Roof Leaks: Understanding and Detection

Roof leaks are a common problem discovered during home inspections. When diagnosing and repairing leaking roofs, home inspections reveal three major issues to consider:
• The roof covering’s condition. Cracked, bent, or dislodged tiles or slates, scratched or corroded roof sheeting, and weathered thatch are examples of this. Any form of roof covering can be rendered ineffective by improper installation. ContractorsIn Roofing & Waterproofing has some nice tips on this.

• The roof’s incline. Most pitched roofs are “weather-proofed,” but only “flat” roofs are water-proofed. This indicates that the roof has been engineered to rapidly shed water in order to prevent rainwater from entering the roof covering. In general, the steeper the roof pitch, the less likely it is that the roof will leak.
• Areas where roof surfaces overlap with walls, chimneys, or other roofs are weak points in terms of possible leaks. These intersections are typically weatherproofed with some sort of “flashing.”
tiling Cracked, broken, or dislodged tiles or slates would be checked by the home inspector. Cracked mortar on ridge or barge capping tiles; lack of mechanical fixing of tiles in weak areas along eaves and ridges; and a roof pitch that is too low are all examples of poor construction techniques that can lead to leaks.

Slates (slates) Slates are usually laid over a water-resistant underlay, which is typically bituminous felt (malthoid). Slates that are damaged or dislodged, as well as a perished underlay, trigger leaks. Corroded nails could also trigger slipping slates if mild steel fixing nails were used instead of copper or aluminum. Slate roof ridges are typically completed with facing ridge slates over a “double soaker,” which is an alternating layer of underlay that runs the length of the ridge. Leaks along the ridges will occur if this double soaker is damaged or perished.
Roof sheeting Corrosion occurs frequently along the overlaps and around the fixing screws on metal roof sheeting. Popular installation errors include too-short end-laps and insufficient side-laps that face the wind. Fibre-cement or plastic roof sheeting that is cracked and weathered may also be an issue.

Thatch is a type of roofing material that is The top layer of grass on a thatched roof that is exposed to the elements eventually rots and must be combed out and replaced on a regular basis to keep the roof’s weatherproof qualities.
Roofs with a semi-flat profile Concrete slabs or board may be used, and they’re usually surrounded by parapet walls. These roofs ought to be well-drained. The top surface of the semi-flat roof needs to be effectively waterproofed – normally with heat-applied torch-on bituminous felt topped with UV ray resistant silver aluminium paint. Leaks may occur if the waterproofing is old or poorly mounted, with insufficient overlaps or poor bonding to the substrate. The torched-on waterproofing must either be patched or removed and reinstalled.

Pitch of the roof Minimum pitch standards for roofs are prescribed by the South African National Building Regulations, depending on the roof covering.
the lights are flashing Where roof surfaces intersect abutments, flashing, normally metal flashing or acrylic membrane waterproofing, is mounted. The flashing is intended to waterproof the roof’s weak spots. Installing metal flashing and counter-flashing correctly is a tradesman’s art that is becoming increasingly rare in South Africa. Modern roofers are increasingly using acrylic membrane to flash roofs. Acrylic membrane flashing is always untidy, but if the acrylic is of good quality and the flashing is recoated every few years, it can be very reliable. If the acrylic flashing isn’t properly maintained, the harsh South African sun will quickly deteriorate it, causing debonding and leaks.

Locating the source of the leak Roof leaks are usually detected from the inside of the home, as damp spots on the roof or walls. Since water tends to flow down the roof timbers until causing a noticeable damp spot, detective work within the roof cavity may be helpful in identifying where the roof is leaking. The best example of where the leak originates is damp staining on the top chords of the roof trusses and sometimes patches of daylight visible through the roof covering.

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