deciding how to approach subfloor repair...

[mandingueiro]

I'm putting down bamboo flooring in a space...it's a large room...

I took up this tiling to see what was underneath...

there are definitely points that are not level and some problem spots, but I'm trying to figure out how much of this subfloor I need to replace/level...

what is an acceptable amount of deviation? Also, if there are boards that are somewhat rotten from some kind of moisture/deterioration, I know I should replace those, but I'm not sure how much of this subfloor I have to replace...

here are some pics...any input is appreciated... I'll try to describe more fully in the comments section...

 

[Kaizen]

assuming this is a click and lock floating floor? if you're running it the same way you need to look for cupping so put a 4 foot level across the floor and shine a light under it. it has to be flat or very close to it. those corners i'd cut out and put in plywood of the same thickness.
Personally if it was my house i'd just pull all of that up and put down new t&g glued and screwed to hell. shim any as you go if the joists are bowed

 

[Falcon67]

Looks like the floor in the kitchen of our old house. We scraped it as clean as possible, ground down any high spot/seams, etc. Floated some low spots then covered the whole mess with 1/4 ply. Floor went on top of that.

 

[PoorOwner]

I am guessing the moisture area could be dog urine. You can probably get down on the ground and sniff it, it may still smell gross. If it does not smell and feel dry you can probably cover it up. The stains iI have seen feels moist because the salt in the urine seem to collect moisture even after 10+ years. Needed to deorderize and soak up.

As for leveling you need to check it with a flat edge. Remember level and flat are two different things. You want it flat, and the flooring manufacturer will tell you that number. Usually though it is a very small number and not always achievable with what you already have. There may be some obvious spots like sudden drop of 1/4" you should patch up with compound.

 

[Zeke]

Always adhere to the new flooring manufacturer's required specifications, for what they state as being required for a substrate for their flooring in order to keep the warranty legit....

From my chair, I say you need to forget working to make that floor good, just block under any really weak points and go over the top of it with new vapor barrier and underlayment. My opinion will vary though, as you have to consider what the step up in elevations (transition strip/thresholds) will do on the adjacent rooms. JMO

Looks like the floor in the kitchen of our old house. We scraped it as clean as possible, ground down any high spot/seams, etc. Floated some low spots then covered the whole mess with 1/4 ply. Floor went on top of that.

I pretty much agree with these cats. As a contractor I've done many. For those spots that are fairly weak and deteriorated I would consider ripping up the sheet and laying down new with adhesive on the joists. Then sheet the whole thing with no less than 1/4" ply, no MDF, particle or flake board.

A good way to get a nice solid floor is to liberally spread out adhesive and roll the new sheet down with a WIDE weighted roller you can rent. You can also use modified thinset using the same process. Nail the edges 12" OC and the field on top of the joists below if you can find them. Don't drive the nails any further than flush. In fact, leave your nails high just holding the floor flat until the adhesive sets (thinset will set faster, the other might take 2-3 days) and then drive them flush. Pull any nails that are not in solid wood, they will become squeaks. Use ring shanks.

I'd put the barrier on top of the new subfloor.

 

[ishiboo]

Was that asbestos tile? Hope you wore a dust mask

That floor doesn't look in great shape. You could use self-leveler, then 1/4 plywood, etc... by the time you've messed with all that, splicing in repairs, etc... it may well be easier to replace it with good new subfloor.

It does not need to be level for the floor to perform well, and it can wave a bit over a distance gradually. What you don't want is localized high/low spots where the floor would be unsupported around them.

 

[Radix2]

the first question to ask
-are the moisture problems understood and resolved ?

roofs, grades, ect.

 

[matt_i]

My opinion is any area which seems "punky" which is to say, take a flat screwdriver and poke at the floor with medium hand pressure. If there are spots (like at the door area) where you are getting more indenting than a brand-new 2x4 scrap then I would focus on cutting those areas out.

As mentioned above, I'd do a lot of planning based on the need to transition to other areas that join the proposed new floor. It's not bad when they are within 3/16" or so but becomes more painful construction-wise and more noticeable, to jump vertical gaps which are more than that.

 

[mandingueiro]

thank you for all the input!!! I think Im going to start by cutting out the problematic corners and putting new ply down. I will give an update from there soon to come....


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[theoldwizard1]

there are definitely points that are not level and some problem spots, but I'm trying to figure out how much of this subfloor I need to replace/level...

If you have ANY signs of rot/mold I would rip the whole thing out and replace it. You do need to find out where the moisture is coming from and solve that. If you are over a crawl space, maybe you need a good vapor barrier under the subfloor.

If you are going this way, you only have to get about 1" away from existing walls unless there is rot under the wall. Tongue and grove plyood, construction adhesive and screws.

If you want you bamboo flooring to look good, remove the 1/4 round shoe molding and the base board. Number the base boards or just buy new. My daughter's father-in-law did her living room and dining room and it came out great.

Anyone with little kids should have real hardwood floors or bamboo. Much more "kid proof" than carpeting !

 

[larry4406]

Criteria on floors for new construction that the company I work for follows:

Wood floor is out of level.
(a) Standard. No point on the surface of a wood floor shall be more than 1/2 inch higher or lower than any
other point on the surface within 20 feet, or proportional multiples of the preceding dimensions.

Wood floor is uneven.
(a) Standard. Floors shall not have more than a 1/4 inch ridge or depression within any 32-inch
measurement. Allowable floor and ceiling joist deflections are governed by the local approved building
code

 

[RWorth]

just my opinion, I've always found it easier to build new than to repair, I would take out the entire floor and lay down new plywood. Don't know how big your room is, but plywood is only around 30 bux a sheet, give or take. that will also take all the guesswork out of the condition of the joists.

 

[mandingueiro]

I took the advice of some and got a 4 foot level...

here is an example of one end of the room. the floor is high on one wall next to some concrete (outside/window/street facing wall)

I cannot be sure, but I think this section of the floor is higher than the rest of the room. when I pull up the plywood, do I somehow scrape/shave that last joist down (if indeed it is a joist there...could it be concrete or something else as it is the wall adjacent to the street?)? This is the largest slope/problem in the room.

all of these pics show the level at 'level'.

^ here is the opposite end of the room. the level is @ 'level' but it there is clearly a dip. Let's say one of the joists in the middle is 'low'... could I put some thin shims on that joist to raise it up to level? or do I need to put a new 2x4 next to the joist and have it support the plywood next to where the original joist is?

last pic, but again... vvv

the joists are clearly out of level a bit... is it easier to stick to the 'high point' and raise up the low joists by setting new beams next to them or shimming a thin piece of wood on top (maybe a bad idea? never saw this in any tutorials), or to somehow plane the 'high point' and bring it down to the level of the other joists...

I know this isn't an exact science and depends upon what I find underneath, but I'm just trying to anticipate what are my options... I guess finding a 'level point' for the entire floor is somewhat of guess work? I'm just mitigating the descrepancies, so does it matter that much?

I definitely appreciate all the replies...you guys are certainly helping me through this...it's only a 250 sq. room, so I'm not against replacing most of the boards if I have to, but I still want to have the best approach...should I just start cuttting the boards out in the problem areas?

thanks again in advance...

 

[PoorOwner]

If you don't want to replace the subfloor you can possibly use floor patch or roofing felt to shim at the dips. The problem could be you got joist that are too far apart and create serious sags. (This was ok back in the days as most house just get carpet). If you have not purchased the flooring have you looked into laminate or vinyl planks as an alternative?

If you have bought the bamboo already are they the nail type or click type (rare). For nailing you cannot use the floor patch product as it would shatter the the patch.

 

[gahrajmahal]

I would be concerned with mold in that floor.

 

[APEowner]

Is there a crawl space or basement under that room? The best way to level that will depend on why it's out of whack in the first place. If the water damage is as bad as it seems looking at picture on my tablet then there's some structural that needs to be addressed.

 

[Kaizen]

the moldy punky parts are a concern. you're looking at 8 sheets of plywood to redo it and do it right. so 200 bucks or so and a lot of hard work to pop up that mess and start new. wouldn't you rather KNOW you didn't bury a problem?
if you have those dips still you should use floor leveler. super expensive. but its the best thing for a half inch gap like you show. shimming like I first suggested might be a little tough if you haven't done floors a lot.
I can speak from experience it absolutely ***** to put a floating floor down and then realize it flexes too much and the floor unclicks. if it makes you feel any better my kitchen floor had 5 layers over the original t&g fir. kind of a walk through a century of flooring but man did it **** to take up.

 

[RWorth]

"I definitely appreciate all the replies...you guys are certainly helping me through this...it's only a 250 sq. room, so I'm not against replacing most of the boards if I have to, but I still want to have the best approach...should I just start cuttting the boards out in the problem areas?"

Go for it, no sense in guessing what's down there. I'm still in favour of pulling the whole floor, it'll save you a ton of aggravation.

 

[mandingueiro]

Im trying to pull the problem areas. if the floor was done before the drywall (i dont think it 'ends' at the drywall... there are about 3 1/2inches between the face of the wall and the brick behind it), how do I get these panels that border the wall up? do i need to cut the drywall to get some space to pry( assuming they nailed next to the brick wall) ?


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[Kaizen]

run a circular saw along the wall getting as close as you can. take up the rest of the piece. then put a flat prybar under the part in the wall and hammer down on the prybar. if it doesn't come out you can cut the nails with a sawzall.
or if you are using tall trim you could just take out the first inch or so of drywall to give yourself more room. I use 6 inch floor moulding so I don't have to worry about damage or screws in that area. if you do take up the drywall consider laying from that wall......if its the way you were going to run the floor..put in some wood nailed to the new subfloor flush with the existing drywall. use a chalk line and make these pieces of wood on the floor your straight starting line. make sure you use manufacturer required temporary spacers that you will remove after leaving a gap for expansion.

 

[MikeF]

I wouldn't worry about level, go for flat. Our house is late 1800's and I just put some home cheapo laminate in a spare room for an office. The joist settled between the main beams about 1/2 and inch and the same on the out side of the beams. Took a 12 foot strait edge on the high spots and used 1/4" underlayment as needed. Tried leveling compound but it didn't work so good, would've taken alot. Bought a roll of roofing material, like a giant shingle roll. Worked perfectly. Just finished the floor and it's great. The Sand from the roofing material made keeping the are clean, interesting.

The paper that came with our flooring said a difference of 3/16" over 10 was acceptable. The roofing material and plywood underlayment made short work of that