Leveling & Straightening SubFlooring

Old 04-15-04, 01:15 PM
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Question Need some advice

Hi I'm new and I don't know much about renovating but I really like it.

I have bought an 80 year old house. It's a real bric a brac. Most of the work on it has been done by the owners and a lot of it is rather weird. I have to redo the kitchen. It was first done in a botched sort of way I figure somewhere around 40 years ago. It really needs a facelift! I need to know a few things before I decide what to do.

The floor is really crooked. I'm talking up to 2 inches difference in a bunch of diffenrent directions. The house isn't leaning, it's just... crooked. The support beams of the floor are 4x4 (and I mean 4x4 they are square lumber) and some (I'm guessing) 1x6. These are interspaced every foot or so. One 4x4, then one 1x6 etc.

Before I do anything, I have to get that floor straight. How the heck do I do that? Plus, it's already got a false floor, built on top!

I'm not saying I'm gonna do it myself, I just want some info from someone who's not going to get $ in the eyes when I talk to them about it.

Old 04-18-04, 04:25 PM
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Wow sounds like quite the fixer-upper.

Might be best to tear out all of the subflooring down to the joists, then shim to joists to a level you can live with.
Old 04-18-04, 05:14 PM
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What's underneath, and what sort of construction?

This might be a situation where balloon framing could save the day. If the walls weren't built on the floor you could remove the interior flooring and install a modern joist system.

If, however, the walls are resting on the floor joists/subfloor (modern 'platform' style) you probably have a mess on your hands.

Did the flooring sag, or was it built crooked? How many interior walls, bearing and non-bearing, would resist an attempt to jack up the sunken areas?

Take out that false floor, it's useless and a firetrap.

How high are your ceilings? Please tell us they are higher than 8 foot.

The more I think about it...

Remove all flooring and subflooring, down to those funky joists. Leave the joists in place.

Now take a good hard look and determine an O.C. spacing that wouldn't be a nightmare to install.

Sturdi-Floor in 1 1/8" thickness will work on 48" centers. You will need to properly size the joists, but only a third as many as usual will be installed.

You could attempt to work with the existing spacing of joists, or a variant. I imagine you could put dimensional or engineered joists on top of the 4x4s if the existing ledge is going to be a headache.

Your hope should be to leave the walls intact and work around the existing joist system if you can't (or won't) remove it.
Old 04-19-04, 06:11 PM
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Additional suggestions:

Don't attempt to level the floor with a spirit level, regardless of size. I guess you could use a fancy laser, but my vote goes for a "hose level", aka "jug level". It's simply a length of clear tubing with colored water in it. Unless you have a wind blowing over the tubing ends and causing a suction, the error will be zero.

With a tube level in use, I doubt you would find a taut line worth the trouble, though I might be wrong.

Find your highest spot and place one end of the hose there.
Mark the proposed locations of your joists, whatever the on-center spacing you decide.

Take the other hose end around the room and start getting a good idea of how much shimming is needed to level.

You can take notes, or create the shim stacks as you go. I use shim in the strict sense of the term, not those chintzy pieces of tapered wood. Depending on your joist system you may need to use steel plates to transfer the loadings. OSB most likely is a good shim stock, and keep them on the large side. If you are building over 1 1/2", start with dimensional lumber.

Don't drive yourself nuts over perfection. Plus or minus 1/4" is accurate enough, imho.

This is where that 48" joist spacing would be useful. Perhaps you end up putting doubled or tripled joists at each bearing point, but that just makes the joint treatments more forgiving.

You don't cut perfectly square, or it's a bit short? Keep going, and come back with floor leveling compound to fill the gaps.

Doubled or tripled joists would need to be nailed together. If the tops aren't level, get yourself a power plane and plane the high spots.

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