Every roofing conversation in Britain ends up at the same benchmark: a three bedroom semi. It is a useful reference because so many houses are one, and it is a trap because two identical semis on the same street can differ by half again on access, on covering and on what is found once the tiles are off.
Why the semi became the benchmark
Postwar and interwar semis are the most numerous house type in the country, they mostly have simple gable roofs of similar area, and they mostly wear concrete interlocking tiles over perished felt. That makes them the closest thing the trade has to a standard unit, which is why every quote conversation starts there. A terrace of the same width has less roof and worse access. A detached house has more roof and easier scaffolding. A bungalow has a large roof and only one lift of scaffold.
The four things that move it most
Access first: a house with clear ground on all sides scaffolds cheaply, and a mid terrace with no side entry does not. Complexity second: valleys, dormers, chimneys and changes of pitch are priced per item and a roof with three of them is not the same job as a plain gable. Covering third, with natural slate at one end and concrete tile at the other. Timber fourth, because nobody knows what the rafters look like until the covering is off, which is why the provisional sum in a quote matters.
Reading the number you are given
Ask what proportion of the price is scaffold and waste, because on a small roof it is a surprisingly large share and it is the same whether you choose a cheap covering or an expensive one. Ask whether the underlay, the battens and the ridge system are included or extra. Ask what happens if the timbers are bad. A contractor who answers those three without hesitating has priced a lot of roofs, and their number is more trustworthy than a lower one that does not.
Questions people ask about how much to reroof a house
Is it cheaper to reroof a terrace than a semi?
The roof is smaller, so the covering costs less. Access is often worse, so the scaffold costs more. The two frequently cancel out, which surprises owners who expected the smaller house to be much cheaper.
Should the chimney be dealt with at the same time?
If it needs anything, yes. Repointing a stack or renewing its flashings is cheap while the scaffold is up and expensive as a separate job later.
Does VAT apply to reroofing?
On an ordinary domestic repair or replacement, yes, at the standard rate. There are reduced rates for certain conversions and for properties empty for a long period, which is a question for the contractor and HMRC's guidance rather than an assumption.