Denali Exteriors

Most common roofing questions

Looking for answers to roofing questions? Here's an FAQ list for roofing.

Roof Slope – What it is and how to measure it

Every roofer will tell you that a big part of the price for your roofing estimate comes from the degree of slope. If you’re not sure what that means, it’s the basically how diagonal your roof is.

So, how do you measure roof slope? If you know what you’re doing and are doing it safely, you can get a 12” level and put one end on the roof, while making it level (so one end is touching the roof, and the other end is in the air). With your tape measure, find how many inches there are from the end of the level in the air to the roof. This is the slope, which is sometimes referred to as pitch.

So, if you get 6 inches between your roof and the level, your roof is 6/12 slope. Likewise, if you get 4 inches, your roof has a slope of 4/12.

measure pitch slope

How does slope affect the cost of a roof?

The greater the slope, the more material necessary to install the roof. If you want to figure out the square feet of roof to be covered, use this formula:

Slope * Area of roof (L X W) = Square Feet of Roof to be covered

How do I know if I need to replace my shingles?

Just like everything else, shingles age and get worn down. A lot of times, it’s hard to tell exactly when you should replace your shingles.

Roofers will commonly say that it’s time to replace the shingles if there’s water getting in. If not, you’re still good. However, that is for the functionality, not the aesthetics. Even though they still may be keeping the water out, there’s a good chance that they just don’t look good, and that’s a problem if you live in an area where upkeep is expected, or if you are trying to sell your home.

UV rays from the sun affect shingles, whether they are organic based, or glass based. The asphalt coating begins to dry, which loosens the granules, essentially wearing down it’s protective cover.

If you see that some shingles are torn or the corners are starting to curl, you might be getting close to having to replace your roof. Another sign is cracks down the center of the shingle.

Why are my shingles curling at the corners?

Just because your shingles are curling at the corners, it doesn’t necessarily mean it’s time to replace your roof. But then again, it could be a very good sign that your roof needs replacing.

Referred to as curling, it’s usually caused by too much moisture on the underside of the shingle. Poor ventilation causes heat and moisture to become trapped in the attic. Eventually, the heat and moisture will penetrate the roof deck, which in turn causes the shingles to curl.

One solution to this problem is to improve the air circulation in your attic, which will help reduce or eliminate the curling progress.

Why do my shingles only curl in the winter?

When your shingles only curl in the winter and go back to flat in the summer, this is called winter curling. This happens more so when the winter conditions are damp and frost forms on the shingle surface. The frost causes the shingles to contract on the surface, while the underneath part of the shingle is exposed to passive heat from the attic. This ‘push and pull’ effect causes the shingles to curl.

Why do some roofs have black streaks and what are they?

We’ve all seen a roof with a black streak running down it, and it’s not a pleasant sight. The black streaks usually happen on lighter-coloured roofs that are North-facing and more than five years old.

A common misconception is that the discolouration is caused by granule loss, dirt or moss. This is inaccurate. The black streaks are actually caused by algae growth.

Areas of the roof that receive less sunlight, in addition to a higher level of moisture, are more prone to black streak. While not a threat to the functionality of your shingles, this discolouration definitely is an eyesore. You can try to clean it as best you can, but please note that it will probably just grow back.

Why do my shingles look wavy?

Probably one of the most anxiety-producing things as a homeowner is looking at your roof and seeing that your shingles are wavy or humpy. If you’re not familiar with roofing, you may start to panic. But, we’ll go over some of the more common causes of buckling shingles.

  • Improper nailing: nails may pop up, which in turn creates the buckling effect.
  • Your shingles are nailed too tightly together.
  • Deck/felt movement: More often caused by moisture levels beneath the shingles. The shift in movement causes the nails to move with it, which forces the shingles closer together or further apart.
  • Decking is too thin: Thin decking, usually 3/8”, over 24” centers can cause the clips that were designed to hold the decking in place to come off or become loose.

How do I fix roof buckling?

Depending on your specific situation, the answer could vary.

Here are some solutions to fixing your wavy roof:

  • Improve the attic ventilation
  • Eliminate excess humidity
  • Remove fasteners and refasten
  • Replacing distorted shingles

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