Building Up A Subfloor - Flooring - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Flooring

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 07-20-2009, 09:52 PM   #1
Newbie
 
Join Date: Jul 2009
Posts: 2
Rewards Points: 10
Default

building up a subfloor


I am wanting add a formal dining room by enclosing my back patio and part of my garage. My foundation is a concrete slab and the area I am wanting to enclose is 3.25" lower than the rest of the living area. I'm looking for suggestions on how to build up the subfloor to meet the height of the current living are foundation. I would rather stay away from pouring concrete, simply from a cost standpoint. The options I have come up with so far are:

1)alternate moisture barrier and stacked 3/4" OSB by gluing and nailing to the concrete foundation.

2)moisture barrier, 3/4" OSB, 2x2's, 3/4" OSB, 1/4" ply

My concern about option #2 is potential bounce in the floor as well as sound going from hollow to solid. Thank you in advance for any and all suggestions.

Advertisement

angelo91 is offline   Reply With Quote
Old 07-20-2009, 10:37 PM   #2
Tileguy
 
JazMan's Avatar
 
Join Date: Feb 2007
Location: Troy, Michigan
Posts: 4,190
Rewards Points: 2,238
Default

building up a subfloor


Angelo,

You forgot to mention one of the key specs for this new room....what are you installing on the floor?

I don't think much of your choices. Attaching wood to a slab is a risky method if you want it to last a long time. In some cases it'll fail almost right away.

Also need to know many other things like where you are and type of soil, terrain and moisture content.

Actually I think pouring a slab over the old may be the cheapest and best way to go. At least you shouldn't have to rip it out and do it again a second time as might be the case with the other method.

Jaz

Advertisement

__________________
Tile 4 You LLC Troy, MI

DITRA Installs - KERDI Watertight-Mold-Free Showers. I have NEVER made a mistake, I thought I did ONCE, but, I was WRONG! A+ BBB rating - est. 1987 - over 50 yrs. exp.
JazMan is offline   Reply With Quote
Old 07-20-2009, 10:47 PM   #3
Newbie
 
Join Date: Jul 2009
Posts: 2
Rewards Points: 10
Default

building up a subfloor


I'm planning on either putting in large tile, 24x24+ or pergo style wood laminate. I live in north texas where the soil is primarily a mix of clay and dirt. Very flat terrain, most often drought conditions for most of the year. My foundation shifts slightly during summer and winter, the house was built in 1957 and have experienced very little foundation issues, if any. I guess I just assumed that pouring concrete would be more expensive, even if it is, I do want to do the project right. Thank you so much for your insight Jaz!
angelo91 is offline   Reply With Quote
Old 07-20-2009, 11:40 PM   #4
Theres more then one way.
 
iMisspell's Avatar
 
Join Date: Jun 2007
Location: N.Y.
Posts: 244
Rewards Points: 150
Default

building up a subfloor


I'm no "floor-er", but things which popped into my head...

- Smooth/Flat/Levelness across the whole current floor.
- Moisture barrier and Presser treated wood on top the current slab
- A wooden floor is "softer" on the feet and knees compared to concrete (being a dinning room i guess that would not really matter)

Something like this might work if you wanted to do wood and the current floor is smooth and flat.
- Moisture barrier
- Presser treated 2x4s laying flat spaced 16" on-center (your at 1-1/2 high now)
- Rigid Insulation between (if desired)
- One layer of 3/4 T&G (your at 2-1/4" now)
- One layer of 5/8's plywood staggered across the 3/4 (your at 2-7/8" now)
- From what i've read, pergo is about 3/8's thick so you new floor will be "close"


No matter what you want to do, pour or frame, you might want to decide on what your gonna finish with because that will determine how much you need to build up.

Good luck

_
__________________
.
~ What was once an opinion, became a fact, to be later proven wrong ~

My current learning experience - 22x22 addition - Work shop, music-room, master bedroom above..
iMisspell is offline   Reply With Quote
Old 07-21-2009, 11:06 PM   #5
Tileguy
 
JazMan's Avatar
 
Join Date: Feb 2007
Location: Troy, Michigan
Posts: 4,190
Rewards Points: 2,238
Default

building up a subfloor


Misspell,

That method might work for Pergo but I wouldn't trust it for a permanent floor like ceramic.

BUT....you should never us pressure treated lumber indoors. It is risky to fasten lumber to concrete and have it all work well for a long time. Moisture is another big problem and a moisture barrier above the concrete may make things worse?

Angelo,

There is a BIG difference between a laminate floor and ceramic tiles. They're not even in the same area code of quality.

Jaz
__________________
Tile 4 You LLC Troy, MI

DITRA Installs - KERDI Watertight-Mold-Free Showers. I have NEVER made a mistake, I thought I did ONCE, but, I was WRONG! A+ BBB rating - est. 1987 - over 50 yrs. exp.
JazMan is offline   Reply With Quote
Old 07-22-2009, 10:50 AM   #6
General Contractor
 
Join Date: Jun 2009
Location: Stafford, VA
Posts: 534
Rewards Points: 500
Default

building up a subfloor


Concrete will not bond properly to cured concrete. If you want to pour you will need to demo the existing slab and pour new. I don't see any reason why using treated sleepers under 3/4" sub-flooring wouldn't work. The installation method for the tile would be the same as installing on a sub-floor.
ARI001 is offline   Reply With Quote
Old 07-22-2009, 09:58 PM   #7
Tileguy
 
JazMan's Avatar
 
Join Date: Feb 2007
Location: Troy, Michigan
Posts: 4,190
Rewards Points: 2,238
Default

building up a subfloor


You can easily bond new cement to old concrete by applying an additive or neat cement slurry, but you don't need it to bond. Might even be better if it doesn't bond.

Sleepers on concrete is an "at your own risk" type of installation. I know it has been done many times and it usually works. But most of the time is not good enough when installing ceramic tiles. Sleepers can be difficult to fasten, but even if they are well fastened, moisture in the slab can cause the sleepers and subfloor to swell over time. There is no amount of fasteners that can stop the force of moisture, not to mention the possibility of trapping moisture in the sandwich.

Needless to say this method is not approved and has never been recognized by any tile installation org. that I know of. Mainly the TCNA.

Jaz
__________________
Tile 4 You LLC Troy, MI

DITRA Installs - KERDI Watertight-Mold-Free Showers. I have NEVER made a mistake, I thought I did ONCE, but, I was WRONG! A+ BBB rating - est. 1987 - over 50 yrs. exp.
JazMan is offline   Reply With Quote
Old 07-22-2009, 10:38 PM   #8
General Contractor
 
Join Date: Jun 2009
Location: Stafford, VA
Posts: 534
Rewards Points: 500
Default

building up a subfloor


First there is a difference between cement and concrete. Second if it doesn't bond and is not reinforced it will eventually crack up. Third all wood expands and contracts to some degree. Fourth concrete slabs expand and contract to some degree.

If properly installed over a vapor/moisture barrier and in a bed of asphalt I don't see where you will have any more movement in the sleepers/sub-floor than you will anywhere else in the structure.

I am aware of the various products on the market that claim to create "bonds" between old and new concrete. I have heard and read very mixed reviews on such products. I have yet to meet a concrete company or mason willing to warranty any such products. They all want to demo and re pour.
ARI001 is offline   Reply With Quote
Old 07-22-2009, 11:13 PM   #9
Member
 
Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Rewards Points: 2,000
Default

building up a subfloor


Quote:
Originally Posted by JazMan View Post
BUT....you should never us pressure treated lumber indoors. It is risky to fasten lumber to concrete and have it all work well for a long time.
Jaz
I'm curious as to your reasoning behind not using PT indoors
Since it is required as a sill plate over concrete
And anyone building in a basement must also use PT against the cement floor
Are you referring to the older CCA PT or the newer ACQ PT wood?

Advertisement

Scuba_Dave is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Need guidance on subfloor problems in new home. wb1026 Flooring 9 10-06-2009 07:29 AM
Subfloor Help, Please! OmahaGirl Flooring 1 01-26-2009 09:06 AM
Subfloor / underlayment question... scheenstra Flooring 7 02-21-2008 08:39 AM
International building code and permits rforsha Building & Construction 4 08-28-2006 07:35 PM




Top of Page | View New Posts