Safe method of work on sub-floor?

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Seasider48
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Joined: Thu Apr 07, 2011 10:11 am

OK, I guess I have to go for the gusto and replace the sub-floor. Having only worked on new construction and repairs on a Victorian house, I don't have experience in this area. What is the proper order of doing things to remove/replace the OSB?

Do you work one sheet at a time - that is, remove a sheet or two of OSB and then replace it with plywood or do all the removal in a room first? I am going to be working with paid day laborers that may not have any experience in this either. I don't want people getting hurt or falling through underbelly. I know how to do the joist work - sistering, hangers etc. - if needed.

Do you use a half-sheet of plywood as a sort of floating safety platform to work from? The soft spots of OSB under the carpeting (which goes also) may not be apparent as the home was vacant for a while.

The entire kitchen will be gutted - the kitchen cabinets are made out of the flimsy wallboard and would most likely breakdown while trying to get under them for floor replacement, have a water heater setting on the floor at the corner (inside the cabinets) and probably are soft underneath. I will be putting in a dishwasher and disposer (neither there now).

Bathrooms will also be gutted - one to upgrade and one to turn into storage/laundry room. Plus I can see a little daylight under a tub and that's where a garden tub will go - so I know that needs replacement and beefing up.

And how do you remove the OSB? What tools am I going to need? Sledgehammer it off? Use a circular saw to cut into pieces and then pull? A reciprocating saw to cut off nails at the joist and then pull off - cutting away the sections between the joists first (with the circular saw) and then going under the strip of OSB left on the joist with the recip. saw? Spray it with some water and let it soften up more? Trained termites?

Sorry if I seem picky but I am a nurse and used to having precise instructions to prevent injury, (Learn from the mistakes of others) and "do it right the first time". I researched home rehab the same way before I dove in. Life is just so much easier when you have a page of instructions. LOL

Thanks!
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JD
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I don't know about precise instructions, but I can give you some ideas of how I go about it. When demo'ing an entire floor in a room, I like to remove all of the floor before installing new. I will use some of the old floor I cut out to bridge over joists to stand/sit on while clean cutting corners and installing blocking. Set the circular or worm drive saw to 1/2" deeper than the subfloor is thick. I will usually make full length cuts, perpendicular to the floor joists every 4' or so and also around the perimeter next to the walls . I don't use a tape measure or straight line, just cut. At this point, the floor is usually still stable to walk on, but step on or near joists. Then I will start in a corner and and make cuts parallel to the joists, right down the middle between joists. With each cut, I will stomp on the subfloor beside my parallel cut. This will pry that section loose from the floor. Use crow bars, hammers, etc. to remove the piece completely. Doing cuts and a stomp like this will often pull the subfloor sections off clean, without leaving mounds of old wood and glue. Also, my cut pieces are pretty uniform in size and easily carried and stacked.

Getting glue off of the joists can be a real pain. While sitting on an old piece of cut out floor, I will make utility knive cuts deep into the wood, trying to reach the wood of the joist. The cuts will be diagonal over the joist in both directions, making it look like a file. Now take your sharp 1" chissel and start chipping away at the glue. The cuts will make this work 3-4 times easier. I will use a dremmel multi-tool if it when needed.

Then install your blocking/framing along the walls and where ever and edge of new plywood will be. I use a miter saw to cut blocking as the straight cut helps me fit the blocking perfectly. I install the blocking with a palm nailer. (love the palm nailer!)

Use a good quality subfloor adhesive on every piece of blocking and joists. Lay your pieces in and nail or screw the piece down. I use screws. The glue will help eliminate squeaks.

I float all plywood edges with floor compound, removing sharp edges and leveling out the edges of the plywood. I will usually go a step further and use a 4 1/2" grinder and make a small trough about 1/6" deep over the connection of two pieces of plywood. This creates a little indention like you would have when taping sheetrock edges. Under carpet it is not so critical, but you don't want a sharp edge of plywood wearing into the carpet pad. Under vinyl flooring you want a very straight and smooth transition.

I hope this helps

PS The light under the tub is probably coming through the big hole needed to plumb the tub drain. This also means your underbelly and insulation is missing at least in that area.
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All information and advice given is for entertainment and informational purposes only. The person doing the work is solely responsible to insure that their work complies with their local building code and OSHA safety regulations.
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Greg
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Circular saws & Wonder bars, 2 must have tools for subfloor work.

The new panels go down just like stick built houses. Stager the ends as much as possible, work with what ever size is easiest.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
Seasider48
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Joined: Thu Apr 07, 2011 10:11 am

Thanks for the info. You are a lifesaver! I can see there are some things I can do on my own before I hire a few guys to help with laying the new plywood. You just saved me a bundle of money and a ton of aggravation!
Seasider48
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Joined: Thu Apr 07, 2011 10:11 am

Have you ever used a hammer drill for the glue removal? Saw it on one of the DIY shows where it was used for power chiseling up old tile. Was figuring maybe it could do the same for the glue on the joists. I just don't have the upper arm strength that I used to - chiseling by hand will take me a very long time. Lowe's and Home Depot both have them in stock along with chisel bits of verying widths - up to 1.5 inches.

I generally buy tools (sometimes second-hand) as I need them and sell them when I am done - no rental fees and generally get all the money back.
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Greg
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I think that would be a major case of overkill. We rent them for tiles on concrete, I would be afraid of digging into the wood. A disc sander with 60 or 80 grit paper should go through it with no problem, or even a cheap 4" grinder and cup wire brush.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
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DaveyB
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Another way of clearing off the excess glue without too much elbow grease involved: Use a hand held circular saw, set to the width of the joist. Lay the saw horizontal so the blade is across the top of the joist, and just skim it along the top surface, taking off all the glue.

Safety goggles are a must for this one, but it will strip all the unwanted glue in very short order, just take care not to cut into the wood itself. You can't look away, even for a second, hence the goggles!
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oldfart
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Just a note here fellers. I've done it like DaveyB mentions and I'll warn ya...be really...really careful doing it this way! Especially if you don't have a lot of upper body strength...like most of us ole codgers. I got tired of chiseling and grabbed the circular saw and did just what Davey said and sometime the saw would bind or grab and jump right at me. It does work wonderfully but again..be careful. And watch out for flying staples! Audie...
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Brenda (OH)
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I have found that an oscillating cutter, such as fein multimaster, or the craftsman version of the tool, is great for cleaning up sections of old subfloor that the circular saw did not reach, such as cutting the last bit of corners, or near the wall... and it also will clean up the top of the joists, but hitting staples can ruin the blade by breaking the teeth...

there is a 3 inch scraper blade for sawsall, I have been wondering if they would work on the top of the joists for the glue and staples.... maybe you can try it, and let us know! lol

I fasten down all temporary flooring with good screws, since I almost fell through a floor while sitting on a section of plywood and leaning too far forward.... enough said....I am clumsy, I only remove a sheet and a half of flooring at a time.


Brenda (OH)
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