Flooring - how flat is flat enough

[Pat Barry]

I'm working on a remodeling project for our cabin. Due to settling, the floor of the cabin slopes approximately 3/4 inch to maybe 1 inch over a 8 foot span in one corner. It is impractical to try to jack up the corner of the cabin to get it back to flat for a variety of reasons (although it does seem to be stable now so I'm not worried about structural issues). And, although we really don't notice the slope (at least it doesn't cause a problem), I'm wondering if I should try to level out the subfloor before putting on a new nail down layer of 3/4" thick T&G flooring and what might be the best way to do this. I don't think that using a self leveling epoxy or product like that makes sense. I was thinking more along the line of fitting in some 1/4 plywood in layers to try and create a relatively level surface for nailing down the new flooring.

What do you guys recommend for this type of situation?

Note - the cabin is sitting over an earthen crawlspace and is not currently insulated. I do need to do something about that as well. At one time I was thinking of laying a piece of 1/2" thick pink styrofoam down as an underlayment over the existing subfloor, but it might also require a layer of plywood on top of that so the total thickness will be quite a lot. Insulating the flooring from underneath might be a better bet.

[Rich Engelhardt]

Level Quick (http://www.homedepot.com/p/Custom-Building-Products-LevelQuik-RS-50-lb-Self-Leveling-Underlayment-LQ50/100192482) is made for exactly the situation you describe.
Mix it up - pour it on - & it will seek it's own level.

One corner dipping like that sounds structural. Any way to open the wall or floor and check for insect damage or rot?
Does it have a musty damp odor?

[scott vroom]

Rich, it sounds like he's nailing directly into the subfloor. I'm afraid the Levelquik will shatter if nails are driven through it.

My suggestion would be to cut back the subfloor over the area in question, glue/screw in sister joists to make the floor flat, and patch in a new subfloor using blocking to secure all unsupported edges.

Photos would help.

[Pat Barry]

Level Quick (http://www.homedepot.com/p/Custom-Building-Products-LevelQuik-RS-50-lb-Self-Leveling-Underlayment-LQ50/100192482) is made for exactly the situation you describe.
Mix it up - pour it on - & it will seek it's own level.

One corner dipping like that sounds structural. Any way to open the wall or floor and check for insect damage or rot?
Does it have a musty damp odor?
The corner that is low is that way because many years ago there was water runoff problem that caused the pier foundation to sink. Now keep inmind this cabin was built as part of a resort back in the late 30's and all they did was build a structure on wooden piers and beams. Sometime later concrete piers were put in about every 8 ft on center. Truth be told I don't know how deep they go but I'm betting it was done with the codes of the time (late 60's early 70's) so they would be below the frost line. The thing is, I don't think they completely leveled the building when they did it. Since then I don't think there has been additional settling and the water runoff problem that created the problem was corrected. Anyway I feel it is stable but I'm not ready just now to try and do a proper concrete block wall foundation.

The subfloor is quatersawn oak, 3/4" thick nailed to floor joints that are 4 inch diameter logs on 24 inch centers. The logs are solid, no rot that I can see so I think they are stable. There are a few locations where the subflooring does need to be replaced due to some rot (former bathroom location) and near old front door.

Sorry, don't have any pictures, I hope my description is clear enough.

I think Scott may be on to something. I need to think about that idea a bit more

[Neil Gaskin]

Is the floor flat but out of level or out level and not flat? If you can run a 6 or 8' straight edge and it's touching along the length you should be fine for a wood floor.

A flat/smooth plane is more important than whether or not the floor is level. If it is flat and the fact that it is not level does not bother you then you can install the floor and not worry about it. If it dips or their is a hump this will prove to be a problem. As already suggested, removing the sub-floor and installing either tapered shims direct to the joists or sistering onto the sides will fix the problem. Install the subfloor above and you're good to go.

Nailing through a self leveler will not work.

[peter gagliardi]

Not being able to see the physical situation of how the cabin sits in the landscape, it's kind of tough. But, if this is simply a small cabin on piers, I would seriously explore the idea of jacking the corner, and filling the void with solid stock or wedges between the pier and frame.
Unless there is a REALLY compelling reason not to, other than its hard or a bit of work. Trying to level inside is most likely much more work in actuality. Rent a couple 5-10 ton bottle jacks and be done in a couple hours.

[Mike Schuch]

Roofing felt. Put the first piece down in the farthest part of the corner. Then make each additional piece bigger filling in towards the center of the room. It will be plenty quiet and the thin pieces will make it easier to build up gradually towards the center of the room. Flooring nails will go right through it unlike leveling compound.

[Jim Dwight]

Seems like you can level either way. If you want to do it inside, what about installing 2x4s on 16 inch centers cut with an opposite taper to level things out. Then you can insulate between the 2x4s, put down new subfloor and then flooring. It's a lot in materials, especially compared to jacking it up and shimming from below. But I don't see why it wouldn't work fine.

[Bill Space]

I hope I'm able to reply satisfactorily using my iPad.

Your question brings up a lot of different issues with respect to solving the problem of a non-flat floor.

We need to keep in mind that many of us desire perfection in what we do. As such we demand a flat and level floor in a living space.

But the reality of life may tell us that flat is more important than level. You have an old house. If you jack up the house to level the floor, then you may find that windows jam up and doors no longer close or open. Think about this.

Ripping off the subflooring and leveling things up is possible, but after you are done you may find out that the distance between the floor in the windowsills is obviously different to the Eye. It is also a lot of work.

Whatever you do you still will have to remove the baseboards and reinstall them.

My son-in-law and I went through a similar issue with out of level and wavy floors in an old house he and my daughter purchased several years ago. After evaluating the situation we determined that the most important thing was to have a flat floor, and not to try to make it a level AND flat floor. Our solution was to leave the flooring in place and use a homebrew 12 foot straight edge to determine what needed to be done to make this floor flat, not worrying about making it level.

What we did is put down a new layer of half-inch plywood on top of the existing floor. To accomplish this we laid out a number of spacers to which the new plywood was screwed into. Strips of material were screwed into the flooring as required to produce a number of strips of support which were 12 inches or less apart, to support over the entire floor. The resulting support lattice was not an evenly spaced matrix, but rather something that ran in an irregular fashion as dictated by requirement that the plywood, that would support the new flooring, be a single plane surface, which sloped somewhat (due to the average slope of the floor).

This was done over five rooms and two hallways on two floors. It required that the new plywood, which was screwed into the spacers, which were mounted to the floor, be marked to make sure the screws went between the new plywood and through the spacers and into the existing floor.

This may be out of the box thinking but it actually worked well and has served well over the last few years. The house floors are not level, but they are much better than what was there to begin with. Actually they are very flat, they just are not level, but they are much better than they used to be because they are flat, and not wavy anymore. The fact that the floor is not flat, and actually slopes a bit, is not apparent to The eye, or to the foot when walked upon.

KISS does work sometimes. I would only use this method if the basic floor structure is sound, as it appears to be from your description.

wish I had some pictures but I don't. I did, but why I don't now is a long story…

Bill

[Gary Yoder]

two suggestions-

#1 I know you said jacking is unpractical, but is there a way to jack the cabin and put shims between the pier and wood framing? If there is, this would be the best option by a long shot. If not,
#2 buy a few 2x4's, with a circular saw cut an angled rip to match the slope, (setting the boards on edge) shimming up the floor to level or flat. Take your time, run the shim boards every 6-12 inches, and screw them down to prevent floor squeaks.

[Rich Engelhardt]

Rich, it sounds like he's nailing directly into the subfloor.Scott- you're right! I don't know why I was reading "nail" and thinking "laminate flooring"!
Too many things going on at once I guess. I'm leveling a section of a concrete basement and ran across the Level Quick. I guess I got my project and Pat's all mixed up in my head.

[Pat Barry]

I appreciate all the feedback and ideas you guys have provided. There are merits to each one of course and I have plenty to consider at this point.

Related to the idea of jacking up the cabin though, one of my concerns had to do with the point Bill brings up about windows not operating correctly, etc. One of the concerns I have is that I don't know what else would change if anything. I do think that if I were to go this way that I would do as suggested by Gary and put the leveling shims in above the piers, under the existing subfloor joists.

The point about the floor being flat or just not level is an interesting one. In fact, we haven't perceived the floor to be non flat or non level in our daily use. Whats funny was that a few years ago, as part of the flipping process the previous owner (a professional handyman as I understand it) installed a Pergo like laminate flooring. He was appparently trying to make the floor level so he shimmed right under the laminate flooring. He used strips from the cardboard box the lamiante came in and slipped and stacked these strips under the laminate. Well, all that did was create a spongy floor. Of course I didn't know that at the time so I can't telll you how many hors I spent laying in the dirt under the cabin having my wife walk around on the floor above so I could try and figure out where the sponginess was coming from. I was concerned it was the log joists, or the span, or some other structural issue. I even put in sister joists in a few places to try and rigidize things. Finally I got fed up and pulled up the Pergo and was amazed at the shimming job. LOL. Some handyman. Thats when I discovered the real problem was the settling.

One other thing to note is that this being an older place, a lot of new work has been done over time. For example, they installed a new bathroom and did a nice modern construction using treated joists and got the floor of the bathroom level. Now, if I jack the foundation up, the bathroom will go from level to out of level by the same amount. Similarly, in the kitchen, there were new cabinets installed on the non-level floor. Walking along the cabinets you can perceive the drop in elevation of about 1/2 to 3/4 inch (12 ft span of cabinets). This is sharing a wall with a new family room addition that was built maybe 10 years ago that has a true and level floor. If I jack this corner of the old cabin up, then I'm sure the addition will have to move also and then create another issue.

Anyway, I do think jacking the structure up at this point might just result in way more problems than I have now due to collateral effects.

So, I think the best solution for me at this time is to 1) live with the floor being out of level but flat and just put the new flooring down or 2) try to shim / level the new floor over the existing non-level subfloor. I need to go back up to the place and really study this to make a good decision.

[Pat Barry]

Not being able to see the physical situation of how the cabin sits in the landscape, it's kind of tough. But, if this is simply a small cabin on piers, I would seriously explore the idea of jacking the corner, and filling the void with solid stock or wedges between the pier and frame.
Unless there is a REALLY compelling reason not to, other than its hard or a bit of work. Trying to level inside is most likely much more work in actuality. Rent a couple 5-10 ton bottle jacks and be done in a couple hours.

Yes, you are right. There is never enough information. The can sits on a hillside near the lake. There is a significant difference in elevation for the lakeside as compared to the front of the cabin. I think approx 4 ft over a distance of about 16 ft front to back. I do think you are right that it could be jacked up pretty easily but see my comments above related to the collateral issues that I would have to contend with.

[Pat Barry]

Roofing felt. Put the first piece down in the farthest part of the corner. Then make each additional piece bigger filling in towards the center of the room. It will be plenty quiet and the thin pieces will make it easier to build up gradually towards the center of the room. Flooring nails will go right through it unlike leveling compound.
I like the roofing felt idea. It would be easier than cutting and fitting 1/4" plywood and would leave a much better transsition. If the previous handyman had listened to this idea I wouldn't have had the issues that caused this whole mess.

[Jason Roehl]

I like the roofing felt idea. It would be easier than cutting and fitting 1/4" plywood and would leave a much better transsition. If the previous handyman had listened to this idea I wouldn't have had the issues that caused this whole mess.

Consider that flooring cleats are 2". If there's 1" of roofing felt in the corner, that doesn't leave much nail to go into the subfloor once it goes through the flooring tongue and felt, if it makes it to the subfloor at all, since it's driven at an angle.

My first preference would be to fix the root problem by jacking up the cabin, but since you said that would cause a whole host of other problems due to past remodeling, I'd pull the subfloor and sister some floor joists level.

I can't stand out-of-level floors--it's like walking on a boat for me. And I'm pretty much a landlubber.

[Phil Thien]

Glue 1" plywood to the existing subfloor, use screws around the edges where not much of the plywood will need to be removed. Now go crazy with a large floor sander to taper it into the rest of the floor?

Full disclosure: Never tried this, it is just a thought.

The idea of the roofing felt is good, too. Will need to use longer cleats (they sell them in up to 2" I think) in those areas.

[Joe Jensen]

Out of level would drive me crazy. I'd pull the subfloor, shim to level and install new sub floor. I just did this for a master bath remodel at my house.

[John Echenrode]

Wood flooring requires a FLAT surface not necessarily a level surface. Sub floor should be flat or made to be flat to 3/16” in a 8ft. radius. 15 or 30 lb felt paper is perfect to accomplish this and would double as a moisture barrier.

[roger wiegand]

Having lived in many old houses with sloping floors, I suggest you regard it as a charming feature rather than a bug and just ignore the slope as long as the floor is flat enough to lay the flooring.