Does the underlayment go in before or after sheetrock?

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Old 08-13-14, 06:57 AM
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Does the underlayment go in before or after sheetrock?

I have a 3/4 pine subfloor. Currently no sheetrock. I'm going to put 1/2" AC plywood in for underlayment, then sheet vinyl.

Question: Does the sheetrock go in before or after the underlayment? Or more precisely, is it over the underlayment.

My consideration being at some point, I could see the vinyl being replaced, and therefor the underlayment would be replaced. And if the underlayment was under the sheetrock, that would be a bear to take out.

Thanks much!

(Didn't see this asked, so I apologize if I missed a previous answer.)
 
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Old 08-13-14, 07:22 AM
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Normally the wallboard would rest on the main flooring, then the floor covering would be applied. However since you think the 1/2 sub flooring may be removed at a future date (I'm assuming because you don't want to raise the floor any more than it already is), rest the wallboard on the pine floor and then install your 1/2 sub. I don't think it makes much difference one way or the other.
 
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Old 08-13-14, 08:16 AM
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Thanks much Norm Seemed straightforward enough, but I'm not the smart guy in the room on this by any stretch.
 
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Old 08-13-14, 08:21 AM
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Why are you using 1/2 for underlayment? Normally 1/4 underlayment grade is used. It's much easier to staple and get a smooth floor with 1/4". Vinyl needs a perfectly smooth floor and you won't find 1/2" that is perfectly smooth.
 
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Old 08-13-14, 08:22 AM
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Most of us are intelligent enough, just in different areas

Normally 1/4" is used for underlayment under vinyl, any special reason for using 1/2"? does it have a smooth face? If the pine subfloor isn't stiff enough, you might be better off installing the plywood permanently and then use a thinner underlayment after the walls are done.
 
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Old 08-13-14, 09:03 AM
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Sam and Marksr, good catch. I should've advised that also. With that in mind, future floors may not have to be raised as high and you won't need to remove any sub-flooring.
 
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Old 08-13-14, 11:48 AM
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I thought I had read that 1/2 AC plywood was the way to go. The subfloor is 3/4 to 7/8 (it was built in the last 50's/early 60's. It's over 2X8 floor joists 16" on center and it's solid as a rock.

So you all would recommend using 1/4 AC plywood then?
 
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Old 08-13-14, 11:58 AM
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Years ago everyone used 1/4" luan for the underlayment but that is frowned upon today. I don't know if the luan isn't as good as it used to be or if there are just better options today. I'm a painter, not a floor guy and I don't know the specific name for what you should use but it's specifically made to be used under vinyl. Sam [and some of the others] can tell you exactly what's called.
 
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Old 08-13-14, 12:25 PM
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Luan is not as good as years ago. It can bleed and stain the vinyl. It also has voids in the layers which can collapse. You need underlayment grade plywood.
 
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Old 08-13-14, 04:05 PM
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Normally the drywall sits 1/2" above the floor to prevent wicking up of liquids. Baseboard molding covers the gap. Also, you would not want to nail or screw that close to the walls that you could not get the anchors out should you need to change out the floor.
 
 

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