Help Installing My Flashing Properly (Pictures Attached)

Old 03-16-09, 07:12 PM
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Help Installing My Flashing Properly (Pictures Attached)

Ok, I don't know all the terms so to save some headache for all of us I added pictures with details. Also, the original flashing is not my handywork, but that fabulous caulking job is (It was meant to be a very temporary solution and it was freezing cold when I did it.)

First off, this is a small roof above the back door that leaks when the rain is blowing and heavy. The only part that leaks is the area on the south wall slightly above the gutter (Area at the top of the 4th picture). However, I have been told the flashing is installed wrong and they are surprised we haven't had worse issues sooner. So I want to make sure that I redo this whole thing right.

I understand the basic idea of flashing but need many questions answered.All of these questions are on each photo but I will also type them out.


On the east wall, I can get the flashing behind the siding but how far up does it need to go?

The vertical part of the flashing should never need to be fastened because it will be behind the siding, right?

Will the bottom part of the flashing go over or under the shingles along the east wall?

The east wall and roof meet at a level point. Will I use the step flashing technique or can I use 1 long seemless piece of flashing?


How do I get the flashing behind the siding? (See picture to see what I mean)

When I remove the old flashing will I put some kind of sealant where the wall and roof meet, or will it not be necessary if I install the flashing properly?


How will I overlap the flashing when it meets in the corner? Is there a special piece that goes here?


How do I place this first piece of flashing? Should the right edge be flush with the shingle or should it over-hang slightly? If I can't get this piece behind the board, do I take it all the way up behind the next level of siding? If so, what do I do to seal that area as that is the direction the rain blows in?

Any help/feedback would be greatly appreciated. I thank you for your time in advance.
Old 03-16-09, 09:38 PM
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Welcome to the forums.

Those are pretty nice pictures and illustrations. I've got to congratulate you on that. We can certainly picture the difficulty you are having. Explaining how to fix it is certainly going to be much harder. I'll do my best.

Question 1. This is open to interpretation, but usually I like to see a vertical leg that is at least 4" long. The problem you have there, however, is that the row of siding which will cover the flashing has seams in it. So what you probably need to do is remove that first row of siding, make the vertical leg of your flashing 4" tall, and either tuck it under your building paper (housewrap) or cover it with additional flashing that will extend up and under the housewrap and/or the NEXT row of siding. This does not "have" to be metal flashing, it could be #30 felt, or similar. Then reinstall your first row of siding on top of that, keeping the bottom edges at least 1" up off the surface of the roofing. (at least 2" if fiber cement)

Question 2. No nails "need" to penetrate the vertical leg of the flashing, but undoubtedly some might, when you go to reinstall your siding. This is fine. In new construction, these flashings are usually installed before the siding is, and a person only puts a couple nails in the vertical leg... just enough to hold it there while you reassemble things.

Question 3. That is a matter of choice. Personally, I like to see the flashing on top, but the length of that leg of the flashing may need to vary depending on the pitch of the roof... the flatter the pitch, the longer the flashing needs to be to provide coverage. Basically, any shingles on top of this flashing are just for looks... so that you see your shingle color all the way up to the vertical wall. Regardless of whether the shingles are over or under the flashing, the flashing needs to be long enough so that it covers the top portion of the row of shingles that it is on top of. So if you remove the shingles on top, and see that the flashing is only 2" long, it isn't long enough to protect the row of shingles that the flashing is on top of. And that's where a leak would originate. So if you look down at your picture on question 6... at a MINIMUM, the flashing underneath that top row of shingles needs to cover the top 2" of the row beneath it. If it doesn't, it isn't long enough. If it was me, I'd put the flashing on top of that last row of shingles, and make sure it covers at least 4" of shingles.

Question 4. That is a tough one, which may require removing a lot of siding, but not necessarily the step shingles. You "can" use a skilsaw to cut 4" up from your roofline, making a cut above the step flashing. You would then be able to remove the shingles above the step flashing. You would then need to make a "counter-flashing" to cover the step shingles. This would need to be custom made, out of sheet metal, copper, or aluminum/vinyl trim coil, and would be bent similar to a drip cap, but with a much longer vertical bottom leg. The top leg of this counter-flashing would again, need to be about 4" high. The top leg would then be covered with a strip of #30 felt or your building paper. Basically you are making it so that the flashing would not leak even if that first row of siding was not on there. That's the mind set with which you approach flashing when you have siding like yours.

Question 5. The answer to this question is no, because you usually never want to rely on caulk to seal anything that might leak. You want a mechanical flashing, not one that comes in a tube. If you ended up removing and reinstalling the step flashings, they do not get nailed to the wall. The top edge of the flashings would be covered with a counter-flashing. In some cases, the siding acts like a counter-flashing, but since your siding is like shake shingles where there are gaps between pieces that could leak, the counter-flashing either needs be behind your building paper... or one made as described in question 4 above, and long enough to reach behind the row of siding above the final row.

Question 6. Tough question to explain. In short, unless you can solder metal, there is going to be a point in the corner that will need to be sealed with sealant. The trick is usually to have all the siding off... and use a large piece of sheet metal to make the last step shingle. To give you an idea of what I would do, take a piece of computer paper and fold it in half the long way so that it is 4x11. Now tear it down the middle, ripping 4" down to create 2 pieces that are roughly 4x4. Lay it flat in front of you. Fold the right 4x4 half of the paper into a triangle by taking the top left corner of that right half and folding it down and to the right. Then bend it back so that it is standing straight up. Now take the left 4x4 and fold it down, creasing it at the bottom, then folding up so that it also sticks straight up. Now take the entire sheet of paper and fold the right side up again so that the right side of the paper is sticking straight up. The triangular portion you folded should be in front of the square portion you folded, and the only point water can get in is at the very corner. So you would fit the flashing, make sure it fits, then put roof tar or urethane sealant behind the flashing, press it into place, then place your horizontal flashing over the last row of shingles, seal the end of it... then counter-flash all of it, making sure the counter-flashing is behind the housewrap or the next row of siding... and then reinstall the final row of siding.

Question 7. Another difficult one to explain. If you Google "kickout flashing" you might come up with some good illustrations. But in short, you usually want that initial step flashing to divert water away from that corner. It also actually should be thought of as kicking out water onto the row of siding BELOW the one it is on now. (whereas right now it is on top of the row ABOVE where it needs to be.) You would also want to add a corner flashing behind the gutter that would flash the siding-fascia connection below. The top edge of this corner flashing would be cut so as to provide a tight seal against the bottom of your kickout flashing. Again, as you try and flash this area, try to make it water tight with flashings and counter-flashings, so that even if that first row of siding was not even on there, it won't leak. If that initial step flashing was bent at a perfect 90 degree angle and was installed tight to the siding like it should be (to the piece of siding on the row BELOW where it is now) you wouldn't have any problem with blow back. It can also be left 1" longer if desired to act as a drip edge. I will usually double up that initial piece of step flashing, making one piece fit tight, as described above... and then lay another one on top that is bent more like a kickout flashing. The resulting gap between the two is just a void that should not leak if done properly.

This may just be my longest consultation reply ever. Hope some of it makes sense.
Old 03-17-09, 07:33 AM
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I have no real comments on the flashing, as XSleeper did a great job adressing the questions.

I just think this thread is a perfect example of how things should be done. Good pictures and descriptions, excellent advice
Old 03-17-09, 12:18 PM
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Thank you very much for the excellent feedback. I think I understand now and will give it a whirl. I prefer to have a plan prior to starting a project and this will certainly get me going. Thanks again.
Old 03-22-09, 08:13 PM
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JoeyP12 this could be a good before and after picture thread. when you get it done the right way put some pictures up.

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