The short answer: no serious contractor can tell you sight unseen, and this article will not pretend to. What it can do is show you what actually moves the price, why quotes for the same roof differ, and how to read a written quotation so the comparison you make is real rather than cosmetic.
Why is there no price list?
Because refurbishment is not a product; it is a response to a condition. Two roofs of identical size can differ several-fold in cost once their circumstances speak: one sits over a garage you can reach from a ladder, the other over a stairwell needing scaffold; one strips back to a sound deck, the other to a soaked one. A figure quoted before those facts are known is not a price, it is bait.
What actually drives the price?
Six levers move nearly all of it:
- Area, though less than people expect, because setup costs do not scale down.
- Access: scaffold, edge protection and how materials reach the roof can rival the membrane itself on smaller jobs.
- The specified build-up: layers, insulation thickness and the system's guarantee tier.
- Condition discovered: wet insulation found under the old covering must be replaced, not wished away.
- The details: every rooflight, pipe, upstand and junction is hand work, and a roof crowded with them costs more than a bigger empty one.
- Disposal: stripping generates heavy waste that is weighed and paid for.
What is the relative ladder?
Without inventing figures, the order is stable. A localised repair costs least; it treats points, not areas. An overlay sits in the middle: new waterproofing over a dry existing roof, with the strip-off and most disposal deleted from the bill. Strip and renew costs most, because it pays for removal, disposal, possible deck work and a complete new build-up. Where a roof sits on that ladder is exactly what a condition survey establishes before anyone should name a sum.
Why do quotes for the same roof differ so much?
Because they are rarely for the same job. One prices an overlay, another a full strip; one includes renewing every upstand, another reuses tired flashings; one carries a provisional sum for hidden wet insulation, another stays silent and plans to renegotiate on the scaffold. The spread between quotes usually measures differences in scope and candour, not differences in efficiency.
What should a written quote contain?
Enough that a stranger could check the job against it:
- The named membrane system and its build-up, layer by layer
- Insulation type and thickness, and whether regulations-driven upgrades are included
- How each detail, upstands, outlets, rooflights, edges, will be handled and with what
- A stated provisional rate for concealed condition, so surprises have a price agreed in daylight
- What is excluded
- The guarantee: whose it is, how long, and its maintenance conditions
A one-line quote with a total is not an offer; it is an ambush postponed.
Two quotes for one roof, read line by line
Imagine the same garage-and-extension roof quoted by two firms, one total noticeably lower. Read past the totals and the story changes. Quote A names its membrane system and shows two plies; quote B says "new felt roof" and shows one figure. A specifies insulation thickness and notes the regulations point; B does not mention insulation at all, which quietly means none. A prices each upstand and the outlet connections; B's details are presumably somewhere inside the number. A carries a stated rate per board for deck renewal if found; B is silent, which is not the absence of the risk, only the absence of its price.
By the end, the comparison is not cheaper-versus-dearer at all: it is a specified job against an unspecified one, and the gap between the totals is roughly the cost of everything B declined to write down. Sometimes the low bid genuinely is efficiency; the way to find out is to ask B to price A's scope, line for line. Contractors with nothing to hide do not mind the homework.
How do provisional sums work in practice?
A provisional item is honesty with a price tag: work that cannot be confirmed until the roof is open, stated in advance at an agreed rate rather than negotiated in a crisis. In practice it runs like this: the quotation says, for example, that deck boards found unfit will be renewed at a stated rate per square metre; during the strip the affected area is measured, photographed and shown to you; you approve the quantity before the work proceeds; and the final invoice reconciles exactly what was found against exactly that rate.
Two disciplines keep the mechanism honest. The trigger must be evidenced, photographs of the actual boards, not an assertion from the scaffold; and the rate must be fixed at quotation time, when you can still compare it, not mid-job when you cannot. Handled that way, the provisional sum is not a loophole in the price; it is the part of the price that respects reality.
Does timing change what you pay?
Substantially, though not through any published seasonal tariff. The expensive way to buy roofing is in distress: a failed roof in a wet November needs immediate labour, temporary protection and decisions made without comparison, and every one of those pressures pushes cost in one direction. The cheap way is on the calendar: a roof surveyed in good time can be tendered properly, programmed into decent weather and booked when materials and crews are not being fought over.
The same logic applies within the job. Discovering wet insulation through a planned core sample before pricing is a line item; discovering it under a half-stripped roof on a Friday is a crisis. Almost everything that makes refurbishment feel ruinous is really the cost of finding things out too late.
How do you budget before any quotes exist?
Commission the survey first and let its findings frame the money conversation. Knowing whether your roof is a repair, overlay or renewal case narrows the range enormously before a single contractor prices it, and the written report lets every bidder quote the same, real job, which is the only way comparison means anything.
That sequencing is the entire trick. Survey, then scope, then quotes, then a decision made in daylight: every step is cheaper than its reverse, and none of it requires knowing a single price in advance.