How to replace a subfloor?

GeneralElectric · #1 07-01-2010, 02:19 PM

Because we all know that TB is the best place to ask about home repairs...

Anyways a friend of mine had a termite problem and an exterminator took care of that. They screwed up a section of her living room floor and ate away most of the subfloor. Since its an old house it doesn't have a plywood subfloor (old house) but rather these wooden beams that measure out to 8" wide and an inch thick and run along the whole floor. The section of the floor that needs to be replaced is 9'x5' and the joists are still intact and structurally sound.

I've done some woodworking before and she asked me to help her with the floor. I wanted to replace the original subfloor with modern plywood since its easier to work with but she insisted I replace the subfloor with replacement beams. So I'm going to have to join the original beams with the old ones. I planned on attaching wooden blocks to some of the joists and attaching the ends of the beams to the blocks.

I'm only going to replace the subfloor and she is going to install new oak planks for the floor.

Anyone see any problems with my plan as I curse the inability to use plywood?

billjr · #2 07-01-2010, 02:40 PM

If she's got true dimensional lumber (older homes), then the thickness of any new material is going to be the tricky part, as the boards are actually 1"thick. Modern lumber will be 3/4 inch thick. You'll have to get 2" thick boards and plane them down to the actual thickness you need.

If you used plywood, you'd have to use two 1/2" thick sheets to get the 1", as I believe plywood is actual dimensions.

Other than that, it sounds like a pretty straightforward project.

mike_v_s · #3 07-01-2010, 02:43 PM

Quote:

Originally Posted by billjr

If she's got true dimensional lumber (older homes), then the thickness of any new material is going to be the tricky part, as the boards are actually 1"thick. Modern lumber will be 3/4 inch thick. You'll have to get 2" thick boards and plane them down to the actual thickness you need.

If you used plywood, you'd have to use two 1/2" thick sheets to get the 1", as I believe plywood is actual dimensions.

Other than that, it sounds like a pretty straightforward project.

I'm a moron in some respects, but would 5/4 decking boards work? They generally measure much closer to an inch in depth than modern "1"x's. The width might be another issue.

Mike

CapnSev · #4 07-01-2010, 02:56 PM

Honestly, I don't even know what the subfloor is.

Is that the crawlspace under houses without basements or something?

MatticusMania · #5 07-01-2010, 02:59 PM

Quote:

Originally Posted by CapnSev

Honestly, I don't even know what the subfloor is.

Is that the crawlspace under houses without basements or something?

I believe its the floor under your flooring. Take up the carpet and pad, then the wooden floor under that, and theres your subfloor? I think...

mike_v_s · #6 07-01-2010, 03:02 PM

Quote:

Originally Posted by MatticusMania

I believe its the floor under your flooring. Take up the carpet and pad, then the wooden floor under that, and theres your subfloor? I think...

Yes, unless you have a slab, then it's straight concrete.

Mike

CapnSev · #7 07-01-2010, 03:08 PM

So its the bracing under the floorboards then?

MatticusMania · #8 07-01-2010, 03:08 PM

Quote:

Originally Posted by mike_v_s

Yes, unless you have a slab, then it's straight concrete.

Mike

Ah yes, like the floor in my fathers den that they added to the house.

I wouldnt know anyways, Id just hire some illegal guy to do the job, GE.

GeneralElectric · #9 07-01-2010, 03:15 PM

FWIW I already purchased the boards and they're supposedly 1" thick. Think I'll have to shim the floor?

Think my method sounds sound? I've never replaced a subfloor before so I wanna check with more experienced minds before I do anything

GeneralElectric · #10 07-01-2010, 03:16 PM

Quote:

Originally Posted by CapnSev

So its the bracing under the floorboards then?

Sort of.

Its the joists, then the subfloor, then the floor.

The joists support and hold up the subfloor while the subfloor gives you a level surface to put down floor boards.

GeneralElectric · #11 07-01-2010, 03:17 PM

Quote:

Originally Posted by MatticusMania

Ah yes, like the floor in my fathers den that they added to the house.

I wouldnt know anyways, Id just hire some illegal guy to do the job, GE.

Hah.

She's not giving me any money for this but she's going to give me this old Danelectro longhorn thats in her basement. Going by her description its a long horn in black metallic flake.

MatticusMania · #12 07-01-2010, 03:19 PM

Quote:

Originally Posted by GeneralElectric

Hah.

She's not giving me any money for this but she's going to give me this old Danelectro longhorn thats in her basement. Going by her description its a long horn in black metallic flake.

If its as cool as it sounds, then it'll probably be worth it.

billjr · #13 07-01-2010, 03:24 PM

The floor of a house rests on big, thick floor joists that are set up on edge and spaced, I think 18" apart (or 12"). Plywood is typically used as a subfloor on top of the floor joists, and this is the surface that the final floor(wood strips, tile, linoleum, etc) rests on. You need a solid surface for the floor to lay on, and plywood is much cheaper and easier than planks.

The problem with 5/4 decking is that it still is not going to be even, and any difference WILL be noticeable eventually. Linoleum would show the tiniest edge in a very short time, whereas hardwood planks would not show as soon, but eventually you'll notice a depression in the area that was replaced, and will also have more squeeking.

The width will also be a consideration if the original lumber was true, but that will just take a table saw to trim the boards. Also, its better to trim all of the boards a little than wait and trim the last one a lot. Keep all of the boards as close to the same width as possible as a general rule.

billjr · #14 07-01-2010, 03:30 PM

Quote:

Originally Posted by MatticusMania

I believe its the floor under your flooring. Take up the carpet and pad, then the wooden floor under that, and theres your subfloor? I think...

I've seen a lot of older homes that place the carpet right on top of the original floor(usually hardwood), so under the carpet, you may still have a finished floor on top of the subfloor.

I once removed carpet from a house that had two inside dogs. We were replacing the carpet because of the horrible smell of urine that showed up "after" we bought the house and wouldn't go away, even after profesional cleaning. Under that carpet was a beautiful hardwood floor that had been ruined by years of dog piss saturating into the wood.

billjr · #15 07-01-2010, 03:36 PM

Do a 9x5 subfloor for a bass? Man why can't I luck out like that?

GeneralElectric, your idea sounds fine. I'm not a professional, but I do a lot of my own work around the house and learned by helping my dad do projects all of my life. When are you getting started? Keep us up to date on how it's going.

MatticusMania · #16 07-01-2010, 03:40 PM

Quote:

Originally Posted by billjr

I've seen a lot of older homes that place the carpet right on top of the original floor(usually hardwood), so under the carpet, you may still have a finished floor on top of the subfloor.

Thats what I meant by the 'floor under your flooring'. Cuz thats how it was in my parents house. They had the subfloor, then the regular wooden floor, and the a pad & carpet on top of that. My Dad tore up the carpet and put a tiled floor on top of the old wooden floor.

GeneralElectric · #17 07-01-2010, 03:48 PM

Quote:

Originally Posted by billjr

Do a 9x5 subfloor for a bass? Man why can't I luck out like that?

GeneralElectric, your idea sounds fine. I'm not a professional, but I do a lot of my own work around the house and learned by helping my dad do projects all of my life. When are you getting started? Keep us up to date on how it's going.

She's got a ton of old cheapo guitars and basses and drums in her basement in cases. I'm going to be helping her in drips and drabs around the house in exchange for instruments so she doesn't go bankrupt with contractors before she sells the house next year.

I already asked her to start sorting the instruments (she inherited the house and its contents) and to put any basses she finds separate and make a list of what she's got. She found a late 60s Fender strat which she sold on NYC CL a few months ago for a couple of grand. Most of its junk most likely and a lot of them need repairs of some kind.
Her uncle, who she inherited the house from, was a band leader in the 70s and 80s and played in a couple of night clubs from what I understand.

So far she found the Danelectro and a bass called a Goya. Judging by her air outline of the bass its a long horn. I've got no idea what a Goya is though.

If there is anything actually valuable I'll help her sell it. Even its a a 1951 P-bass she's offering to give me for free.

I start tonight by ripping up the floor boards