Video: Basic Roof Features

shed, ridge, gable, rake, hip, peak, eave, gutter, fascia, soffit, rafter tails, sub-roofing: felt/tarpaper underlayment, membrane (pitch below 3 and 12 — explain roof pitch terminology), decking, skylight, , plumbing vents w/ neoprene collar, attic vents several types, chimney – stack, flue/liner, cap, damper, spark arrester, weather cap,
Can’t tell a rake from a ridge? Hi. This is Nathan Harrison for Let’s nail down some basic terminology on roofs.

When you take a flat surface and tilt it up at an angle, the rainwater sheds off of it. So this flat part of the roof is a shed. At the top we have the ridge. This area created by the ends of the shed roof, is called the gable. The sloped overhangs of the gable, are known as the rake.

If a house does not have a gable, then it sheds water in all directions and must have hips which are the places where the different sheds meet each other at a downward sloping angle. It may have a short ridge at the top or simply a peak.

The edges of the roof shown in red are know as the eave. That’s where we put the gutter. At the eave, we may find a facia with a border on it, as here, or rafter tails exposed, as we see here.

Beneath the shingles on a typical roof is an underlayment that is known as felt. I’m pretty sure it’s just tarpaper. By the way, there’s acturally some significant disagreement about whether this stuff actually helps. If the roof is not steep enough, then rather than just have felt overlap to allow water to shed, you actually would need to go with a membrane underlayment. The membrane works on the concept of sealing/waterproofing the roof because wind would be able to blow water up the roof, creating a situation of essentially standing water on a shallow, not-so-steep roof. And so that’s where the membrane comes in.

The terminology I just used to refer to the steepness of the roof was 3 and 12, and that is the limit for underlayment whrere you have to go to membrane if it gets lower than that. For example, 2 and 12 or 1 and 12 would be less steep than 3 and 12. Here’s what that means.

In 12 inches of horizontal travel, if the roof rises 3 inches up, that’s the 3 and 12. This roof is probably more like a 6 and 12. Maybe steeper than that, maybe is an 8 and 12. If you get to 12 and 12, that’s a roof that is at a 45 degree angle; it rises just as much as it runs.

A very sttep A-frame type cabin may have a roof pitch of 24 adn 12 or 36 and 12 – where it gets so steep there’s no way you could stay on it. It’s more like a wall than like a slope.

Beneath the underlayment of a roof is the decking. Roofs made before the 1060s would have of boards that are 3/4 inch thick running this way. Roofs coming after that would have 4′ by 8′ sheets of plywood or, more recently, OSB, like that, joinging the rafters together and providing a solid surface to put the shingles onto.

Other things typically seen on a roof are a skylight, the very important vent for your plumbing system, which would be sealed tight by a neopryne collar here; various types of attic vents to keep the attic cool and dry. The most popluar method of venting an attic right now is a ridge vent like this, which allows air to escape all along the ridge of a roof.

Last but not least, we have the chimney. The main body of a chimney is known as the stack. It has an interior tube made of a heat-resistent clay material known as the liner for hte flue. The flue being the air passage inside of the liner.

Then at the top of the chimney, we have a cap that’s designed to shed rainwater off and obviously to block off the rest of the cavity around the liner.

On top of the opening in the liner is the weather cap. Typically there will be a screen around the exist for hte gases that serves as a spark arrester. And if there was a flap inside the top of the liner, that would be a damper. The damper could be located here or down where the fireplace is…or better yet, both.