Inspecting a flat roof

A flat roof doesn’t give up its secrets easily. To get a good look at it and inspect its condition, you have only one option, and that’s to move to a high vantage point – afforded by a ladder or a taller nearby building that overlooks your roof. Otherwise, it’s easy to forget about it – until the day it falls in on the heads of the people it’s meant to protect!
Any wise homeowner can prevent that nightmare scenario by conducting, as recommended, a preventive inspection of the roof covering at least twice a year: in the autumn, after the leaves have fallen, and in spring, once the snow melts. By inspecting regularly, you improve the odds of detecting anomalies early (and the damaging, costly water infiltrations that can result), and in turn you maximize your roof’s lifespan.

Since you probably don’t have a periscope…
Many homeowners have never been up on the roof of their house: they handle its maintenance blindly. Wouldn’t you rather get a look at the situation by yourself before giving specialists the green light for any work that may need to be done?
While there is no match for the trained eye of a professional roofer, the most common symptoms of roof problems can be easily spotted by a well-informed owner or a general building maintenance specialist. If you ask someone you trust to do the climbing for you, have that person take a camera. The pictures will be worth the proverbial thousand words…

Roof should be clean and dry
The same procedure for a flat roof inspection applies whether you have a traditional built-up roof covered in asphalt and gravel or a newer elastomeric-membrane roof.
The first step is to clean the roof surface: remove any debris that may be lying on the roof or blocking the drain and its strainer basket. Incidentally, if the basket shows any sign of deterioration, it must be replaced.
The best time to inspect is 48 hours after an abundant rainfall. This makes assessing the condition of the roof structure easier: under normal drying conditions, there should be no puddles left anywhere on the roof after 48 hours. If water is still apparent, it could mean the roof is sagging or that the drain is either too high or blocked. If this is the case, you should immediately call in a roofer to prevent degradation of the covering.

Something doesn’t look right? Leave it alone!
You should also call a professional immediately if inspection reveals any membrane deformation or alteration: waviness, blistering, shrinkage of the felt, fabric or mat plies, or membrane joints coming unglued. The roofer will determine what corrective action to take.
The Association des maîtres couvreurs du Québec states that during a new roof covering’s warranty period, any modification, repair, addition or other intervention on the roof covering must be performed with prior notice to, and authorization from the roofing contractor.

Inspecting the cap sheet
Next on the inspection list is the membrane cap sheet. Every membrane, whether built-up or elastomeric, must have a gravel- or granule-surfaced cap sheet, designed to repel damaging ultraviolet radiation. Wind, running water and foot traffic on the roof covering are factors that can cause the protective gravel to shift or granular covering to be lost, laying bare some areas of the membrane. Adding gravel is a fairly simple operation, but if new granules must be bonded to an elastomeric membrane, the job will definitely have to be done by a roofer.
You must also inspect the condition of the flashing, the strips of steel or aluminum that run around the roof edge and weatherproof the base of projecting elements (chimneys, vents, skylights, etc.). Check to see whether they are still firmly attached. Has rust affected them – or worse, penetrated them? Is the caulking cracked or detached? A nail or a screw may seem like a trivial repair, but can be crucial in a rainstorm with strong gusts of wind.

After you check the flashing, examine the chimney. Check that it is stable and, in the case of a masonry chimney, check the condition of the mortar joints.

Finally, examine the roof vents. If they move as a result of the slightest push, their structure or anchorage will have to be corrected.

Rule number one: safety
This inspection tour is meant as a preventive measure, but you should exercise plenty of prevention when you go about it as well! You don’t climb a ladder without taking precautions, and walking on a roof isn’t a walk in the park.
If you have a fear of heights, you’re better off entrusting the work to a professional. Otherwise, if you want to do it yourself, be sure to take the following basic precautions:

– The right clothing is a must: make sure your feet fit snugly in your shoes. Sandals are an absolute no-no. Also, make sure you don’t wear loose-fitting clothing that could catch on anything.
– It’s best to have a helper on the ground when you climb a ladder. This person can hold the ladder steady and act quickly in an emergency. If you do work alone, be sure to secure the ladder at the top – you don’t want to be stuck on the roof if the ladder is blown down by a gust of wind.
– Never leave a raised ladder unattended. A child could try to climb it and be injured.
– The ladder should extend at least three feet (900 mm) past the roofline. Keep your body centred between the ladder rails and always follow the “three point rule”: always have three points of contact on the rungs (two hands and one foot, or two feet and one hand). It’s not a good idea to climb while carrying materials. Besides, don’t reach too far to one side: climb down and reposition the ladder instead.
– Concentration is essential when moving around on a roof. Remember, a roof has a beginning… and an end. You should keep this uppermost in mind. And always be aware of the very real danger posed by electrical equipment.