Planning a replacement roof covering, from survey to handover

Leaks can start at a chimney flashing, lap or fixing. Water may travel along a roof layer before it stains the ceiling. Inspect the exterior and the roof space. Note whether damp appears after rain or even in dry weather, when condensation may be involved.

Inspect corrosion and the condition of the substrate. An isolated scratch needs different treatment from perforations across several sheets. Damp timber or insulation may extend the repair. Before pricing, ask for a photographic defect record identifying where opening up is necessary.

Raising the roof, changing its shape or altering the framing goes beyond renewing the outer covering. Establish what design work and formal procedures apply. Consider changes in covering weight as well. A lighter covering can reduce some loads but cannot restore damaged structural connections.

For older buildings, compare the actual structure with the available records. Listed buildings and asbestos-containing materials may require special procedures. Agree the removal method, protective measures and waste arrangements before the crew arrives. Asbestos removal requires a different approach from taking down ordinary sheets.

Measure the slopes, pitch and support layout. Assess T18 and T35 using the documentation for the exact profile. Cut-to-length tile-effect sheets can suit a simple slope. Smaller modules can be easier to handle on broken roof lines. Match the choice to the framing and the appearance required.

Where the work includes insulation, specify the complete build-up. PIR boards can reduce the thickness needed for a given thermal resistance, but joints and moisture control still need detailing. Insulated roof sandwich panels are a separate system. Check the supports and junctions throughout the building before specifying them.

Agree the area to be opened up in each phase and the rain protection to use if the weather changes. Coordinate deliveries, installation conditions and safe storage. Confirm the new sheets and accessories will be on site in time before stripping a whole roof. The structure and the safety of the crew also govern phasing.

Provide space for unloading long sheets, scaffolding and waste. Check vehicle access and room for lifting equipment. Store sheets and panels according to their instructions and protect them against damage and moisture. Bundles left on the ground under a loose tarpaulin can trap water and dry slowly.

Once the old covering is off, inspect supports and connections. Agree repairs before installing new components. Check the underlay, penetrations and ventilation path while they remain accessible. Photographs and work records preserve details of the actual roof build-up.

Pay close attention to eaves, valleys, chimneys, ridge and verges. Match fixings to the substrate and detail flashings so that water drains away without relying solely on sealant. Include swarf removal after cutting and timely removal of protective film in the work schedule.

Compare the finished work with the contract and agreed variations. Inspect the surface, fixings, flashings and drainage. Check that waste has been cleared and that service points can be reached safely. Include the roof space and areas previously affected by damp in the inspection.

Keep the material documents, maintenance instructions and signed handover record. Agree who will inspect after the first season and how defects should be reported. Follow up the original fault as well as the appearance of the new covering. That check connects the final inspection to the problem the work was commissioned to solve.