Historical Context and Manufacturing

The Dennis-Wild house, a notable example of system-built properties, emerged in the 1920s as a response to the housing shortage in the UK. Manufactured by James Wild & Co (Housing), these homes were designed to be both cost-effective and quick to construct. The design and construction of these houses were overseen by a team of skilled designers who aimed to create durable and affordable housing solutions. Approximately 10,000 Dennis-Wild houses were built during this period, primarily in urban and suburban areas across the UK.

Identification Characteristics

Dennis-Wild houses are typically two-storey semi-detached or terraced homes. They feature a medium pitch hipped roof covered with tiles or slates. The external walls are constructed of brick up to the first-floor level, with the upper sections rendered in pebbledash or clad with tile or slate hanging. Some variations include a single-storey bay window at the front elevation. The roof structure is supported by a cradle roof truss with iron tie rods, a distinctive feature of this property type.

Construction Details

Substructure

The substructure of Dennis-Wild houses consists of concrete strip footings and concrete pads below the stanchions. The brick underbuilding provides additional support, and a damp-proof course (DPC) is sometimes present, although not always.

Frame

The main frame comprises nine rolled steel joist (RSJ) stanchions, two rolled steel channel (RSC) beams, and one RSJ floor support beam. The frame is further reinforced with two rolled steel angle (RSA) perimeter ties. The steel components are typically coated with a red lead or oxide primer for protection.

External Walls

The external walls are constructed of brick and block cavity walls up to the first-floor level. Timber perimeter beams at the first floor and eaves level are connected by timber studs, which are then clad with tile or slate hanging and lined with blocks. The separating wall between properties is a block cavity wall, providing sound insulation and structural stability.

Partitions

Ground floor partitions are made of brick and block, while the first-floor partitions are constructed of block. This combination provides both strength and fire resistance.

Floors

The ground floor features tongue and groove (T&G) boarding on timber joists, with the kitchen area often having a concrete floor. The first floor also uses T&G boarding on timber joists, providing a consistent and sturdy flooring solution throughout the house.

Ceilings

Ceilings in Dennis-Wild houses are typically made of asbestos cement sheets, a common material used during the period of construction.

Roof

The roof structure consists of timber rafters, purlins, and tiles or slates. The cradle roof truss with iron tie rods provides additional support and stability to the roof.

Typical Hazards and Risks

Corrosion

One of the most significant risks associated with Dennis-Wild houses is the moderate to severe corrosion of RSJ stanchions, particularly at their bases. This corrosion can compromise the structural integrity of the property and may require extensive repairs.

Damp-Proof Course (DPC)

The absence of a DPC in some properties can lead to rising damp, which can cause damage to the brickwork and internal finishes. It is essential to check for the presence and condition of the DPC during an inspection.

Cracking

Vertical cracking of brickwork at stanchion locations and vertical cracking of upper floor render at timber stud locations are common issues. These cracks can indicate movement or settlement in the structure and should be investigated further.

Wall Ties

Insufficient wall ties, failure to bridge wide cavities, and corrosion of wall ties are common problems in Dennis-Wild houses. These issues can lead to bulging or bowing of external walls, which can be a significant structural concern.

Timber Decay

Decay of timber perimeter beams at the first-floor level and bowing of timber purlins and tilting of timber wall plates are typical defects. These issues can affect the stability and safety of the property.

Defective Premises Act

Dennis-Wild houses are not classed as defective under the Defective Premises Act. However, the presence of the typical hazards and risks mentioned above means that potential buyers and investors should exercise caution and conduct thorough inspections before purchasing.

Inspection Guide for Surveyors

When inspecting a Dennis-Wild house, surveyors should pay close attention to the following areas:

RSJ Stanchions

Check for signs of corrosion, particularly at the bases of the stanchions. Use a moisture meter to detect any dampness that could accelerate corrosion.

Damp-Proof Course (DPC)

Inspect the DPC for continuity and effectiveness. Look for signs of rising damp, such as salt deposits or damp patches on the walls.

Cracking

Examine the brickwork and render for vertical cracks, especially at stanchion and timber stud locations. Note the width and length of the cracks and assess whether they indicate structural movement.

Wall Ties

Check the condition and spacing of wall ties. Look for signs of corrosion or failure to bridge wide cavities. Use a borescope to inspect wall ties in cavity walls.

Timber Components

Inspect timber perimeter beams, purlins, and wall plates for signs of decay or bowing. Use a screwdriver or awl to probe the timber for softness, which can indicate rot.

Roof Structure

Examine the cradle roof truss and iron tie rods for signs of corrosion or damage. Check the condition of the timber rafters and purlins.

Asbestos

Asbestos cement sheets are commonly used for ceilings in Dennis-Wild houses. Ensure that any asbestos-containing materials are in good condition and not releasing fibres. If asbestos is damaged, recommend professional removal or encapsulation.

Variants and Modifications

Dennis-Wild houses come in various configurations, with differences in steelwork sizes, protective coatings, and external finishes. Some properties may have RSAs as corner stanchions, stanchions encased in concrete, or no protective coatings on the stanchions. External walls may be finished with facing brick to the eaves level or rendered (pebbledash) block at the first-floor level. Single-storey bay windows and brick-on-edge external wall inner leaf partitions are also common variations.

Maintenance and Repair

Corrosion Treatment

Addressing corrosion in RSJ stanchions is crucial for maintaining the structural integrity of Dennis-Wild houses. Treatment options include cleaning and recoating the steel with a protective primer or replacing severely corroded sections.

Damp-Proof Course (DPC) Installation

If a DPC is absent or ineffective, consider installing a new chemical DPC to prevent rising damp. This process involves injecting a damp-proofing solution into the walls to create a barrier against moisture.

Crack Repair

Repairing cracks in brickwork and render is essential to prevent further deterioration. Use flexible fillers for minor cracks and structural repair methods, such as helical bars or resin injection, for more significant cracks.

Wall Tie Replacement

Replacing corroded or insufficient wall ties can prevent bulging or bowing of external walls. Stainless steel wall ties are a durable and long-lasting option.

Timber Treatment

Treating decayed timber components with preservative solutions can extend their lifespan. In cases of severe decay, replacing the affected timber may be necessary.

Asbestos Management

Managing asbestos-containing materials involves regular inspections to ensure they remain in good condition. If asbestos is damaged, professional removal or encapsulation is recommended to prevent exposure to harmful fibres.

Conclusion

The Dennis-Wild house represents a significant chapter in the history of UK housing, offering a unique blend of affordability and durability. However, potential buyers and investors must be aware of the typical hazards and risks associated with these properties. Conducting thorough inspections and addressing any identified issues promptly can ensure the long-term safety and stability of Dennis-Wild houses.

At Flettons, we’re committed to safeguarding your investment. When considering a property purchase, trust our seasoned expertise to reveal any hidden threats. For a thorough building survey, get your instant quote through our quote calculator or reach out directly at 0203 691 0451. Your home’s safety is our top priority.

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