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Wood floor expansion joints

edwardh1's picture

I can not find an answer to this on the net.

For nail down 3/4 strip hardwood floors- what is the maximum end to end length allowed before an expansion joint.

I know in a room you need a gap around the edges but what about when the rooms floors line up with the hall floor and the end to end distance will then be 30 ft

- should you put in a sill piece at the door with a gap under it to allow for expansion?

(post #108951, reply #1 of 24)

I've never done a room big enough to require it. I've done about 35 feet with no expansion gap, and haven't had any problems.

(post #108951, reply #2 of 24)

 Your floor will expand across the width not the length. The amount of expansion depends on the type of wood and your climate. That being said I know people that don't leave any expansion gap and have not had a problem. Check with your supplier of the flooring, usually they want to make sure you don't have any troubles.


 Good luck, Vern.

(post #108951, reply #3 of 24)

"should you put in a sill piece at the door with a gap under it to allow for expansion?"

No

you been given some good advice-the point of a hardwood floor is that it is able to grow and shrink without it being noticed if all is done right...look at a hardwood gym floor

the main thing is moisture...is your subfloor dry? is the house dry?

acclimate the flooring in the rooms it will be installed in for 1 week minimum in the boxes with the ends open

site humidity should be 35 to 50%

I leave a 1/4" around the edges of the rooms-never had a problem.

check the manufacturer's website for the fine print

silver

(post #108951, reply #4 of 24)

I always leave 1/4" on the ends and at least a half inch on the sides. Never had a problem, and some of those floors are well over 35'.

(post #108951, reply #5 of 24)

it won't expand at the ends, only at the width

 

 


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We did the best we could...

(post #108951, reply #6 of 24)

Piffins dead right.  Wood doesn't expand lengthwise, only width wise..


 Well, not enough to affect anything..


 width wise though some woods expand a lot more than others..

(post #108951, reply #7 of 24)

IMO running a threshold piece across a doorway is a nice touch.

We'll have a kid
Or maybe we'll rent one
He's got to be straight
We don't want a bent one
He'll drink his baby brew
From a big brass cup
Someday he may be president
If things loosen up

www.tvwsolar.com

The Village Woodworks, Inc

Chapel Hill, NC

 

We'll have a kid Or maybe we'll rent one He's got to be straight We don't want a bent one He'll drink his baby brew From a big brass cup Someday he may be president If things loosen up

(post #108951, reply #8 of 24)

Depends on house style. Around here almost every doorway has a threshold.

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #108951, reply #9 of 24)

not IMO... <G>

We'll have a kid
Or maybe we'll rent one
He's got to be straight
We don't want a bent one
He'll drink his baby brew
From a big brass cup
Someday he may be president
If things loosen up

www.tvwsolar.com

The Village Woodworks, Inc

Chapel Hill, NC

 

We'll have a kid Or maybe we'll rent one He's got to be straight We don't want a bent one He'll drink his baby brew From a big brass cup Someday he may be president If things loosen up

(post #108951, reply #11 of 24)

"Depends on house style. Around here almost every doorway has a threshold."

I haven't seen one since the one's at my grandfather's home in Mass.

Do they sit on top of the floor-beveled to 1/4 on both edges or are they part of the floor?

(post #108951, reply #14 of 24)

both.

By part of the floor I presume you mean flush set

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #108951, reply #10 of 24)

Gymnasium floors do not require an expansion joint.


Control humidity, cupping and crowning are the things to worry about when it comes to hardwood floors.


 


 

 

(post #108951, reply #12 of 24)

Since it's nailed down, your "expansion joints" are in each row where the groove meets the adjacent tongue. Unless you're using really wide flooring, the expansion/contraction should be minimal. An installation per the manufacturers instructions (acclimation, vapor barrier, etc, etc) should come out just fine.

(post #108951, reply #13 of 24)

Just did a house that can be seen all the way through. It's 55' from the front door to the back. That's the direction of the floor and haven't had a problem.


Runnerguy

(post #108951, reply #15 of 24)

http://books.google.com/books?id=zjJTsHvHoZ0C&pg=PA118&lpg=PA118&dq=radial+longitudinal+shrinkage&source=bl&ots=riLDQwxf4a&sig=d0obZt05waphLlftjupB1qCMMX0&hl=en&ei=OI7ESsv-CYfp8Qaqpt00&sa=X&oi=book_result&ct=result&resnum=9#v=onepage&q=radial%20longitudinal%20shrinkage&f=false

.
.
"After the laws of Physics, everything else is opinion"

-Neil deGrasse Tyson
.
.
.
If Pasta and Antipasta meet is it the end of the Universe???
.
.
.
according to statistical analysis, "for some time now, bears apparently have been going to the bathroom in the woods."

. .

(post #108951, reply #16 of 24)

Wow!!!
That book is great.
Maybe PVC furniture will win out after all

(post #108951, reply #17 of 24)

I need to change the question.
The new wood floor is being installed lengthwise in a room and the ENDs of the wood strips point toward the rooms door.

Outside the door, the existing wood in the hall is NOT end on end down the hall (like I said before) but side to side in the hall for 12 ft, (where the hall flooring ends at a step down) . the door end of the hall flooring then will be butting up against the ENDS of the room strips if no sill joint is installed.

So, with 12 ft of hall flooring that can expand width wise , on the one end against the ends of the room strips-- is an expansion joint needed at the door?

(post #108951, reply #18 of 24)

wood swells and shrinks width wise and almost none at all length wise. 


 (no gaps needed on ends) 

(post #108951, reply #20 of 24)

So the new question is will the 12 ft of floor expand and push against the ends of the other floor, because it can only shrink as much as one board can shrink leaving a very small gap, but it could expand by the amount that all the boards expand together buckling the floor?


I think the safe answer is probably that as long as there is a gap at the far end of the 12 ft of flooring, giving it an out if there is expansion, you are safe to leave out any threshold and butt the floor tight.

(post #108951, reply #21 of 24)

fingersandtoes;


 wood expands and shrinks length wise so very little that it's not worthy of note..


  Depending on the species of wood in the order of a maximum of .02 per foot.  while width wise depending on mositure present it can expand over a 1/8th inch per board..  (one eighth is .125)  so over a typical one foot section of width its possible for some species to move as much as a half inch from 100% moisture to 5% moisture..

(post #108951, reply #22 of 24)

I probably wasn't clear. I was referring to the 12 ft of floor which is laid the other way so the movement would be across the width, not length.

(post #108951, reply #23 of 24)

yes I reposted the question, the repost was

I need to change the question.
The new wood floor is being installed lengthwise in a room and the ENDs of the wood strips point toward the rooms door.

Outside the door, the existing wood in the hall is NOT end on end down the hall (like I said before) but side to side in the hall for 12 ft, (where the hall flooring ends at a step down) . the door end of the hall flooring then will be butting up against the ENDS of the room strips if no sill joint is installed.

So, with 12 ft of hall flooring that can expand width wise , on the one end against the ends of the room strips-- is an expansion joint needed at the door?


Edited 10/4/2009 10:03 am ET by edwardh1

(post #108951, reply #24 of 24)

I think I now understand what you are asking about and if the wood is sideways as it approaches an entry you will need an exansion joint..(wood doesn't move in just one direction as it swells and shrinks) 


I've seen it very cleverly done with a half lap and a slip of cork inserted to achieve that without significant detraction from the look desired. In fact if you really wanted a statement you could border the wood with cork and use it as a decorative element..


 If you can stand a threshold you can also put the expansion joint under the threshold. And simply leave part of the threshold cantalevered over the expansion joint thus giving the appearance of a solid floor..  

(post #108951, reply #19 of 24)

Hi I did a wide strip oak floor in a rental house I was reding and they are cupped . We left a gap around the room wood doesnt expand in length . I used a good felt paper under the wood . The floor was installed about 4 yrs ago . It cupped and never got really bad . Most people wouldnt notice it I do cause I did it . The guy who finished and sanded says that there may be moisture comming from the basement . Its an old house . Im almost thinking that the wood didnt acclimate long enough I switched from forced air to radiatiors right after it was installed the whole house was getting rennovated . A lot of people have trouble with wide oak here in the northeast . Im thinking that when they are refinished at some point that they will lay flat then  Time will tell