With every single window or door opening for the whole project, sitting back under 42 inches of roof overhang, and its 5/4 x 6 head casing sitting right up against the horizontal soffit, I’m wondering, why flash the heads?
The attached pic shows my typical section, and the arrow is pointing to the top of the window or door opening.
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Replies
up against the horizontal soffit, I'm wondering, why flash the heads?
Gene, I've run up against about a thousand individuals who couldn't understand, nor agree with this question. When faced with the logic that it is impossible for water to penetrate in that situation, they ultimatly use the picture on the window installation guide to say "it shows a flashing in this picture".
I'm not going to comment any further. These are the same type of guys that think you need a 2x12 double header, bearing on trimmers, for a 25" bifold door, when the partition is running parallel with the joist, and there' no weight at all resing on the door opening.
"That's how I was taught" is another normal answer.
My answer: You don't need flashing in that situation. Use your common sense.
blue
Just because you can, doesn't mean you should!
Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!
Yeah for big overhangs!!!! Too many are 3 inches and everything below gets water washed
Too many are 3 inches and everything below
And that, only because the fascia trim uses 2 2x . . .
Mind you, we had a bit of weather the other day, and it was raining up against the living room wall, the one behind 122" of porch overhang (the pitter-patter of the hail was an interesting sound, bouncing around off deck boards, wall, windows, deck furniture & all).Occupational hazard of my occupation not being around (sorry Bubba)
When faced with the logic that it is impossible for water to penetrate in that situation,......."
Blue eye,
Let's take a step back for a second...How does water manage to get to the top leaves of a several hundred foot redwood from the roots below?
It is feasible (depending on the house design) for a house to develop negative internal pressure sufficient to draw water up...Yes Likely?????????
Jon
Jon, anythings possible.
Lets assume that this window well will collect water/mist and create a type of pressure system trying to force water into the crevices. If that's the case, I definitly DON'T want that flashing, becuase it interferes with my ability to use a high grade flexible exterior window and siding caulk.
When you really get down to the nitty gritty, the use of flashing creates a natural path, underneath the flashing, that never get sealed. So, if you were trying to create a impervious skin above the siding and windows, I'd skip the flashing and use the caulk to bridge the gap between the window paint/skin and the siding paint/skin.
blueJust because you can, doesn't mean you should!
Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!
It looks like a 42" flashing to me.
Some will look for any excuse to cut a corner, but in this case it's clear that a drip cap would serve no purpose.
Al Mollitor, Sharon MA
One reason to flash might be, for instance, when the HO uses a hose or pressure cleaner to clean the house or the windows. In some areas, driving rain can be a problem, even with large overhangs. If it is a north-facing wall in a damp climate, and the prevailing wind puts a greater pressure on the north side of the house, there is a possibility of a constant intrusion of damp air into the area around the windows.
Even a one mile per hour wind will create a pressure differential, although you would hardly feel it. Actually, any wind at all would do that. Add, say a 90% humidity, and you end up with a constant flow of very moist air into any avenues of opportunity.
Having said all that, your situation might well justify the absence of flashing. These factors should be considered, though.
All in all, I do treat windows under overhangs less stringently than, say, gable wall fenestration.
> In some areas, driving rain can be a problem,
But what would it take for wind driven rain to reach the point indicated by the arrow? It's 5 1/2" down from an overhang that's 42" wide. So, the wind would have to be blowing 42/5.5 = 7.63 times faster than the raindrops are falling. Terminal velocity for typical raindrops is 6.1 - 6.9 meters per second (Foote & DuToit, J. Appl. Meteor, 1969), so the math works out to 104 - 118 MPH wind, not taking into account the fact that the wall blocks the wind.
Bottom line, the only way wind driven rain reaches the indicated point is when the roof blows off.
-- J.S.
And when the roof blows off, "we don't need no steenking flashing!"
Let’s say the rain is falling your given 6.1 m/s, or 20 ft/s, or 240 in/s (13.6 mph).
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Let’s also say we have a 68 mph wind, horizontal, which gives us 100 ft/s horizontal, or 1200 in/s.
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Our overhand is 42”, so the rain blowing horizontally will travel that distance in .035 seconds, during which time it falls 8.4” at your given terminal velocity.
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Considering the turbulence in that area as the wind hits the house, I do not think it is unreasonable to consider that zone wet.
68 mph winds are not uncommon in many parts of the country.
I am on the Wash coast and I have seen rain blow in horizontally and the soffits on the porch over hang are dripping water.. When the wind comes in, it pushes the water upward, downward, right and left.. We are required to have 110mph rated roofing shingles out here. I have overhangs on my porch that are 6' and some even more... Why not flash the $hit out of every opening. Doesn't really cost that much more in time/materials.
That reminds me... I have some caulking to do tomorrow
I would like to point out to all the contractors that may be reading this post that flashing is not just the little z-bar or whatever-one-may-call-it in any particular area of the country or the world. Flashing is, in the broader sense, something that is applied to keep out the deleterious effects of moisture on a structure at an opening of opportunity. It can apply to the entire area around an opening, not just the top of a window, a little fact which is often forgotten. Caulk, while not in the true spirit of the long-term benefits of flashing, definitely helps to keep moisture in control (if used correctly).
Migraine - I do not wish to cause you any additional headaches by attempting to communicate with others on your dime (or your post). I know much about migraines, and do not wish to cause any - well, maybe a few more headaches in the world - the kind caused by thinking things through.
So now, I will get to the point - I was recommending that the original poster should think about a few things when planning to avoid water intrusion problems. I was not really fixated on the 42 inches of the overhang in his particular case. I was also thinking about the folks who have only a twelve inch overhang. I was thinking about other readers, visitors to Breaktime, who would be looking for advice of a more general nature. I tried to provide some general advice.
Thank you very much for giving an example of how things can go bad in certain parts of the country. I could not agree with you more on your statement, which should become a mantra:
Why not flash the $hit out of every opening. Doesn't really cost that much more in time/materials.
Peace to you.
If a homeowner is using a pressure washer to clean his house he deserves some leaks!
I do it every year on my vinyl siding, as do many others. How would you clean vinyl siding?
I would use a soft car wash brush and soap and water. I just don't like blasting that water everywhere it shouldn't be going.
I tried that the first year, and got tired of reaching 20 feet up, moving the ladder, and so on. On the gable side, it is closer to 30 feet. A carefully directed pressure washer is much easier. But to each his own.
Around here most windows are vinyl with a 1 1/2" mounting flange. Paper and siding go over the flange and then the window is caulked.
There is absolutely no way for the window to leak but the inspector still in insists on flashing the top.
I can see the point of doing this with wood sashed windows but not vinyl.
I don't get it?
As far as overhang protection goes, they must be concerned with blowing snow........
Or maybe it is something more visible for the inspector than a floor flexing 1/2" in a 10' room.
"Rather be a hammer than a nail"
Bob
"Around here most windows are vinyl with a 1 1/2" mounting flange. Paper and siding go over the flange and then the window is caulked. There is absolutely no way for the window to leak but the inspector still in insists on flashing the top."Absolutely no way? Paper tears easily. Even if the window is installed and the tar paper is intact, the trim and siding guy can still screw it up. One rip across the top flange or some missing caulk on the side, and all that vinyl means nothing.
Not only is no flashing needed, it is practicaly impossible to put it in.
You having Noah over to do the inspection?
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Having said all that, your situation might well justify the absence of flashing. These factors should be considered, though.
Perhaps my message was not read closely, as is not unusual in this forum. If anyone bothered to read down far enough before sounding off, the above statement was included. I merely gave a different point of view. The result was sarcasm to the point of stupidity.
Often in this forum, the personal experiences of several prominent posters get on a priority train in a single direction and leave little room for other opinions.
Maybe we should just not say anything if we disagree with Piffin and Blue and a few others?
Hello Noah. You feel better now that you have that off your chest?Gene posted a question here. I responded to his question. How is that sarcasm? I had not read your post when I wrote to him. I don't mind you having some other opinion, and it may be valid, but with an attitude like you expressed here, I doubt many folks will listen strong or long to what you say, no matter how valid it is. Just post your views, back them up if you feel the need, and get on with life. Demanding that everyone listen and agree is kind of dangerous for your health. Lighten up dude.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I will give credence to your recommendations.
I will think.
Eventually, I will grok.
My hope and wish is that you will do the same.