Plywood needed before carpet install? Plank subfloor.


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Old 02-28-13, 06:27 AM
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Plywood needed before carpet install? Plank subfloor.

Hey all,

I've renovated the upstairs in my 1953 bungalow. We're ready to install carpet but I'm unsure if my plank subfloor is sufficient to lay carpet over - my installer recommended laying down a 3/8" plywood underlay to keep things uniform.
There are few holes and it is level for the most part, he had said the end results would be better if I took the time now. Thoughts?


Other questions - is t&g necessary or are standard 4x8 sheets ok? Should I leave space between the walls for expansion? I've read to drill into the planks not joists - 1-1 1/2" decking screws?


Thanks in advance. Looking forward to finishing this project.
 
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Old 02-28-13, 09:09 AM
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Welcome to the forums!

I don't think you can get T&G in anything thinner than 5/8" but I don't think it is necessary. I would follow your carpet guy's advice and install plywood - either 3/8" or 1/2"
 
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Old 02-28-13, 10:02 AM
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I agree in that I don't think you are going to find 3/8 or 1/2" tongue and groove plywood, and also agree that it doesn't matter, as it's not necessary. Before deciding on which to use though, I would measure the stair risers, because they are all supposed to be within 3/8" of each other. Although this particular code may not have existed when the house was built, a good builder or carpenter would have nevertheless cut the stringers such that the risers were ideally the same, and, most likely, the more you add to the floor, the more inconsistent the top step is going to be. If you were to find this to be an issue, I would explain the situation to the carpet installer, and ask if 1/4" plywood or luan might be a viable option. As for laying any of it, I would leave something like a 1/16 - 1/8" gap at the perimeter, and lay the sheets against each other, but not any tighter than just pushing them in place. If you do use 3/8" or 1/2" plywood, I would lay it to fall center on the joists, and would probably nail it with ring shank nails, but you could use screws as well. If you use 1/4" plywood or luan, I would first go around and ensure that the existing subfloor is nailed securely, and would probably screw down the plywood or luan, 6" on center in each direction, and would not be as concerned about it falling on the joists, although would still prefer that. Lots of opinions I'm sure, so this is just one guys' 2 cents worth.
 
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Old 03-03-13, 10:02 AM
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Similar situation

I'm about to lay carpet in a small bedroom in an older 1920's built house. The existing floor is 1x4 solid planking and appears to have been used as the finish floor at one time because there are signs it had been painted. The wood is so dry that it has some serious splinters. I was concerned about the splinters possibly working up thru the carpeting so I put down a layer of hardboard which has a very smooth finish.

Hardboard is very inexpensive compared to plywood and it should conform easily to the existing framing and will cover small knot holes. I've only seen 1/8" and 3/16" in home improvement centers but 1/4" is available, I'm using 1/8". I tacked down with pneumatic wire nails, about 24"o.c. around the perimeter and a couple in the field, just to help keep it from moving around. Decking screws always seem to leave a small splinter or the head itself raised above the surface. Although plywood is claimed not to warp I always end up finding a bow in just about every sheet after getting home even 3/4" thick.

I left 1-1/4" to 1-1/2" gap between edge of hardboard and wall to leave a space for carpet tackless strip and a space for the carpet edge to be tucked in. Leaving a gap for the tackless to be placed into helps eliminate the raised carpet edge around the room but you may not want to do this depending on the thickness of padding. I didn't use a pad. I've seen situations where bookcase like furniture leans out from wall along top because of solidness of the tack strip and the eventual compression of padding. Sheets are butted together. There is relatively no expansion or contraction with hardboard.

Hope this info comes in time to help.

Justin
 
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Old 03-04-13, 05:23 PM
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Wow, thanks for the responses!

Justin - great idea! Question, why did you go 24 oc?
 
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Old 03-05-13, 11:10 AM
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For whatever reason the hardboard I'm using has a continuous rounded edge and being only 1/8" thick I thought there might be a possibility of one sheet trying to dive under another so I just wanted to make sure the sheets didn't move around possibly while stretching carpet or whatever.

I used the term wire nails which may be correct. I used 23 ga. pins. The spacing just worked out that way. Tacked down each corner and then another centered between those which was 24" on narrow end and 48" on the long edge which seemed a bit far so did another halfway between again. Put a couple out in the center just to hold center of sheet down in case there was a crown or bow of some sort.
 
 

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