Have you ever seen a flat shingle roof? Probably not – and if you have, then you have seen one of the most disastrously ill-advised roofs on the face of the planet.
You don’t need a Harvard degree in roofing to appreciate why a shingle roof has to be slanted. Shingles are waterproof, but they do not create a seamless waterproof surface. There are gaps between them. If a shingle roof isn’t slanted – or isn’t sufficiently slanted – then water that falls on it doesn’t have enough potential energy to flow down to the ground. Instead it remains on the roof where it takes a less desirable path of least resistance: between the tiny gaps separating the shingles.
When a shingle roof isn’t slopey enough, water will permeate it and proceed to do all the horrible things water does inside a house: stain ceilings, damage drywall, rot framing, and sustain black mold.
What Is the Minimum Pitch for a Shingle Roof?
First, let’s explain how a roof’s pitch (i.e. slopeyness) is measured. It’s expressed as either a ratio (X:Y) or as a fraction (X/Y), but it means the same thing either way. X is the number of units the roof rises vertically; Y is the number of units the roof extends horizontally, and is virtually always 12 (at least as far as residential roofing is concerned). A roof with a pitch of 2/12 therefore rises 2″ for every 12″ it runs outward.
Incidentally, 2/12 is the absolute bare minimum pitch for a shingle roof. Atlas Roofing qualifies a roof pitch of 2/12 to 4/14 as “low slope.” As a Platinum Elite Installer for Atlas Roofing, we defer to their expertise on the matter.
A low slope roof may prove adequate for homes in drier climates. Minnesota does not occupy such a climate, which is why we advise a slightly higher minimum pitch for a residential roof: 35°, which comes out to an unwieldy 4.2/12 when expressed as a fraction.
Our recommended minimum pitch is pretty close to the 4/12 most roofing contractors consider standard, but we have noticed that the slightly steeper angle of a 4.2/12 roof is worth it. It helps the roof shed rainwater and meltwater just a little more freely, which reduces our customers’ risk of leaking and seepage.
What Are the Advantages of Choosing a Higher Roof Pitch?
We only offer 4.2/12 as the minimum acceptable roof pitch. With higher roof pitches come several benefits, including:
- Better water drainage, which further reduces the risk of leaks and pooling
- Greater durability, as a steeper slope prevails better against strong winds and heavy snowfall
- Longer lifespan, which goes hand in hand with greater durability
- More attic space, which is nice if you have a lot of Christmas decorations you need to keep out of the way until the fourth Friday of November
- Better ventilation, which can help to increase energy efficiency
Here’s One More Pitch Before You Go
We’d like to pitch our roofing services, if we may. If you live in the greater St Cloud, Little Falls, Alexandria or Brainerd, MN area, then we welcome you to contact Exterior Pro today for a free estimate on shingle roof installation, repair or replacement. We use the best materials. We employ the best people. We’re locally owned, and we’re standing by to make everything flow smoothly – especially when it comes to water that lands on your roof.