Re-roofing usually means stripping the existing covering back to the structure and laying a fresh covering, new underlay and battens, while a full replacement extends to repairing or rebuilding the timber structure beneath. A simple re-cover, by contrast, lays new material over what is already there without removing it. The right call depends on the condition of the tiles or slates, the state of the underlay and battens, and whether the roof timbers remain sound.
What re-roofing actually means
The word "re-roof" is used loosely, so it helps to separate the terms. A re-cover places a new layer directly over the old covering. A strip and re-cover removes the existing tiles or slates, renews the underlay and battens, then lays a new covering on the same structure. A full replacement goes further and addresses the rafters, joists or other structural timbers as well.
Underlay is the membrane laid beneath the tiles or slates that catches any water getting past the outer covering and channels it to the gutter. Battens are the horizontal timber strips the tiles hook onto. Both have a shorter working life than good slate or tile, which is why a re-roof often renews them even when much of the outer covering could, in theory, be reused.
In ordinary speech, "re-roofing" most often refers to a strip and re-cover. It is the middle option: more thorough than a patch repair, less involved than rebuilding the structure.
When a repair is no longer enough
A simple re-cover, by contrast, lays new material over what is already there without removing it.
Isolated faults — a few slipped tiles, a cracked ridge, a small area of perished felt at a valley — are repair territory. Repairs make sense while the rest of the roof has years left in it and the problem is contained.
The case for repair weakens once faults stop being isolated. Signs that a roof is approaching the end of its serviceable life include:
- Recurring leaks in different positions rather than one persistent spot.
- Widespread slipped, cracked or delaminating tiles and slates, where delamination means the layers of a slate flaking apart.
- Underlay that has torn, sagged or turned brittle, visible from inside the loft.
- Nail fatigue or "nail sickness", where the fixings holding slates have rusted through, so slates slide off across the whole roof.
- Sagging lines along the ridge or between rafters, which can point to structural movement.
When several of these appear together, money spent on repairs tends to be money spent twice. A structural assessment — a closer inspection of the timbers, fixings and load paths — helps establish whether the problem is confined to the covering or runs deeper.
Re-cover or full replacement?
The dividing line is the condition of what sits beneath the covering. If the rafters and supporting timbers are sound and dry, a strip and re-cover renews everything that wears out — covering, underlay and battens — without disturbing the structure. This is the more common outcome on a roof that has aged but not been allowed to leak unchecked.
Full replacement becomes the realistic option where the structure itself is compromised. Long-term water ingress can rot rafter ends, decay the wall plate the rafters sit on, or encourage timber-attacking fungus. Past alterations, undersized timbers or a previous re-cover that added weight the structure was not designed for can also force a more extensive rebuild.
A re-cover laid over the existing covering is the lightest-touch option, but it carries caveats. It adds weight, it hides any decay underneath rather than addressing it, and it cannot renew an underlay that has already failed. For those reasons it suits a narrower set of situations than a full strip. Building control approval may be required where work affects a significant proportion of the roof; whether that threshold is reached is worth checking before work begins.
What a re-roof project includes
A typical strip and re-cover follows a recognisable sequence. The covering is removed and the structure is inspected once exposed, because some defects only become visible at that point. New underlay is laid, new battens are fixed, and the covering goes on — either the original tiles or slates if enough are reusable and sound, or new material.
The detailing around the edges and penetrations usually forms part of the same project:
- Ridge and hip tiles, increasingly dry-fixed with mechanical clips rather than bedded in mortar alone.
- Flashings — the metal weatherproofing where the roof meets walls, chimneys or abutments.
- Valleys, where two roof slopes meet and carry concentrated run-off.
- Fascias, soffits and guttering, often renewed at the same time while access is in place.
- Ventilation, to limit condensation in the loft beneath a modern, less breathable underlay.
Scaffolding is generally needed for safe access and for managing the removed material. A full replacement adds structural work to this list, which may involve replacing rafters, repairing the wall plate, or strengthening timbers before the new covering is laid.
The main things that move the price
No single figure fits every roof, but the variables that drive cost are consistent. Roof size and pitch set the baseline, with steeper and more complex shapes — hips, valleys, dormers — taking longer to cover.
Other factors that tend to move the figure include:
- Covering material. Natural slate, clay tile, concrete tile and synthetic slate differ in price and in the labour they require.
- Extent of work. A re-cover, a strip and re-cover, and a full structural replacement sit on a rising scale.
- Hidden defects. Rotten timber or a decayed wall plate found once the roof is opened up adds work that cannot always be priced in advance.
- Access. Height, restricted space and scaffolding requirements affect cost, particularly on terraced or detached awkward layouts.
- Associated work. Renewing fascias, gutters, insulation or ventilation at the same time.
- Disposal. Removing and skipping old material, with extra handling where older roofs contain cement-bonded products.
Because the structural condition is often only confirmed once the covering is removed, it is reasonable to expect a contingency for findings during the work. Asking how a firm handles unforeseen structural repairs, and whether their quotation is fixed or subject to revision, gives a clearer picture than the headline number alone.
Reviewed: June 2026