Roof Survey Case Study: Rendered Semi-Detached House, Maghull

The numbers

What the survey found, and what it was worth

The property was already sold subject to contract when the buyer called us. Our inspection covered the hipped principal roof, both chimney stacks, the front entrance canopy, the gutters and downpipes, the accessible loft and the ground-floor extension with its roof windows — and concluded the roof could not presently be regarded as reliably weather-tight. Below is the evidence exactly as it went into the report, with the property details removed.

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The evidence

Nine of the 24 photographs, nine of the findings

PHOTO 01

Missing and displaced tiles High

Missing, displaced and irregularly seated small-format concrete tiles on more than one slope of the hipped principal roof, with general weathering and biological growth across the coverings.

This roof has no modern continuous underlay — it is a traditional torched roof. Every open tile joint is therefore a direct route for wind-driven rain, not a cosmetic defect.

PHOTO 02

Hip and ridge mortar High

Mortar bedding and pointing to the ridge and hip lines has failed in several positions, with open joints, lost mortar and damaged sections along the hip-tile line.

Loose ridge and hip units admit water and can come off in high winds. The correct repair is to lift them, clear the failed bedding, and re-bed with mechanical fixing.

PHOTO 03

Main chimney leadwork High

Leadwork at the front and rear chimney abutments is missing, displaced or inadequately dressed, with open joints straight into the roof. Stack pointing and flaunching are weathered too.

Chimney abutments are one of the most common leak points on older roofs. Correctly formed soakers, cover flashings and back-gutter details are the proper fix — not mastic.

PHOTO 04

Gutters and rainwater goods High

The front gutter is buckled and partly detached from the fascia, and gutter runs contain mortar fragments, moss, soil and established growing vegetation.

Blocked, back-falling gutters overflow against the fascia, masonry and roof edges. This is cheap to fix and expensive to ignore.

PHOTO 05

Front entrance canopy lead High

The lead sheet over the entrance canopy has visible tears and splits, surface deterioration and evidence of previous patching. Water can enter the canopy structure and the entrance below.

Where multiple splits are present, complete renewal in correctly sized bays that allow thermal movement is more reliable than another patch.

PHOTO 06

Loft: failed torching, no underlay Medium

From inside the loft, the traditional lime-mortar torching has detached and fallen from the underside of the tiles. Daylight is visible through open tile joints, and fallen mortar has contaminated and compressed the insulation.

Torching is not a substitute for modern underlay, but its failure further reduces resistance to wind-driven rain — and it feeds a steady stream of debris into the loft and gutters.

PHOTO 07

Extension ridge tiles High

On the ground-floor extension, the mortar securing the ridge tiles has cracked and failed, with open joints and biological growth along the line.

The extension defects interact: failed ridge and abutment details let water in from above while blocked drainage holds water on the roof. They need treating as one coordinated repair.

PHOTO 08

Wall-abutment lead chase High

The mortar or seal securing the extension lead flashing into the main wall has failed, with gaps and loose sections, and the lead laps at the extension-to-house junction are insufficient — water was observed breaching the joint.

Flashings only work if they are restrained in the chase and lapped correctly. Re-form, dress and mechanically secure the lead, then seal with a proprietary flexible lead sealant.

PHOTO 09

Roof-window drainage channels High

The head and side drainage channels around the extension's roof windows are heavily obstructed by moss, soil and established vegetation. Water had backed up around the frames and was contributing to internal water ingress — and the blocked extension downpipe had submerged the eaves membrane, letting moisture track through by capillary action.

Roof windows rarely leak through the glass. They leak because water can no longer get past them. Clearing and water-testing the channels is routine maintenance that had simply never been done.

The recommendations

The repair schedule, in the order it should be done

1. Immediate (0–4 weeks)Replace missing and displaced tiles; clear every gutter, downpipe and roof-window channel; rectify the blocked extension outlet and submerged eaves membrane and fit felt-support trays; renew the defective extension lead laps; renew the main-chimney flashings; make unstable ridge and hip areas safe; address the torn canopy lead.
2. Short term (1–3 months)Re-bed and mechanically secure ridge and hip tiles and replace damaged sections; repoint both chimneys and renew both flaunchings; fit suitable terminals once flue use is confirmed; repair or renew the front gutter and inspect the fascia; complete the extension ridge and roof-window flashing work.
3. Planned (3–12 months)Hand-remove heavy moss; clear the loft of fallen mortar and debris; remove contaminated insulation and re-insulate to current Building Regulations after the external repairs are complete; and compare the combined repair cost against a complete renewal of the principal roof.

Each item was costed separately in the report so the buyer, their solicitor and the vendor could see exactly where the money went, with concealed timber repairs treated as provisional until opening-up.

The outcome

Inspection findings and costings

What this job teaches

Read another real example: read the Bootle case study →

Questions

Pre-purchase roof surveys — what buyers ask

Related: Professional Roof Survey Report — Maghull · Roof Survey — Maghull · What happens during a roof survey · Survey reports across Merseyside · Chimney repairs Maghull · Flat roofs Maghull

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