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Old 11-07-2019, 01:45 AM   #1
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Subfloor


Hello all, need some input. Need to build up a subfloor, 3/4"hardwood will be installed. Back story: house in the chicagoland area built in late 60's. Will be installing 3/4" hardwood throughout the house save for the bathrooms. Bedrooms and front room were carpeted but kitchen, dining room and hallways are all tile. While beginning to take up tile in the kitchen I come to find that tile was laid atop 2"mortar bed. Not just in the bathrooms, EVERYWHERE, (2400 sq'). I didn't know whether to laugh, cry or run. The mortar bed was thankfully poured over tar paper. In order to have subfloor flush with existing bedrooms and front room subfloors I need to make up 2 1/4". I am seeking any words of wisdom in the best manner to tackle this. (FYI-all floors must be same height) Thanks in advance to all.
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Old 11-07-2019, 03:17 AM   #2
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Re: Subfloor


2X4 sleepers and 3/4" subfloor.

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Old 11-07-2019, 05:20 AM   #3
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Re: Subfloor


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2X4 sleepers and 3/4" subfloor.
Obvious as the nose on your face.
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Old 11-07-2019, 07:48 AM   #4
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Re: Subfloor


I would do the same but just use 1/2" and 1/4" ply instead of just the 3/4" plywood. Glued and screwed of course. I find it squeaks less and stronger too.

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Old 11-07-2019, 10:15 AM   #5
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Re: Subfloor


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I would do the same but just use 1/2" and 1/4" ply instead of just the 3/4" plywood. Glued and screwed of course. I find it squeaks less and stronger too.

Bob
But... why? That seems more expensive and labour intensive. I'd argue it would not be stronger and likely more prone to squeaks.
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Old 11-07-2019, 10:34 PM   #6
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Re: Subfloor


Yeap. Sleepers glued and screwed, 3/4" T & G OSB, glued and screwed, is how we'd do it. Nice opportunity to shim the subfloor perfectly level while you're at it if needed.

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Old Yesterday, 06:56 AM   #7
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Re: Subfloor


My way is more labour but it works great. Glue and screw sleepers down shimming as needed or scribing and cutting to get level. Then glue and screw 1/2" PLYWOOD down. I hate OSB. Check for any low spots and pour SLC if needed. Then glue and screw 1/4" Plywood down. If down right will never squeak and if it gets wet will not swell up like OSB. And it makes it stronger because you end up with more thinner layers then is 3/4" plywood was used. The old houses i work in need all the help they can get, and this way was taught to me many years ago and i have been following it ever since.
But if you don't need that much strength or just need to get it done fast, 3/4" over sleepers will be ok for hardwood. I would not do just 3/4" for tiles. had to redo too many tile floors from other contractors that i do not trust it.
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Old Yesterday, 10:53 AM   #8
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Re: Subfloor


Quote:
Originally Posted by onmywayup View Post
Yeap. Sleepers glued and screwed, 3/4" T & G OSB, glued and screwed, is how we'd do it. Nice opportunity to shim the subfloor perfectly level while you're at it if needed.

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Don't know if you want to use OSB if your going to shoot down the cherry--unless the mfg's specs/okays it.
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Old Yesterday, 11:16 AM   #9
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Re: Subfloor


imagine the weight on those floors . wonder if the reduced ceiling height is noticeable .
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Old Yesterday, 12:28 PM   #10
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Re: Subfloor


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Don't know if you want to use OSB if your going to shoot down the cherry--unless the mfg's specs/okays it.
Every hardwood flooring manufacturer I've ever laid specs 5/8" osb as a suitable subfloor
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Old Yesterday, 01:12 PM   #11
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Re: Subfloor


Boy do I feel like dope, this was obvious. I think I was still in shock after discovering the mortar bed. 9’ ceilings so it won’t be bad. Thanks gentlemen for the quick replies and info. Really appreciated. Pinwheel, I’m stealing the witty reply, that was a good one.
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Old Yesterday, 01:36 PM   #12
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Re: Subfloor


Damn 2400 sq ft of mortar bed!!!

yikes that is a huge change order and weight in dumpster!!

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Old Yesterday, 07:38 PM   #13
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Re: Subfloor


No pun intended, hdavis nailed it.
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Old Yesterday, 09:04 PM   #14
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Re: Subfloor


sure that's not gypcrete?

I've run into 1-1/2" gypcrete floors in multi-family units, although it was all carpeted. little rot goes a long way and joist failure from overloading.

some projects I might try to sell the upside by installing new doors/trim. that's based on the fact that base always gets replaced when I install new flooring and it's usually upsized from the old 3-1/4 to a taller profile. turn lemons into lemonade for $$
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Old Yesterday, 09:09 PM   #15
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Re: Subfloor


When someone says osb subfloor that translates directly to advantech for me.
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Old Today, 06:44 AM   #16
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Re: Subfloor


austinDb, you may be correct about the gypcrete. house is from late 60's/early 70's. hopefully it is, it'll be easier for me to take out. awaiting permit and dumpster so i'll be digging in in the next week. advantech is nice but too costly for the area.
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Old Today, 07:06 AM   #17
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Re: Subfloor


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advantech is nice but too costly for the area.

And not necessary in dry conditions like you've got.

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