How long does it take to replace a roof?

No single figure fits every house, and anyone quoting one before seeing the roof is guessing. Size comes to mind first, yet shape counts for as much. A plain gable, with two slopes and flat walls at each end, has fewer cuts than a hip roof, where all four sides slope. Every hip, valley and abutment has to be cut and finished by hand.

The covering matters. Large interlocking concrete tiles cover ground faster than small plain clay tiles or natural slate, which are laid one at a time with a deeper overlap. Chimneys, dormers, roof windows and soil pipes each add a detail needing lead or a flashing kit.

Then there is access. A roof reached from a tidy scaffold beside a wide drive goes quicker than one hemmed in by a terrace, a neighbour's wall or a steep bank. We read all of this on the survey, so the timetable in the written quote follows the roof you actually have.

Many people count only the days on the roof and forget the weeks before them. A visit to survey comes first, the quote follows in writing and a start window is then agreed. Erecting scaffolding across a public footway or road needs the highway authority's licence, a requirement that comes from section 169 of the Highways Act 1980.

West Sussex County Council, the authority for Arun, Chichester, Adur, Worthing and Horsham, asks for a minimum of 10 working days' advance notice, counted from the application. Hampshire County Council, which looks after Havant and East Hampshire, needs a gap of ten clear working days between lodging the application and the planned start, and expects the scaffolding contractor to file the paperwork. Scaffold set up wholly inside your own boundary may need no licence at all.

Materials need ordering as well. Special orders such as reclaimed or matched tiles can take longer to arrive than stock items. We put the likely start in writing once the survey tells us what the roof needs.

A roof is taken apart in stages, so only the area that can be made watertight by evening is opened, but some days simply do not suit the work. Strong wind makes lifting sheets and tiles unsafe, and persistent rain halts work on a flat roof, where the deck must be dry before a covering goes down. Our answer on rain during a roof replacement explains what happens when the forecast turns.

The second source of extra time is what lies beneath the old covering. With the tiles and battens gone, the rafters, wall plates and boarding can be looked at properly for the first time. If some are rotten, they need replacing; the extra work is photographed and explained to you before it is done, and the programme is adjusted. It is the one part of any re-roof that cannot be known from the ground, which is why a wise timetable carries some slack.

A roof is not finished when the last ridge tile is fixed. Site clearance and waste removal come next, and the gutters are cleared of whatever dropped into them while the old covering came off.

If the job is notifiable under the Building Regulations, a building control inspection may follow. Arun District Council's building control team says it cannot fit in a visit asked for that very morning, that completion inspections run Monday to Wednesday and that a full day's warning is needed. Other councils and registered building control approvers have their own arrangements, so ask whoever is dealing with yours.

Some re-roofs need no application. The Planning Portal says none is normally required when less than 25 per cent of the building envelope and less than 50 per cent of the roof is affected, although it lists exceptions, and Arun's own page names replacing roof coverings among work needing approval. Where the job is notifiable, we make the notification for you and explain what happens afterwards.

Ask for three things in writing: the expected start window, the expected number of working days on the roof, and what happens if weather or hidden timber work stretches the job. A firm that answers all three has thought about your roof. One that says it will be done when it is done has not.

If your roof is leaking now, say so when you book the survey. A leak gets attention ahead of routine work, and a make-safe visit can hold the position while a full replacement is arranged. The colder months bring their own considerations, set out in our guide on replacing a roof in winter.

To follow the stages in order, read what happens during a roof replacement, day by day. The overview of the work itself is on roof replacement and new roofs. Price is dealt with separately, once the survey is done, as a single figure in writing.