I would prefer to avoid breaks if possible for a smoother flowing floor. Can it be done without losing sleep worrying about buckling on a continuous run? Excuse the quicky floor plan. I'm ready to order flooring and was in a hurry or at least the wife is. Thought she might forget, but nooo!
~630 s/f of Kahrs builders grade engineered white oak II floated over a slab with Kahrs combo underlayment. The slab tested @ 3lbs with a Tramex in multiple places in all rooms. I will pull all the base, undercut the rock to get the max expansion room. This is my 1st wood floor install and it's in my house. This is in west Texas with some massive RH swings. 4% on some of our 100+ days and up to 100% RH on the 2 or 3 days it rains. Forced air HVAC and a humidifier running all winter. Thanks in advance for your opinions.
edit2: The floor will be running parallel with the 3'x18' hall.

edit: Mods, who do I contact to get my first login/password working? I timed out and never got an activation link so I created a 2nd login. Ken is on vacation according to his autoresponder.

Ive heard texas is pretty humid. I live in Boise and we never have expansion gaps because we has shrinking problems not swelling problems.

If you have any sustained lenght of days with high humidity you will probably have to have expansion gaps in doors at least I would think.

Not my part of Texas Steve. We don't have much humidity at all and run the AC 8-9 months of the year.
Thanks for the reply.
Why I thought I might get by without a few T moldings was Kahrs instructions:
Connected Area Required Expansion Connected Area Required Expansion
Connected Area Required Expansion Connected Area Required Expansion
Width Space*....................................... Length Space*
up to 24’ 1/2”....................................... up to 72’ 1/2”
24’-40’ 3/4”.......................................... 72’-120’ 3/4”
* Determine the required expansion space for both width and length, then use the larger of the 2 on all
sides, and around all obstructions.

Good job on the floor plan and your reading of the instructions. This is a quality floor and you should be very happy with it. We all would prefer to have no breaks in the floor. But, in reality the final determiner is not me, or you, or Kahrs. It's your house and the way it is layed out.

The manufacturers do a lousy job explaining this part. Having the required expansion gap everywhere is only one part of the story. Rotating lock, glue-less, floating floors have an issue with them, be it a plastic laminate or an engineered wood ,and that is called floor integrity. One could leave 2 inches of expansion gap and that would not stop what could happen if the floor loses its integrity.

When I sit down with my customers and go over the details of my proposal I never use the word t-mold. I call it a wish-bone and then everything becomes alot clearer to the homeowner. If you have a large room with X amount of sq.ft. then you narrow it down thru a doorway and then expand the floor back out with another X amount of Sq.Ft. that's where a problem may or may not arise. It's hard to explain but one room could be on the warmer South side of the house and have its own rate of movement and the other room could be on the colder North side, that will move a little different.

When, or if, those two rooms decide to move at a slightly different rate the problem will show first at the narrowest part. It will start to separate right there, ie, the wish-bone. I would have to see your house but it is possible to have no breaks depending on which way the flooring will run. It looks like the foyer to the 12 x 12 room could be a problem spot. I suggest you order a wish-bone regardless and stick it underneath a bed just to be safe. You can always cut the floor out and put in in later. Just keep a keen eye on it for a year.

When you start down that long hallway make sure there are butt joints in those rows. Hallways can be another problem area on this type of floor.

Jerry thanks for the kind words and taking time to reply.
The floorplan is shown with the correct N,S,E&W layout, I just forgot to reference that. There is most definitely a difference in temperature between the northern 21'x18' room with coffered 10' ceiling, 6'0"x6'0" twin insulated glass window unit, 3'0" full view insulated glass door and the southern 12'x12 room with a 6'0"x6'0" insulated twin window unit. I was fully expecting this reply, but hoping otherwise after lurking here for a month or so (knowing what you should do and what you want to do are usually two different extremes).
The 6'x7' foyer currently has dated ceramic tile and now I'm wondering if it would look better, due to the texture change of the two types of flooring, to go back with tile there to give it the needed expansion break. The transitions might not jump out at you so much with two totally different surfaces and it also takes two rooms out of the movement equation.
The 18'x3' hall will have the Kahrs running with the length, so all butt joints on the long run all the way to the closet at the far end and is fairly neutral in temperature swings, being in the center of the house.
Would you recommend "wishbones" centered in the casement opening where the hall begins off the 21'x18' room and what about under the door going into the closet at the far end of the same hall?
Also before I forget, thanks to all the pros here for letting us pick your brains for free to save a few bucks on our DIY installs.

SWMBO (she who must be obeyed) has spoken! I shouldn't have asked!
If I stay with the Kahrs on all the floors as originaly planned, all running with length of the floor plan; Should I install T moldings in every cased opening? I really don't like the thought of this, but practical and my ideal install are two totally different things.

I would still like to hear suggestions on my previous post with tile in the 6'x7 foyer. This is my personal preference

I think a tile foyer would be a nice touch. It is also functional in that it collects a bit of the dirt that otherwise the wood would have to deal with.

Dave, I think so too. In fact it does since we have tile there now, it's just outdated in it's looks. The other advantage besides the obvious dirt catching, is I can lay tile, get it for a really good price with my discount and be done in no time. Although I don't relish the thought of demoing the old stuff, it has to be done either way. Oh well, only 42 s/f, so it won't take long

This is my rule with floating floors. I have no idea if the manufacturers agree or not. My common sense tells me if it has strength, it is ok.


If the doorway runs the length of the planks and is less then 4 ft. wide, I "T" mold it. If the planks are going to run the lengths through the doorway, with stagger to add strength, I'll do it in a hearthbeat.

I only "T" mold doorways, with doorjambs. Cased openings I run through and glue all planks together around the cased opening area, if the lengths are running across/with the cased opening. If they are running through it, It is strong enough with the staggered end joints.

The only operating door I will pass through is a 2'0" door on the east end of the 18'x3' hall into the 3'6"x2'6" closet. I don't mind having a T molding under that door at all since it won't be visible.
Do you clamp your planks where you glue up in the openings or is painters tape ok and what kind of glue do you recommend for the T&G?
Thanks Floorguy for your advice. If you ever get up around the Concho valley, we'll go get a beer.

You don't need a t-mold at the hallway or the closet door. You may need one t-mold in the foyer to be safe. I personally would rather see tile there anyway. Then all the transitions are taken care of.

Does your front door get wet from rain storms? If so, I would highly recommend tile so the door won't drip on the wood when it swings in. You can also put a little tile at the other exterior door to match the foyer. I do this frequently, most of my work is tile.

I would rather replace the tile myself , for the same reason and it it adds a buffer zone for my wood floor.
No the front door doesn't get wet, this is a ranch style with a deep front porch.
I have tile running under the threshold and wrapping the stepdown at front door right now. It adds a lot for a simple touch.
Thanks for your advice Jerry.