Should You Re-Roof When Having an Extension Built?

Why the Timing of an Extension is the Perfect Moment to Think About Your Roof

Having an extension built is one of the biggest investments you'll make in your home. Builders are already on site, scaffolding may already be up, and the roof junction between the old house and the new addition has to be dealt with regardless. That makes it the single best moment to take a serious look at whether your existing roof deserves the same lifespan as your new extension.

We work with homeowners across Brandon, Feltwell, Mundford and the surrounding villages regularly, and the same situation comes up again and again — someone spends £30,000–£50,000 on a rear extension, then a couple of years later ends up calling us because the original roof has started failing. The two jobs could easily have been done together for a fraction of extra cost.

What Condition Is Your Existing Roof In?

The honest answer depends on age, material and how well it's been maintained. A clay or concrete tile roof in good condition with a sound felt underlay may have another 20–30 years left in it. But if the tiles are 40 years old, the lead flashings around your chimney are cracking, and you've had a couple of minor leaks patched over recent winters, then you're essentially attaching a brand-new extension to a roof that's running out of time.

Brandon sits inland on the edge of the Brecks, but that doesn't mean roofs here get an easy ride. Cold snaps, easterly winds, and the freeze-thaw cycles that affect the Norfolk and Suffolk border each winter take their toll on mortar, ridge tiles and aged felt. If you're seeing moss growth, slipped tiles or failing pointing on ridge caps, those are genuine warning signs — not just cosmetic issues.

A roof replacement on a standard semi-detached in Brandon typically costs in the region of £4,000–£8,000 depending on size, pitch and material — considerably less painful when scaffold is already standing for your extension build.

The Practical Case for Combining Both Jobs

Scaffold costs money. Every time a roofer needs to access your roof, a scaffold contract is involved — erection, hire period, and dismantling. If your extension build already has scaffold up for two to four weeks, adding a full re-roof to that programme could save you £600–£1,200 on scaffold costs alone.

There's also the junction to consider. Where the new extension roof meets the existing house wall, a roofer needs to form new lead flashings and step flashings regardless of what else is happening. If your existing roof covering is incompatible or degraded, having it properly tied in at that point makes the whole system weathertight in one go rather than half-patching around a new opening.

• Scaffold is already on site — share the cost across both contracts
• New and old roofing materials can be matched before the extension is built
• Lead work at the junction is cleaner when the existing tiles are being replaced anyway
• A single guarantee covers the whole roof rather than two separate warranties with a gap in between

Planning Permission and Building Regulations

Most re-roofs fall under permitted development and don't require planning permission, provided you're using similar materials and not altering the roofline. However, if your extension itself requires full planning consent — or if you live in a conservation area, which covers parts of the wider Brandon district — you'll want to check with the Government's planning guidance before specifying materials.

Building regulations do apply to re-roofing work where more than 25% of the roof covering is being replaced. This is actually straightforward in practice — it means the insulation in your roof space needs to meet current standards. If your loft insulation is thin or missing, a re-roof is the ideal time to upgrade it, which will show up in your energy bills year-round.

We'd always recommend using a contractor registered with the National Federation of Roofing Contractors so your work is independently backed and meets compliance requirements without any grey areas.

When It Might Not Be Worth Re-Roofing at the Same Time

If your roof was re-covered within the last 15 years with good quality tiles and a breathable membrane, and the inspection shows no movement, no cracked mortar and sound flashing detail, then a full replacement isn't necessarily justified. In that case, a targeted roof repair at the junction point — new lead work, re-bedded ridge tiles, fresh pointing — may be all that's needed to make the whole roof coherent again.

We'll always tell you honestly what we find. There's no value in selling a full re-roof to someone whose existing covering has plenty of life left. But that assessment needs to happen before your extension builder breaks ground, not after.

Get a Free Roof Survey Before Your Extension Build Starts

If you're planning an extension in Brandon, Feltwell, Hockwold or anywhere nearby, contact us before work begins — not after. We'll inspect your existing roof properly, give you a straight assessment of its condition, and quote for any work that makes sense alongside your build. Get in touch for a free local roof survey and we'll make sure your new extension starts life with a roof that matches it.

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