Replacement
Flat Roof Replacement & New Flat Roofs
When a flat roof is truly finished, the honest job is to take it back to the structure and build again properly. Pluvian Roofing strips, re-boards where needed, insulates to current standards and lays a new RBM covering, on existing roofs and brand new extensions alike.
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When is replacement the honest answer?
Three findings close the argument. Saturated insulation: once water has spread through the boards beneath the membrane, no covering laid on top can dry them out. A failed deck: rot, delamination or sagging in the structure itself. And a roof whose one sensible overlay has already been used, leaving nowhere to go but down and back up. Our refurbishment guide walks through how that verdict is reached; this page is what happens after it is.
The deck decides
Here is the truth that shapes every replacement quotation we write: nobody can price what is under a saturated roof until it is open. Pretending otherwise produces either padded quotes or mid-job renegotiation. So ours separate the known from the provisional: the strip, build-up and covering are priced firm, and boarding or joist work carries stated rates that only apply if the opened roof shows the need. The surprise, if there is one, is procedural, not financial.
What a proper strip and renew involves
- Strip. Every layer of old covering comes off and into the skip, down to the deck. Overlays hide history; the strip ends the guessing.
- Deck inspection: the moment of truth. With the structure exposed, its condition is photographed and assessed against the quotation's provisional items, with you informed before any extra work proceeds.
- Re-board where needed. Failed sections are cut out and renewed; where decay is general, a full redeck gives the new roof a sound start.
- Insulation. New boards to the specification, which is also where regulatory upgrade requirements are met.
- The new build-up. A fresh RBM system, laid as specified, with liquid-applied waterproofing at any detail the Safe2Torch assessment keeps flame away from.
- Details and handover. Upstands, edges, outlets and penetrations finished properly, then a photographed record of the completed roof for your file and the guarantee's.
Warm roof or cold roof: the build-up decision
Every replacement and every new roof answers one design question early: where does the insulation live? A warm roof puts it above the deck, keeping the structure at room temperature; it is the default modern build-up because it manages condensation by design and lifts thermal performance without touching the ceilings below. A cold roof puts insulation between the joists under the deck, which keeps build-up height down but demands ventilation paths and care over condensation risk to stay healthy.
Which applies is a matter of the roof's construction, its height constraints and its use. One regulatory note belongs here, stated generally: replacing a flat roof covering can trigger insulation upgrade requirements under current Building Regulations, so a like-for-like membrane swap is not always the whole scope. No invented figures on this page; the survey and the specification settle what applies to your roof.
New flat roofs for extensions, garages and dormers
Not every job starts with an old roof. For builders and homeowners mid-project we design and install complete new flat roofs: joists checked, deck laid, warm or cold build-up designed to suit the construction, insulation to current standards and an RBM covering detailed to outlast its guarantee paperwork. A new roof done right then earns cheap upkeep: a planned maintenance programme keeps its manufacturer guarantee demonstrably valid from year one.
What moves the scope
Honestly, and without a price list: the area and its access, how many layers the strip removes, what the deck inspection finds, the insulation the regulations require, and the count of details to rebuild. A condition survey turns those unknowns into a scoped, written quotation before anyone lifts a torch.
Frequently asked questions
Can you replace just the felt without the boards?
Where the deck proves sound, yes, and that is the cheaper job. The catch is that nobody knows for certain until the old covering comes off, so our quotation states the price for the expected case and a pre-agreed rate for boarding work, and the strip itself delivers the verdict.
Do you replace roof decks?
Yes. Re-boarding, whether patching bad sections or a complete redeck, is part of the replacement trade, not an extra we shy away from. Rotten or delaminated boards are cut out and renewed before any new build-up goes down, because membranes are only as good as what carries them.
Can you install a brand new flat roof on an extension?
Yes. New flat roofs for extensions, garages and dormers are designed and built from the deck up: joist-level checks, warm or cold build-up as the design requires, insulation to current standards, a new RBM covering and the detailing that decides how long it all lasts.
How long does a flat roof replacement take?
We will not invent a number here, because size, access, weather windows and what the strip reveals all move it. What you get instead is a written programme before work starts, updated the moment anything found on the roof changes it, so the schedule you hold is always the real one.
What happens if you find rot?
It gets photographed, shown to you and priced at the provisional rates already agreed in your quotation, then fixed once you have said yes. Finding rot under an old flat roof is common; being surprised by the bill for it should not be.
Roof past saving, or extension waiting for one?
Either way the next step is the same: tell us about the building and we will look before we quote.
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