Roof Replacement Cost Calculator

For a full strip and re-cover in Northern Ireland in 2026, expect roughly £90 to £140 per square metre for concrete tile, £100 to £150 for clay, £85 to £130 for fibre-cement slate, and £140 to £280 for natural slate depending on the slate's origin. A typical semi-detached roof of about 75m² therefore lands between roughly £6,000 and £16,000 with scaffolding and contingency, concrete tile at the bottom of that range and natural slate at the top.

In this calculator, yes — it is shown as its own line so you can see what it costs, typically £800 to £1,600 for a standard semi in Northern Ireland. Always check a roofer's quote for the same thing: a price that looks cheap sometimes turns out to exclude scaffolding, and it is not optional on a full re-roof.

If you re-cover with a significantly different material — for example concrete tile in place of slate, or anything that changes the roof's weight or fire performance — the work needs a building control application to your district council, and the structure may need checking for the new load. A like-for-like repair generally does not. Rules are applied by your local council, so confirm with them before the strip starts.

A handful of slipped or cracked tiles is a repair, and a good roofer will charge a few hundred pounds. The case for replacement builds when the battens or nails have gone — called nail sickness, where slates keep slipping across the whole roof — or the membrane beneath has failed. If you are patching the same roof every winter, the repairs are buying time, not fixing it, and the money is better going towards the re-roof.

The honest answer: what the strip reveals. Rotten rafter feet, a flat roof hidden behind a parapet, failed valleys, or a chimney that needs repointing once the scaffolding is up. That is exactly what the contingency line is for. Access matters too — a terraced street with no rear access, or a roof over a conservatory, makes scaffolding more involved.

Natural slate is the long-run winner — a well-fixed Welsh slate roof can pass 100 years, Spanish slate 60 to 80. Clay tiles manage 60 or more, concrete tiles 40 to 50, fibre-cement slates around 40 to 50, and a modern EPDM flat roof 30 to 50. The cheapest covering per year of life is rarely the cheapest covering per square metre.