Roof parapets

If roofs cannot be seen from street level, then the chances are they may well be hidden behind parapet walls. Parapet walls are a low wall that extend above the junction of the roof and the building facade.

Such will often incorporate and hide the dreaded valley gutter, some of which are square shaped and then as box section gutters. These hidden gutters are found at the low point where two adjacent roof slopes meet and are usually a design feature of London Butterfly roofs. It is especially important to maintain them in good condition and ensure they are kept clear at all times as any leakage is likely to let water into a building and over the bedroom ceilings below.

Parapet gutters, as the name suggests, run directly behind a raised parapet wall and then sometimes discharge water via internal gutter channels through the floors, allowing the rainwater to reach a downpipe.

Parapets may have coping stones (see photo) but sometimes feature without. Such are commonly found on attached garages. Rainwater percolation over the years coupled with a lack of a decent damp proof course or the breakdown of such is often characterized by dark staining to the top courses of brickwork. In time, this can percolate to an extent to affect any timber lintel installed over an up and over garage door, often characterized by an external sag or in the worse case scenario, by obvious dampness and rot within the lintel.

Often the only way to address such a defect is to take down the parapet wall brick by brick, reinstate a new catnic lintel incorporating an appropriate coping stone finish.

Often high level parapets such as those that front a Butterfly roof are rendered. Crazing of the render is often seen due to the effects of moisture and direct sunlight. Such can be causing unseen damage to the brickwork, with the true effect only really being seen across the front of the bedroom below at ceiling level.

Again, repairs can become costly if such necessitates working at height in order to hack off the render and make good any defective brickwork behind and incorporate a new damp proof course before re-rendering and often reinstating a new flashing at the abutment with the roof slopes behind.

If you are concerned about the condition of a parapet wall, contact Woodward Chartered Surveyors in Herts, Middlesex and London to arrange for an inspection.

James Bush MRICS is a Chartered Surveyor and Director of Woodward Chartered Surveyors with 29 years experience as a Chartered Surveyor.

Woodward Chartered Surveyors cover an area from East of Oxford, High Wycombe, Beaconsfield, Amersham, Berkhamsted, Watford, Rickmansworth and into London, Northwood, Uxbridge, Harrow, Ealing and Mayfair.