Full re-roof vs overlaying an existing covering
Overlaying is faster and cheaper, and occasionally it's a reasonable engineering decision. More often it postpones the real work while making it more expensive later.
What you lose by not stripping
Stripping is the only way to renew the underlay and battens, replace corroded fixings, and see the rafters. An overlay leaves all of that in place, unseen.
Weight
Adding a covering on top of an existing one increases dead load. On tiled roofs this is usually the point where an overlay stops being viable at all.
Where overlay can work
Flat roofs with a proven dry, sound deck are the realistic case, and even then a moisture check should come first. A wet deck under a new membrane rots quietly.
What a proper re-roof includes
Strip and dispose, replace defective battens and timbers, new breathable underlay, re-lay or renew the covering, new ridge and hip system, renew flashings, and eaves protection at the gutter line.
Warranties
Manufacturer-backed system warranties generally require correct installation onto a suitable substrate. Overlays frequently fall outside them.
FAQs
Only where the existing felt is well-bonded, dry and flat. We check the deck first; if there's any doubt we strip.
Rarely. If it fails, the strip you avoided has to happen anyway, plus the wasted overlay.
Yes — a re-roof without new underlay isn't a re-roof.
Related reading
More on comparisons and the jobs that usually come with it.
- Slate vs tile: which suits your propertyComparisons
- Repair or replace? How to decide honestlyComparisons
- How long should a roof last?Comparisons
- Roof cleaning: what it costs and when it's a bad ideaCosts & budgeting
Looking for something specific? See our roofing services, cost guides, common roof problems or the areas we cover.
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