It is unfortunately too often that I see things on a roof that puzzle me. I shake my head and think, “Didn’t he know this would happen?”. Of course I’m talking about a roof leak and the bad workmanship that leads to it. In the case I found in South Vancouver today it was clear what was happening. A shingle roofer (and maybe he doesn’t deserve the title of “roofer”) had installed a zinc strip up the backside of an attic space roof vent and created a negative slope in the process. Any water on the zinc strip would thus roll back “up-slope” and get into the vent at the top of the flange. DUH! Now I’ve figured it out a while ago that there is good and bad in all professions. I have VERY few customers and co-workers, over decades of roofing, who would put me in the latter category. Granted a roof is a very important aspect of a house. Everything below it depends on the integrity of it. But let’s think about more important occupations than a roofer where you want to ensure you get the best-at-his-job out there. For the Sickly? – Surgeon. I want to make sure there are no mistakes happening when they have my body exposed on an operating table. For the troubled? – Lawyer. For the bad driver? – Paramedic. But how do you know? How do you tell? You solicit friends. That’s a good place to start. And here’s a friend telling you – Crucial is the roofer you want.
There are two main categories of roofing. Low slope and steep slope. Low slope is anything that has a pitch of 4/12 or less and Steep slope is everything above that. Slope or pitch is usually noted in a fraction of twelve. Twelve is used as it relates to the old school measurement of 12 inches. Slope is based on rise compared to run. Rise is how vertical the roof climbs and run is the horizontal distance on an equal plane to the flat ground. So a slope of 4/12 means the roof rises 4” on a horizontal distance of 12 inches (or one foot). So if I may jump ahead and offer this example, a pitch of 12/12 would be a 45 degree angle. This is not a pitch someone can walk on without any form of help or fall protection gear.
The general rule of thumb for usage of roof systems is that everything above 4/12 gets shingled with asphalt, cedar, concrete, clay, metal or composite shingles. Anything below 4/12 should get roofed using a membrane system such as SBS torch on, EPDM rubber, TPO, PVC and the quickly disappearing tar and gravel roof systems. Shingles depend on positive watershed and are not entirely self-sealing. They rely on overlap and gravity. A membrane roof is equivalent to enveloping and is a continuous membrane system with no weaknesses. I have waterproofed planters in torch on membrane and they are continuously holding water.
Now shingle manufacturer’s want us to buy more of their product so they say we can put shingles on roofs that have as low a slope as 2 or 2.5/12. They have their low slope requirements and necessitate changes to the roof system other than what would be done on a 4/12 or greater roof. I have seen it done and it has worked. I exclusively use a GAF-Elk shingle because they are so well self-sealing and become almost membrane like once they have had the heat of the sun to activate the patented Dura-grip adhesive on the back of each shingle.
The steeper the slope/pitch of the roof the less water is going to adhere to the surface and erode the waterproofing material. Therefore it goes to say that a flat roof requires a qualitative waterproofing system as it may hold a large quantity of ponding water for extended durations, depending on the effectiveness of the drain placements. Flat roofs commonly settle over time also (or sag in the middle of the roof area where the structural support is at the least) and when the rigid drain, supported by cast iron plumbing pipes, doesn’t move it results in excessive standing water as the drain is now “high”.
The attached photo shows an interlock shingle application on a low slope roof in which the contractor should have chosen a membrane roofing system. Trust Crucial Roof Services to choose and install your low slope roof system. Roof system selection and integrity thereof is of primary regard in all our roofs installed resulting in absolute customer satisfaction and continued referral business.
The most common asphalt shingle roof leak happening today has to do with T-lock or Interlocking shingles. These are also known as duroid shingles and should not be confused with a metal shingle made by Interlock. Back to the leak issue: Of course, as previously blogged, leaks commonly happen where there is a protrusion or change in direction of the roof plane. However with these T-lock shingles, leaks can show up anywhere. First let’s get a history of this shingle. No longer in production today, this organic shingle was originally sold promoting the feature of wind uplift resistance. It’s my understanding that these shingles were sold with a 20-25 year life expectancy but current evidence details that most roofs in Vancouver and the Lower Mainland area are not achieving that extent. Technically, the unique design of this shingle allows for water to get in behind a corner of the shingle but escape out from underneath, lower down on the shingle. This critical water-entry point is where the tabs or T-Locks interlock with the below fastened shingle. This is all fine and dandy while the shingle is lying flat but as this ORGANIC shingle ages, it becomes dry and curls. It is at that age point the shingle systemically fails. Because of the curling, water will begin to travel sideways…which is never a good idea on shingle roofs…and leaks become inevitable. Because this shingle is no longer in production and extremely rare in ability to acquire, (I found some guy in Richmond BC selling bundles that used to cost $20 for $100 on the internet) roofers are left to try and stop the leak with our magic muck called mastic. BUT, unless the repairing roofer is aware of the “unique” feature of water entry and exit on this shingle design, he could potentially cause more problems than benefit by applying the mastic at the exit point and actually trapping the water under the shingle. If you have a shingle roof leak and want the best in service, contact Crucial Roof Services where “Your Satisfaction Is Crucial”.