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What Materials Make Up Your Roof?

The roof is a part of your home that you think very little about, but it protects everything you own. Milholland Solar, Electric & Roofing describes the materials that make up your roof and how it functions.

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Sean: The roof is a part of your home that you think very little about, but it protects everything you own. Brian Milholland from Milholland Roofing is here. Brian, today we’re going to walk through the elements of a roof and what really composes a roof. Let’s start with the base. What’s the lowest foundation level of the roof? 

Brian: Well, the lowest is the decking, which is like this table, and it helps to support everything.

Sean: So that would be basically plywood? 

Brian: Right, plywood. 

Sean: Okay. And that’s to put on the joist, and that’s what forms the foundation. What’s the next layer upon the roof? 

Brian: So to protect the plywood and to protect your home we have an underlayment. So we have a synthetic type underlayment and then we have the traditional, you know, felt underlayment. 

Sean: So those are rolled out and covers all the area of the plywood beneath?

Brian: Right. 

Sean: And is it nailed down? How is that put down? 

Brian: They are nailed down. There are some that are peel and stick that they use primarily in areas where there’s a lot of ice damming. But, in Southern California, we primarily use nailed down. 

Sean: Then we come to the flashing, the metal portion. Define the flash for us, what do they use? 

Brian: So flashings help to divert water away from objects that are sticking through the roof, or the walls, the roof to walls, so we use the flashing to help the water go on top of the underlayment. And then end up on top of the overlayment. 

Sean: So it’s just another layer of protection protecting the underlayment. 

Brian: Right, so this helps to seal any of those small crevices where water can get into there. 

Sean: And next is the part that everybody sees and thinks of it as the roof which is the overlayment. What is it? 

Brian: Overlayment, typically it’s concrete tile, clay tile, or asphalt shingles. And this helps, it allows the water to be diverted down. These are usually the, you know, the real hefty type materials, they last a long time. And it’s designed to have the water flow on top of these and so it’s more difficult for water to erode it away.

Sean: Now the underlayment is the real water protection layer and that’s what tends to go bad, not the tile. The tile can have some abuse, but the underlayment, that’s what wears out. 

Brian: Yeah, through heat over time this underlayment starts to break down and will crack. So we want to make sure that, you know, you have your roof inspected to make sure there’s no gaps in the roofing material, to allow the water underneath it. ‘Cause the water gets underneath the roofing material, it’ll still run off due to the underlayment, but it’ll erode that underlayment and wear it out a lot faster. 

Sean: And getting a roof inspection, that is the critical thing you have to get a roof inspection. And if you don’t know the last time you got one, you need to get one right away, at least every two years.