Industrial roofing cost per square metre (16 figures)

Every row is a verbatim sentence read from the named source's own page through our fetch service on the date shown, hash-pinned to the stored read (the sha of the page's visible text; the raw page is mirrored to R2).

15 of the 39 named sources that could be read published a usable figure; 24 published none and are recorded as not published, never filled in; 2 could not be read (blocked, dead or unreachable) and count nowhere.

The headline figures (median, minimum, maximum, quartiles) are over ONE figure per source for each breakdown it prices, in GBP (a source's median where its page yielded several accepted sentences for one breakdown), so a page that gives figures for several breakdowns gives one for each and N counts 16 figures, never sentences; 270 candidate sentence(s) were refused by a reviewer with the reason recorded.

The fuller derivation this dataset is chartered to grow into (not yet what the figures above are; they are each source's own published figure as read): median, minimum and maximum published installed cost per square metre for each roof SYSTEM (single-ply membrane, built-up felt, liquid-applied, profiled metal, insulated composite panel, fibre cement, standing seam) crossed with each SCOPE (repair, coating, overclad, strip and re-sheet, new build), computed across every UK contractor that publishes a figure; the count and share of contractors publishing a rate at all versus quote-only; the overclad-versus-replace saving each publisher states; the spread between the cheapest and dearest published rate per system; and the movement in each system's median between reads.

Nobody publishes this: every contractor publishes its own range for its own systems, and no one joins them.

270 candidate sentences on these pages were refused by a reviewer; each refusal and its reason is recorded in the review ledger.