Thread: Flashing between new trim band and brick?

I am repairing deteriorated Masonite panel siding on a rental house I bought. The bottom of the siding was not sealed well, so it has swollen up and pulled apart at the seams. On my test section, I cut off 5 1/2 inches at the bottom of the siding and primed and painted the cut edge. Then I added z-bar flashing behind the siding and on top of a new 5/4 x 6 trim band. The trim board is thick enough to match 1 x 4 vertical trim that is installed on top of the siding at the corners of the house.

My question: Do I need even more flashing or building paper or something else at the top of the bricks? If so, should it go behind the existing building paper, which is partly nailed to the studs (as shown in blue in my diagram) or on top of the existing building paper? There was nothing like that in the original installation.

One detail not shown in my diagram is that the bricks have a rather rough front, so there are small gaps between the trim board and the bricks where the brick surface juts inward by 1/4 inch or so. When the siding was there, someone filled some of the gaps with expanding foam or caulk, but I doubt that it's a good idea to caulk these gaps, because the caulk would inhibit drainage.

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Originally Posted by Bob Hucker

I am repairing deteriorated Masonite panel siding on a rental house I bought. The bottom of the siding was not sealed well, so it has swollen up and pulled apart at the seams. On my test section, I cut off 5 1/2 inches at the bottom of the siding and primed and painted the cut edge. Then I added z-bar flashing behind the siding and on top of a new 5/4 x 6 trim band. The trim board is thick enough to match 1 x 4 vertical trim that is installed on top of the siding at the corners of the house.

My question: Do I need even more flashing or building paper or something else at the top of the bricks? If so, should it go behind the existing building paper, which is partly nailed to the studs (as shown in blue in my diagram) or on top of the existing building paper? There was nothing like that in the original installation.

One detail not shown in my diagram is that the bricks have a rather rough front, so there are small gaps between the trim board and the bricks where the brick surface juts inward by 1/4 inch or so. When the siding was there, someone filled some of the gaps with expanding foam or caulk, but I doubt that it's a good idea to caulk these gaps, because the caulk would inhibit drainage.

Hi Bob,

Ideally, that upper Z-bar flashing would go behind the paper, but if not, any water that gets behind the siding would be caught by the lower flashing. I'm sure others will disagree with me.

Originally Posted by Gunnar Alquist

Hi Bob,

Ideally, that upper Z-bar flashing would go behind the paper, but if not, any water that gets behind the siding would be caught by the lower flashing. I'm sure others will disagree with me.

You could set the upper 'Z' flashing in roof cement, and if you have working room you could use flexible flashing tape along the top of the upper 'Z' flashing.

The lower 'proposed' 'Z' flashing would direct the water out so it does not enter the wall below, but the lower 'Z' flashing would not do anything to protect the wood trim the upper 'Z' flashing is there to protect.

You have the right idea, but under pressure water can enter at the bottom Z and get behind the bricks and wet whatever else is back there.

I would suggest that you extend the lower Z about 1/4" lower than the trim board and put an approx 45 degree bend on it to create a drip edge. I would also seal between the bottom of the flashing (Z bar) and the brick.

Originally Posted by Steven Turetsky

You have the right idea, but under pressure water can enter at the bottom Z and get behind the bricks and wet whatever else is back there.

If the brick veneer is installed properly (and that is not shown in the drawing), then water little water gets past the flashing should be able to be handled by the required 1" minimum air space and weep holes ... which we know are there ...

Hmmmm.

I didn't look at it that way, so in that case he should remove the rest of the flashing too.

Seriously speaking though, based upon the diagram alone and without assuming anything; in my opinion that detail is prone to failure.

I'm not sure everything we need to know is in the picture. Is there framing and substrate above the brick? If not then what is the flashing attached to? if there is then I agree with Steven as the framing and substrate would need to be protected. i also agree that the paper needs to go between the siding and the top flashing

Steven, trouble sleeping? or have you not been to bed yet?

Originally Posted by stanley frost

Steven, trouble sleeping? or have you not been to bed yet?

Both, and I'm up this time every day.

But why r u up so early?

Always up this early

Originally Posted by stanley frost

I'm not sure everything we need to know is in the picture. Is there framing and substrate above the brick? If not then what is the flashing attached to? if there is then I agree with Steven as the framing and substrate would need to be protected. i also agree that the paper needs to go between the siding and the top flashing

Thanks to all for the replies. To clarify a few things...

Yes, there is framing above the brick, and the building paper is nailed to it.

If I cut off the building paper and put the top flashing behind it, I agree that that would ensure that water on the inside of the building paper would make its way to the front of the trim board. However, that would leave no building paper behind the trim board, unless I add another strip.

If I do put the upper flashing on the inside of the building paper, is additional building paper behind the trim board necessary? Also, if the top flashing goes behind the building paper, then is the lower flashing necessary? As the diagram shows, the trim board extends below the top of the brick.

To answer the other comments, the wall does have weep holes at the bottom. I don't know about the required airspace. There is no practical way to tape the upper flashing to the outside of the building paper; doing that would require prying out the already fragile siding more than what seems safe.

bob
yes the lower section needs to be flashed and sealed as Steven said. What will protect the framing from getting wet (Capillary action)? You may be able to get away with not putting in the top flashing and let all the moisture drain to the bottom flashing and drain out but you do need to follow Stevens advice re. extending the flashing, angling it down 45 degrees and sealing the bottom of the flashing.

...and have some type of space/spacer to ensure that the bottom cavity does not become a dead end.

The easier it is to drain; the better it will drain.

Originally Posted by Bob Hucker

There is no practical way to tape the upper flashing to the outside of the building paper; doing that would require prying out the already fragile siding more than what seems safe.

Then apply a thick coat of sealant, roof cement will probably work, to the back of the upper leg of the flashing and shove it up behind the existing siding, then press in place as best possible. That will be about the best way to seal the back of the top leg of the flashing in cases as you describe.

... or you could use a strip of peel and stick, which may be neater. But I really believe if the bottom flashing is done correctly, the top one is not critical.

Originally Posted by Steven Turetsky

But I really believe if the bottom flashing is done correctly, the top one is not critical.

The flashing on top is critical and required, not for stopping water from getting into the lower section of the wall, but because that is wood trim which projects out and a flashing is required there to prevent ('reduce' is a better word) water damage to the wood trim.

Drifting off question: You show 5/4 SPF trim in your drawing. Why not spend a little extra and save yourself maintenance and rot replacement by using cellular PVC? The 5/4 SPF available in my neck of the woods is new growth, finger jointed, pure trash white pine that will start rotting at the first drop of water.

Yes I agree,

I was going to get into that but stopped myself. The top one is serving as little more than a cap, and if made wrong may even have a negative pitch to it, so maybe it would be better to be bent with a pitch away from the building and or replace trim with non water sensitive materials, and or to slope the top of the trim piece itself.

Anyway, if the purpose of that upper flashing is to protect the top of the trim, as is; is prone to failure,

Originally Posted by Steven Turetsky

Anyway, if the purpose of that upper flashing is to protect the top of the trim, as is; is prone to failure,

All 'Z' flashings are prone to failure.

First, because they are made with too small of an upper (hidden) flange and way too small of a lower (exposed) flange.

Then because the 'Z' flashing is usually installed wrong by: a) being installed pushed down tight to the top of the board underneath the flashing, this takes any made-in angle for drainage out by making it flat; b) the upper board is pushed down tight to the top of the now-flat part of the flashing instead of being up at least 1/4" to allow for drainage; c) when the upper board is installed up to allow for that 1/4" air gap between the flashing and the upper board, some unknowing person comes along and caulks that 1/4" gap and sealed back any and all water trying to drain out.