Getting subfloor level for laminate


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Old 10-06-05, 09:06 AM
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Getting subfloor level for laminate

Hi guys, long-time lurker, first time post.

There is alot more to this issue but I'll try to be brief for now.
I'm getting ready to put in laminate tiles (quick step Quadra) in dining room and kitchen. Howevert he floor is not level due to some sagging issues; take a look at this pic
http://www.rewazule.com/home_project...room_floor.jpg

Just for orientation this is a 40 yo (some kind of) leinoleum floor that had black carpet pad on it, aparently disintegrated and stuck and so PO (also original owner) had it scraped up and new pad put down, that has been removed now.
If you look closely, you can see lines, making 4x8 rectangles. they are where the foam is worn away, and in some places the flooring is worn also. I figure this is from the hous settling and the underlayment (3/4" plywood) didn't on the edges.

Do I have to pull all of this up? This plywood is on top of 1x4 diagnoal slats.
2 concerns - WOW, what a pain, since there are counters/cabinets on top of this plywood, and, perhaps more, could this be an asbestos product? Built in '64. The kitchen has some sort of 10" tiles glued to the plywood, currently covered by 1/4" sheathing and vinyl. Obviously if anything is absbestos I don't want to touch it.... how would I know?

Or, how could I build on top of this? Would just 1/4" sheething be okay? not confident. Or what about a foam underlayment (like used for laminate) UNDER sheathing to "buffer" the uneven-ness?

I'm open to ideas, just researching options now.
 
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Old 10-09-05, 08:28 AM
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So ,I've done some more research etc and here's how it seems, the currentt flooring in teh idning room is most likely not as asbestos product; however, there is a reasonab;e chance the tiles in the kitchen are... so it's seems my best choice is to "let sleeping dogs lay" and just build up on top of it.

So what is the best way to get this level? Some sort of leveling compound?
Aside from the "rectangles" seen in the post above, there is a sort of "hump" that runs the length of the whole kitchen and dining room.... it is maybe 2-3' wide w/ a rise of (guessing) 3/8 or 1/2". You can't really see it in the pic. Aparently, this corresponds to a beam that runs the length of the whole house, that is supported by poles on the basement floor... it runs perpedicular to all the floor joists and is in teh center of the house. My guess is that over 40 years, the whole floor/house has sagged a little, but b/c this beam is supported by the poles it didn't, and the rest kind of sagged on either side of it.
Is there any way to deal with this, or am I just kind of stuck w/ this hump? Obviously ist can't be removed, what I mean is, ow can it be best "hidden" for this laminate floor?
Again maybe som kind of leveling compound, but since its essentialy a "rise" and not a "sink" it seems it'd take a whole of it.
I'm wondeirng if I were to lay down some cushy pad, then plywood on top of it, and tighten that down w/ screws, maybe a little tighter on the hump than the the sides, the do the this laminate underlayment and laminate on top.... idea beoing it will "cushion" around the hump a tad?h
 
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Old 10-09-05, 03:49 PM
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I have a similar question/issue with the floor I just uncovered in preparation of a wood installation. There is a very slight "hump" down the middle of the floor, probably no more than 3/16" higher than the edges of the floor, so I need to get that down to 2/16" or less according to the reqs.

Is RatLabGuy's idea of putting a "cushion" on top and another layer of ply feasible?

Is sanding the way to deal with this? If so, what kind of sander is recommended?

Is raising the rest of the floor to meet the "hump" easier/recommended?
 
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Old 10-13-05, 12:14 PM
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Hey MCM, did you have any luck w/ an answer? I haven't yet...
Anybody else got an idea?
Seems my "hump" is more like about 3/8" over maybe 2.5-3".
Wondering if a slightly less pliable subflooring like 11/32s or 3/8s ply would be better than the classic 1/4" on top of some thin foam substrate?
 
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Old 10-13-05, 07:24 PM
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You need to get the substrate as flat as possible, or expect it to be a concren later.

The manufacturer of your flooring, has their own ideas and requirements for their flooring.
 
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Old 10-14-05, 05:59 AM
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Originally Posted by Carpets Done Wright
You need to get the substrate as flat as possible, or expect it to be a concren later.

The manufacturer of your flooring, has their own ideas and requirements for their flooring.
Thanks. I think we're all in agreement that it needs to be flat... the question here is whether it would be a bad idea to do this extra layer of padding deal below a sheet of plywood (I'm thinking 11/32s-3/8s ply just 'cause its a little more ridgid). Because its a "hump" getting it truly flat really won't be possible w/o spreading hundreds of lbs of leveling compund across the whole room...
 
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Old 10-14-05, 06:35 AM
Heler Hiwater
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similar situation

Hi RatLabGuy,

I have a similar situation in my house but just the opposit. My subfloor dips almost 3/4 inch in the center of my livingroom. The subfloor is 2x6 T&G over 6x10 joists, spaced 46 inches o/c. Below the living room is an entertainment room with the nice, exposed beamed, T&G ceiling. I'm about to lay wideplank pine floors in the same direction as the T&G so will need to lay 1/4 inch OSB down first.

I've heard that you can use asphalt roofing shingles as shims to level your subfloor. Supposedly, you can lay a straight 2x4 with one end on the high spot and the other stacked on whatever you can to bring it level. Then just stack and fan out your shingles up to the bottom of the 2x4. This is supposed to work with either a hump or a dip. Appaerently, asphalt shingles don't break down or compress over time like floor leveler does (turns to powder).

My livingromm is about 30 feet by 20 feet and seems like it might take a lot of shingles to fill it up!

I haven't tried this yet but maybe it will help. Has anyone else heard of this before? And since I have an exposed ceiling downstairs I worry about nails poking through the T&G since I need to use longer ones in the center where the shingles will be stacked (almost 3/4 inch difference). At any rate, this is supposed to be an old school cure for an age old problem. Anyone have any new techniques?

Thanks
 
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Old 10-14-05, 04:31 PM
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Originally Posted by Heler Hiwater
Hi RatLabGuy,

I have a similar situation in my house but just the opposit. My subfloor dips almost 3/4 inch in the center of my livingroom. The subfloor is 2x6 T&G over 6x10 joists, spaced 46 inches o/c. Below the living room is an entertainment room with the nice, exposed beamed, T&G ceiling. I'm about to lay wideplank pine floors in the same direction as the T&G so will need to lay 1/4 inch OSB down first.


Shaking head sideways!



Your going to need no less then 5/8" CDX over the 2x6's and run at a 45║ to the 2x6's, or your going to experience panelization.
 
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Old 10-14-05, 05:55 PM
Heler Hiwater
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Subfloor thickness

Hi Perry, thanks for the response. Unfortunately I cannot lay 5/8" CDX. There was originally carpet in the livingroom layed over 5/8" PB. My floor stock is 3/4". This would raise the floor way too high for the thresholds and none of my doors would open (8 sets of double french and one entry).

I do plan on laying the OSB @ a 45 to the T&G with the addition of SF adhesive. This still gives me a 1 3/4" subfloor plus a hair for 15# asphalt felt.
I plan on using an oil finish on them when done, so sidebonding and panelization will not be an issue.

I've double screwed each 2x6 t&g to each joist with 3" screws. Hopefully this will solidify the t&g and lessen excessive movement.

Do you feel this is sufficient? I can't seem to find any other way of doing it.

Thanks again.
 
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Old 10-14-05, 07:20 PM
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I like the idea of shingles. Hmmmmmm. Iwonder what anyone else thinks? Do you think they should be nailed to keep from sliding around?
 
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Old 10-15-05, 07:20 AM
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In reading on other sites, folks say you don't have to nail down teh shingles themselves b/c when you screw in the sheathing on top the screws will end up going through the shingles anyway. Plus, the weight/friction of the floor should keep them in place, I'd think you you have enough lateral slippage to slide a shingle around then you've got bigger problems anyway....

Actually I'm thinking noiw that this is hoe I'm gonna go, break down and lay shingles across *most* of the floor except where my hump is. Its only ~250 sq ft so it shouldn't break me in teh shingle cost (besides super-cheapies will do nayway, eh?). Then on top of that maybe some cheapo foam underlayment just to even it ou ta tad, w/ 11/32s on top of that. Then I'll do teh standard laminate underlayment and flooring.
Downside it teh total new floor height will be like 3/4"or more...that will be really fun at doorways where it meets the original hardwood!
 
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Old 10-15-05, 09:55 AM
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I just did a place that had a one inch hump. I could not see myself levelling the whole floor because of time and effort. Also the 1 inch rise would not have worked well at transitions.
I got some 30 grit sandpaper for my belt sander and took about 3/8 inch off the hump. It made a huge difference but I still have a hump. I was out of province and on a time line so I just put the floorign down and am hoping for the best. There was no flex in it that I could feel so I might get lucky. Also, the hump is where I could probably put in a hokey transition strip if the laminate starts to crack up a bit.
I might have tried the shingle idea had I know before but only to reduce the hump and graduate to the walls. Perry has posted levlling pictures in another thread so next job, I'm going to use the levelling compound where appropriate. I've used it before but never to the extent he does.
 
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Old 10-16-05, 01:51 PM
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I'm in the process of laying down traffic master laminents and I too suffer from a hump where the floor sags around a joist.

The worst section was where the builder had the subfloor seam meet at this high spot. I guess the two seperate subfloor panels meeting at the high spot enhances the problem - where as the hump is mitigated where the subfloor panel spans over the hump - if that makes any sense..

So - I took a chisel and removed 1 layer of the plywood subfloor (about 1/8") and then bought a pack of 30grit belt sander paper and have been doing a lot of sanding. I have to say that it is getting a lot better. It's time consuming, but it's my personal house, spare room, so I really don't have a timeline.

I also have 2 50lb bags of floor leveling compound. After I'm done sanding, I will use the leveling compound.. Then, finally, if needed - 15# roofers felt.

This is my 3rd floor I've done (my house 3/4" hardwood and this laminant and my parents 3/4" hardwood) - with much credit to the guys on this board for all their help. There are no shortcuts to leveling a floor - at least I haven't found any yet.
 
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Old 07-01-14, 05:41 PM
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Well... here we are are 9 years later... I was looking for something else and happened across this thread- figured I should review what happened!

After a lot of consideration about just how much "filler" it would take to even out that large space, I came up w/ a different approach...

I went and bought several sheets of plywood (1/2" maybe?) and Robertson square-head screws... and screwed that stuff real tight to the floor... so that it conformed to the large hump.
Then , I rented a large drum sander, and sanded down the hump on the new floor!
It took darn near forever, but I was able to shave it down so that the plywood on top of the hump was probably only about 1/8" thick - down to a single ply - and slowly got thicker on teh sides.. .so the top was flat!
Here's a pic I snapped during the progress
http://www.rewazule.com/home_project...t/IMG_1718.JPG

Kinda neat how you can see the different plys of the wood.

It wasn't exactly perfectly flat... but was pretty darn close... covered w/ a good thick underlayment and thick laminate tile floor, you couldn't tell at all!
I'm sure whomever pulls up the new floor will be very confused, lol! But I did leave a note taped to the plywood
 
 

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