# Installing unfinished oak flooring at 35% humidity..



## Texwing (Dec 13, 2008)

Hello, I am about to install 3/4 inch unfinished white oak hardwoods in a lake cabin in a 35% (low for north texas, but its winter) enviroment, and need some advice. 
My concern is that I may have buckling or swelling problems in the summer when 70% or greater humidity levels are possible, since this is a lake place and will be shut in most of the time, with temperature swings from 45 to 105F possible.
The 3 and 1/4 inch wide unfinished white oak will be installed on the middle floor on 3/4 plywood sub floor, 16 inch O.C., about 24 by 24 foot square.
I will install on felt, but should I take any other precautions like using spacers on every fifth board to build in some expansion space? Or should I just not worry about it? Installers up north must have experience with this-this is our first hardwood floor installed in winter, low humidity levels, and in a vacation house that will be shut in much of the time. Your comments are appreciated.


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## Floordude (Aug 30, 2007)

What is the moisture content of the wood, right now??


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## Morning Wood (Jan 12, 2008)

I would go by moisture content of the wood not the humidity level of the air. You will be bummed if you get crazy gaps in your floor. How the floor is sawn should be considered too. Is it vertical grain, rift sawn, or flat sawn? You might want to leave maximum spaces at the sides against the wall so the floor can swell comfortably.


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## jamestrd (Oct 26, 2008)

Dont use or leave spacers..they will never close...every floor this is spec'd for, usually commercial sport floors(maple), remain open..

On any span greater than 20 ft, its better to start in the middle..

measure and square up, strike a line down the center, and start from that point..
cut dummy pieces to use as a guide and nail to subfloor. after your first 2 courses are nailed in secure, install slip toungue on the other side and reverse the direction.

I may also advise nailing to the joists and it may be wise to use dehumidification of some sort.

Wood floors expand towards the toungue side of the boards, so if you reverse, you cut the distance in half of expansion..leave typical 3/4 " expansion at perimeter(long side more important)..

you wont buckel unless you get a direct water source, but if moisutre is that high, you may cup, but i wouldnt worry so much.

The time it takes for the humidities to raise that high, will be gradual and the floor should acclimate acocrdingly and not react.. the finsihed floor will hinder the absorbtion rate of moisture..


you can only install for the conditons currently present and can not anticipate the future..

if overly concerend,use dehumdifier and set some kind of drainage for it outside.

Dimensional chnage will usually occur when the moisutre content of the wood reaches 4% higher than installation content. assuming floors go in around 7-8% MC, chnage will occur at around 12%... at 14% is when you will see severe twisiting. Higher tyhan this, the floor will look to buckle if enough expansion is not present,, but this will be greatly reduced by reversals of direction.


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## Burby (Nov 25, 2008)

A very handy tool, I have had mine since the mid 90's, still works as good today as did then. There are some nice digital scanners for moisture inspection without penetrating material, but for the dollar amount & service I have from this one, I not found the need to change. 


  Delmhorst J-4 Pin-Type Moisture MeterItem: DEJ4Manufacturer : DelmhorstPart Number : J-4W/CSSale Price: $240.00*Package Upgrade - 26ES Hammer*Instrument & Case Only - (as priced)Add Package Upgrade - (+110.00) DEJ426Quantity:


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## Texwing (Dec 13, 2008)

Thanks guys! HVAC is my normal profession, the lake house is mine and floors are my first real hardwood floor job. I dont have a moisture meter (at least not for wood) but i will try to get one. The white oak is flat sawn, I think, I paid about $1.55 a square foot (3/4 by 3.25 no.2 white oak) if that answers the question in a left handed manner.

I really don't understand the "reverse direction" advice, if i start in the middle, how would I nail the wood, since the tongue would not be visible? Will do on the joist and full 3/4 spacing. 

I will see If I can get a moisture meter and get back, thanks for the help.


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## SLSTech (Sep 13, 2008)

Texwing said:


> I really don't understand the "reverse direction" advice, if i start in the middle, how would I nail the wood, since the tongue would not be visible?


Insert a spline in the center board - now you have a board with 2 tounges


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## Texwing (Dec 13, 2008)

Got it! actually I have a good table saw on the job site, I may try to just mill a piece with two tongues. I am trying to find a moisture meeter. Tried two from harbor freight, neither worked, just would not register even on firewood.
thanks for the help.

PS. What should I use for leveling compound for low spots? the folks at home depot seemed to have no idea.


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## Poor Floorman (Jul 20, 2008)

Texwing said:


> Hello, I am about to install 3/4 inch unfinished white oak hardwoods in a lake cabin in a 35% (low for north texas, but its winter) enviroment, and need some advice.
> My concern is that I may have buckling or swelling problems in the summer when 70% or greater humidity levels are possible, since this is a lake place and will be shut in most of the time, with temperature swings from 45 to 105F possible.
> The 3 and 1/4 inch wide unfinished white oak will be installed on the middle floor on 3/4 plywood sub floor, 16 inch O.C., about 24 by 24 foot square.
> I will install on felt, but should I take any other precautions like using spacers on every fifth board to build in some expansion space? Or should I just not worry about it? Installers up north must have experience with this-this is our first hardwood floor installed in winter, low humidity levels, and in a vacation house that will be shut in much of the time. Your comments are appreciated.



I install in installer friendly So. Cal.
Don't see that kinda swing here.
I'd be more concerned with the 'Greenhouse Effect', keeping the house closed up will create problems in any part of the country.
30 to 50% R/H and 60 to 80 degrees will put your wood M/C between 6-9%.
For properly acclimated 3/4" x 3 1/4" W/O plank, industry standards say you must be within 2% plus or minus of the M/C of the subfloor.
If your wood comes in at 8% M/C then your subfloor can be no less than 6% and no greater than 10% M/C to be properly acclimated at time of installation.
You need a good moisture meter to do the job right. A few hundred $$$ is a very small investment for the amount of time and money you'll be dishing out.
A properly acclimated wood plank floor and keeping your house between 30 to 50% R/H and 60 to 80 degrees is required for the installation of hardwood flooring. It's mathematical, stay within these parameters and you can enjoy your floor for years to come. 
Don't want to or can't and maybe a wood floor is not an option.

If you're not comfortable running the HVAC all year around,
remember, it's all mathematical.
Hire a professional that has a combination for your circumstances.
Don't intentionally leave gaps or spacers in your install and cheat the math, all you will have is the same problems with the addition of gaps and spacers.

Where I'm from, the math is cheated and gotten away with so often, most have never even heard of it.
Your area might not be so lucky.
Don't cheat the math.


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## Floordude (Aug 30, 2007)

The reality of it is... A change of just 3% moisture content in a 5" wide plank floor, can equal almost 2" of shrink or swell in just 10 feet of flooring.


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## Cdat (Apr 18, 2007)

Floordude said:


> The reality of it is... A change of just 3% moisture content in a 5" wide plank floor, can equal almost 2" of shrink or swell in just 10 feet of flooring.


But it ain't 5 inches wide:


> 3 and 1/4 inch wide


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## Floordude (Aug 30, 2007)

The reality of it is... A change of just 3% moisture content in a 2¼" wide strip floor, can equal almost 2" of shrink or swell in just 10 feet of flooring. Same for 10 feet of white oak, that is 3¼" wide. Almost 2" of dimensional swell, in 10 feet.


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## Poor Floorman (Jul 20, 2008)

Floordude said:


> The reality of it is... A change of just 3% moisture content in a 5" wide plank floor, can equal almost 2" of shrink or swell in just 10 feet of flooring.



Dudefloor, check the math.
The dimensional change coefficient of red oak is .00369.
Calculation:
3 x .00369 = .01107 x 5 = .055 per board over 10' or 24 boards will be 1.3284 inches.
Every different species of wood has a different dimensional change coefficient.
It's all mathematical.
Applied knowledge is the key to success.

Sorry, I couldn't help myself.


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## Floordude (Aug 30, 2007)

Poor Floorman said:


> Dudefloor, check the math.
> The dimensional change coefficient of red oak is .00369.
> Calculation:
> 3 x .00369 = .01107 x 5 = .055 per board over 10' or 24 boards will be 1.3284 inches.
> ...



Your right! I was going off memory(which is fading fast)

I was confusing the calculations on page 6 of the NWFA manual "Growing Boards", where it goes from 7.7%MC to 12%MC =1.9"


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## Poor Floorman (Jul 20, 2008)

Floordude said:


> Your right! I was going off memory(which is fading fast)
> 
> I was confusing the calculations on page 6 of the NWFA manual "Growing Boards", where it goes from 7.7%MC to 12%MC =1.9"



The ECM of every species of wood is different.
It all mathematical, (plug in the % of change x the DCM # assigned to that species of wood) x the width of the board = the dimensional change per board.
My point is, that there's allot more to 'just putting in sticks' to installing a hardwood floor correctly.
Simple math can put the flooring craftsman far ahead of the game.:clap:


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## Floordude (Aug 30, 2007)

Ya, if you do the calculations, you will know what expansion is needed out in the installation, and theoretically, the perimeter expansion space, when installing dry acclimated wood, that you know will gain that MC back and swell come the spring and summer months, after the drying heater is turned off.


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## jamestrd (Oct 26, 2008)

the real reality is a floor will never expand that much as no 2 boards will expand at the same rate...

in the same room, you can get a fluctuation of 2-3 % just taking readings in different parts.


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## Texwing (Dec 13, 2008)

Well thanks for the help-the reality for me is I have already bought the wood, its acclimated for weeks, and i still cant get a moisture meter that is worth a durn-I dont mind spending some dough, I just dont know where to go shopping for a decent one. Got a chinese model, and it seems to work-after sawing a piece of the white oak in half, I drilled holes to get depth, and was seeing about 4%, but the reading was flaky and would change, so who knows I will check the subfloor tomorrow, although its about ten years old (OK, this has been a long project). 

Still would appreciate 'best shot" advice-I can live with cracks and gaps in this rustic lake house (don't want them, but would not be a disaster), but not buckling (that would be a disaster). You know, i really don't know what the inside summer and winter humidity levels would be, but the temperatures will be 100F to 40F. With a half basement below, would skipping the felt and gluing as well as stapling the planks buy me any anti buckling insurance?


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## Bud Cline (Feb 12, 2006)

Two questions Texwing!!!

1. Are we talking Texoma?
2. Is the place for rent?


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## MALCO.New.York (Feb 27, 2008)

Texwing said:


> Tried two from harbor freight, neither worked,


I know nothing about Flooring...But I do know what the problem with the Moisture Meters was............The person who got el cheapo and decided that it would be a wise move to go with that ABSOLUTELY CRAPOLA COMPANY!

Wise NEVER means Cheapo!


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