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Risks to structure by replacing a subfloor


edee_em's Avatar
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02-19-16, 10:04 AM   #1  
Risks to structure by replacing a subfloor

I am wondering about the effect on the structure of a house if I remove the existing subfloor and replace it. I have seen and heard of people who cut around the perimeter of the room with a circular saw, remove the old subfloor and then fill in with the new subfloor. They then carry on with putting on their new flooring and all is well. But is it?

As little as I know about subfloors, I do know that they are pretty important as a structural component of the entire house, yes? If I take that existing subfloor out what damage is being done to the structure? If I cut out that subfloor, have I created a break in the ability of the subfloor to keep all the bits together? I get that the replacement subfloor will tie all the joists back together as the original subfloor did but I keep thinking about that cut around the perimeter of the room.

The issue is my house was built with 5/8" waferboard (early form of OSB) back in 1985. I want to replace the carpet in our bedrooms with hardwood flooring. Most manufacturers call for 3/4" plywood or OSB as a proper subfloor, so I would need to replace the existing subfloor, as one option.

Am I overthinking this? Thoughts...
Thanks

 
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joecaption's Avatar
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02-19-16, 10:34 AM   #2  
Removing the old subfloor is not going to have any effect on the rest of the house.
Should be using a Toe Kick saw so you can cut the flooring right up to the bottom of the wall and a sawsall with a short wide course toothed blade held at a steep angle or Ossilating to cut the inside corners.
Home Depot rents Toe Kicks or you could buy a cheap one at a place like Northern Tool.
A tool like this makes it much easier to remove the flooring.
Gutster Tools - Online
Once I cut around the outside walls I run a ciruler saw down between the joist, then stomp on that section which will cause it to twist and start to pull the nails up.

 
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02-19-16, 11:09 AM   #3  
I have done something similar many times. Often to have access to replace joists or work in the crawl space below but the process is the same. First I remove the base molding. Then I have a circular saw which I have removed most of it's shoe so one side can cut within about 1/2" of the wall and I cut around the perimeter just to the depth of the sheeting. In your case 5/8" deep. Then I remove the sheeting and put down your new 3/4" material. I like Advantech brand OSB. It's extremely strong and performs much better than standard OSB. Unfortunately it's heavy. I don't worry about the slight bit of old sheeting around the perimeter as it will be underneath the base molding. And cutting the perimeter with a circular saw is much faster than many other saws that can cut flush. Another option is to use a reciprocating saw which can allow you to get very close but be careful to not cut your joists.

 
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02-19-16, 02:55 PM   #4  
Thanks for the info and tips guys!

 
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02-19-16, 04:07 PM   #5  
A ciruler saw can only cut within 1-1/2 of the wall and just the wrong saw to use on this one.
Advantech is 3/4" thick if your subfloor is now 5/8 thick do you want to have to deal with a step around the edge of the room?

 
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02-20-16, 04:24 AM   #6  
I have an old saw I modified by cutting the shoe down that allows it to cut about 1/2" away from the wall. The limiting factor is the blade mounting bolt head. There are also close cut circular saws. The key is getting the cut down to something that will be concealed by your base molding.

 
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