Install Flashing Metal Roof

Hi, I'm Tim Carter, askthebuilder.com. Have you ever wondered how to put in a plumbing vent

flashing or maybe a B vent flashing in a metal roof and want to know how the old-time roofers

did it when they didn't have caulk? Because caulk is not a proper roof material. Caulk is always

going to fail, so don't even think about using caulk. Right, well guess what? I'm going to show

you how to do it right now, but I'm going to do it with some old file folders. Let's get started

This piece of red paper, you know, is just a file folder and it represents, you know, a piece of the

metal roofing. And I don't care what kind of metal roofing you have. It doesn't matter

And up here is the top of the roof. So in other words, you know, it would be sloping, you know

down like this. This would be the direction that the water would travel. Okay, so here's what I've

done. Here I made up out of just another piece of yellow file folder and a paper cup. This is a

flashing that you might use that could be, you know, like a plumbing bed flashing. And this

cup represents the raised part of the flashing that is always humped up above the flat piece of

metal. So what's going to happen is, what has to happen is, you can see I drew a pencil mark here

that represents the halfway mark, and this half of the flashing, in other words, the uphill part

of the flashing, has got to slide underneath this part of the metal roof. Now how do we do that

So you can use all kinds of mathematics. You have to figure out what this diameter is, and you cut

a, you know, you're going to have to cut a semicircle out of the metal roof, and you actually

have to cut some here to get the pipe up through, but I don't need to do that for this demonstration

But the point is we have to make two cuts We have to make a slit in the metal roof here and you can do that with a very very sharp one inch wood chisel and you have to cut out this so that the metal roof fits around

that humped up part of whatever the flashing might be it could be a flashing for a plumbing

vent pipe it could be a flashing for a furnace it could be a fresh air vent it doesn't matter

so what you have to do is here's the most important cut

the cut in the metal roof the width of this metal cut must be exactly what the width of the flashing

is it could maybe be at most a sixteenth of an inch wider because you need to be able to slide

it in. You can't have this cut in the metal roof any wider than the flashing. So, I'm going to go

ahead and make that cut right now. Make the two cuts and you'll see what happens. You're not going

to believe how simple this is. Watch. So, I'm going to put, you know, a piece of cardboard here so that

can... but here what we have to do first, really important, we need to put our... I did some

orientation marks, so I happen to know that this, where I have the yellow flashing right now

it is centered where that big cut's going to be. So all I need to do is I've already made a pencil

mark over here so I know where to start the cut, and I need to know here, over here, where

to stop the cut. So I'm going to make a pencil mark right here. I've got a pencil mark here

I know I'm kind of blocking it. So now I need to make a cut from here to here

and we need to cut this circle out. Let's do it. I just using a razor knife since I got you know paper I dealing with You wouldn be able to use this razor knife you know for goodness sakes up on a metal roof but i just doing this

you know for my demonstration for you all right now we just have to cut this out

All right

This comes out. I'll get this out of the way of the box

And you can see we've got that cut. And you can see, I can flip that up, I can flip my hand under here

Imagine this is the metal roof, you know, and then here's your flashing

And so all you have to do is start to slide it underneath the metal roof like this and

slide it up and it's that simple. And that's all it looks like when it's done

You know, in other words, the water flows down, hits here, and then continues on down the roof

You want to make this tight so that there's, if this is tight, if this metal flashing

if you have to kind of tap it lightly with a hammer, that's perfect. Because these will be pinholes

And if you've got any type of roof underlayment underneath, you'll never have a leak

there's a really good chance that you'll have to put a screw here here and here and all the metal

roof manufacturers make special screws that have neoprene rubber washers underneath them to seal

that but there's no need at all to put caulk under here you don't have to do that remember

this is tilted you know it's going to be tilted up on the roof like this

water is just going to flow right on down just like it does for any other flashing on an asphalt shingle roof this is a long lost secret This is how the old tinsmiths used to put flashings in on roofs that are 120 150 200 years old It actually a lost kind of art

So it's really that simple to do. I'm sure you understand exactly what happened here. And by the

way, if you have questions, I offer a service where you can talk to me on the phone, look in

the video description to set up a phone call if you want. So what did you think of that? See how

easy it is to do? There's nothing to this. The key is to just make sure that that slit you make in the

metal roofing is the exact same width of the flashing you're trying to slide up under the

metal roofing. You know, that half, because half of the flashing is going to go up underneath the

roof, and the other half is going to be over the metal roof below, because that's how shingles work

and that's how roofs work. In other words, each successive shingle or piece of roofing as you

march up the roof overlaps the one below it. So this is something that was done for many, many

years. It's one of those secrets that has been lost in the industry. I don't know why, but now

you know how to do it. And if you have a seam, you know, some hump in the roof

some ribbing in the roof, there's ways to deal with that. I'm more than happy to answer those

questions over the phone and walk you through it. So if you need to talk to me on the phone about

any of this, just go into the video description, click the link, set up the phone call. I'm Tim

Carter, askthebuilder.com. If you want to discover more home improvement tips, go to Askthebuilder.com