As above...National Hardwood Flooring & Supplies beat me to it.

You are welcome to have the wider hardwood planks - as soon as you update your HVAC system to include "pin-point-accurate" humidity and temperature control. That means you are able to step up to your digital thermostat and program the Humidistat (the humidity control) to "sit" between 45% - 55% at all times. Depending on where you live, you could be adding a whole-home humidifier or dehumidifier or both. These can be a $6K - $10K upgrade depending on the system you already have.

Once you have paid for the upgrade, you can have 8" wide planks if you like....but until then, you will want to stick with the narrower planks (3" would be about as wide as you want to go).

3-1/4" could be a good choice. It sets you apart from the standard narrow width but not so wide as to cause problems. It's almost the same price as 2-1/4" also.

What are the humidity extremes you experience there?

I have a 50 year old house and we had 3" wide white oak installed. Site finished.

Our contractor did a great job. No gaps visible 4 years later. And Missouri is the Humidity King.

I agree with jfcwood. 3 1/4 is a good width. It's not too wide and with proper installation, acclimation, care and maintenance, you shouldn't have problems with gaps and spacing.

We have installed 4" and 5" many many times. It is important to let these floors acclimate in your home for a while- a least a week- with the proper temperature and humidity controls. It's always a good idea to glue and staple 4" and is a MUST to do so with 5"+ hardwoods. Don't let anyone tell you otherwise- it is VERY important to glue wide plank hardwoods as well as staple.

All of the pro's on this post make valuable points.

Oh, one last point- you said the floors were squeaky- maybe it would be worth having your contractor assess the current state of the sub-floor. Depending on what he finds- another layer a plywood MAY be worth adding for extra support and stability of the new hardwood. We find with older homes, screws weren't used, only nails, which causes movement and thus squeaking. Maybe a new layer isn't needed and some screws will get the squeaks out. Its worth the conversation with him. good luck to you!

Most of what's been mentioned above is futile unless the area underneath resides in the same relative humidity zone as the newly installed area. Problems happen too frequently with wider solid hardwoods. IE: wet basements, crawlspaces.

And felt or others won't do the trick either after the installer punches thousands of holes through it. And I have doubts about using adhesive as well unless it's full spread and nailed. Moisture is deadly strong. After all, the ancients used wood to split stone after it got wet enough and swelled.

$ 20,000 nightmare. High moisture levels in basement.

Ken Fisher

Think about premium quality engineered floors

Is that repairable?

With band aids then you never know if that'll work. This was an inspection. The customer had it ripped out and reinstalled, once all ducks were in order. Fine to this day. 5 inch width solid. Good idea to use a hygrometer or two as someone mentioned but in the crawlspace also. Good time of the year for it with rainy months.

As obsessed as some people are today with new hardwood floors, it's not so uncommon to have dehumidifiers in crawlspaces too. Keeps mold away too.

Oh concrete slab. Didn't see that.

I had 4.75" wide solid hardwood installed a couple years ago and I have some gaps (nothing major) and they don't bother me. The floors are beautiful after having ugly worn carpet and orange oak.

"....we will have plywood subfloor on slab."....Ummm????

I'm not a fan of using plywood over concrete. It often causes FAR more problems then it "solves". And I know MANY hardwood flooring professionals who shake their head at that sort of technique.

My other concern about that statement: "...and he is putting some kind of moisture barrier underlayment under the flooring where we will have plywood subfloor on slab". That indicates a vapour barrier OVER plywood that is sitting on the slab. Oh. No. He. Didn't!

When it comes to wooden subfloors, a vapour barrier is NOT allowed. A vapour RETARDANT is allowed (with caution)....but I'm still very worried about "plywood over slab" and then "vapour barrier over the plywood over the slab". These could be red flags.

My spidy senses are tingling. I think you need to speak with someone who is NWFA certified to see how this whole plan is going to "work out". It *might work....or it could go south very quickly.

Thanks for the helpful feedback. I am probably not explaining things well and doing a disservice to my contractor. There is one part of our home that was a garage and previously converted to a family room. I know he is redoing the sub-flooring and we are also doing spray foam insulation in this area of the house which includes the floors. I'm not sure the exact order of how everything will be done regarding the foam, barriers, and sub-floor, but I will be sure to ask him now. Thanks again!

Short version - If your contractor is putting some plywood over concrete, make sure there's a moisture barrier between the concrete and plywood, not on top of the plywood. Also, felt paper is not a moisture barrier so use heavy poly sheeting or an actual flooring membrane.

As jfcwood mentions, when adding "plywood" over a concrete slab, the most technically "sound" approach is to build a sleeper subfloor over a vapour barrier. These sleeper subfloors often raise the height of the floor by 6" or more. For that reason, many people balk at this idea (not many rooms in a home can "lose" 6" - 8" of floor-ceiling height. And that pushes people to want the less stable "plywood on concrete" option (plywood laid directly over concrete - with or without vapour barrier). This "plywood directly over concrete" is the version I'm not very happy with.

If this is a garage conversion, hopefully you have the space to build up a sleeper subfloor. That would be the proper wording to use when asking your contractor for more details. As you say, it may be your wording - not his approach - that is what is causing us some confusion. Let's see what he says.

People in Florida use plywood on grade all the time. As long as it's protected from moisture from underneath there should be no issues.

"People in Florida use plywood on grade all the time."

Have done plenty of those too. Quite frankly I cannot recall a sleeper job. I remember fixing some. It's really become outdated. The black mastic method replaced it. Then urethane adhesives with plywood scored on the backside, cut into 2 x 8 foot sections. Then there are floating plywood sub floor options. And now 5/8 or 3/4 inch thick engineered glued direct without plywood.

I would guess the plywood method will eventually be a thing of the past as well, except for those that think they need the real thing.

It's cost effective, reduces labor time and vertical height of the finished floor, provides better stability and a few other factors.

3/4 Inch engineered unfinished
3/4 Inch engineered prefinished

An illustration...

Ken Fisher

Uptown Floors

In the days before plywood, and even after, we used sleepers a lot. At one time we even owned a tar pot. We would mop hot tar on the concrete and lay pt 2x4s 12" on center then nail flooring directly to the sleepers.

Still need to talk to my contractor about this (we are a ways away from the flooring in the project), but we do have what looks like about 4" sleepers between the concrete and old sub-floor. I will confirm with him what the plan is.

Ken - I didn't know you can get unfinished engineered. That's interesting. I wanted to finish on site to avoid having a bevel. How many times can you refinish a 6mm wear layer? Is unfinished engineered be nailed and finished just like a solid hardwood? Is it also tongue and groove?

Sorry for all the questions. This is all new to me.

"How many times can you refinish a 6mm wear layer?"

Practically the same as a solid hardwood. You'll get varying opinions on this. I'd say three using 1/16 of an inch taken off each time. Solid maybe four, but the top of the grooves (photo) may begin to fall out. But if the sub floor isn't flat it will reduce the number in both cases.

Every job is different. Numbers could be higher.

"Is unfinished engineered be nailed and finished just like a solid hardwood? Is it also tongue and groove?"

Yes and yes.