At what wide does flooring have to be face nailed? 5in? 6in? 8in? This would be red maple 3/4 in flooring. Thoughts?
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I've read that 5-6" is the limit for blind nailing. At widths above that I would consider blind nailing as usual plus face screwing and plugging where it will look nice. For my house, I'm planning to blind nail only on 5" wide plank flooring (will have back cuts to help prevent cupping).
Are you putting this over RFH? Even with back cuts, I am still concerned about cupping at 5". I keep going back and forth between 2.5" reccomended and the look I really want 5". Thanks for your input.
I was going to do the RFH, but decided against it due to cost and the insulating properties of the wood itself (i.e. the hardwood flooring actually insulates against the RFH). Didn't think about cupping that might be caused by the RFH. I think that the RFH might not cause extra drying of the wood if the Moisture Content of the wood is already at a good level, but I don't know what that number would be with RFH in your area (without RFH in central North Carolina I'm looking to have my flooring at 7% MC). Anyway, any extra drying caused by RFH would be on the bottom of the board which would cause the board to cup up in the center (because the dryer bottom of the wood shrinks relative to the "wetter" upper side).
RFH by itself is not too much of a problem -- it's when it is combined with a film finish that the excessive drying/warping occurs owing to the ratchet effect of the drying.
When the heating is on, moisture is driven out of the boards through the joints by the steep temperature gradient. When the heating is off, and the temperature gradient between board and room interior is almost flat, the moisture recovery through the joints is much slower. The solution is to use a permeable finish like penetrative oil so that moisture can be shed/re-absorbed by the whole board, not just through the joints. This leads to far less warping and cupping of individual boards.
I agree that it doen't make much sense in the first place to put an insulating material like timber over RFH.
IanDG
What is the R value of 3/4 solid wood? 1.5? 2.0? How much has to be overcome?
The R value really isn't an issue as I understand it.. in that eventually wood will heat up to amibant tempurature.. Put a log in a 70 degree house and at somepoint it will become 70 degrees.. same with wood.. the issue is the slow rate that wood will react to heat. in other words if you turn up the thermstat plan on it getting warmer tomorrow.. or the day after...
I'm gonna use planks that are 20 inches wide (hard maple and burl Oak) my technique is going to be I'll predrill all the holes in the subflooring and then from the bottom up I'll put screws in. that way you won't have the disfigurement of plug holes (filled or not) Since expansion is going to be a major issue with planks that wide what I'll do is wait to install them after the highest humidity we experiance is firmly in place..
I'll clamp everything tightly together, install and then as the air dry's out there will be gaps but they will be the smallest gaps possible..
With boards that wide don't you think there's a danger of the boards themselves splitting when they dry out if they're screwed down tight at maximum humidity?
I'm wondering if a more flexible way of fixing the boards might be better -- something like Bostik's Best, which is capable of being stretched without giving way, or maybe have oversize pilot holes in the sub-floor to allow for some movement.
IanDG
Edited 1/24/2005 2:52 pm ET by IanDG