Has anyone run across this technique before?
My architect spec’d a line of shingle for the roof eave, overhanging the facia & trim by about 1/2″, acting as the drip edge for the roof.
It’s not shown, but I expect the ice&water shield to be underneath it.
Any suggestions as to why this might be used instead of more common metal drip edge?
thanks,
-TJ
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Replies
TJ--
Admit the architect probably correct in assuming that gravity will control the situation--overcome cohesion and cause the water to drop instead of flowing "uphill" towards the trim, and then that little water will migrate between the shingles and ice & water shield.
However, drip edges are expressly designed to redirect any water that does "wrap around" the shingle edge and keep it off the trim,
and
the ridges in dip edges present another hurdle for such water to overcome prior to reaching the sheathing.
and
drip edge protects joint between ice and water shield and sheathing/trim,
May he be "theoretically right", sure: but given the low cost of drip edge, is there really a issue?
Actually, given that the ice & water shield also was not shown--perhaps the architect is just not familar with common deailing of this area....
Regards,
Rework
Edited 10/11/2002 4:17:15 PM ET by Rework
Edited 10/11/2002 4:17:39 PM ET by Rework
Edited 10/11/2002 4:19:23 PM ET by Rework
I agree with what you said, but wanted to add one thing.
To me the drip edge is almost a necessity for 2 more reasons. It also covers the often uneven edge of the roof plywood, and allows for aluminum fascia cover to slip up underneath it.
I can't imagine NOT using it.
One nice thing about egotists - they don't talk about other people.
all roofs used to be done this way when i started... one course of w.c. #2 then the starter course of asphalt ..often times it was used to straighten the eave line..
then aluminum drip edge became standard.. and it's spec'd by all the shingle mfr's
your architect is either an anachronism.. or he's dumb..
the first thing that goes on these roofs is the white cedar drip edge.. it rots out long before the asphalt shingles fail..the capillary action keeps the white cedars wet for prolonged periods of time..
if he wants the WC's there .. fine , but they have to be protected by a metal dripedgeMike Smith Rhode Island : Design / Build / Repair / Restore
Mike, he never mentioned any cedars. You #### umed.
;-).
Excellence is its own reward!
yeah, and your point is ?...... hah, hah, hah..
i don't know if this makes it worse or better... with no drip edge.. the paint will peel right off the fascia.. because now the fascia will be forever wet..instead of the white cedar shingles... arrrrgh !
but i sure could see those white cedars hanging over the edge as if it were yesterdayMike Smith Rhode Island : Design / Build / Repair / Restore
The description is given as 'typical' for all the rooflines in the project. While most are 12in12, others are 9in12, and 4in12.
Cedar shingles were specified.
It seems to me that even though physics suggests that the water will always go _down_, the 1/2" or so exposure of the shingle tails presents a potential for rot.
I think my question is really one of: am I setting myself up for a problem should I leave the shingles _out_, and use only the I&W shield and metal drip edge, under the roof shingles?
BTW, the facia & trim are to be Perma-Trim, so rotting of those is not a problem.
(BTW2 - I _did_ check through the archives using the Search function, but didn't see anything pertaining to wooden drip edge. Possibly my search terms were not general/specific enough.)
thanks,
-TJ
TJ--
Was a bit timid in my initial response, deferring to the architect's credentials and to my betters (i.e.: Boss and Mike who have now weighed in). The cedar makes no sense. Granted I used them as the archy wants to when reroofing my 60 year-old goat shed, but that was a goat shed. Makes even less sense given that rot has been considered (e.g. the perma-trim). The cedar will still act as nice wick. (By the way, have criticized my own paranoia before, I roof cement down both the starter and first courses).
Regards,
Rework
When it is a cedar roof, 1-1/2" is more typical for the overhang, if no metal is used.
If the cedars are for a support for asphalt shingles, it does become a wick. Metal drip should be used..
Excellence is its own reward!
Let's add this to the list of questions that get asked every four or five weeks that could be answered from the archives with a search.
I suppose the archy could havve just forgotten the drip edge. What is the pitch of this roof?
Excellence is its own reward!
unless you want to be back in 2 years replacing trim (fake wood trim notwithstanding - but if not the trim, then the rough fascia then the rafter tails will eventually fail due to rot) always use metal drip edge. no matter how steep the roof, water from the roof will cling to the shingles & either on its own or with the help of the wind, will look for something to soak. drip edge provides a break that is not provided by the method you see on your plans. Without a chance to see the plans, I don't want to judge the architect, so I'll keep the rest of my opinions to myself...
best of luck
Thanks to everyone for their comments and suggestions.
I had pretty much decided to skip the shingles and just use metal drip edge - these comments suggest I'm on the right track.
Two last questions for this topic then: drip edge goes over or under the I&W shield?
Is the drip edge is outside the facia/trim? Another way to put this is do I install the facia & trim before applying the drip edge and/or I&W shield?
Thus far, I have already installed the sub-facia ( a 2x4 ripped to match the roof pitch), and brought the roof sheathing down flush to the face of the sub-facia.
thanks,
-TJ
TJ--
Drip edge goes over the ice & water along the eaves, and under along the rakes.
Fascia and trim installed before drip edge; i.e drip edge goes over them.
Regards,
Rework
You CAN apply the cedars per architects directions and THEN install the metal drip edge over them. The drip flange is deeper than the shingles and will cover them. We've done that and the cedars help hold the metal further out from the fascia to let water drip free without surface tension pulling it back.
In my mind it is best to lay the ice and water over the metal to keep all laps facing down hill. But practical concerns often prevent this. You want to get the roof dryed in immediately. Then you can do fascia and other trim materials. Then the metal. Now, you do have a lap facing up so another ply of bituthene goes here if you want to be 100% good but not totally necessary.
I was reading this back over to see where things went off and I was not sure if you got what you wanted out of it.
Most archys are ok with changes in details if you run it by them first. If they have the control of project manager on the job, you better get approval before changing. They can hold up your money on an ego trip.
.
Excellence is its own reward!
TJ. I would recomend against that. I have seen that applied before and in a short period of time the shingles curled. This curling enabled the water to track back against the facia and in one case wick up on top of the facia, puddle, freeze and not only bulged the facia but blew out the soffit below. Yuck. Metal drip edge is peanuts in the cost of a roof and gives the ice and water something solid to seal on to, not to mention, the drip edge supports the shingles. Now you can hang the shingles over the metal maybe a 1/4" tops to account for shrinkage that might take place over time.
I'm an architect and I don't have a metal drip edge. If anybody wants to know more, please let me know.
dear tim... do tell..inquiring minds want to know...Mike Smith Rhode Island : Design / Build / Repair / Restore
To answer the question, I'd be installing the drip edge with the ice & water over lapping it. If water got under the shingles, but was stopped by the ice & water it should run over the drip edge. If the drip edge was installed over the ice & water it would be directed under and would then run down the facia or be absorbed by the edge of the sheathing. I thing that it would also be acceptable (and arguably better) to put the i&w under the drip edge with a second sealing strip over it.
My home has about a 7:12 pitch. I had originally intended to use a drip edge, but my roofer suggested omiting it. He hung the starter course of asphalt shingle (a solid piece) about 1/2" beyond the edge of the roof deck. I've watched how the water runs off the roof in both a misting and a heavy down pour and the water is always making a clean break off the shingle. There is no sign of capillary action occuring as the underside of the shingle is dry. I would be comfortable using this detail on roofs that are 6:12 and steeper. However, I would use the metal drip edge though on roofs that are 4:12 and shallower. At that pitch I'm not confident that the water wouldn't break cleanly off the edge and ultimatly may cause problems. Another item that needs to be considered is the gutter detailing. The drip edge provides a convient slot for a K style gutter to be inserted into. This creates a foolproof clean and easy flashing detail. On my home this wasn't an issue as I either omitted the gutter or used a half round gutter-neither of which could benifit from the counter flashing of the drip edge. However, the drip edge could provide a secondary benifit in that it may reduce rot by deflecting some of the spash that could come back out of the gutter.
Tim: no word-a-lie... your roofer is a doofus.. 7/12 is not a steep pitch.. and you will get blow back & capillary action so some water will run down behind your fascia...
and this can occur even on a 12/12... the drip edge brings the drip point below the top of the fascia... a starter course hanging out a 1/2" doesn't.. as an architect you should be up on these things.. if you don't want teh appearance of a conventional drip edge , you should come up with a better alternative... i can't think of one...
but hey, whadda i no ?Mike Smith Rhode Island : Design / Build / Repair / Restore
I'm sorry to have wasted the boards time.
tim.. why would it be a waste of time ?... any discussion is helpful... lord knows i learn something here every day.. even if it's that there are doofus roofers out there..
anyways.. you just keep stating your opinion... .. just keep your shin guards on....Mike Smith Rhode Island : Design / Build / Repair / Restore
Tim:
You are not wasting anyone's time (and I'm even pro-drip edge). Basically you just need to follow up your observations with a properly labelled vector diagram of the forces involved...
Regards,
Rework
Stick around. Mike is a little more blunt than many of us. That can be the nature of top guns sometimes. But he is right. Over twenty years specializing in roofing with experience in several climates and roof styles lead me to agree with him. The overhang would need to be at least one inch and the pitch more like 8/12 to 12/12 for me to feel comfortable with no metal edge. We are obseving these things, not from standing occasionally on the porch watching it rain and drip but from removing huindreds of roofs and seeing the rot and/or other water sign. When it comes to keeping dry, experience beats theory every time.
Like was said already, discussion is good. It's batting these issues back and forth that challenges and refines our craft..
Excellence is its own reward!
Well, here is the detail of my roof edge. It was an existing unvented roof that was furred and resheathed. The roof was replace two years ago and to date there are no signs of water on the fascia.
Ultimatly, it's not that you guys disagree with me. That's fine. But, I still stand by my statement that IN CERTAIN situations the drip edge can be omited. But, what really PISSES ME OFF is when people come with this bar room slander proclaiming that everybody else (and in particular my trade) "is either an anachronism.. or he's dumb..". Comments like that mean that I'll be exercising the ignore button because that person obviously has nothing constructive to add.
BTW-how many 100 year old victorians with their cedar roofs had a metal drip edge? All of the old barns (many of which have the original shingle roof over laid) in this area also don't have a metal drip edge. But each of these situations have the fascia either omitted or pulled back a couple of inches from the roof edge. Point being, if I was detailing a modern house with the fascia right at the roof edge, I'd use the metal drip edge. If I was going to omit the fascia or pull it back, then I'd study the option of omiting it. There really is some thought that goes into these details. Often when the installer says that we are "dumb" and don't know what we are doing is when things get really screwed up. Comments like "we do all the new homes like this" are not acceptable. If you don't like the way something is detailed, then go back to the designer. Don't just change it, there may be other elements that you are not considering.
Edited 10/15/2002 1:53:38 PM ET by Tim
But, what really PISSES ME OFF is when people come with this bar room slander proclaiming that everybody else (and in particular my trade) "is either an anachronism.. or he's dumb..".
Tim:
Not trying to speak for Mike, but would you consider that a person could have a high respect for your profession, yet extreme dislike for the person providing outdated or bad advice? Will gladly pay for the next round, if Pi would add it to my tab, if that will help patch things over...
Regards,
Rework
tim.. who cares what really pisses you off ?
lot's of things piss me off.. get over it.. life is short.. since i cut my teeth working on 100 year old shingle style victorians i guess i know what works and what doesn't .. and what details mckim meade wishes they could have changed.. and what those guys wouldn't give for some of the materials we have available to work with in maintaining their grand old ladies...
no matter what they did.. the eaves rotted out first.... two big improvements in longevity were metal drip edge at teh eaves and rakes... and metal caps at the window trim...
on restoration work we'll use copper, or lead coat.. or aluminum painted to match the trim... but we always use it... wether it's a 1670 Cape.... or an 1890 Shingle Victorian... the cost of labor , materials , and painting is just too expensive not to give it all the help it can get..
your roofer was wrong.. and i'll tell him to his face if you want...pick up any roofing manual .. or any shingle mfr. spec.. .. drip edge will be there...
if you choose to ignore.. too bad for you.. i've never ignored anyone on these forums...argued with them , sure... but i've learned something from everyone here.. and i'm sure i'll learn something from you, too..
here's a tip.... if you want to post pics or diagrams & you want everyone to be able to see them... use a .jpg format..
you can get freeware like irfanview that will convert from one format to another..
but hey, whadda i no ?Mike Smith Rhode Island : Design / Build / Repair / Restore
Tim,
I am also an architect and have gotten some very good advice on these forums. You need a thick skin sometimes. Most people are trying to help. The metal drip is a good idea. If you want a more historic look use copper. The shingle overhang detail was a standard in the 1900's (architectural graphic standards of that era show it) but it is not the typically used today (better methods perhaps). Ice and water shield were not used in the 1900's but it works on todays jobs.
tim, Let me know if, in the course of translating your DWG to the more common JPG format, any information was lost.
To answer a couple of your questions, the detailing on the old homes was different than yours. As a general rule, the shingle overhang was 1-1/2" to 2" and the wicking that resulted produced a generous amount of rot to keep carpenters busy. Another factor lies in the paint and lumber available then as opposed to now. Old virgn pine contained copious amts of piotchy resin and closer growth rings, making it much more rot resistant than todays plantation grown lumber. Use today's wood in yesterday's details and you are inviting disaster. Add to that, the fact that, instead of protecting that wood with lead paint you are now required to use latex in most applications. Latex is far less able to resisit water penetration.
Viewing your very nice drawing, (thanks for submitting it to peer review, BTW) I see that you don't have a fascia board, but exposed rafter tails capped with a squared, not plumb, trim piece. This probably lets you skate by but I still believe that the 1/2" is not suifficient to control the water flow adequately. BTW, I'm curious what is holding the trim strip on? Presumably there is more furring right at the edge that is not drawn.
attachment edited to next post
.
Excellence is its own reward!
Edited 10/16/2002 1:42:42 AM ET by piffin
Edited 10/16/2002 1:45:48 AM ET by piffin
I'll try this again.
Excellence is its own reward!
No, actually it translated very nicely. I had tried to convert it, but the quality wasn't good enough and I wasn't in the mood to futz with it. Thanks for the help.
I'm trying to recall a situation, but I think that you are correct about the overhangs and detailing on older homes. I know of one situation where the original shingles were still on a structure, while I can remember what the sheathing looked like, I can't recall the overhang distance. I remember there being a slight amount of decay, enough to raise the grain, but a perfectly acceptable amount on a 75 year structure.
Yes, if that trim piece was plumb, there is no way I would have skipped the drip edge. That was one of the conditions; the fascia must be pulled back from the edge. Older homes often used a piece of crown moulding here, so that would qualify. I think that you are also correct about todays wood and paint vs. the older stuff. In hind sight, I wish that I had used a piece of synthetic material for that small fasca. Time will tell if that be critical or not.
Yes, I didn't draw the furring. The deck was furred with 1x2's placed on top of the rafters. There is also a piece of furring placed perpendicular to the rafters right on the edge. The trim piece is nailed on using 2 rows (top & bottom) of 2" trim nails driven at 30 degree angles.
Yes, sometime we don't want things to be changed because of our ego. I guess that anybody that is proud of their trade would have an ego. But honestly, it's often because a simple change often affect other things that may not be considered in the field.
Hey, how about a little study. It's dry out right now, but we'll proably have some snow showers later in the week. That should be a good slow rain/melt that would be ideal for a wicking situation. I'll take some strips of paper and tape them onto the fascia with a cut edge touching the underside of the shingle. If there is any moisture on the underside of the shingle, it should show up on the strip of paper. I'll put a bunch of them on so that I can check the status over a period of a day or two. I'll honestly report the results back here so we can discuss them some more.
Tim:
Appreciate your experiment--was tongue-in-check about my vector diagram idea. Seems that this is one of those areas which could be debated in theory until the cows came home...
Regards,
Rework
That paper test for water wicking sounds educational, Tim. I woinder if you have some card stock that you could use to print a field of blue or green from your printer, and cut it into strips for the test. The ink washing away will tell more than looking for wrinkled paper. Just the humidity might wrinkle paper. blown drops would speckle the ink and wicked water would make it bleed and run from the top down.
"Yes, if that trim piece was plumb, there is no way I would have skipped the drip edge. That was one of the conditions; the fascia must be pulled back from the edge. "
I think we're basically all in agreement here because it was not clear originally that you didn't have a plumb fascia, which is more typical.
With crown, when avoiding metal edge and before metal was prevalent, it was propeer to be sure to extend the cedar shengle far enough that the lowest edge-corner was at a slightly lower elevation than the last top break it the detailing of the milled trim. Maybe I can find or make a detail drawing of such later..
Excellence is its own reward!
I'm thinking regular 10lb paper. I think the 10lb will be moisture sensitive than the card stock. Your idea of using a bubble jet to increase the sensitivity is a good one. I was originally thinking that I'd look for a stain line.
All ears!
Metal drip edge is cheap insurance. The drip edges goes on top of the Ice and water shield. If you are paranoid (like me) you add a strip of ice and water shield over the top of the drip edge (ice backs up and it can't get under the drip to the trim (I know there should not be ice but it happens)).
ARCHYII:
Not to start a "ridge wars" type thread, but doesn't drip edge go under the ice & water along the eaves, and over the ice & water along the rakes? Just don't want to confuse the guy, as we have now given conflicting answers to his "under or over" question...
Regards,
Rework
We had a big discussion going on this a while back. I think it was split about 50/50 on the over/under thing.
I think ice and water over drip edge myself. Don't take life too seriously. They will soon repeat it on cable TV.
I liked archy's idea of iceshield, then metal drip, then a band of 6" wide iceshield again. That is similar to the procedure for meatl edge on hot asphalt roofs..
Excellence is its own reward!
Overlord--
Also like it. Believe it is a glass half full/empty situation: depending on which direction of water flow captivates one's interest. Water/ice backing up from drip edge: drip over; water flowing down under shingles: ice & water over. One possible advantage of shield over drip: adhesive bonds ice & water shield to drip; with drip edge over shield just a mechanical (nails) bond between the two. My method (and Archy II's) both seem belt and suspenders: ice and water over drip, and then roof cement starter course to drip edge, and first course to starter; Archys method seems faster...
Regards,
Rework
I don't like cementing the starter course to the drip edge unless you get it 100% because then any water that gets in above and is traveling down the roof between the shingles and the tarpaper gets trapped at the starter..
Excellence is its own reward!
Ah Overlord:
"Edge wars, edge wars, edge wars..." Agree completely with your logic. Same logic applies to putting Ice & Water shield under the drip edge: water travelling down over the tarpaper and I&W may be trapped under the drip edge (at points where it contacts the sheathing/trim). However, Archy II's detail of an additional 6" of I&W forestalls this. However, the 6" strip must come from somewhere and the material is not inexpensive. However, asphalt shingles should be banned and replaced with metal (at least on N.E. farmhouses). However, my tag name remains appropriate...
Regards,
Rework