Finlock concrete gutters were very popular back in the sixties  – we come across them every now and then when we survey for cavity wall insulation problems and rarely, if ever, are they found in good working order.

The gutter system is usually known as Finlock. The system comprises an integrated concrete gutter, lintel and eaves product that is fitted in sections. Typically the concrete gutter sections are 200mm to 250mm in width and this incorporates a cavity closure at their head.

The Finlock gutters are fitted to the top of the cavity and the outer face of the wall forming the gutter. A waterproof coating or lining should be applied within the gutter trough before cavity wall insulation is installed. However in many cases this has been overlooked, resulting in issues damage within the cavity wall – normally to the cavity wall insulation.

Problems with Finlock gutters and cavity wall insulation

Having an inadequate number of outlets can cause flooding and leakage. Gutters have often been badly lined or sealed with an asphalt or similar liquid applied product – older repairs very often not only fail but worsen the problems as the finish can be crude and uneven.

Gutters are generally laid level and are consequently extremely liable to blockage and flooding. Over time the sections settle and become misaligned making this situation worse.  As these sections settle, the joints open up and can start to leak within the cavity wall, causing the insulation to become wet.  This leakage can become apparent on the inside of the building with ingress water damage showing. Condensation and dampness become evident internally, typically to the upper 800mm of the wall.

If you have these concrete Finlock gutters in your home and are suffering from damp, please call Extraction4Homes on 0208 8199152 to see if we can help.