Hello Everyone,
I am in need of some recommendations as I have never before received so much conflicting information than when I have begun researching installing my new kitchen floor.

Here is the background information:
material is 1x8 white pine that I will be ripping to 6 1/2" and then will be milling my own tongue and groove on. The tongue will be 3/8-1/2". I will be spacing the boards 1/16 -1/8 between the boards to allow for expansion and to more closely match the rest of the house. subfloor is 1-1 1/4" plywood. Kitchen is located over a basement. I will be adding some cut nail in the face to match the rest of the house.

Conflict 1 - to glue or not to glue. Depending on where I've looked some people recommend never gluing and some say I should absolutely should be gluing the floor. I originally was against gluing at all but have given in somewhat. I think I have settled on the blind nailing and gluing with PL 400 (as seen on the Carilse site). This as opposed to just nailing or doing a full spread urethane glue.

Conflict 2 - vapor retarder? Most would probably recommend tar paper or some other layer between the plywood subfloor and the pine, however this isn't possible with a glue down. I've also been told to do the full spread urethane glue that will also act as a vapor barrier, but to be honest the cost of doing so is too much. I am thinking to forgo the barrier and just nail and glue to the plywood. This would get many people up in arms but the perm rating of plywood is much better than tar paper.... Another option that I thought of was to coat the subfloor with shellac primer (perm rating (0.4). However this actually might be too high of a perm rating for wood over wood? The basement below is pretty dry but it is not conditioned space.

Any help would be greatly appreciated.

Hi John, A few questions for you to gather more information on your particular installation.

What thickness is the pine? Is it reclaimed wood, or freshly cut?

How do you plan to space the boards before nailing? I wouldn't think this would be necessary for expansion, at least not at every single row. Room for expansion should be at the perimeters of the room, especially across the grain. Is trying to match the rest of the house more of your concern with the row spacing you are planning?

How many square feet are you installing in the kitchen? Cabinets first or after?

When was your house originally constructed? Do you know if a vapor barrier was placed under the concrete basement floor before it was poured? What is the humidity level of your unconditioned basement? Your HVAC system is designed to work with the whole house and would pull humidity out of the basement if the ducts were opened. Is the rest of the house conditioned year round? Do you monitor your indoor humidity levels? What is the climate where you live?

I'm not sure of the thickness of your plywood subfloor. Are you saying an inch and one quarter? Normally, a single layer 3/4" plywood subfloor would be 23/32's actual.

More information would be helpful to accurately answer your concerns. As far as conflict 1, to glue or not. Usually gluing is done over a concrete slab. No reason I can see to do it in your situation. I like to glue my last couple of rows to avoid, or minimize, top nailing. I use PL ProLine polyurethane construction adhesive and only cut back my vapor barrier where it will be glued.

Conflict 2: Yes by all means use an approved vapor barrier. This is very important. I like the silicon coated paper by AllGlobe Inc. out of Canada. It provides a nice clean surface to work on and no smell. Roofing felt is okay too. Do not skip this step.

Additional info will be helpful to specifically and accurately address your concerns. It may take awhile before you get a response as the board can be slow at times but there is a lot of knowledge here.

First off thank you for your time and help. Let's see if I can get the rest of the info here.

The spacing is more to match most of the current floor. I was thinking of make spacers out of rips of wood.

Pine is freah, 3/4 inch. It has been on site for 6 weeks and now that it is milled I have it stickered and it will sit for another 10 days or so.

Sorry for the confusion on the plywood subfloor. I knew it was two layers but I was at work and couldn't remember if it was 3/4 and a 1/2 or two layers of 1/2. It is two layers of 1/2.

Cabinets are going in after floors. It is about 275 sq feet.

House was originally constructed in 1900. Although it was moved in the 60s, so the foundation was built then, and it was also raised at some point too which I think happened in the 90s. I believe that the current pine flooring was put in when it was moved.

I am not sure about the vapor barrier in the basement but I would guess no. Where we are the water level is fairly high, we are close to a tidal river. I do not know the current basement humidity level. The house is a single floor. I live in new jersey where are seasonal swing are pretty dramatic.

I think I at least got most of it. Let me if I should provide any further info.

Thanks again!

You're welcome, glad to be of help.

Ok, this would probably work BUT getting the spacers out after banging the floor together might be a bear. Seems like a lot of extra work, not to mention a place for dirt and debris to collect, especially in a kitchen. I can understand trying to match what is already down but personally, I wouldn't do it. Unless it was installed that way, the flooring you are trying to match gapped for a reason, likely too dry conditions in the winter.

Stickered?, not sure what you mean. I assume it was kilned and seasoned, so your acclimation period should be good. When you say "on site", I take that to mean indoors where it will be installed, not "on site" stored in the garage or basement. Did you buy this wood from a mill, or a lumber yard? What species of pine is it? Also, it might be good insurance to check the moisture level of the pine and sub floor. Sometimes meters can be rented, (or maybe even borrowed?). Kind of expensive to buy for one time use tho'.

You should be good there. Best if the second layer was installed perpendicular to the joists but slightly offset from the first layer, properly screwed or nailed and NOT attached to the joists.

Sounds good. 275 square ft is not a huge installation but with wide board pine make sure to leave recommended expansion space around the perimeters and by any fixed objects. Don't forget that all important moisture barrier!

With the foundation being done in the 60's, I'd say it is likely that no vapor barrier is under the concrete. I don't know when that became code, or standard practice. Not sure what you mean by "raised at some point".

You can check moisture migration from below -through the concrete- by duct taping down a 1ft square piece of plastic film around the edges and leaving it for a few days. Do it in a couple in different locations. Check to see if any condensation appears under the plastic. If it does, you probably should be dehumidifying the basement air. This would be more important to do during the wetter months of the year. You can buy a digital humidity monitor to get a better idea of actual levels. They are inexpensive enough that you might want to get one for each floor. 'Acurite' brand digital units are available at HD for around $10-12.

Living where you do and especially with wide board pine flooring, you want to keep the house humidified in the winter and dehumidified in the summer, 30-55% range if possible.

How are you planning to finish the floor? I know you are planning to match what is already down but if poly'd, it will slow down seasonal moisture changes to the wood over a waxed finish. Since you have so much gapping in the 'original' floor maybe that was a factor? Or perhaps it was installed with gaps for a "vintage look".