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Finlock Gutters

Updated: Nov 24, 2023

Finlock gutters were introduced between 1950 and 1970 to replace cast iron gutters and there were several different styles introduced. They are constructed of precast concrete units embedded on the top of the walls and across the cavity. The top of the unit is then lined with bitumen or similar material to provide a waterproof guttering system. They are renowned for causing problems where the gutters leak and cause significant dampness to the wall below. Also, the joints between the precast concrete units can fail and allow dampness into the building. A thermal break is also caused where the concrete units bridge the cavity wall, which can cause condensation problems within the loft and to the top of the walls at first floor level internally.

This concrete guttering system can sometimes act as lintels above window openings. If the Finlock guttering system is poorly installed or replacement windows are not installed correctly they can sag, which can put pressure on the window frames and prevent them from opening.

There are numerous companies that have sprung up over the years that specialise in their repair or removal.

Author: Tony Waring is a Chartered Building Engineer (C.Build E MCAB), an Associate of the Royal Institute of Chartered Surveyors (AssocRICS) and a member of the Faculty of Party Wall Surveyors (MFPWS).  He has over 30 years of surveying experience and 20 years as an engineer.

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