Roof inspections and surveys in Bath

The ridge is the horizontal line where two slopes meet at the top. From the ground it looks like a thin dark line, and almost nothing can be judged from it. A proper inspection starts with a view from above, because that is where the first clues sit. There are three ways to get one: a drone, a pole camera and a person on the roof. Each has strengths and limits, and the right choice depends on the roof.

A drone flies over the roof and photographs every slope in detail, which suits tall buildings, steep or fragile roofs and large flat areas. It saves putting ladders against a roof where the covering is brittle, and the images can be zoomed in afterwards. A pole camera is a camera on an extendable pole, held at roof level from a ladder or from the ground. It reaches ridges and eaves cheaply and quickly, and works well on a low roof. Neither can touch, lift or test anything, and a drone cannot see a joint that faces away from the sky. Where the roof is safe to walk, we also go on it, because tapping a ridge tile or lifting a slate shows more than any lens.

What the ridge tells us

A sagging ridge line points to a problem with the timbers below: the ridge board, the rafters or a purlin that has dropped. A ridge with a wave in it over a short span needs a closer look from the loft. Loose or cracked ridge tiles show where the bedding has failed. Since BS 5534:2014, bedding mortar has not been trusted to hold ridge, hip and verge fittings by itself, so repairs add mechanical fixings. Clip-and-screw dry systems have their own test standard, BS 8612:2018. On an older roof we note whether the fixings are original or have been added, and whether the mortar has cracked away from the tile.

The ridge also shows where one roof joins another. A hip, which is the sloping ridge at the corner of a hipped roof, ends at a corner where tiles and bedding are cut to an angle, and that is a place where wind lifts the covering. The verge, the edge at a gable, is a similar weak point. We look at both from above before any ladder goes up.

What an aerial view cannot tell you

Photographs do not show whether a slate is soft, whether a nail has rusted, or whether a batten is rotten underneath. They also miss anything hidden by a neighbouring roof or a tree. A report should say directly what was and was not visible. We list what we could not reach, so a gap in the inspection is never mistaken for a clean bill of health.

Figures: MyBuilder roof inspection cost guide, 2026

Our guides to drone roof surveys and pole-camera roof inspections explain what each shows and where it falls short. The roof survey cost page goes through the price ranges and what drives them.

A valley is the inside corner where two slopes run together. Both slopes drain into it, so it handles a heavier flow than any other line on the roof. It is also built with awkward cut tiles or slates along its edges, and often with a strip of metal at its centre. Leaves and moss collect in it. Because of the volume of water, a defect in a valley shows up inside the house quickly.

The table below lists the common kinds and what an inspection looks for in each.

What an inspector looks for

We clear the channel first, since you cannot see a crack under a drift of moss. Then we look at the metal for splits, thin patches, nail holes where someone has fixed through it, and corrosion. We check the edges of the covering for cut pieces that have slipped, and the line of the valley for sagging. A soaker, a small piece of metal woven between courses at a joint, can slip out of place and let water through the join, so we note any that are visible. From the loft, we look at the timber under the valley for stained or soft boards.

A valley gutter between two parallel roofs, common on double-pile town houses, is a level channel in lead, not a sloping valley. Trust casework on Grade I 33 St James's Square backed re-leading both its central and side valley gutters. These gutters fail like parapet gutters: lead cracks, outlets block and the boards beneath rot. They are difficult to see from below and are best checked from a ladder or by camera.

Reading the signs inside

A stain on a ceiling that follows the line of a valley points straight to it. The same stain after heavy rain and not after light rain suggests a blocked outlet or overflow, not a split. A report should record the stain, the pattern and the rain conditions if the owner knows them. The cause may be a tile gap, a metal crack, or a blocked channel, and the fixes are different.

Lead has limits on how long a single length can run before it needs a step or a joint, because the metal grows and shrinks with temperature. A long unbroken run tends to crack along a fold. Where a lead valley or gutter looks long, we look for the joints and drips, and note where a crack has formed beside one.

When a valley fault is found, slate roofing describes how slate valleys are formed and rebuilt. Our roof inspection checklist lists the other places we look, and inspection after a storm covers what to do once the weather has passed.

The loft is where a roof tells its truth. From outside, a slate roof can look uniform, but from underneath you see daylight through gaps, the state of the battens and underlay, and the condition of the timbers. We go into the loft with a torch and a moisture meter, the instrument that reads how damp wood is, and we work along the boards, taking care not to step between joists onto the ceiling below.

What we look for

Rafters, purlins (the horizontal timbers that support the rafters) and the wall plate (the timber that runs along the top of the wall) are checked for wetness, rot and insect damage. Dark patches around a chimney breast or valley suggest repeated wetting. Pinpoints of daylight show gaps in the covering, though some roofs are designed with small gaps for ventilation. The underlay, a membrane laid beneath the battens, may be torn, brittle or sagging between rafters. On older roofs there may be none, with the underside of the slates pointed with lime instead, a method called torching.

Insulation is noted as well. Compressed or missing insulation raises heating costs, but it is the way it sits against the roof that matters for the structure. If it is packed hard against the eaves, it can block the airflow that keeps the timbers dry. If foam has been sprayed onto the underside of the roof, the timbers behind it cannot be seen. The RICS consumer guide cautions about uncontrolled condensation and tells owners to ask their mortgage provider whether its lender policy allows foam. We record it in the report and leave the judgement to you.

Condensation or a leak

Moisture in a loft is not always a leak. Warm, damp air from the house rises into a cold roof space and condenses on the coldest surfaces, which leaves droplets on the underlay and nails. A leak leaves a track, with staining that follows the line of the water. We look for both and say which we think it is.

We also look along each gable and party wall from inside, since wind-driven rain most often works in at those joints. A line of light along a wall plate, or a hairline gap between purlin and rafter, is recorded with its position, so anyone repairing it can go straight to the spot.

Bats and nesting birds have legal protection, so if we see signs of either we stop and tell you before anything else happens.

The loft roof inspection guide describes what a safe loft visit involves, and a roof nearing the end of its life explains the signs of age. For pre-sale work, pre-purchase roof surveys puts the loft findings into a buyer's context.