Hardwood flooring expansion gap from walls

[branimal]

I'm about to install hardwood flooring. 3/4" prefinished white oak. The directions call for 3/4" spacing off all vertical planes. This is also the National Wood Flooring Association's (NWFA) recommendation.

My main installation areas are 10' wide. From my understanding wide rooms (say 20') will expand more than narrow rooms (10'). There is one area that is 15' wide. But the tongue installation will get reversed in that area - meaning there will be 2 tongues on one board. Other areas are 9' wide.

Can I get away with a smaller gap? Say 3/8" or 7/16". Most baseboard is 9/16" - 11/16". A 3/4" gap will require shoe moulding, which I'd prefer to avoid. My floors are dead level.

I could undercut the sheetrock, but I'd rather not go thru the hassle.

Thank

 

[ItsNemo]

Let the hardwood sit in the room for a couple weeks before install but I just can't see it moving a full 3/4", there's no way. If it moved that much it would de-nail itself from the floor.

 

[branimal]

Let the hardwood sit in the room for a couple weeks before install but I just can't see it moving a full 3/4", there's no way. If it moved that much it would de-nail itself from the floor.

Woods been sitting there for at least 4 weeks. I got busy with other projects. So it’s definitely acclimated. Thanks

 

[Bill Wright]

Total 3/4” from vertical planeS
Would be 3/8” at each wall?
We’ve gapped 3/8”-1/2” max at walls so base will cover expansion space.

 

[nafterclifen]

Undercutting drywall is a hassle? Wow, ok.

 

[Sluggo0018]

I've done a few oak floors over the years using 3/4 inch solid strips. The most gap I've ever provided is 1/2 inch and I've never had an issue with expansion. Allowing the wood to acclimate is key, but you've already taken care of that.

I agree with not wanting to back cut the drywall. It is an unnecessary inconvenience and mess.

 

[egdede]

Undercutting drywall is a hassle? Wow, ok.

He didn't say it was physically demanding. have you ever cleaned up drywall dust from such a project? Why would it not qualify as a hassle?

 

[branimal]

Total 3/4” from vertical planeS
Would be 3/8” at each wall?
We’ve gapped 3/8”-1/2” max at walls so base will cover expansion space.

The instructions call for 3/4 at each vertical wall. 1 1/2” total at all parallel walls. Edit** One last thing I forgot to mention is the boards at 5” wide.**

 

[rsanter]

Is this floating or nail,down application?
Unless it's a big room you don't need that much space.
If mail,down you should not neeed that much space.
Even with floating floors I don't leave more than 3/8 to 5/16 in a room that is 12 to 14 foot

 

[branimal]

Is this floating or nail,down application?
Unless it's a big room you don't need that much space.
If mail,down you should not neeed that much space.
Even with floating floors I don't leave more than 3/8 to 5/16 in a room that is 12 to 14 foot

Nail down.

 

[Showkey]

Total 3/4” from vertical planeS
Would be 3/8” at each wall?
We’ve gapped 3/8”-1/2” max at walls so base will cover expansion space.

Agree ......this is 1/2” 6” wide solid white oak nailed and glued, 40’ runs 3/8” gap under the trim. Against the door Threshold or against tile or against the brick fireplace there is no gap. In winter when inside humidity is really low ( 20-25%) we get more shrinking or small gaps in the width.

 

[tjansson]

I would take the 3/4 recommendation with a grain of salt... intended for worst case situations.

I installed 3/4" solid birch in my 12x12 bed room last summer. 2.25 & 3.25 mixed width, short lengths, (average about 24") I could not go under the drywall because I had added an additional subfloor layer. I really wanted to use 9/16 thick base without shoe molding, so I used only a 1/4" gap to the drywall instead of the recommended 1/2 or 3/4 or whatever. I glued and nailed the flooring down to minimize movement. The narrow and short flooring pieces I used should move less and my small rooms really shouldn't have that much expansion. I also installed in the summer so the wood would only get smaller in the winter. I haven't had any issues yet...

 

[Toomanytools?]

Where are you located? Humid region or dry? I'm in eastern Washington it's pretty dry. When I installed my white oak 4.5" wide, I left a 1/2" +. I have had no problem with movement. I had a pro come in and sand and finish it, he said 1/4" is fine for our area.

 

[branimal]

New York City. It does get humid here in the summer.

 

[Professor Fate]

You don't have air conditioning?

 

[branimal]

You don't have air conditioning?

I do but I’m not running it when I’m not home.

 

[Git]

Just keep in mind that most of the movement is going to be across the grain. Longitudinal movement (lengthwise) is almost minimal. So in reality, your only dealing with that 3/4" gap on the walls that run parallel with the grain of the flooring

 

[Jlbc212]

I've installed numerous 3/4" thick, solid oak strip flooring. I install them as tight as I can wedging in the last couple of rows. I've never had an issue with expansion.

 

[nafterclifen]

He didn't say it was physically demanding. have you ever cleaned up drywall dust from such a project? Why would it not qualify as a hassle? Are you 13 years old?

I undercut my drywall when I installed some LVP in a new construction sunroom room. It was the easiest part of the job. Lay down a piece of wood the proper height, mark the wall and cut the drywall using oscillator tool. Throw pieces in trash, vacuum up and you're done.

I did it as insurance policy to give my floor some extra expansion gap beyond the 1/4" spacers that I used. It's a southern facing room with almost floor to ceiling windows so lots of sun. Better safe than sorry.

 

[PWC Repair]

Most of my house is hardwood, 1/4" is plenty. I mean really, my wood deck is NOT hardwood, AND is right out IN the weather, and I've never seen it grow that much..........that's just silly talk.

 

[egdede]

nafterclifen, I'd still call that a hassle. I pretty much hate when I have to use my oscillating tool even though it's gold when you need it. I was thinking about it, and I'd probably use a razor knife if I had to.

 

[MushCreek]

With my luck, I'd hit a row of drywall screws right where I was trying to undercut it. I've always wondered about leaving that much space. As was said, if the floor moved 3/4", the nails would be sheared or pulled out. My flooring is reclaimed heart pine from a textile mill. I left about 1/4" on each side. I have a sample piece that I have measured at different times of the year, in different humidity, and it only moves a couple thousandths of an inch over the 3-1/2" width. it is 125 years old, though, so maybe more stable?

 

[toolmiser]

Each individual board moves a little, but the whole floor doesn't shift back and forth. Tradition hardwood might show some gaps in the winter, but the close up in the summer when the humidity returns.

 

[duneslider]

If your floor grows 3/4" from moisture the wood flooring moving is the least of your worries. I've been installing wood for 20+ years and never seen that much movement. Seen lots of stuff that shrinks a lot. Seen houses flood and not move 3/4" in any direction, cupped and crowned like crazy but if it is nailed in tight it isn't going anywhere.
I like having a gap under the drywall but if the drywall is so low the wood doesn't fit I usually leave an 1/8-1/4 to make it easy to get my flat bar in to make sure I can snug up the board.

I don't work back east where it is a lot wetter but if you have serious moisture issues in your house you will get cupping and crowning long before it swells enough to be an issue. If you house regularly sees high humidity then maybe 3/4" wood isn't the best choice.