Building Survey Scarborough: Identifying Roof Failures in Victorian Homes

A building survey case study from a Victorian terrace in Scarborough

Victorian terraced houses are robust, characterful buildings, but they rely heavily on one thing to remain healthy: a watertight envelope. This case study highlights how defects at high level, particularly the roof coverings, chimney stacks and rainwater goods, can manifest as severe internal dampness and structural concerns if left unaddressed.

During a full building survey of this late-1800s solid-walled property in Scarborough, a clear pattern emerged. Multiple internal defects were not isolated issues, but symptoms of long-term water ingress originating at the roof and chimney level.

Roof coverings: widespread failure rather than isolated defects

The main pitched roof is covered in natural slate, likely original or near-original. While slate is a durable material, it is not indefinite. Across multiple roof slopes, numerous slates were found to be cracked, slipped, loose or missing, with deterioration described as widespread rather than localised.

The mortar bedding to the ridge tiles has eroded significantly, and the roof verges, particularly to the rear projection, are in poor condition, with cracked and friable mortar no longer providing effective weather protection. Importantly, the roof has no sarking membrane, meaning any wind-driven rain that bypasses the slates has a direct route into the roof structure and internal fabric.

Several neighbouring properties have already undergone full roof replacement, which is often a reliable indicator that the roof covering in this terrace is approaching the end of its serviceable life. In practical terms, this means ongoing reactive repairs may no longer be cost-effective, and strategic planning for larger-scale works is sensible.

Rear chimney stack: the primary source of severe damp in Bedroom 3

Slipped and broken slates.

The most serious internal defect identified during the inspection was severe damp penetration to Bedroom 3, concentrated around the chimney breast and adjacent external wall.

Chimney stacks of this age were typically constructed without modern damp-proof trays, making them particularly vulnerable to water ingress. Once defects develop at the top of the stack, water is absorbed into the masonry and migrates downward, often presenting internally at the first-floor level around chimney breasts.

In this case, the internal damp staining and elevated moisture readings in Bedroom 3 align directly with the chimney’s external condition, the lack of a sarking membrane under the slate, and the poor state of the roof slating. It's also worth noting that, as this chimney would have burnt fossil fuels, there could also be elements of hygroscopic salts, which would also need treatment as well.

The effects of water ingress, physically wet to the touch, delaminating wallpaper from the wall, and high moisture readings on the damp meter.

Secondary damp source: failed mortar verge above Bedroom 3

A second, distinct area of dampness was identified in Bedroom 3, separate from the chimney breast. This area aligns with the external mortar verge, which is cracked, eroded and no longer weather-tight.

Mortar verges are inherently vulnerable details, particularly on exposed elevations. Once cracking occurs, wind-driven rain can track beneath the roof covering and enter the solid wall below. In this property, the verge defects are sufficiently advanced to allow water penetration, contributing to damp staining beneath the roof slope.

This secondary moisture pathway is significant, as it demonstrates how multiple high-level defects can combine to worsen internal conditions, accelerating plaster failure and increasing the risk of timber decay in concealed areas. Mould has also started to form.

What also does not help here is that this is a traditionally built building, meaning it has no cavity walls, and the underlying brickwork is typically pointed with lime mortar; with these walls, they rely on a certain amount of breathability for the walls to dry. The cement-based render (tested with acid) stops a certain amount of this natural drying process.

Left: The rendered wall and verge. Right: The effects of this damp ingress, damp to the touch, high moisture meter reading and mould growth.

Bathroom damp: traced to defective guttering rather than internal condensation

Damp staining was also noted to the bathroom ceiling. While bathroom moisture is often assumed to be condensation-related, the survey findings point to an external cause.

Drone inspection revealed standing water and debris within the rainwater gutters, along with poor falls and potential joint defects. These defects are positioned directly above the bathroom, making them the most likely source of the ceiling staining observed internally.

This distinction matters. Treating the bathroom internally by redecorating or improving ventilation would not resolve the problem if water continues to overflow or leak from defective gutters during rainfall. The correct sequence is always to address external water management first, then repair internal finishes once the structure has dried.

Structural movement: front bay window brick arch lintel

Failed brick arch requiring urgent repair.

At the front elevation, movement was identified in the segmental brick arch lintel above the bay window. The brick courses are uneven, indicating that the arch has dropped slightly over time.

While the movement observed does not suggest imminent failure, it is structurally significant. A dropped arch can affect load distribution above the opening, promote cracking and water ingress, and lead to progressive deterioration if left untreated.

Remedial works are likely to involve temporary support, careful dismantling and rebuilding of the affected section using compatible materials, ensuring both structural stability and breathability are maintained.

The wider lesson: follow the water

This property is a clear reminder that damp problems rarely originate where they first appear internally. In traditional solid-walled buildings, water ingress from roofs, chimneys and rainwater goods is one of the most common and most misunderstood causes of internal dampness.

Addressing symptoms without understanding sources leads to wasted expenditure and ongoing frustration. A proper building survey allows defects to be traced logically, ensuring repairs are targeted, proportionate and technically appropriate for the building’s age and construction.

What the client said (🌟🌟🌟🌟🌟Google review)

“Being a first-time buyer is daunting. Being a first-time buyer purchasing an old house with many issues is scary. Finding Ricky to carry out our survey was a weight off our minds. If you have Ricky in your corner, you will receive a very reasonably priced and extremely detailed survey. He has been available to talk through the findings, answer questions, and provide excellent advice regarding our older property, knowledge he has clearly gained through many years of experience. Thank you, Ricky.”

Dan, first-time buyer, Scarborough

Thinking of buying a Victorian property?

If you are considering a period home, particularly one that has not been recently refurbished, a detailed building survey is essential. Roofs, chimneys and rainwater goods are high-risk elements, and defects in these areas can have far-reaching consequences throughout the building.

At Skyline Property Surveys, we focus on identifying root causes rather than surface symptoms, so you can make informed decisions before committing.

If you are thinking about having any type of building survey or homebuyer survey carried out in Scarborough, Filey, Bridlington or Driffield, please have a look at our Home Buyers Survey page or give us a call on 01723 671094 for a friendly chat.