A roofing quote that just says 're-roof with new tiles' tells you nothing about how the roof will actually perform. Tile exposure, batten gauge, underlay grade and leadwork detail are what separates a roof that lasts and one that starts leaking at the first hard weather after the guarantee period most contractors don't offer anyway.
Roofing is also one of the trades where a specification genuinely needs to follow a strict sequence — strip, felt/underlay, batten, tile, flash — and each stage needs naming.
Tile or slate specification and exposure
The spec should name the actual tile or slate product, its size and the required headlap and side lap for the roof's pitch and exposure category, calculated to the manufacturer's fixing specification (usually referencing BS 5534). A shallower pitch or an exposed coastal location needs a tighter lap and often mechanical fixing throughout, not just at the perimeter — this is a real cost driver that a headline price can hide.
Batten gauge and fixing
Batten gauge (the spacing between battens) must match the tile manufacturer's specification for the roof pitch, and battens should be treated timber of the correct grade and cross-section for the tile weight and rafter spacing. The spec should state whether battens are being reused or fully replaced — reused battens on an older roof are a common shortcut that risks fixing failure.
Underlay and ventilation
The underlay grade (breathable membrane versus traditional bituminous felt) and its installation detail at eaves, ridge and valleys should be named, along with the ventilation strategy — eaves ventilation, ridge ventilation, or a combination — required to prevent condensation within the roof void under current Building Regulations guidance.
Leadwork and flashings
Flashings at abutments, valleys and chimneys should specify the lead code (thickness) appropriate to the detail, following the Lead Sheet Association's recommended practice. A cheap quote will often specify a lighter-gauge lead or substitute a flexible flashing strip at a chimney abutment where proper stepped and soakered leadwork is needed.
What cheap roofing quotes tend to leave out
Scaffolding for the full roof (not just a tower for chimney access), disposal of old tiles and felt, replacement of damaged rafters or roof timbers found once stripped, and eaves/verge detailing (fascia, soffit, dry verge system) are frequently missing or under-specified.
- Full perimeter scaffolding with edge protection
- Disposal of stripped tiles, felt and battens
- Provisional allowance for rafter or timber repairs found on strip
- Ventilation detail at eaves and ridge
- Lead code specification for each flashing detail
Common questions
Does the roof pitch really affect the tile specification?+
Yes. Lower pitches require greater headlap and often a different fixing specification to keep the roof weathertight, and some tile products aren't rated for use below a certain pitch at all.
Should old roof battens be reused when re-roofing?+
Generally no — battens are inexpensive relative to the whole job and reusing old, weathered battens on a new roof covering risks fixing failure over time. A proper spec should state new battens throughout.
What is the risk of not specifying roof ventilation properly?+
Insufficient ventilation in the roof void can lead to condensation build-up, which rots timber and degrades insulation from the inside over years, well after the roof covering itself looks fine.
Get a roofing specification with batten, underlay and leadwork named
We specify tile, batten gauge, underlay and lead detail before quoting, so nothing is assumed on the day.