Five roofing defects to look for at handover

Agree with the contractor on the inspection points for works that will be covered up. The battens, membrane and some connections will later be invisible. It is worth taking photographs with the roof slopes marked. For the final acceptance, prepare a material specification and detail drawings. This will allow you to discuss specific discrepancies rather than only a general impression.

You do not have to go onto the roof yourself to organise a reliable inspection. Access should be safe, and difficult issues can be entrusted to an independent person with the relevant knowledge. The most important thing is to check function and conformity of execution. An attractive photograph from the ground does not show the hidden layers or all the fixings.

For tile-effect metal roofing, the battens must correspond to the module and the requirements of the profile. Under trapezoidal steel sheet, the support spacing is selected according to the loads and the data for the specific sheet. Confusing these rules can lead to deformation and fixing problems. Simply adding a few screws does not replace missing or incorrectly positioned support.

Also check the evenness of the battens and the condition of the components. A warped batten can force the sheet to deform. At roof valleys, chimneys and accessories, additional supports may be needed. If these were omitted before installation, the repair may require the roof slope to be exposed. It is worth catching this problem before wide flashings conceal the bearing point.

The screw should be suited to the substrate and the application. The correct compression of the seal is important. Overtightening can deform it, while undertightening can leave a leak. The number of fixings and their distribution depend on the system and the roof zones. A single general value does not always describe the entire roof slope.

The connection should not be judged solely by the colour of the head. It must be checked whether the fastener has actually reached the correct support. The brackets for roof walkways and snow guards require separate attention. They transfer loads other than an ordinary sheet overlap, so a random method of fixing is particularly undesirable.

A poorly laid overlap, an excessively narrow roof valley or an unsuitable verge strip at the eaves can direct water the wrong way. The detail should be assessed as a flow path. It is not enough that it covers the gap and has a nice colour. Water should leave successive elements without steps or pockets that trap debris.

At the chimney, all sides and the connection to the layer under the metal sheet must be checked. An excessive amount of sealant can hinder assessment instead of confirming care. The sealing should support the correct detail. If the geometry is wrong, the correction should change it, not merely cover the problem with another layer of compound.

In a typical ventilated system, an unobstructed inlet, a gap and an outlet are needed. Closing one of these places can worsen the moisture conditions. Water drainage above the underlay must also be maintained. A fold in the membrane or an accidental obstacle can hold water under a seemingly sound covering.

Not every visible gap is a defect to be filled with foam. Designed airflow must be distinguished from leakage. The airtightness of the layer on the room side is also important. These functions do not replace one another. Where the arrangement is unclear, it is worth comparing the workmanship with the project section before the loft is closed.

Sheets can be scratched during cutting, handling or walking on the roof slope. Swarf left on the surface rusts and forms stains. After the works are completed, the roof should be cleaned of fine metal and offcuts. Roof valleys, gutters and profile recesses are particularly worth checking.

Damage to the coating should be assessed before any random touch-up. The repair method depends on depth and size. A large painted-over area may look worse and may not meet the material requirements. In the case of extensive damage, replacement of the element may be necessary. It is worth documenting the condition before the correction is made so that the scope is clear.

In the protocol, indicate the location, describe the defect and state the agreed method of correction. Add the deadline and photographs. Avoid general entries from which it does not follow what is to change. If assessments differ, an opinion referring to the design and instructions will be helpful. Not every aesthetic difference can be resolved on the basis of a single photograph.

After the corrections, check the same points again. Keep the material documents and photographs of the works that are covered up. At subsequent inspections it will be known which places were repaired and for what reason. Acceptance should lead to a specific, verified result, not merely to signing a piece of paper that ends the crew’s presence on site.