I recently inspected a new construction home with Hardie siding and trim. On the front of the home there are two horizontal, decorative trim boards. The lower trim board has flashing installed while the upper board does not. I called out missing flashing.
However, the builder said, “ When a Hardie panel is installed to the OSB wall the decorative horizontal trim in wall & gable doesn’t have to be flashed. The reason is because the trim is fastened to the Hardie panel not to the OSB. Installing the trim this way will
cover the area correctly & will making sure no leaks occur.”
I have tried to find a reference to support their claim but haven’t been able to find any. I may not be looking in the right.
Can anyone who’s smart on Hardie installation help me out?
Right! So, for the bottom trim board, there should be a 1/4” gap above the flashing surface. And, if there’s a panel joint behind the upper board it would also require flashing. But if it’s simply attached to the surface of a panel, it would not need flashing.
That’s my opinion. If there is no panel joint, then the flashing is not necessary. If there is a joint, the flashing should be installed at the top of the lower panel and horizontal batten. Please note, the horizontal batten does not actually cover the joint. As a matter of fact, the batten is not even necessary, it is just there for looks. The main thing is to have flashing covering the top edge of the lower panel (and the top edge of the batten if one is installed).
As far as the gap, I don’t have a big issue if the required gap is filled with flexible caulk. But the issue is that you are not able to determine if the gap is actually there.
Is that board and batten with Hardie and Hardie® Trim Batten Boards?
I don’t know if this helps but these are the installation instructions for Hardie trim boards.
There is a panel joint, don’t let them pull that BS! I will bet my last dollar there is no panel long enough (vertically) to cover both the gable and the sidewall without a joint.
You would have to cut the panel to slip in the z-flashing. That does not make sense to me.
The downside to face attached horizontal trim is that water can collect behind it. I wish they would not attach it flush but rather space a small gap and allow water to drain behind it (like a drain plane).
If installing a decorative horizontal trim (no joint behind), I would preferer caulk over the top. The obvious issue with no caulk and a drain plane is water intrusion through the fasteners that hold the trim on.
That, or glue the trim on so there is no fastener holes. There are some serious adhesives out there nowadays.
Caulk fails and the ledge directs water towards the home. I small bevel would help.
Tiny pin nail holes on a vertical surface are not going to direct water behind the cladding. In the end, it is a big nothing burger either way in most cases.
But lack of flashing at horizontal butt joints, that’s a problem. The OP was on point to question this.
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2: Don’t argue. Act within a professional capacity.
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4: By helping them understand, manufactures installation instructions trump improvisational installation techniques. Do that and everybody wins. The contractor, tradesmen, homeowners, AHJ.
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If filled with caulking, then the water has nowhere to go, and will get trapped behind the siding, and could back up behind the house wrap.
That could lead to major issues.
I have called this out numerous times on brand new construction. Nearly every two story home in my area is block on main floor, and wood at second, covered by hardi on the second. Occasionally, I find the flashing caulked, which completely eliminates the drain path.
