Flat Roof Deficiencies Check List

Punctures are usually found where blisters have been broken. Rising nails, screws or exterior mistreatment [step on screws left by service man] will also cause punctures.

When flashings are carefully inspected, you will usually be able to find punctures, deterioration, open laps, ridging and blistering.

Flashings and sheet metal

Punctures

Counter-flashing is a piece of metal installed to cover the flexible flashing at the adjoining walls, to protect the top edge of flashing against rain water. Any punctures or lossening of sheet metal may cause water to penetrate the wall.

A clogged roof drain will result water to pond. It will increase the “dead load” weight on roof that may not be engineered to carry that load. Also. ponding water will find its way to flashing seams easily. If temperature is low, water can freeze into these seams.

Drains

Counter-flashing

Sheppard Pearl Waterproofing

Member of GTHBA, CHBA (Since 2004)

Phone: 416-677-0888

Fax: 416-757-0672

E-mail: info@iwaterproofing.ca

Deficiencies cHeck list

On a flat roof, you have to estimate where the leak or damage might be. Water is very tricky, the leakage could come from 10 feet away of the damaged sport. However, common deficiencies which can be visually detected on a flat roof easily.

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Ponding usually caused by the building structural settlement and localize roof failure. The practice of installing tapered insulation is widely employed to correct this deficiency, due to the difficultness to install an extra new drain [eg. compliance plumbing code] to existing structure.

Ridging [wrinkling or buckling] occurs in bituminous roofing, normally found around joints of insulation [or recover board] area. The ridges are normally long and narrow [caused by interior moisture condensation on the underside of the felts].

Fishmouthing happened as a result of the lifting of the laps at the edges of bituminous membrane roofs, or the unglued edges in PVC roofing due to heat welding workmanship deficiency.

Blistering usually happen between layers of felts [felts and substrate] in Build-Up-Roofs (BUR). It is raised contained swelling and feel spongy when step on. The trapped air pocket in between layers of felt causes the upward movement on the felt when temperatures raise in hot summer days. May also separate the felts.

Splitting is the long cracks in the roof membrane. They are usually occurred parallel to felts and insulation joints and may be the result of physical stress, ponding, freezing and thawing, a crack at the substrate or bad workmanship.

Ponding

Blistering

Fishmouting

Ridging

Splitting