Underlayment

[Jeff Eastman]

........

[Jerry Peck]

An inspector said:

"The underlayment has been installed beneath the metal drip edge. The manufacturer requires this on the rake edge of the roof. The underlayment should be installed on top of the drip edge at the downhill side of the roof. "

I always thought it was the other way around:

Underlayment UNDER the metal drip edge at eaves.
Underlayment Over the metal drip edge at rakes

Depends on where you are at.

In high wind prone regions (hurricane regions), and in South Florida for sure, the underlayment is under the metal drip edge 'all the way around the roof'. The metal drip edge is set in a bed of roof cement (the better way) or is simply nailed down with a 4" wide bed of roof cement applied over the drip edge / underlayment joint.

The metal drip edge *is on top* of the underlayment to hold the underlayment edges down during high wind events. This helps prevent the wind from getting in under the underlayment, once the wind gets under the underlayment, the entire roof system just peels right off, like peeling off a band-aid.

Other areas, however, insist that the only proper way to install drip edge is under the underlayment, other areas insist the only proper way is to install the drip edge over the underlayment along the rakes and under the underlayment along the eave over hang.

[Aaron Flook]

Jerry nailed it,

There are exceptions to almost every rule, however, under at rake for wind protection, and over on eave to allow for water to drain over the drip edge and into the gutter.

Aaron Flook
AM Inspection Services.

[Jerry Peck]

Jerry nailed it,

There are exceptions to almost every rule, however, under at rake for wind protection, and over on eave to allow for water to drain over the drip edge and into the gutter.

"and over on eave to allow for water to drain over the drip edge and into the gutter"

Nope, for that same "wind protection" you need to install it UNDER the drip edge to keep it down, AND seal it to keep it from leaking. That is, if you are in a high wind area and the AHJ has any knowledge of high wind conditions and what needs to be done to help keep the roof covering on.

[Richard Rushing]

Jerry,

There are indeed differences regionally. You are absolutely right about the Florida requirements. However, Aaron is also right about requirements at some of the other parts of the country that are non-high wind exposure.

Take a look at page 3 of 4, top left hand corner detail...

[Richard Rushing]

Ooops... hit'em wront button.

[Jerry Peck]

There are indeed differences regionally. You are absolutely right about the Florida requirements. However, Aaron is also right about requirements at some of the other parts of the country that are non-high wind exposure.

I am fully aware of that.

The reason from my follow up post after Aaron's post was because he said (bold and underlining are mine) "however, under at rake for wind protection, and over on eave".

"for wind protection"

For wind protection, it is under at both, with the drip edge being sealed "to allow for water to drain over the drip edge and into the gutter."

[Jerry Peck]

Richard,

I forgot to add to my previous post:

Look at the top left detail on page 4 of 4 pages.

It shows, starting at the right end: (in order from underneath to on top)
1) Deck
2) Underlayment (the white layer)
3) Drip edge
4) Eaves flashing (if required)
5) Shingles

Those two detail (the one you pointed out and the one I am pointing out) contradict each other. :D