I am having a new home built here on Vancouver Island in British Columbia, Canada. We do not have the funds to have the flooring done professionally, so I am going to do it myself. It is to be a solid 7" plank, pine floor going onto a plywood subfloor which sits on a 4' crawlspace. I will have a few helpers that have installed their own floors and I have all the necessary tools. I have called two installers for their advice on how to go about this installation. They gave me slightly different advice.

My request is this: can any of you offer me a safest approach to this job? We have built at a bad time of year -- wet with painting is just finishing -- and I am worried about moisture and cupping. I will be running heaters and dehumidifiers in an effort to get the moisture % down to 6%-8% in the subfloor. I will then have the flooring delivered and leave it to acclimate until it and the subfloor are within 2%. I have been told to use a vapour barrier of 6mil poly barrier (taped) cover with 30 minute builder paper. One installer told me to be sure to use cleats instead of staples and to use headless screws along the face of each plank (6 screws and 6 cleats per 8 feet of board). Does this sound like a good approach?

Any argument or advice you can give me would be much appreciated. I am going to have to wrestle with 2200sf of it!

Thanks.

Christopher.

ps. We plan to stain it and finish it with a penetrating oil product.

Make sure to acclimate at least two weeks and that your relative interior humidity (RH) is between 40 to 50 %. Is your plank T&G? If so, you could glue to the subfloor and blind nail into the tongue. Also, face nailing is also done with pine plank. But which nails to use? Trim head screws sound like a good option if your fastening from the top. Your poly vapor barrier needs to go on the ground under your house. Be sure to provide lots of venting to your crawl space and good lot drainage as well. If you choose to glue and toe nail, you can use a quality urethane aqdhesive (like Bostick's) or go with the bead of adhesive every 8" using PL400. Cleats or staples will work the same in this case as the glue or face nailing will be doing most of the job of holding the floor down.

Thanks for your thoughts Gary. When you say the vapour barrier poly needs to go in the ground under the house, do you mean in the crawlspace? Our crawlspace has a concrete floor to it. Do I still need some sort of poly barrier under the house?

As for the gluing,I assume that means gluing the planks directly onto the plywood sunbfloor. Or do I still need some vapour barrier between the planks and the subfloor? Thanks again.

Sorry. The planks are T&G.

You still need a 6 to 8 mil polyethylene vapor barrier UNDER your house IN THE CRAWL SPACE over the concrete. DO NOT put the poly over the plywood. Once your plywood registers around 8 to 10 % MC, then it is dry enough to install over. The poly under the house will keep it dry, along with good cross flow ventalation and proper lot drainage. Then you can glue the pine plank down instead of face nailing it. Personally, I think it would be better to glue in this case because you are using 7" plank; and not the usually much wider pine plank which has been tradionally face nailed. Because your planks are narrower than the normal pine floor, I think face nailing may look odd. Full spread gluing with Bostick's Best works great BUT is messy and expensive. Similar results can be had using PL400. Apply a generous bead two inches in from the ends and every 8" across the back of the boards. Keep away from the T&G's. I lay the boards face down, glue them, flip them over and tap into place. Then I toe nail (blind nail) with a Bostitch M111-FS using 2" staples. I only face nail when I cannot use the blind nailer anymore (up against a wall). For this system to work well, your subfloors need to be dry, flat and clean. You do not place a vapor barrier over the plywood as you are gluing directly to the subfloor. 15 lb or 30 lb asphalt felt are NOT vapor barriers anyway. They are vapor retarders. You absolutely need a good moisture meter. If the readings are not correct, you could have big problems. Your subfloors need to remain dry at all times. That is what the poly vapor barrier under the house is for. But it will fail if you allow water to infiltrate under your house. That is why your need to have the ground around your house fall away from the house and use piping to divert rain water from the gutters and downspouts. If you do all this properly, you should have no problems. This is one way Carlisle Restoration recommends installing their pine floors.