Drip edge and underlayment

I recently obtained my FL HI license. I’m having a new home built. I’ve been going round and round with the builder on the roof. It’s peel and stick underlayment. The roofer has the drip edge over the underlayment all the way around. I say it’s suppose to be under the underlayment on the eaves ( per my training). The roofer says it would NOT pass inspection that way. So I guess it all boils down to what the AHJ says. If I were to call this out on an inspection I would look like an idiot! Very confusing to me what’s right and what’s wrong.

1 Like
5 Likes

R905.2.8.5 Drip Edge

A drip edge shall be provided at eaves and rake edges of shingle roofs. Adjacent segments of drip edge shall be overlapped not less than 2 inches (51 mm). Drip edges shall extend not less than 1/4 inch (6.4 mm) below the roof sheathing and extend up back onto the roof deck not less than 2 inches (51 mm). Drip edges shall be mechanically fastened to the roof deck at not more than 12 inches (305 mm) o.c. with fasteners as specified in Section R905.2.5. Underlayment shall be installed over the drip edge along eaves and under the drip edge along rake edges.

UpCodes Diagrams

P

Drip Edge for Asphalt Shingles

Drip Edge for Asphalt Shingles

3 Likes

It appears that the Florida Building Code is different.

R905.2.8.5 Drip Edge

Provide drip edge at eaves and gables of shingle roofs. Overlap to be a minimum of 3 inches (76 mm). Eave drip edges shall extend 1/2 inch (13 mm) below sheathing and extend back on the roof a minimum of 2 inches (51 mm). Drip edge at gables shall be installed over the underlayment. Drip edge at eaves shall be permitted to be installed either over or under the underlayment. If installed over the underlayment, there shall be a minimum 4 inch (51 mm) width of roof cement installed over the drip edge flange. Drip edge shall be mechanically fastened a maximum of 12 inches (305 mm) on center. Where the Vasd as determined in accordance with Section R301.2.1.3 is 110 mph (177 km/h) or greater or the mean roof height exceeds 33 feet (10 058 mm), drip edges shall be mechanically fastened a maximum of 4 inches (102 mm) on center.

8 Likes

I looked it up as well. Yes FBC is different. Thank you for looking into it for me and posting

3 Likes

Always defer to local requirements. Why? Because the local building department knows the local weather conditions better than anyone else in the rest of the world. The IRC model code is a general code that cannot possibly work everywhere. Something that might work in earthquake prone California is not necessarily going to work in hurricane prone Florida or the snowy states up north. Hence the local modifications and amendments which they develop from data of previous building failures, natural disasters, and so on.

The drip edge is nailed down on top of the underlayment to reduce the likelihood of the edges of the underlayment getting caught by the wind easily during a hurricane. It is supposed to provide additional wind resistance along with wind nailing the shingles.

The point being you need to not only understand what the local construction practices are, but more importantly the “why?”

5 Likes

Alex, I am very much “down to earth”
Roofers, Roofing Contractors do their trade every day. Very seldom they will measure, read Codes and engineering specifications. They just do what they know how to do. And the lead roofer or contractor is not overlooking all the atrocities that his crew does on-the-job. They are usually in-and-out in ONE day and that is IT…! Whatever you know is way, way more technically supported than what these people do…! Yeah! You may be lucky and you hire the PERFECT academic roofing contractor, but 80 to 90+ % of the time, That is not the case.

So take all this specifications that your InterNACHI peers are giving you and seat down with this fellows and have them understand that you will not give them the final check ($) if they do not listen to you. You are their customer and a Licensed PROFESSIONAL Home Inspector with 100s of Experience inspectors behind your back at InterNACHI.

Take a look at this picture and make an evaluation of the poor quality of a task done by roofing contractors. Another thing to consider is your Gutter/Downspout contractor. If those two contractor do not work in harmony, the will defeat the whole purpose of protecting your home’s roofing and exterior envelope. The height of the gutter in relation to the shingles edge is critical, if too close/tight… it will not fall by gravity and will fly over the gutter and the gutter will not be able to catch the water to take it down the downspout were it should be directed 6 to 10 feet away from the foundations. In a nut shell… You need a contractor with attention to details and with good communication skills that can provide for a harmonic holistic integration of your gutter, downspout, drip edge, fascia, shingles, underlayment, and so on…!

In this picture you can see how critical is the engagement of the drip edge, the underlayment of the roof, the shingles and the gutter.

The shingles are within the 2" per code, but if it rains hard, the storm waters will overshot the gutter. Usually most 100% contractor use the less expensive gutter. A wider gutter will ensure the roof running storm water does not fly over the gutter. Depending on the overall surface (sq2 feet) of the roof, the water collected during astorm may or may not exceed the volume that the gutter can handle. If the installer of the gutter or roofer does not carefully install each part of this system properly, out of plumb, for example, not sufficient retainers, the weight of the water itself will separate the gutter from the fascia que the drip edge will loose all purpose.

2 Likes

I totally agree with you. Thank you for your information.

The builder sometimes drys the roof in with ice and water shield and underlayment before the roofer gets to the job. The roofer then installs the drip edge over the ice and water shield and applies a 12’’ strip of rubber over the top of the drip edge, sealing the drip edge to the ice and water shield.

3 Likes

Yes, in Florida, you will actually find it done under the drip edge more often, but they MUST use the roof tar over the edge. The reasoning (I believe) is so that the high winds can not get under the underlayment, and then take the shingles with it.

3 Likes

I had figured logically that was the reason.

2 Likes

Sorry, wasnt meaning to respond to you directly, just using your research. :grinning:

1 Like

Otherwise known as ice & water shield around the country. Around here most AHJs require the first course of underlayment to be ice & water shield. The problem is that most roofers don’t peel off the backing and stick it. They just nail it down with enough hanging over the edge so it covers the edge of the sheathing and a small portion of the fascia. The drip edge then will get nailed on over the top with a different underlayment placed over the drip edge.
Per the building code that @mcyr posted what your roofer is doing is correct in your area provided they overlap the drip edge with the roofing cement, or tar as @dhorton2 put it.

That makes total sense. Double duty sealing in hurricane country. If the water shield isn’t stuck to the fascia behind the drip edge though, it doesn’t work up to it’s full potential for sealing things off…

1 Like

If the drip edge is sealed to the underlayment, the water shouldnt make it under the drip edge. However, what I dont get, and have been thinking about lately, was if it is done this way, and the starter strip is sealed to the top of the drip edge, than any water that does happen to get under the shingles would get trapped. If it cant go under the drip edge, and it cant exit over the drip edge, then where does it go? Sometimes I see the starter strip sealed to the drip edge, and sometimes not…

1 Like

If the drip edge is sealed with a narrow strip of rubber, the water would not get trapped above the drip edge.

2 Likes

What I mean is the drip edge is installed on top of the underlayment, then sealed with tar. And then the starter strip gets sealed to the drip edge as well, but then, the first shingle is ALSO sealed to the starter strip. So everything is blocking water from escaping. (can get trapped between the starter strip and the shingle)

1 Like

Hi Alex.
Lets get down to earth.
With peel and stick underlayment, or sticky one-side vapour barrier, do you think roof water will be able to pass between the sticky one-side and underlayment and migrate to the top surface of the roof sheathing? Only the starting edge of the sheathing is exposed, unless the roofer covered that surface as well. Everything else, the top surface of the roof sheathing, is covered with sticky one-side vapour barrier.

If the roofer put the drip-edge flashing first roof water would be able to get between a wider surface, not much mind you.
Using normal underlayment, 15/30/50pounds on non perforated felt, the drip-edge flashings in placed underneath the vapour barrier and roof covering material goes on top. Raked ends, drip-edge flashing is placed over underlayment to hold it down to prevent blown in weather. Eave side underlayment, Raked ends on-top.

Seal tabs are not continuous and will let moisture out.
Or you can use edge seal instead of a starter course.

Good point. I think I have seen manually sealing of the first row of shingles, which, technically could be a problem. Something to watch for.
Thx

I believe the IRC required drip edge from 2012 - 2018 and spelled out the installation method…and then in 2018 it is is phrased as, shall be provided if required by the manufacturers. The issue is under or over the roofing paper. Of course it goes under the paper at the eves but since the framers are the ones who install the roofing paper (to dry the house in) and the roofers install the drip edge who are there later; it doesn’t get done. Mostly because the roofing paper has nails along the bottom and it’s hard for the roofer to fit it under as nails are likely in the way. You can call it out but in my experience it’s unlikely to get fixed.