Localised repair
Right when faults are isolated and the covering is otherwise sound: a split at a lap, a cracked upstand, a failed detail. The cheapest option, and often all a roof needs.
Flat roof and leak repairsRefurbishment
Flat Roof Refurbishment: Overlay, Recover or Replace
When a flat roof nears the end of its life you have three honest options: repair it locally, overlay it with a new membrane, or strip it back and renew it. Each is right for different roofs. This page is the decision guide; a survey of your actual roof makes the decision.
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The three options, honestly compared
How the survey decides
The decision is evidence, not preference. A condition survey establishes the facts that matter: is the substrate dry, is the existing covering bonded, what state are the upstands and details in, and what can the structure take. Overlaying a wet roof traps moisture and buys a few years at the cost of the deck; stripping a dry one wastes money and fills a skip for nothing. The survey exists so neither happens to you.
Which overlay: liquid or RBM?
Both are real options and the survey picks between them, but in practice the liquid route carries most of our overlay work. A cold-applied liquid membrane bonds to a prepared surface without heat, follows the details it meets rather than being cut around them, and adds very little weight to a structure that is already carrying an old covering. It needs conditions to be met first: the existing roof has to test dry through its build-up, hold firmly to what it sits on, and take preparation without breaking up. Where any of that fails, or where the roof would be better served by a fresh built-up system, an RBM overlay is specified instead. The system named in your quote is the one the roof argued for.
The cost logic, without invented numbers
We price each viable option in writing after the survey, and the logic is consistent: repair costs least; an overlay saves the strip-off, disposal and much of the disruption; strip and renew costs most and delivers a completely new covering. Where options are genuinely close, we say so and explain the trade instead of steering you to the dearest one.
Frequently asked questions
Does a tired flat roof always need replacing?
No. If the deck and insulation underneath are dry, a localised repair or a full overlay is often the better answer, at a fraction of the cost and disruption of replacement. Replacement is the right call when moisture has spread beneath the membrane or the covering has failed across its whole area.
What is a roof overlay?
An overlay is a new waterproof layer installed over the prepared existing covering, most often cold-applied liquid waterproofing using the HYDRONYLON system, with reinforced bituminous membrane used where the survey favours it. Where the base underneath is dry and sound, it saves the cost, disruption and waste of tearing that base off.
When is strip and renew the right choice?
When the survey finds wet insulation or a damaged deck, when previous coverings have been layered too many times, or when the roof has failed widely rather than locally. At that point an overlay would trap the problem, so the honest option is to strip back and rebuild the covering properly.
How do you decide between repair, overlay and replacement?
With evidence from a condition survey: whether the substrate is dry, how well the existing covering is bonded, the state of the details, and what the roof structure can take. The decision is written down with the reasoning, so you can see why each option was or was not recommended.
How much does flat roof refurbishment cost?
There is no honest single figure: the cost depends on the option, the size, the access and what the survey uncovers. The logic is consistent though: repairs cost least, overlays avoid the cost of stripping and disposal, and replacement costs most but resets the roof completely. You get each viable option priced in writing.
Not sure which option your roof needs?
That is exactly what the survey answers. Tell us about the roof and we will take it from there.
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