expansion joints for glue-down install questions

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  #1  
Old 10-16-08, 05:45 PM
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expansion joints for glue-down install questions

so I've already purchased about 2200 sqft of bamboo flooring to install in my house, about 1400 engineered and 800 solid strand woven.

So here are the questions:

I'm using the strand-woven downstairs on a concrete subfloor that will be sealed with Bostik MVP. The planks are approx 6' long by 4" or so. I will be gluing this down with Bostik Best flooring glue. The largest open space will be a room approx 20'x20' which is connected to a long hallway.

-I'm considering doing all joining spaces perpendicular to the hallway, I'm assuming it will be crucial that all the tongue/grooves are matching right?
-I was advised my an installer that there will need to be a small expansion space between the planks approx the width of a dime every 4-5' in the large room. Is this correct information?


upstairs will be the engineered flooring, and I will be installing it as a floating or possible floating/nail-down hybrid. I know that a nail and glue-down install will be more solid feeling, but takes a long time, so I'm thinking I could modify the floating install by stapling the entire length of the room every couple feet or so? good thins is these planks are 6'x10" so it should go faster than the narrow planks downstairs.

-the underlayment just needs to be there, and does not necessarily need to be completely glued down does it? I want to use cork or a premium matting. would it be okay to juse use some liquid nails along the edges of the underlayment to keep it in place while installing the floating or naildown flooring above it?
-expansion for a floating floor acts as one giat piece right? what if I were to do a float/nail hybrid or a nail down? how is expansion handled then?
-The baseboards are already installed in my house and have an undercut already, but I think the current undercut is too narrow for the flooring, so I'm going to use 1/4 round along the edges to give the flooring a 1/2" expansion space along the walls. This should be enough?

Lastly, I am really considering doing this all myself with the help of a few friends, but not sure if I would really have the time to do so. What would be a decent expected install coverage rate once everything is prepped and all materials are ready to go? (assuming I have all the correct tools.)

Thanks!!
 
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Old 10-16-08, 08:17 PM
Join Date: Nov 2000
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It sounds to me like your installers don't know what the heck they are doing and making it up as they go!!!!



YIKES!!!!


What you just typed out, scares the %%^#$#& out of me!!

What a bunch of HACKS!!!!
 
  #3  
Old 10-16-08, 10:08 PM
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What part of it is wrong? the only part I'm wondering about is the small expansion gap needed ever 4'-5' on the glue-down planks.

It doesn't help me when you say "they're wrong" since I don't know what they're wrong about. Can you please elaborate a bit?

everything else is what i've read online and in books. I'm a little wary about nstalling the glue-down since concrete prep, MVP, and glue are a lot more tedious than a floating install.

I also want to know if I can make the floating more stable by doing a hybrid staple/float install (this theory I came up with myself).
 
  #4  
Old 10-17-08, 07:04 AM
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Originally Posted by aznatama View Post
What part of it is wrong? the only part I'm wondering about is the small expansion gap needed ever 4'-5' on the glue-down planks.

It doesn't help me when you say "they're wrong" since I don't know what they're wrong about. Can you please elaborate a bit?

everything else is what i've read online and in books. I'm a little wary about nstalling the glue-down since concrete prep, MVP, and glue are a lot more tedious than a floating install.

I also want to know if I can make the floating more stable by doing a hybrid staple/float install (this theory I came up with myself).





What formula are they using to determine a dime size gap MUST be left in the installation every 4-5 feet??? Do they own a wood moisture meter and a hygrometer, and know what they are looking at when they use them??? Or do they own them for a smoke & mirror presentation???


To determine if gaps need to be left in the field of the installation, the moisture content of the flooring is read with a pin type wood moisture meter, after it has acclimated out of the cartons, and come to moisture content equilibrium, where it is no longer gaining or losing moisture content. This could take as long as 2 months to be basically ready as the cartons are opened. Only your wood moisture meter is going to tell you, not your wrist watch set on a 2 day alarm!!!

The with a hygrometer you can determine what humidity the flooring was acclimated in and verify if the two reading correspond, as humidity determines moisture content. Now is where some wood science education comes into play. If the moisture content is a little higher then the regional average moisture content levels, which are well documented by the NWFA and NOFMA, you will need to dry the boards a little to bring them down within the "safe levels"
If the flooring is a little dry for the regionals average moisture content, then a little math comes into play. All species of wood and bamboo have what is called a shink and swell coefficient. This is a measurement is use to determine just how much shrink or swell, given a rise or loss of moisture content as seasonal humidity changes. Right now, it is the most humid time of the year, leaving gaps in an installation at this time of the year, is asking for huge gaps come the heating season and drying out the flooring, shrinking it.

Leaving gaps in a gluedown is not going to accomplish anything, as the glue bond is pretty strong, unlike a nail down installation, which goes back to proper acclimation. Leaving gaps just because, tells me they have been bitten, from their lack of wood science education, and as a scapegoat, they are going to now leave gaps that may or may not need to be there!!!! They are guessing.

Nailing into any part of a floating installation, is just asking for a bad experience!!! Either float it, or fully nail it, no hybrid reinventing the wheel with this one. Your installers should have informed you that was a very bad idea and why.
 
  #5  
Old 10-17-08, 10:01 AM
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Thanks for the information.

Also, if the glue is going to hold the flooring in place, then how much of an expansion gap is needed at the walls?

So it seems like nailing or stapling down the flooring will be my only choice for the 2nd floor then.

Lastly, would it be safe for a glue-down installation without any expansion joints in the middle for such a large room (20x20), or a long hallway (~45ft long)?
 
  #6  
Old 10-17-08, 03:02 PM
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Yes, but it all goes back to proper acclimation.
 
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