The 1960s through 1980s was the era of concrete interlocking tiles in UK house building. They were cheap, fast to lay, and required no specialist skill to install. They were also made with a surface coating over a concrete body — and that surface coating has a finite life.

What Concrete Tile Deterioration Looks Like

Two main mechanisms: surface aggregate loss (the exposed coating weathers and erodes, leaving a more porous concrete surface) and delamination (the surface layer separates from the concrete body). On a Maidstone estate property built in 1968, both are typically visible on inspection — the question is how far they've progressed.

The Scale of the Problem in Maidstone

Maidstone's largest post-war estates were built between 1955 and 1980. Penenden Heath from the mid-1950s; Park Wood and Shepway in the 1960s; Larkfield and Coxheath in the late 1960s–70s. A very large number of properties are simultaneously reaching the same stage of deterioration — we currently carry out more full re-roof jobs on these estates than in any other category across our coverage area.

The Repair vs Replace Threshold

For concrete tile roofs: if surface deterioration affects more than 20–25% of the roof area, replacement is more cost-effective than continued repair. Scattered nail sickness affecting more than 15% of the roof also tips the balance towards replacement. Below these thresholds, targeted tile replacement and ridge repointing can extend life by 5–10 years.

What Replacement Costs

A standard 3-bed semi on Penenden Heath or Park Wood — approximately 65–75 square metres — costs £5,500–£8,500 for a full re-roof in modern concrete interlocking tiles with breathable underlay, all scaffold included. Upgrading to clay interlocking tiles adds approximately £1,500–£2,500 but significantly extends service life.

For a free survey, call 0162 229 6232. See also our Penenden Heath and Park Wood pages.