I'm taking you for your word about keeping the RH at or above 35%. But that sure sounds like the result from extremely low humidity .... say 20% or lower.

Does she have any vent-free gas appliances such as non-vented gas logs?

She has a gas fireplace that is vented to the outside. There are no other gas sources. For heat she has hot water / baseboard heaters so there's no way to add humidity so that's why she uses the 2 portable ones.

The flooring salesperson advised going with the engineered hardwood as opposed to regular full-thickness hardwood flooring b/c of that type of heating and the climate being dry in winter.

Is all engineered hardwood prone to checking? Any species better than others? I can't seem to find much info about this. Thanks for any help.

I have seen face checking often with engineered wood.

Be careful with the gypcrete issue. Gypcrete has been known to be problematical for some flooring installs, so I am not as surprised as the Mannington reps are about the 'movement problem' with your floor.

Make sure a leveling compound is used that is compatible with Gypcrete...not all are. There are some made specifically for smoothing and filling Gypcrete. Search the internet for recommended brands. I remember seeing an advertisement claiming 'suitable for use over Gypcrete'...but I cannot remember the product name or manufacturer.

Good luck.

Hickory does not lend itself well to climate and moisture extremes. It is more unstable than most domestic wood species.

The issue with Gypcrete was poor bonding of adhesives. Get the species your mom wants, but Jerry is correct regarding moisture extremes.

A sawn veneer product will have less checking than those produced by the rotary peel method. The difference here is how the veneers are cut from the log. One is sawn while the other is peeled from the log (much like peeling an onion).

jerry t,

DW likes the look of Hickory for a remodel we are doing. Your post has me a bit worried about that.

We get humid summers and dry winters, controlled as best as we can with the HVAC. We were seriously considering an engineered Hickory - is that a mistake? We are already concerned about our 110 lb. dog and concrete subfloor.

What is face-checking, btw? I'm a flooring rookie...

Jerry t,

You mention "domestic wood species" so I'm thinking that means we should pass on the species like sapele, tigerwood, etc.?? Four of the suggested Mannington options they gave my mom that are in the same color range as her hickory that they said would be less prone to checking than hickory are Madison oak, sapele, Bennelong cherry and Canelo teak. I think at least 2 of those are from tropical places (and the teak and cherry are a lot more money) so I'm still confused about the checking issue--which species would be less likely to check? Thanks.

And I was trying to be so careful how I worded that :). Hickory is fine to use. NOFMA has a well written article on selecting a species that I will link to below.

Checking is not a common problem one will run into everyday. It is where the wood drys out too much and starts to split in the top face (wear) layer of an engineered wood. Inside environments should be maintained at above 30% RH. Some parts of the country the inside RH will drop down to the teens or single digits during the heating season. That is where dry cupping or checking can occur. If you are partial to an exotic wood, most will work if they are manufactured correctly, installed correctly and maintained correctly.

When i asked about non-vented gas logs, they can be problematic too because they emit huge amounts of moisture into the inside environment. If a house is too tight you can get condensation forming on colder flat surfaces. That can cause the wood to gain too much moisture, then when it drys out it can and will check. Too high of an RH level is just as bad as too low.

Not every single home built in the US is a prime candidate for a wood floor. The manufacturers recognize that and throw the responsibility of maintaining the RH levels on the end user. Fair or not, that's the way the current system works.

Here is a link that might be useful: NOFMA species selection

Jerry, thanks for the reply and the link to that article. I just checked in quickly before going to work but will read the full article tonight. I also did a quick search of the FCI database and saw an article on imported wood so will have to read that too. We're going looking at wood tomorrow as my mom is living with a partially ripped up floor and not enjoying it of course :(

Thanks again. I really appreciate all of the help here!!

I have another question for you experts....

Today I went looking at engineered hardwood and tried to get some questions answered. When the salesperson said that engineered hardwood (as well as solid hardwood) isn't recommended for installation in condos above the second floor I was pretty surprised; since my mom's condo is on the fourth (and top) floor he said that really wasn't optimal and we should be looking at something else. He said it's harder to maintain decent humidity above that and it "wasn't as stable." I've never heard this before and am sure a lot of condos have hardwood but I just want to check this out. Thanks once again.

There is a known phenomena referred to as "stove pipe effect" or stove piping. It is a legitimate concern for the upper floors in hi-rise condos. I hear of this problem mainly on the upper east coast region. Heat rises and it can create a problem in the heating season known as dry cupping in engineered wood. Solids can be a problem too but in that instance solids would gap, instead of cup.
Inside RH levels have to adequately maintained within a reasonable range to over come that. I don't believe a 4th floor would be that big of a deal, but I am not an expert on this subject.