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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.


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

  • You should probably ask the people making the claim (or at least link to them in your answer). I subscribe to your reasoning. – isherwood Jun 28 '18 at 21:16
  • @isherwood I updated my question with some links. On a couple articles, I seriously think they got "horizontal" and "vertical" backwards! idk.. – tehDorf Jun 28 '18 at 23:47
  • I think verticle has more problems when in a driving rain or when the wind is blowing I have both kinds of homes and less problems with horizontal, if dammaged horizontal is easy remove the bottom 3, 4 boards and replace, if verticle repair work looks like cap as every board needs to be cut new z flashing installed and whatever in the new section because matching it years later is not really possible because of the z flashing so it might be better to totally change it up. – Ed Beal Jun 29 '18 at 19:07
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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.

  • Thanks for the response, that was helpful! I hope my question didn't come across as "which is better overall", though. I tried to keep the question title short, but the focus of my question was specifically for shedding water (not leaking). I'll try to think of a better title that can communicate that succinctly. – tehDorf Jun 28 '18 at 23:56
  • @tehDorf Yes, shedding water is one thing, but actually water gets “pushed” up hill when it hits the house, so to speak. When wind hits the house it creates pressure and will push water around boards and up under lapped building paper. Where I live, it comes horizontally and a wall works better than a roof keeping you dry. – Lee Sam Jun 29 '18 at 1:00
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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.

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    That's interesting that your siding failed from the boards splitting. Was it stained or painted, and how long did it last? – tehDorf Jun 29 '18 at 0:03
  • @tehDorf I think they may have been painted but they were in pretty rough shape.. The house was around 75 years old when I replaced them. I have old pictures from when it was built so it could have been original unless they were replaced to match. So again, they were probably long overdue for replacement. – JimmyJames Jun 29 '18 at 13:46
  • @tehDorf I added a note based on your links. – JimmyJames Jun 29 '18 at 17:18

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