Do I need planning permission to replace a roof?

Like for like replacement is usually not development, but changing the material or the roof shape may need consent, and on listed buildings or in Conservation Areas the material choice matters. Check before ordering.

Does a re roof need building regulations approval?

Where a significant proportion of the roof covering is renewed, thermal upgrade requirements are usually engaged, so it is treated as notifiable work rather than repair.

Is natural slate always better than fibre cement?

Natural slate lasts longer and looks right on traditional Cornish stock. Fibre cement is lighter and cheaper and can be appropriate on modern buildings or where structure limits load. The setting and the roof structure decide.

Why does my roof leak only in storms?

That pattern points to wind driven rain being pushed past an edge detail or through a verge rather than to a hole in the covering, which is why patching individual slates rarely cures it.

Roofing · Cornwall

Slate roof replacement in Cornwall, the specification matters more than the slate

A roof on an exposed Cornish elevation does a harder job than the same roof twenty miles inland. It takes salt, sustained wind and rain arriving horizontally, and the failures that follow are rarely the fault of the slate itself. They come from the fixings, the underlay, the ventilation path and the edges, which are the parts of a roof nobody looks at once the scaffold comes down.

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Fixings and wind uplift

Uplift is highest at verges, eaves and ridges, and those zones need enhanced fixing rather than the same pattern used in the middle of the slope. On the most exposed sites double nailing throughout, hooks where appropriate and mechanically fixed dry ridge and verge systems all earn their cost within a few winters. A specification that simply says slate to match existing leaves the most important decision to whoever is on the roof that week.

Enhanced fixing zones at eaves, verges, ridges and around abutments
Fixing type suited to the slate thickness and the batten, not to habit
Dry systems where wind driven rain would defeat a mortar bedded verge
Consideration of slate size, since smaller units cope better with high uplift

Underlay and ventilation

Modern breathable membranes changed how roofs behave, and on older Cornish houses they need thought rather than assumption. A vapour permeable underlay under a cold loft still requires ventilation at eaves and, on many designs, at ridge. Where insulation is moved to the rafter line the whole build up changes and condensation risk moves with it. The section drawing is where this is resolved, showing insulation, membrane, batten cavity and airflow path in one place.

The edges are where roofs fail

Valleys, abutments, chimneys, parapets and the junction with a rendered wall are the recurring sources of leaks in Cornish housing. Lead widths, cover flashings, soakers and secret gutters all need drawing rather than describing. Where the roof meets a neighbouring property in a terrace, the detail also has to be buildable from one side, which quietly rules out some textbook solutions.

When to reuse and when to replace

Sound natural slate can often be sorted and reused on the weather face with new slate on the sheltered side, which suits both budget and appearance on an older building. Where slates are delaminating, or where the roof has been repeatedly patched with mortar and mismatched units, wholesale replacement usually costs less over ten years. Battens and rafters should be inspected once stripped, because rot at the wall plate is common and is far cheaper to fix while the scaffold is up.

Frequently asked

Straight answers.

Do I need planning permission to replace a roof?: Like for like replacement is usually not development, but changing the material or the roof shape may need consent, and on listed buildings or in Conservation Areas the material choice matters. Check before ordering.
Does a re roof need building regulations approval?: Where a significant proportion of the roof covering is renewed, thermal upgrade requirements are usually engaged, so it is treated as notifiable work rather than repair.
Is natural slate always better than fibre cement?: Natural slate lasts longer and looks right on traditional Cornish stock. Fibre cement is lighter and cheaper and can be appropriate on modern buildings or where structure limits load. The setting and the roof structure decide.
Why does my roof leak only in storms?: That pattern points to wind driven rain being pushed past an edge detail or through a verge rather than to a hole in the covering, which is why patching individual slates rarely cures it.

Planning a re roof on an exposed property?

Send photographs and the address and we will tell you which details your specification needs to nail down.

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