If you live in an older UK property you may be familiar with Finlock concrete gutters. These gutters were popular during the 1960s, especially in post-war housing. While they were innovative at the time, many homeowners now face issues with these gutters. This blog will explore what Finlock concrete gutters are, their advantages and disadvantages, and the options available for repair or replacement.

Finlock Concrete Gutters is a concrete guttering system designed as durable and robust alternatives to traditional metal gutters, which were in short supply after World War 2. Made from precast concrete, an integral part of the property’s structure, often doubling as lintels above windows and doors. They’re built from two troughs that are horizontally positioned and sit at the head of a cavity wall.

Advantages of Finlock Concrete Gutters-

  • Durability: concrete is a strong material and is resistant to weathering action, chemical attack, abrasion, and other conditions of service.
  • Cost-Effective: during the post-war period concrete was more readily available and affordable compared to metal
  • Dual purpose: gutters also serve as structural components that provide support as lintels.

Common problems with Finlock concrete gutters-

Despite their initial popularity, Finlock concrete gutters have several problems that have become apparent over time, these problems include.

  • Water ingress: is when water from the outside makes its way into the building. Concrete is porous which can lead to absorption. Over time this can cause internal dampness and mould issues.
  • Thermal Bridging: weak points in the building envelope allow heat to pass through more easily. Concrete has poor thermal insulation properties, which can result in heat loss and condensation problems inside the property.
  • Cracking and Spalling: concrete can crack and deteriorate, especially with freeze-thaw cycles which then lead to leaks and further damage.
  • Complex repairs: they are integrated into the structure of the building, repairing, or replacing Finlock gutters can be more complex and costly than standard gutter systems.
  • Sagging and Uneven Gutters: Finlock gutters also function as lintels for doors and windows. However, they can sag slightly if not adequately filled or strengthened during installation. Sagging can also occur due to poorly replaced windows, making them difficult to open or close.


    Typical elevation


    Empty reinforcement trough when viewed from inside the property when the unit is positioned over a wall.

    Concrete-filled trough unit acts as lintel

Repair and Replacement options-

If you have a Finlock concrete gutter and are experiencing some problems, there are several options you can pick to repair or replace it.

1.     Repairing Finelock gutters:

·      Sealants and linings: applying waterproof sealants or installing gutter linings can help address leaks and water ingress. This is a relatively affordable short-term solution but may require ongoing maintenance.

·      Sectional repairs: involves the repair of an isolated defect within the gutter. Damaged sections of the gutter can be repaired with concrete patching or by replacing individual blocks. This can be labour-intensive and might not solve issues like thermal bridging.  The availability of a replacement section may be problematic.

2.     Replacing Finlock gutters:

·      Full replacement: Removing finlock gutters and installing a modern gutter system is a comprehensive solution. This involves significant work, including modifying the roofline and installing new fascia boards and gutters.

·      Overcladding: installing a new gutter system over the existing Finlock gutters is another option. This method can be more efficient without extensive structural changes.

·      One method that’s sometimes used is to cut off the gutter projection leaving the main section over the wall, but this does not eliminate the issue with cold bridging.

Choosing the right solution is important when deciding whether to repair or replace depends on several factors like the extent of damage. Assessing how severe the problems are. Minor leaks could be fixed with sealants, while extensive cracking may have to be replaced. Considering the cost of both short-term repair and long-term solutions, repairs may be cheaper, but replacement could save money over time. Thinking about your future with the property is crucial because if you plan to sell, potential buyers might be put off by ongoing issues, so replacement is often a better option.

Although Finlock concrete gutters were a practical solution in those times they now can be an annoyance for homeowners today. Understanding the issue and knowing your options for repair or replacement is crucial to maintaining the property’s integrity and value.