I have Mohawk 5" Hickory that is 3/4" thick that I'm preparing to install. The Directions from Mohawk say to leave a 3/4" expansion all of the way around the room.

Is this an unusually wide gap when you consider that most baseboard is 1/2 to 5/8" thick?

Is it just expected that you will have to use base and quarter round to cover the gap?

How do you deal with with door trim? If you undercut the trim so the floor slides under but still 3/4" from the wall, then there is a big gap showing on the thin side of the trim.

They also say to nail and glue any flooring wider than 4". Is this normal?


Thanks for any help that you can give.

Will

I steer my clients away from carpet manufacturer wood flooring. For one their tech dept will screw you in a heartbeat and they are not very well read in wood science....mooo

Leaving a 3/4" expansion space is typical for a 3/4" product.
The options are....You can use baseboard & quarter round, you can use shoe moulding on top of the base ( not as bulky as quarter round), or you can undercut the drywall and just go with base.

Door jambs & casings are undercut deep, to allow for the 3/4".

There are more and more manufacturers specifying gluing in addition to nailing on 3/4", on their wider products. IMO this is a questionable necessity on a 5" width, although a more solid installation. But if the manuf. calls for it, do it.

Your going to see big issues before any ¾" gap is taken up in expansion.

I have seen numerous buckled floors and the expansion gap is still there.

Depends on the geographic location of the home, and obviously alot of factors.
In coastal areas I have seen 3/4" expansion space left on 3/4 solid and theres 1/8" to 1/4" left, at certain times of the year, and the floor is flat.

I dont think it's worth taking the chance, or flushing the warantee.

What I don't understand is: If the flooring material is nailed or glued to the subfloor, and the surrounding wall framing is nailed or screwed to the same subfloor, how and where are the expansion gaps changing?

Wood moves. If you dont leave adequate expansion space, if it expands with no where to go, it will buckle. Especially critical on solid, ( engineered with it's cross grain construction, is more stable, although expansion space is still needed).
It will move more in the width of the planks, minimal if any at the ends.

Re: One of your original questions regarding Mohawks requirement for gluing in addition to nailing... One of their considerations is that adding gluing to a naildown installation, with a solid, you will experience less movement. BUT the floor will still move.

I know wood moves, but it seems most of the stress would come from where the flooring material is nailed and glued to the subfloor. I'd think there would be more chance for buckling in the center of the floor than movement at the perimeter expansion gaps. It's almost like you should leave small gaps between the planks, while installing the floor. I can see how a floating floor would move a lot.

Imagine if you have a 5" plank in a 20'x20' room. That's 48 plank widths. If each of the 48 planks expand microscopically, and pushes the plank next to it, by the time this expansion reaches the wall , you need that release space, or the floor will buckle.
The expansion will also tend to cause more movement toward the tongue side of the plank.

You bring up a good point about space inbetween planks for movement. We have done commercial installations ( long stretches ), of solid, unfinished, 2 1/4" widths, where we have set a penny in the seam rows, every so often, to allow for extra expansion. Cosmetically this doesnt go over well for pre-finished.

when we lay a gym hall we hit the tounge of every 6th row plank to allow for expansion. flat steel face of the mallet as we find this works better than the manufactures own brand spacers

That was my argument also. That is why wood science is so important to learn.

If a fastened board next to the wall, moved ½", what happens when it loses the moisture it gained.
What happens to a fastener with a ½" pull on it, especially one that is in at a 45º?

Or was it not properly acclimated to a higher MC, to begin with?

I've installed the flooring in one of the two rooms and am very happy with the appearance. It was installed with "S" beads of liquid nails under every board and 2" nails every 8-10 inches in the field per the mfg specs. When the floor sits for multiple hours or overnight, the first time you walk across it, you hear a little bit of a "crinkling" sound that is kinda like breaking a toothpick but not quite that loud. Is this typical in a new installation? Does the floor set in and this sound go away with time? It isn't enough noise to worry about, I'm mainly just curious.

Now as far as the flooring manufacturer is concerned. I'm very unimpressed with Mohawk (or whoever did their mill work) in case anyone on this forum is considering buying wood from them. A significant number of boards (10-15%) are missing all or part of the tongue. Upon inspection, you can see that when the planks were cut rough, some boards taper in width from one end to the other. The result is that one end is only 5" wide leaving no wood for the tongue to be milled out of. The other end is the correct width (5.25" with the tongue) for proper milling. You can tell this b/c the tongue isn't split off where it is missing. You can actually see the rough saw marks on the edge of the board. I've discussed this with Lowe's who sold me the product and they are going to replace the defect boards but it still ticks me off. You shouldn't have to sort through all of the boards to determine if they are usable or not. I'm trying to use as many of the longer boards that have most of the tongue for cut pieces on the ends as I can. Hopefully I won't run out of wood in the 2nd room (bought 10% excess). Let me know if anyone else has experienced the same.

Look at the side of the tube of Liquid Nails :Not for wood flooring:

Too brittle when it sets up.

Mohawk tech support recommended Liquid Nails. What do you recommend?

Call them back and ask them if they ever actually read that tube. Perry is correct, like always.