In detail
What matters when specifying complete re-roofs
The best-looking option is not automatically the right technical choice. Roof pitch, exposure, structural capacity and the way the building is used all influence the specification. Understanding these details makes it easier to compare proposals on substance rather than appearance alone.
Replacing like for like or changing the covering
A re-roof can retain the existing material style or introduce a different covering, subject to suitability and any relevant restrictions. A change from slate to tile, or between tile types, may alter the load substantially. Pitch compatibility, wind exposure and the building’s appearance also matter. The replacement should be checked against the roof’s construction rather than selected solely because it resembles a neighbouring property.
Some existing slates or tiles may be suitable for reuse, but that depends on their condition and the intended specification. Reclaimed coverings can have variable dimensions and remaining service life. New battens, underlay and fixings still need to be appropriate for the assembly. Discuss whether reuse is technically sensible and how it affects the scope and applicable warranty rather than assuming every salvaged piece should return to the roof.
Underlay, battens and ventilation work together
Slates and tiles shed most rainfall, while the underlay provides a secondary line of protection beneath them. Underlay laps, support and drainage at the eaves must suit the roof design. Battens provide the fixing positions for the covering, so their grade, spacing and support matter. A covering installed over unsuitable battens or poorly arranged underlay can conceal problems rather than solve them.
A breathable membrane does not automatically remove the need for ventilation. The arrangement depends on the roof construction, insulation position, membrane specification and moisture conditions inside the building. Cold roof spaces and insulated roof slopes need different consideration. Blocking the eaves with insulation, or adding ridge ventilation without a suitable overall strategy, can leave moisture trapped where it causes condensation and timber deterioration.
Stripping back without overlooking the building below
Complete re-roofing involves a period when the existing covering is removed, so the sequence and weather protection are important. The workable approach depends on roof size, shape, access and conditions. Large areas should not be exposed casually on the assumption that the forecast cannot change. Properties with multiple slopes may allow a staged approach, but the details need to suit the individual building.
Stripping can reveal timber decay, inadequate supports or old alterations that were not visible during the initial inspection. Those findings should be explained and any necessary additional work agreed. A roofer’s inspection does not replace structural engineering where structural adequacy is uncertain. Keeping that distinction clear helps ensure the new covering is installed on a roof capable of supporting it safely.
Junctions, rainwater and approvals
Water concentrates at valleys and changes direction around chimneys, rooflights and adjoining walls. These locations need compatible flashings, adequate overlaps and unobstructed drainage. Lead flashing must accommodate movement and be detailed for its location; simply adding sealant over a failed junction is not equivalent to rebuilding it correctly. Eaves details must direct water into the gutter rather than behind the fascia or onto vulnerable timber.
Building Regulations approval is normally required for substantial re-roofing, and thermal upgrades may need consideration where applicable. Planning permission is a separate question: listed buildings, conservation areas and some alterations can have additional restrictions. Establish the relevant route before work starts. Structural changes or a materially different covering load may also require professional assessment rather than an assumption that the existing roof can accommodate them.
Occupied homes and commercial premises
On an occupied home, roof work needs to account for people moving through entrances, items stored in the loft and rooms directly beneath the work. Dust and disturbance cannot always be eliminated, but discussing likely effects helps you prepare. Extensions, porches and adjoining roofs also need attention because the main roof must connect to them without creating awkward drainage or maintenance problems.
Commercial premises may have different access constraints, shared boundaries or activities that cannot simply stop during roofing work. The appropriate sequence depends on the building, not just the covering selected. Explain opening hours, sensitive internal areas and any restrictions on scaffolding or deliveries before the scope is agreed. A realistic plan should also account for weather interruptions rather than treating the proposed programme as an unconditional completion guarantee.