# Leveling a VERY unlevel/wavy floor



## Baltimoron (Jan 12, 2013)

I went to take a look at/take measurements for a potential job putting hardwood in a future barbershop. The subfloor is VERY unlevel, VERY wavy, as much as 1.5" differential in height in 10 feet. What's the best way to level this? The guy who called me on this said he's previously installed a new subfloor over a subfloor like this, using 3/4 OSB, shimmed to level. Sounds like an ok idea, and I can't think of anything besides that except tearing out the old subfloor, sistering in level floor joists and installing a new subfloor. And I'd rather not do that.


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## Chris Johnson (Apr 19, 2007)

Look for a product from a ready mix supplier called Agillia Screed A. Not sure if you have it available in the US but it's a fantastic product and fixes these issues with no problem.


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## CO762 (Feb 22, 2010)

If a wood subfloor is that wavy, I'd worry more about what's underneath it.


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## EthanB (Sep 28, 2011)

I'd rather rip out the old subfloor and put in new joists than try and shim OSB. It would probably take the same amount of time and give a better result.

If the floor's that out of whack I'd think long and hard about whether it can support the weight of additional layers or levelling compound/screed.


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## Chris Johnson (Apr 19, 2007)

http://www.lafarge-na.com/wps/porta...ctDatasheet_Concrete_1277365309597/Product_EN

Search it, you will be impressed


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## Builder Butch (Jan 30, 2012)

EthanB said:


> I'd rather rip out the old subfloor and put in new joists than try and shim OSB. It would probably take the same amount of time and give a better result.
> 
> If the floor's that out of whack I'd think long and hard about whether it can support the weight of additional layers or levelling compound/screed.


i agree 100%. anything else would be a bandaid. Ive used floor leveler but only when I'm sure the structure will suppport it.


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## ArtisanRemod (Dec 25, 2012)

Chris Johnson said:


> http://www.lafarge-na.com/wps/porta...ctDatasheet_Concrete_1277365309597/Product_EN
> 
> Search it, you will be impressed


That is impressive. Do you know the cost?


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## Chris Johnson (Apr 19, 2007)

ArtisanRemod said:


> That is impressive. Do you know the cost?


Almost $500.00 per m3, 25mm minimum thickness

In English, about $430 cu.yd. 1" minimum thickness which translates to just under $1 per sq.ft.

Product is not considered structural but cures out around 6000 psi. It is great for InFloor heating tubes and out of level/wavy floors. No on site mixing of bag products, pump able and has a truck life of 4 hours. You can place 40,000 sq ft a day with 3 competent guys, actually 2 competent guys and a laborer and only need expansion joints after 10,000 sq ft.


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## stombaugh85 (Jul 23, 2012)

Definitely sounds like a floor joist issue. Is there a basement?
I saw one time a homeowner built a room in the basement and cut the studs all to the same length forgetting about the sloped concrete. Needless to say the floor joist all reflect the concrete now. Sounds like you may have some busted joists or moisture issues causing excessive sag. Could be undersized joist also. I would start with them.


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## CO762 (Feb 22, 2010)

Chris Johnson said:


> http://www.lafarge-na.com/wps/porta...ctDatasheet_Concrete_1277365309597/Product_EN


gypcrete?


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## WarriorWithWood (Jun 30, 2007)

Thinking outside the box here but can you level the low spots with sand and install 3/4 ply over that? Sand won't compress, you can screw through it, and it will fill the voids in a cost effective manner (welcome to commercial). This will not work in some areas but some flooring guys have used it for years (ask the older ones). Just throwing it out there.


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## Chris Johnson (Apr 19, 2007)

CO762 said:


> gypcrete?


No, it's a superior upgrade from gypcrete, not effected by water if a flood happens, can be walked on next day, can be loaded in 3-4 days, all recycled material, no on site mixing required


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## Inner10 (Mar 12, 2009)

Chris Johnson said:


> No, it's a superior upgrade from gypcrete, not effected by water if a flood happens, can be walked on next day, can be loaded in 3-4 days, all recycled material, no on site mixing required


Is it as light?


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## Chris Johnson (Apr 19, 2007)

If I remember correctly 1 3/4" thick is 12lbs per sq ft


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## PrecisionFloors (Jan 24, 2006)

WarriorWithWood said:


> Thinking outside the box here but can you level the low spots with sand and install 3/4 ply over that? Sand won't compress, you can screw through it, and it will fill the voids in a cost effective manner (welcome to commercial). This will not work in some areas but some flooring guys have used it for years (ask the older ones). Just throwing it out there.


Yep, it works and works well. I would still want to know what's up structurally with that floor.


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## WarriorWithWood (Jun 30, 2007)

Same here. It sounds structural and adding more weight isn't going to help but I've seen some funky sh!t out there that you'd swear would fall down and yet there it's been for 70 years.


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## moorewarner (May 29, 2009)

WarriorWithWood said:


> Same here. It sounds structural and adding more weight isn't going to help but I've seen some funky sh!t out there that you'd swear would fall down and yet there it's been for 70 years.


I lived in a place that had a 15x20' second floor, joists were set on a 1x4" notched into the studs (studs unevenly spaced at 28" or so) that were mostly rotted where they went into the concrete sill.

Landlord said "what problem?". :blink: :laughing:


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## WarriorWithWood (Jun 30, 2007)

Rentals are the worst. Imagine trying to tie in a floor on a addition only to crawl under it and see half logs as floor joists after getting way different measurements everywhere you put the laser.


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## CO762 (Feb 22, 2010)

Chris Johnson said:


> No, it's a superior upgrade from gypcrete


Figgured as IIRC, it was an acrylic.


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## CO762 (Feb 22, 2010)

WarriorWithWood said:


> out there that you'd swear would fall down and yet there it's been for 70 years.


I'd guess old wood vs. newer wood. So it just takes longer to sag/fail.


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