expansion joint questions


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Old 04-17-03, 09:15 AM
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expansion joint questions

I know that I need 3/4" expansion joint for my solid wood floor along the length of the boards. Is this same expansion dimension needed for the side walls? What about when you butt up to a kitchen cabinet, do you still use 3/4" gap? If yes, how do you hide this, since shoe moldings are only 1/2" wide. Also, how do you handle a place where you butt up to a ceramic tile section?
 
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Old 04-18-03, 11:21 AM
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Expansion joint

Wood floors require expansion space at all walls because wood tends to expand and contract as temperature and humidity levels change in the home. The expansion space is covered with a molding. Shoe and quarter round are available in different sizes. Shoe tends to be from 3/8" to 5/8" thick and from 1/2" to 1" high. Quarter round (1/4 of a full round) tends to be from 1/2" to 1" and can be used as shoe.

If ceramic tile and wood are the same height, you can use a T-mold. If wood his higher than ceramic tile, you can use a reducer.

To learn more about installing wood floors, the NOFMA technical manual is at www.installingwoodfloors.com
 
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Old 04-18-03, 12:21 PM
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Re: Expansion joint

Originally posted by twelvepole
Wood floors require expansion space at all walls because wood tends to expand and contract as temperature and humidity levels change in the home. The expansion space is covered with a molding. Shoe and quarter round are available in different sizes. Shoe tends to be from 3/8" to 5/8" thick and from 1/2" to 1" high. Quarter round (1/4 of a full round) tends to be from 1/2" to 1" and can be used as shoe.

If ceramic tile and wood are the same height, you can use a T-mold. If wood his higher than ceramic tile, you can use a reducer.

To learn more about installing wood floors, the NOFMA technical manual is at www.installingwoodfloors.com
I've looked at this website, but it doesn't answer my specific questions. For example, with a T molding, you don't have 3/4 inch to the base part of the T. Also, for the kitchen cabinet question, are you saing that you need to use a thicker shoe or quarter round. I would think a 1" quarter round would look funny around the cabinets to hide the gap. But I'm just looking for people to tell me what they have had success with.
 
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Old 04-21-03, 01:38 PM
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Expansion Gap

If you look at the illustration, at http://www.nofma.org/installation2.htm, you will see the 3/4" expansion gap from the wall. Over this gap sits the baseboard and the shoe mold, covering the gap.

A T-mold is used as a transition piece between hardwood flooring and another hard surface floor of the same height. A 3/4" thick T-mold typically has a base width of 3/4" to accommodate the expansion gap between the two floor surfaces. I have read that as much as 1 1/4" be left for this gap. Because it is 3/4" installed in a gap between 3/4" thick solid flooring, the bottom of the T will not touch the subfloor equivalent to the amount of the thickness of the 'wings' on the T, leaving approximately 3/16" gap between the bottom of the T and the subfloor. The T-mold is drilled and nailed to the subfloor.
 
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Old 04-21-03, 08:17 PM
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Re: Expansion Gap

Originally posted by twelvepole
If you look at the illustration, at http://www.nofma.org/installation2.htm, you will see the 3/4" expansion gap from the wall. Over this gap sits the baseboard and the shoe mold, covering the gap.

A T-mold is used as a transition piece between hardwood flooring and another hard surface floor of the same height. A 3/4" thick T-mold typically has a base width of 3/4" to accommodate the expansion gap between the two floor surfaces. I have read that as much as 1 1/4" be left for this gap. Because it is 3/4" installed in a gap between 3/4" thick solid flooring, the bottom of the T will not touch the subfloor equivalent to the amount of the thickness of the 'wings' on the T, leaving approximately 3/16" gap between the bottom of the T and the subfloor. The T-mold is drilled and nailed to the subfloor.
You are still not understanding the question. If the base width of the T mold is 3/4" and you leave only 1 1/4" gap between the 2 surfaces, than your total gap is 1/2". But since the T mold will be placed in the center of the gap, you are only giving yourself 1/4" for expansion on each side of the T mold. However, everything I've read about installing hardwood states that you need 3/4" gap for expansion.

In order to get 3/4" gap at a T mold, then you would need to leave the gap between the two butting surfaces at 2 1/4". 3/4" would be taken up by the base of the T and the remaining 1 1/2" would be split between the two floors on either side of the T mold. The problem with this is that the T mold is only 2 inches wide, so this doesn't work either. Doesn't anybody know how to handle this??
 
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Old 04-22-03, 07:57 PM
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Expansion

Wood tends to expand more along its width than its length. Thus, any expansion in excess of 1/4" would tend to cause wood strips or planks to expand into each other and across the room where it would tend to move into the 3/4" expansion joint. Thus, the T-mold would be saved from being pushed up out of the floor because of the small space left on either side of it and it would move with the flooring. Most forum posts tend to reveal a slight gap in flooring during winter, but only slight. That is, if temperature and humidity are maintained nearly constant year round and there are no other mitigating factors regarding moisture.

If temperature and humidity in your home is maintained at nearly constant levels and you have no moisture issues in crawl space or basement, then extreme expansions and contractions tend not to take place. It is also very important to acclimate (allow wood to adjust) to temperature and humidity of home before installation, placing wood in rooms where it will be installed and allowing it to rest there for 3-4 days. Because a quality hardwood flooring product is kiln dried to very low moisture levels and is being relocated to a home that may have higher moisture levels, it is important to acclimate in order to minimize problems with expansiona and contraction.
 
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Old 04-22-03, 08:20 PM
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Re: Expansion

Originally posted by twelvepole
Wood tends to expand more along its width than its length. Thus, any expansion in excess of 1/4" would tend to cause wood strips or planks to expand into each other and across the room where it would tend to move into the 3/4" expansion joint. Thus, the T-mold would be saved from being pushed up out of the floor because of the small space left on either side of it and it would move with the flooring. Most forum posts tend to reveal a slight gap in flooring during winter, but only slight. That is, if temperature and humidity are maintained nearly constant year round and there are no other mitigating factors regarding moisture.

If temperature and humidity in your home is maintained at nearly constant levels and you have no moisture issues in crawl space or basement, then extreme expansions and contractions tend not to take place. It is also very important to acclimate (allow wood to adjust) to temperature and humidity of home before installation, placing wood in rooms where it will be installed and allowing it to rest there for 3-4 days. Because a quality hardwood flooring product is kiln dried to very low moisture levels and is being relocated to a home that may have higher moisture levels, it is important to acclimate in order to minimize problems with expansiona and contraction.
So are you saying that you only need 1/4" expansion gap from the last board to the base of the T mold?

I am acclimating the wood in my house for about 4-5 weeks prior to installing (it is taking me that long to get everything ready since I only have limited time to work on this with a full time job and two kids). I also use a humidifier to keep the humidity in my house at around 45% year round. Finally I have a dry basement underneath the floor where the hardwood will be installed.

Also, do you know how to handle the gap at the kitchen cabinets? The shoe molding is only 1/2" wide. Do I go with a smaller gap at the cabinets than 3/4 inch?

Thanks!
 
 

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