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They wear sweaters.

In all seriousness though - throughout most of my life heating in most homes in this part of the country was limited to a wood burner in the living room. Maybe a space heater here or there. Other than that you dressed for the season while at home. Winters were short and the hot seasons long, so it really didn’t make sense for anyone to install expensive central heat. You put the money into AC for the summer months, if you had it. This was when AC was for cooling only.

In the last few decades the reverse-cycle split AC system has become very popular so now many people now have that as a heating option in winter but it’s more commonly mini-splits than ducted so still not every room in a typical home will be heated.

Data are always better than conjecture (always assuming that data are not faked, manipulated, or misrepresented... see the axiom 'When a person shows you who they are, BELIEVE THEM.'). The FPL General Technical Report FPL–GTR–282 (aka, Wood Handbook), states that most timbers change length by between 0.1-0.2% from wet to oven dry. Practically speaking, that is as Mr. Arnold suggested close to zero elongation within the range of RH which allow a flattop guitar to survive without stresses in the wood or across glue lines exceeding structural limits.

This post will now be departing the realm of established science with a bit of conjecture concerning my observations and discussions with the Greenridge fellows:

Hypothesis 1: Extended drying times for common fretboard woods such as African and Indian ebonies may induce relief changes in necks over the first decade or two after construction.

Discussion:

- The air-dried timbers such as the rosewoods and particularly the ebonies used in fretboards take much longer to reach EMC than the lower density timbers we commonly use for necks. Ebony seems to be the poster child for being happiest when eventually incorporated in a guitar when having sat in the timber storage room for a decade or two. At least since I've been paying attention to wood supply issues, the most vexing problems seem to be in getting properly seasoned fretboard and bridge stock.

- This would suggest that in general, new guitars would see need for larger and recurring relief adjustment than on older instruments, and that notion seems to agree with what I saw in the Greenridge shop and in the shop records on the recurring 'health and welfare' inspections which we offered our customers. New or near-new Asian-built instruments seemed need at least a yearly tweak to maintain a constant relief setting, while older instruments with adjustable trussrods (e.g., early Taylor, post 1984 Martin, Gibson) seldom needed trussrod tweaks once properly adjusted by a competent luthier.

Hypothesis 2: Slippage due to mechanic wear or movement/wood compression in the channel - particularly of two-way truss rods not fixed in the neck and tension rods - require periodic relief adjustments.

Discussion: The Greenridge crew observed that newer tension rod equipped guitars and those with captured-but-not-fixed-in-position 2-way rods required greater relief adjustments than those instruments with bonded-in-position 1- or 2-way rods or reinforcement rods such as T-bars.

Greenridge saw a very broad range of instruments come in the door, which is likely a consequence of not having had an established reputation for repair of any particular type or brand. Another more generous way to say this is that a reputation existed which was not limited to a particular subset of the guitar or player population. I would assume this is also the case for Mr. Breakstone's shop, as well as others not associated with a particular set of work or marque. That suggests that shops and repair people predominantly working with a focused subset of the guitar population (e.g., vintage Martin guitars) might have seen what is a very different range of experiences re: truss rod adjustments than a shop handling a broader range of instruments. This in turn suggests some qualifiers be applied to statements surrounding truss rod adjustments as expressed within the range of experiences either observed during or related to me at Greenridge:

- For guitars built with well-seasoned neck and fretboard timbers or for older instruments (20+ years), truss rod adjustments due to seasonal RH variations will usually be smaller and less frequent than for instruments made with less well seasoned neck and fretboard timbers

- Marques by builders without access to very well seasoned neck and fretboard timbers might reasonably be expected to require more frequent attention to trussrod settings than those with deep stores of well-seasoned timbers

Obviously, I stand to be corrected, but hope that in the most general sense, some guitars just need a lot more fiddling with stuff than others (PRS US-built Custom 24 as my personal cross to bear re: trussrod stability... often 2-3 days for neck relief to restabilize).

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A constellation only takes shape when one maps the whole.
- Beth Brower

I had a guy come in last year with a guitar I built him 20 years ago and the first thing I look at is the neck and it looked great. I asked him, "did you set the truss rod?" And he didn't even know what I was talking about. The only 'seasonal' changes I notice, at least here in this part of Virginia, which in all fairness doesn't see swings like in the great white north or down under, is 'abuse' changes. Typically that is in the form of fret sprout too.

Not all of course but most it seems. Some necks were just born to be wild. I remember one guy with his electric guitar every winter the neck had a twist in it and come summer it was perfectly flat. Still playable year round though.

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I think that most of the normal action changes we see here in the dry winters and damp summers is because of the changes in the body as mentioned. Many times you can clearly see it. If you don't mind changing the relief then it can be used to make minor action adjustments but I prefer to set and forget relief and instead make two saddles if necessary. I've always delivered two saddles with classical guitars but have had to do it on a few steel strings as well.

I completely concur John. But as most any complete setup will entail at least some tweaking of the truss rod, my comment remains true.

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Pierre Castonguay