What affects the cost of a new roof?

Area is the obvious factor, but complexity often matters more. A simple gable roof of a given area is a straightforward job; the same area broken up by valleys, dormers, chimneys, roof lights and changes of pitch involves far more detail work, and detail work is where the labour goes.

Pitch affects both the covering specification and how the work has to be carried out.

Natural slate, reclaimed slate, clay tile, concrete tile and metal all sit at different points on cost and expected life. Where a building needs to match its surroundings, or is listed or in a conservation area, the specification may be set for you.

Leadwork, dry-fix ridge and verge systems, ventilation provision and rainwater goods all form part of the figure.

Until the roof is stripped, nobody knows the condition of every batten and timber. A responsible quotation says how that is handled: a stated allowance, a rate for additional work, and an agreement that you are consulted before extra work proceeds.

A quotation that is silent on this is not cheaper; it has simply left the question for later.

Scope, specification, access, duration, how unknowns are handled, what happens to the old material, and the workmanship guarantee. Comparing two quotations on those points is the only fair comparison.

Beyond the roof covering itself, a full renewal can involve scaffolding for the duration of the project, protection of the property and its contents while the roof is open, and coordination with other trades affected by the work, such as guttering or solar arrays that need temporary removal. These practical elements are part of what a specification should address, since they affect how long the property is exposed and how the site is managed day to day.

It is worth asking how the contractor sequences the work to minimise the time the roof is open to the weather, particularly on larger properties or where the forecast is uncertain. A specification that sets out the order of operations, and what contingency exists if weather interrupts the programme, gives a clearer picture of what to expect than one that only describes the finished result.