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post #1 of 11 Old 08-16-2013, 10:13 AM - Thread Starter
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ok so i just bought my house (its a 3 story townhome, with the living room on the second floor), and the first thing i did in the living room was rip up the carpet (i thought it had floorboards), so i can run some cables to a centralized media cabinet which is also located on the 2nd floor. well as soon as i lifted up the carpet, it looks like its a plywood subfloor rather than floor boards. any ideas on how to attack this project? is it even possible to remove plywood subfloor without damaging it?
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post #2 of 11 Old 08-16-2013, 11:26 AM
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I did one piece in my theater and about killed myself it was so much work. Now, that was a custom builder putting 50+ nails into 1-1/4" subflooring, and it was 90+ degrees in the unfinished room at that point, but still...

Yes, you can do it, just be careful. A medium pry bar and a hammer you can pull out the nails to get a sheet out. But note that you'll only get sheets that don't run under non-load-bearing walls that were build after the subfloor was installed. Check that all sides of the sheet are clear before you start, or you'll be wasting your time.

If you're really lucky, they used screws (only), which makes the job really simple. My subfloor was nailed during initial construction, and they screwed down the sheets later.

Once you get one piece up, you can run under the floor with the joists for quite a while.

Put the piece back in place using screws...

Good luck and be careful!

Jeff

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post #3 of 11 Old 08-16-2013, 11:45 AM - Thread Starter
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Ok,let me ask u this, can I drill a small hole into the plywood to run the wire and then patch the holes up somehow without affecting the integrity of it? I'm planning on having LVT flooring installed too.
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post #4 of 11 Old 08-16-2013, 12:53 PM
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Quote:
Originally Posted by hvtopiwala View Post

Ok,let me ask u this, can I drill a small hole into the plywood to run the wire and then patch the holes up somehow without affecting the integrity of it? I'm planning on having LVT flooring installed too.

Run the wires from where to where? A hole isn't a problem, but that wire has to begin and end somewhere...

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post #5 of 11 Old 08-16-2013, 01:08 PM
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Plywood subfloor is going to be a nominal 3/4 inch thick and likely tongue and groove. It's also quite likely that construction adhesive was applied to the joists (reduces squeaking) if the construction is at all recent. It's a real job to remove. tongue.gif

There is another way, and yes I've done it, many times, whenever it's necessary to get to something under a subfloor: Or to repair damaged areas of subfloor. I'm a retired finish carpenter/contractor.

If the route you propose to take is in the direction the joists run, it's simple. Locate two adjoining joists and at each end find the center of each one. Take a circular saw and set the blade for a cutting depth of, say, 7/8 inch. There will likely be a butt joint or two somewhere along the joist that will help you locate the joist center. There will also be nails holding down the subfloor, of course, to provide a guide. Pull the nails with a cat's claw tool. Snap a couple chalk lines along the length of the nail holes, then cut with your circular saw. Remove the subfloor with a flatbar. Run the wires, and use wiring staples every so often to secure the wires to a joist. Then apply construction adhesive or liquid nails (in a caulk tube) and screw your subfloor back down. You won't be able to get right up to a parti-wall, but for your purposes, close enough. At each end of the run, you should put in supports (see below).

If you're going across the joists, it's more difficult. Snap a couple chalk lines several inches apart following the route the wires will run. Wide enough so you can get an electric drill to where you can drill holes through the joists for the wiring. Then cut the subfloor along the lines and remove with a flatbar. Drill your holes and run your wiring.

Here's the important part: To patch the floor, you absolutely must provide support between the joists. Typically this is done by using scrap plywood, and half-inch or thicker plywood or OSB will do.

I'm going to try to explain and I hope it's clear. Say you cut a channel the length of the floor 6 inches wide, and the joists are 16 inches on center, for a distance between the joists of 14 1/2 inch. The supports should be about 14 inches long and about 10 inches wide. The supports go *under* the existing subfloor between the joists. Drill a couple "helper" screws dead in the middle (lengthwise), with heads protuding to hold on to so you can maneuver the support to where it needs to be. Apply construction adhesive (subfloor glue or liquid nails in a caulking gun tube) liberally along both edges where it will lap under the subfloor. Then slip it into place, lapping under the subfloor evenly on each side. Run drywall screws through the subfloor into the support every couple inches. Those "helper" screws you put into the support earlier will give you something to hold on to and apply upward pressure until the screws bite. Make sure the supports are drawn up tight. Remove your "helper" screws.Then apply adhesive along the length of the supports and replace the 3/4 thick subfloor cutouts you removed earlier (assuming you didn't bugger them up when removing them). Screw back down into the joists and supports.

For best results, you'd then apply 1/4 inch lauan underlayment plywood over the repaired subfloor to make it perfectly level. This will be necessary if you're going to lay down resilient (vinyl) flooring. If you intend to put down carpet or hardwood flooring, that won't be necessary. Though you should still trowel on "floor leveler" mix along the length of the repair. It mixes with water like mortar to fill in any gaps or unevenness.

I hope I didn't miss anything. It all sounds like a worse job than it is. But you'll have to be fairly handy with tools to tackle this job. Otherwise, get a contractor to do it.

Good luck
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post #6 of 11 Old 08-16-2013, 01:12 PM - Thread Starter
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well when i pulled the carpet and also pulled the baseboards running along the wall, there is enough space for me to tuck wires under the plywood so i was going to make holes every so often to make sure the fishing wire doesnt get snagged anywhere.

fritz: when i go check it out again tonight, i will let u know which way the floor joists are going (im hoping its the easy way). i didnt see any nails when i looked last time, but i also wasnt looking that hard.
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post #7 of 11 Old 08-16-2013, 07:16 PM
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When I wrote that you can't get right up to a parti-wall (with just a circular saw), I'm assuming you don't own or can't borrow a sawzall.

Another way to do it across joists is to go, say, 4 feet on center. Then you have to do supports along each edge. The whole point of the supports is so the floor isn't "mushy" between the joists where two sections butt together. As I wrote before, if done right subfloor will have tongue and groove along the long sides to prevent that. With wider access, you can use 2x lumber headers at 14 1/2 in. (for a tight fit) instead and toenail or screw them into the joists.Removing wider pieces will require more grunt to break loose the adhesive, but it can be done.

All the above assumes you can't access from below or don't want to bugger up a finished ceiling below.

Good luck.
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post #8 of 11 Old 08-17-2013, 06:20 AM - Thread Starter
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Luckily I am going in the direction of the joists! So what's the easiest way to do it? I can get a wire under it between the drywall seam I think, so can I make small holes to continue fishing the wire and patch it somehow?
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post #9 of 11 Old 08-17-2013, 08:30 AM
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I'm not quite clear on what you mean.

If you're saying: "can I run the wires below the drywall and just above the subfloor?", then yes. Typically the drywall comes within about a half inch of the subfloor, leaving a gap. Or you can make a gap with a drywall saw or even a utility knife. You'll have to be careful you don't damage your wires when putting the baseboard trim back on the wall, so remember not to drive nails near them. Also hold the baseboard up from the subfloor about 1/2 inch (for carpet or vinyl or pressed wood pattern manufactured flooring), or a bit more than 3/4 inch if you plan to do a real hardwood plank floor. For anything except carpet, you'd also need some shoe mold to finish the job.

Or are you saying: "can I make small holes in the wall at the studs, so I can drill holes through them and fish the wires through?", yes again. Keep the holes as small as you can to make patching easier, using mesh tape and joint compound. Big holes will require something similar to the supports I described earlier to provide backing. Make them longer than the hole and use liquid nails or similar plus drywall screws to hold in place. A drywall patch doesn't need much support, but it needs some (so the joint compound won't develop crack lines), and it's easy.

Your original focus was on the subfloor, but personally, I'd rather do a job like that from below, assuming it's a drywall ceiling in the story below. The direction the joists run favor it, and you'd only need a few easily patched holes.

Good luck.

[EDIT] My own home theater is on the upper floor of my house. I fished wires for my surround speakers down through the wall from the roof truss space, then over and down the opposite wall. That required drilling through the top plates of the walls from above. After that, patching the drywall was easy.
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post #10 of 11 Old 08-18-2013, 06:10 AM - Thread Starter
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i was asking a bit of both, some of the wires i can run around behind the baseboard area (luckily those are the ones that run perpendicular to the joists), but some have to go across the other side of the room but in the same direction of the joist (and there isnt a wall connecting the 2 sides that the baseboard runs around).

ill see if i can do it from below because it would make life easier.
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post #11 of 11 Old 08-18-2013, 10:02 AM
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Quote:
Originally Posted by hvtopiwala View Post

ill see if i can do it from below because it would make life easier.

Much easier.

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