Is vertical siding more durable than horizontal siding, all things being equal?

Question

I'm looking into choosing the siding for a new construction and I'm finding that blogs and websites seem to be suggesting batt & board is better than horizontal siding (e.g. vinyl, hardiplank, etc) for shedding rain water.

This seems counter intuitive:

• In horizontal siding, gravity would be pulling the water away from the seams. In vertical siding, gravity would be pulling the water along the seams.
• I would expect some amount of warping/twisting in either setup (or at least expansion/contraction with the heat of the day), which would seem to affect the vertical siding more. If horizontal siding sags, twists, or separates 1/4" from the piece above or below it, no problem, right? If a batt separates 1/4" from the board, I wouldn't be surprised if water gets sucked into the crack from surface tension.

I think I must be missing something, either in one of my above assumptions or in a lack of understanding of batt & board construction.

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Reference Articles from Google search batt and board siding vs horizontal siding:

• "One downside to horizontal siding, in terms of durability, is the potential for rainwater to leak underneath the siding strips. This risk is relatively high, especially if you opt for wooden siding panels that will warp over time and can lead to mold and mildew growth, as well as expensive water damage. Vertical siding panels have far fewer instances of this kind of water damage, because any water that hits the surface of the panels drops immediately to the ground." https://modernize.com/home-ideas/33834/choosing-between-vertical-and-horizontal-siding
• "For starters, horizontal siding can be less durable than vertical siding. That's because it's more prone to water damage over time." https://www.exteriormedics.com/blog/picking-sides-vertical-versus-horizontal-siding-installation
• "durable, weathers well" http://farhas.com/which-siding-style-is-right-for-your-home/

Answer 1

Unfortunately rain doesn’t just “run down the siding”. The storms that bring the “weather” also bring the wind.

All siding manufacturers know their product leaks, that’s why they all require a “moisture barrier” installed under their siding. This is mainly because siding is not absolutely stable. That is to say, all boards , (regardless of the shape: board, bevel, shingle, etc.) will twist, warp, cup, etc. because of its grain, species, grade, etc. That’s the beauty of natural wood AND that’s why some of us prefer to use it than use manufacturered wood-looking material, (like Hardi planks, bevel boards, etc. )

If we wanted perfectly uniform and absolutely equal sized siding boards, we’d use vinyl or plastic...or something like that.

Now the horizontal and vertical issues. I see very little difference. I think it’s aesthetics. Often we’re looking to accentuate the vertical and other times the horizontal. There are pros and cons of both: 1) backing for installation, 2) grain orientation, 3) available lengths

1) Studs are vertical so installing horizontal siding is logical. But when you start installing vertical siding you need to plan ahead for horizontal supports to nail the vertical siding into something.

2) Grain runs the length of a board. So, when you install the siding board horizontal, the water will run across the grain, which will tend to “lift” the grain, depending on how the siding was cut from the log. However, vertically installed siding will generally allow water to run “with” the grain, (except the grain doesn’t always run perfectly vertically either).

3) Full boards can be manufactured longer and kept straighter, stable, etc. than beveled siding boards, so there will be more end joints using bevel siding than board and batt siding. Also, the flashing isn’t always visually attractive when “splicing” vertical siding, (that’s why horizontal boards are often used to create an aesthetic horizontal termination appearance).

So, to answer your question, “which is better?” It depends. Just make sure you understand all the ramifications of using each AND then pick the style and pattern you like.

Answer 2

I didn't know it was called that but I had batt & board siding and the result aligned with your intuition. One caveat this siding was many decades old when I bought the home so keep in mind that replacing it was long overdue.

The main problem I noticed with the siding is not that there was an issue with the seams so much as that water shed along the grain of the wood. Over time this resulted in splits in the boards. This allowed water inside the wall and created some problems in the structure of the home.

I replaced it with pine clapboards partly for aesthetics but also because I believe them to be superior. With clapboards, there is overlap. If a board cracks or opens up, there's another underneath (or over it.) I think it's better if the water runs across the grain, not with it. From what I think I understand about wood, water will more easily be absorbed if it drips along the grain.

P.S. Looking at your links, it's important here to distinguish between horizontal siding and lapped horizontal as discussed in the 'farhas' article. I would think vertical is preferable to horizontal if we are talking non-lapped. Water will stick to the underside of a board and ride in between the seams. Once it's on a flat surface, there's no natural path out and it could get behind the board or simply sit on top of one below.