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‘Lap en plak’: poor mortar work on roof capping causes roof leaks

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One of the most common problems found by HouseCheck inspectors when checking roofs with concrete tiles is badly installed ridge capping tiles. This common defect is often difficult for the layman to spot from the ground – all the more reason for cautious home buyers to invest in a professional home inspection.

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Unless attended to, damaged mortar joints on ridge capping tiles will result in roof leaks. These important tiles need to be laid on a bed of mortar in order to properly secure and waterproof the ridges of the roof. Because of incorrect building techniques a very common problem found is cracked, loose and missing mortar along the ridge capping.

The root of the problemroof tiles ceramic

The usual cause for this problem is a failure by the roofer to wet the capping tiles before laying – resulting in the mortar drying too fast. This problem is worsened if these tiles are laid on a hot day.

For a neat repair job to cracked ridge capping, the offending tiles should be lifted and properly re-fixed with new mortar. Usually, however, the ridge is simply untidily waterproofed with an acrylic membrane (often called “lap en plak”). This usually results in a permanently unsightly repair to what should have been a neatly tiled roof. A lot of imported acrylic waterproofing used in South Africa is also of poor quality – even a good quality acrylic should be recoated every two years because of the harsh South African sun.

This story was originally published on HouseCheck

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