I've heard and read talk about installing washer rows to allow expansion in wood floors.
I must admit that I've never done this.
i am, however concerned about installing right now, humidity levels have been crazy lately -- subfloors are reading 12-15% moisture avg. and all of the flooring we're getting comes in at 6-7%. Problem is trying to get that mc up in the flooring, seems to take forever.
We try to never install until in the safe range,but homeowners often get antsy and decide to "hope for the best" instead of giving it another week.
Just wondering what you guys do this time of year when you anticipate expansion after installation...and what about washer rows??

if by washer rows you mean spacers then well they never really made a difference for me. I've done this with prefinished wide plank boards using putty knives and it was pointless. Guess it all depends on the flooring, prefinished or unfinished. Unfinished isn't a bid deal because you can install it at the 6-7% let it do it's thing for a few days then sand it. Prefinished varies alot... any of the kinds i've used never swelled when i thought they would. I Figure it's better to have a little expansion than having permanant gaps but thats just me.


Not sure where your located either but where i am it's cold and dry so it's not a problem now.

I generally leave 3/8" expansion everywhere possible. I've never left gaps in a floor, but another floor guy told me he does that when he anticipates expansion. I didn't have time to go into detail with him, got me curious I guess.

Using washers works.If you know for sure that your flooring will expand, then you try to anticipate how much and space accordingly. On a 3-5-7 random plank floor, I spaced every 3rd row and the floor closed right up after I got to the finishing stage. During sanding, nothing much happened because the moisture was coming up through the wood and out into the house.By the time I got to the third coat, the floor closed up tight and two of the boards cupped a little but 90% of the floor managed to stay flat.Sealing the wood or using pre finished is different than installing bare wood. With bare wood, some of the moisture coming up from underneath can escape out of the board.

On a different floor, I installed washers ever 5 rows.It was a 5 inch maple floor and ever single space closed up.In the winter time, one of the rows opens back up but none of the other rows do.

If you don't space and the floor cups, you can get checking and splitting.Another installer put in a 5 inch white oak floor and didn't' allow for any spacer rows.The floor cupped severely and some of the boards "checked" from all the pressure being exerted on them. So yes, you can sand the cupping out but you can't sand out a split/checked board I sanded the floor flat but a few boards gave way to the pressure.And spacing some rows could have prevented that .

You can calculate the expansion and contraction if you know a few figures. The dimensional shrink swell coefficient is directly related to the m/c the specie type and width. almost all the gym floors I see have the rows in there. those guys have been doing it that way forever especially since schools gyms are notoriously left in an uncontrolled environment.

I unfortunately do not know how to make these calculations. I use the force mostly and choose somewhere between 3 and 6 rows to add the spacers.

here is how page six.
ttp://www.crescenthardwood.com/nwfa/water_and_wood.pdf
these calculations are unbound boards so in service the numbers a diminished a bit.

I think it's gonna be necessary on an upcoming job-5" hard maple select, unfinished.
Kevin, I couldn't get the link to work. Right now we're sitting at 9-11 mc in the floooring and 12-13% in the subfloor. Been that way for 3 weeks no changes. Still not close enough for me to feel safe nailing it tight, homeowner is chomping at the bit,i'll probably use washers about every 4-5 rows. Maybe i can delay sanding for a week or so.

Sounds like a good plan. You might find that the spaces don't close up until you actually get some finish on the floor or shortly thereafter.Maple is a very diabolical wood.Never turn your back on it

I never ever used spacers and am glad i did..saw so many floors never close..

Why not just split the job?
start in the middle?..
leave proper expansion on all perimeters and voila..nothing..
hit the beams when nailing..proper barrier...should yield you a great probelm free result.

as stated..Maple is a bitch even when everything seems perfect..

It will be a split install, changing directions in every doorway, big rooms so we'll need to start from each transition, the hall worries me most as it has doors on all four sides and these guys are adamant about using grout between tile & wood so no expansion room at all in this area.

use matching grout caulk at doorways to tile..its a must ..not an option..

I agree, can't convince the contractor he says he's never had a problem using grout, and the home owner is antsy so we're moving with it I guess.
He's been warned, and will probably have to caulk there anyway when the wood pushes the grout out. I'll probably leave the grout joints wide so if it does expand they don't close up.