If you have a concrete slab under the carpet pad then a traditional nail down floor is out. That leaves snap together floating floors. They are finished with each companies secret sauce. They will probably yellow over time. Have you decided against a quality tile floor?

Classic Structures, sorry, but we really do not like tile floors (we do have tile in several of our rooms).

We might consider something like LVP or laminate, but not yet a fan of either of those choices.

Patricia Colwell Consulting; thanks, hadn't thought about a dehumidifier. I'll have to look into those, and see what they are like (maintenance, purchase & operating costs, effectiveness, etc.). Also, I should have mentioned, we were likely going for engineered, not solid wood. That does seem preferred for installation over slab (otherwise we'd need to lay a plywood subfloor -- ugh!).

Thanks!

The whole home dehumidifier (attached to your HVAC system) will do the trick. Installing the wood flooring in the spring or the fall (the shoulder seasons) will certainly help. New windows that block a tremendous amount of UV (75% block is probably where you want to be in CA).

As for yellowing, stay away from maple...it turns yellow just by turning on an overhead light. And yes it is normally the finish that yellows and not the wood species (maple and cherry being the two notable exceptions for local species that are photo sensitive). And if you want to stay away from yellowing (we are assuming you want a factory finish) then new windows would be an excellent place to start (75% UV block will pretty much do the trick).

And for LVP...it doesn't like heat. In fact it does some REALLY strange things when direct sunlight hits the floor. The ROOM temperature might be 85 F (which is too high for LVP) but the sunlight on the FLOOR can be 115 F or higher. LVP is vinyl. Vinyl melts when it gets to hot. As it heats up and then cools down (day time high to night time low), it warps and discolours. Some vinyl products turned purplish-black when exposed to too much heat (anything over 85 F is excessive for indoor furnishings). To stop the EXCESSIVE heat, you will want new windows. The 75% UV block would be the lowest you would go (which is a mid-range product...not super cheap but not super expensive either). You could look at the best of the best = 95% UV block (indoor plants die at this level of UV block) if you are really interested in LVP and keeping the home cool.

Laminate has few issues with direct heat...but even laminate has limits. Some will fade in direct sunlight that is SUPER hot. You will void the warranty on the laminate once the home temps reach higher than 85 F. And again the humidity needs to be between 40% - 60% for laminate. To block some of that heat (you guessed it), you will want to look at new windows. For laminate, the entry level UV block of 45% - 50% is going to be "good enough".

Some great information, SJ McCarthy -- thank you!!

Our windows are actually all covered in summer (i.e., we keep the window covers down), PLUS all windows have 80% or 90% UV-blocking sunscreens on them. The high indoor temps are simply from high outdoor temps. It doesn't happen often or long (usually 85F is the limit), but it does happen. Mainly because we rarely run the A/C.

Neither of us wanted carpeting again, but it sounds like that is the choice with the fewest issues. I realize you're saying we can get around all of these problems and install whatever we like. But I'm not sure we are willing to go through the necessary steps. To be honest, it's likely the heat & humidity problems would be solved by simply using the heater & a/c more (like "normal" people). That's the simplest solution of all, but over several decades it would not be the cheapest. (But it would be the most comfortable!)

Lots to think about. By the way, the yellowest of all our woods are our cabinets -- we selected maple throughout. Had NO idea!

Thanks again.

If you don't care for carpet, why not go for engineered wood? we had laminate installed in our home with slab foundation (in Sacramento) and it's been great! super easy to live with and huge improvement over carpet. They used a high quality underlayment/vapor barrier so it had a reasonable sound as well. If your neighborhood can sustain the cost of engineered wood why not visit some showrooms and learn about your options?

Even though your indoor RHs have hit some high numbers, it's pretty dry here. Arid. Consider looking at you seasonal averages not your extremes

Thanks, melle-sacto, great to hear experiences from our area. Haven't given up on wood, so I think you're right. The next step is to start visiting some local showrooms and talk, listen, and look. We had a laminate floor in our previous house, and I really hated it (my wife did not). But it was the original Pergo, and I understand that laminate has come a long way since then. So more to explore.

It is supposed to be dry here (but not tomorrow!). I'm sure a lot of it is because we don't run our heater often, so we might consider doing that if we settle on hardwood. Our seasonal average is probably fine, but I'd be worried the extremes are relevant, too. But I'm sure we'll learn once we start visiting showrooms.

Thanks!

Engineered wood flooring will give you a little wider range of temp/humidity. High quality Engineered can also be finished on site like Solid. It can also be refinished again in the future.

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That's some darned fine homework. I've never seen someone go into that much detail. Quite frankly I see no warning signs. Maybe a few weeks where it was under 40%. The higher periods are balanced out. Not long enough to create any issues, unless the material choice has a high moisture content when installed and shrinkage occurs.

I'm curious where all this emphasis of staying so tight within a Rh range came from? Geez, it's like a death threat if you go outside that range. That's the internet for you! Sure, if you're in the desert and the Rh stays in the teens and twenties for prolonged periods of time, any hardwood or other floor coverings for that matter can be affected. Constant high Rh is tropical areas without any HVAC systems can create issues as well, unless the material is acclimated to that level of comfort.

"But I'm sure we'll learn once we start visiting showrooms."

That is likely to create confusion as you'll hear ten different opinions.

Good luck!

Oak & Broad - Finishes are something that I've just barely started reading about. One thing that bothered me was it seems there are broadly two choices: A type of (factory applied) metal oxide (usually aluminum), which provides a tough finish but makes it very difficult and expensive to repair or refinish. Or an oil or polyurethane finish that can be factory- or site- applied, allows for normal repairs and refinishing -- but requires annual or semi-annual maintenance (i.e., re-application). Pros and cons to both; yet another tough choice!

Uptown Floors - The worry about staying with a tight RH range comes from reading "advice" on the internet, of course. But also numerous manufacturer's warranties that say the RH must be within a specified range (and I've seen ranges as tight as 30 - 50), or the warranty is voided. Since we have had times when we've spent many weeks > 50% RH, that concerns me. But I suppose I just need to narrow the search to flooring that allows for 55% or even 60% RH. I'm not concerned about the low end, despite outside summer humidity that often drops to 20% or lower -- our house always seems to be 30% or higher. Ha!! You're undoubtedly right -- the more I speak to people, the more confused I will likely become.

Thanks for your thoughts.

I too wanted to comment (but forgot) about the amazing "home work" done by the OP. Great work! And yes, running the A/C a bit more can and will do everything you want. It will reduce the indoor temp to keep the home more comfortable (high 70's could be a goal) AND A/C has the secondary capacity to reduce humidity...it's actually part of the cooling system itself.

If you run the A/C during the hottest times of the year (set it for high 70's) and then see what your HUMIDITY does while it runs, you will have figured out the final piece of the pie! And let's just say you are 18 steps ahead of anyone else who has contemplated hardwoods! Good work! You are almost there.

If carpet is something you don't mind and you feel you are content with your home's current situation/energy use, then you are heading in the right direction. Hardwoods are beautiful and the increase the value of the home (you pretty much get back what you paid for with hardwood). But you need to be able to life with your house and live with your energy expenditures at the same time.

If you ever feel like selling, you can invest in hardwoods at that time...or simply sell the property 'as-is'.

Good work. The only thing missing is the A/C running a bit more during the hottest months so that you can monitor the HUMIDITY while it runs. That's the last piece of the puzzle....if you choose to continue the homework you started a year ago.

Ha; thanks! I figure if we're going to spend $15K - $20K, we should at least make sure (as much as possible) that we're aware of any potential pitfalls.

Unfortunately I couldn't get the dates to show up in that graph, but most of the periods of higher humidity actually occur in the winter time, not the summer. But the principle is the same -- we just need to run the heater more. We usually warm it up to 65F in the morning, then let it cool down during the day (no lower than 60F). If we simply kept it at 65F all day, we'd be more comfortable, the indoor humidity would be lower, but we'd be out about $500 or so per year. Might be worth it, though, regardless of flooring choice (we have been thinking about it).

This is our "forever" house; we expect to die here. So resale value is of very minimal concern. We both love the look of wood flooring, but are unsure how we'll be living with a houseful of it. We are very used to carpeting, but like the idea of knowing we can more easily clean any dust and dirt (rather than have it embedded in carpet). But the softness and warmth of carpeting is nice, too. Ha!