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Extension Roofs — Tying New Into Old
Extension roofs almost never leak in the middle. They leak where the new roof meets the old house — and that junction is usually the last thing anyone prices properly.
- Abutment, apron and step flashings in lead
- Valley tie-ins to the existing roof
- Flat-to-pitched junction detailing
- Tile and slate matching to the main roof
- Coordinated with your builder's programme
- Guarantee covers the junction, not just the field
The junction is the job
Where an extension roof abuts the existing house wall you need an apron or stepped flashing raked and wedged into the brickwork, dressed the right distance over the covering, and run in bays so it can move. Where the new roof runs into the existing slope you need a properly formed valley on a valley board. Both take a leadworker. Neither is a job for mastic and a flashing tape.
- ▸Raked and wedged into the joint, not surface-sealed
- ▸Correct lead code and bay lengths
- ▸Valley boards fitted before the lead
Matching the existing roof
A new extension roof in a slightly different tile reads as an afterthought forever. We sample the existing covering, source the closest current or reclaimed match, and where nothing matches well we'll suggest a deliberate contrast that looks intentional rather than a near-miss that doesn't.
Working to a builder's programme
We work as the roofing trade on extension projects regularly, and the key is being on site at the right point — after the structure is up and before the scaffold comes down or the internal fit-out starts. We'll book against your builder's dates and flag if the sequence puts the roof at risk of weather exposure.
FAQs
Can you work for our builder rather than us?+
Yes — we're often engaged as the roofing subcontractor and invoice the main contractor directly.
Our extension has a flat roof against a pitched roof — is that a problem?+
It's a common and perfectly sound detail when the upstand height and flashing are right. Getting the upstand too low is the usual cause of failure.
Do you handle Building Control for the roof element?+
We provide the specification and supporting product information for your building notice or full plans application.
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