a dormer, fixing ridge and hip tiles and clearing a blocked valley all sit with a roofing specialist. So do the details that fail first near the sea, such as the verge, where the covering finishes along a gable end, and the ridge along the top.

These skills come from repetition. Tiles have to be fixed so they stand up to wind, and BS 5534, revised in 2014, no longer counts a bed of mortar alone as enough to hold the ridge and hip, so those tiles get mechanical fixings as well. A roofer works to that as routine, and it is one reason the top of a roof is worth entrusting to someone who does it every week. A builder who handles the odd roof may know the same rule, so ask directly how the ridge will be held and what happens at the verges.

When the roof forms only a small part of a wider change to the structure, a builder usually leads. An extension, a porch, a loft conversion, rebuilt brickwork or taking out a chimney breast all involve work below and around the roof. The Planning Portal is clear that Building Regulations cover a chimney breast being removed, since the breast is structural, and a chimney breast on a party wall also brings a party wall notice.

A sagging ridge, or a roof that is pushing its walls outward, needs a different first step, and the cost of getting it wrong is high. Start with a structural engineer or surveyor, then decide who carries out the repair. Our answer on sagging roofs describes the signs to look for. A roofer will tell you plainly when the trouble lies in the timbers or the walls rather than in the covering, and will suggest who should look at it next.

Several jobs straddle the line. A flat-roofed extension needs carpentry for the deck and the falls, then a waterproof covering on top, and that second half is roofing. A new roof on a house under renovation may be priced inside a builder's total, with a roofer brought in as a subcontractor. A chimney needs brickwork and lead flashings, so repairs often call on both skills.

None of this means you must manage two contractors yourself, and it is worth asking whether one firm can coordinate the whole sequence. Plenty of roofing firms deal with the carpentry that belongs to the roof, including battens, rotten boards and fascias, and bring in a specialist for anything structural. For flat roofs, our answer on extension flat roofs shows how the timber work and the membrane fit together, and our chimney repairs page covers the stack and its lead.

On a large project, find out who is on the roof. A builder may use their own labour or a subcontractor, and either can be sound. What matters is that you know who is responsible for the covering, and in what order the trades arrive, so the weatherproofing is not left until last and the scaffold is not up for longer than it has to be. The order of work often matters more than the names on the invoices.

Ask each firm to name who will fit the covering, what the written quote includes, and who deals with building control if the work is notifiable. A roofer can explain consent and handle the Building Regulations notification where it applies. Our questions to ask a roofer work just as well for a builder. If you are comparing prices, see too how many roofing quotes are worth collecting before you decide.

Ask what is wrong and where it starts. If water is getting in through the covering, the flashings or the flat-roof membrane, call a roofer. If the problem is in the walls, the structure or an extension that is still being built, start with a builder or an engineer, and bring a roofer in for the covering when the frame is ready.

If you cannot tell, a survey sorts it out, before you commit to either trade. You get pictures of every fault we find, a view on whether the answer is mending, patching or re-covering, and the price in a written quote at one total. Our roofing services cover the covering end of any project, from a single repair to a full re-cover, and we will say so if the real problem sits outside the roof.