What’s the Best Subfloor for Georgia Homes?
- Georgia’s humidity puts real stress on subfloor materials. What you build on matters as much as what you put on top.
- A flat, dry, structurally sound subfloor is required before any finished flooring goes down.
- Plywood and OSB are the two standard choices. Each has tradeoffs worth knowing before you order.
- On remodel jobs, subfloor problems are often hidden. Check for moisture, flex, and high spots before you commit to a material.
Getting flooring right in Georgia starts underneath. The finished surface gets all the attention. But the subfloor decides whether that surface holds up, stays flat, and stays quiet for years. Get it wrong and no amount of careful finish work fixes it.
Why the Subfloor Matters
The subfloor’s job is simple: give the finished surface a flat, stable, dry base. If it cannot do that, nothing on top will behave the way it should.
Georgia’s climate makes this harder. Summers bring long stretches of heat and high humidity. Even in winter, the air holds enough moisture to affect wood-based panels over time. A subfloor laid without thinking about that will move.
Three things matter most.
Flatness. Most finished flooring can only handle a small amount of variation across a span. Floating floors, click-lock products, and tile are especially sensitive. High spots or low spots will show up in the finished surface within a season or two.
Dryness. Panels that take on moisture swell, come apart, or lose strength. This happens more often in slab-on-grade construction, over crawl spaces, and in older homes where vapor barriers have failed. In neighborhoods like East Lake or Avondale Estates, check subfloor condition carefully before starting any flooring project.
Structural integrity. The subfloor needs to be fastened tightly to the joists with no soft spots, bounce, or movement. Squeaky floors are often a fastening problem, not a flooring problem. Fix it at the subfloor stage.
Plywood vs. OSB: Which One Is Right?
Both are standard subfloor materials. Both work. The right choice depends on the project and the conditions. For a full look at what we carry, visit our lumber and panels page.
Plywood
Plywood has been the standard for decades. It is made from layers of wood veneer stacked in alternating directions. That gives it strength and makes it a solid surface for fasteners. It also handles moisture better than OSB when panels are exposed before the building is sealed up. It dries out more predictably after a wet event.
Plywood is also easier to work with on remodels. You can cut it cleanly and match thickness more closely when patching or leveling an existing subfloor.
Best for: Remodels, projects where moisture is a concern during construction, and jobs where you need a consistent fastener surface.
OSB
OSB is made from compressed wood strands held together with resin. It is uniform in thickness, widely available, and common in new construction for both subfloor and wall sheathing.
It performs well when it stays dry. The trade-off is what happens to the edges when it gets wet. They swell and can push through the finished floor above. Subfloor-rated OSB is made to tighter specs than standard panels. Make sure you are ordering the right product before it goes on the truck.
Best for: New construction where the building will be closed in quickly and moisture exposure during the build is controlled.
How They Compare
| Factor | Plywood | OSB |
|---|---|---|
| Moisture handling | Better edge stability when wet | More likely to swell at edges |
| Fastener holding | Excellent across surface | Good, slightly less consistent at edges |
| Thickness consistency | Slight panel-to-panel variation | Very consistent |
| Remodel work | Easier to patch and level | Harder to work into repairs |
| Cost | Typically higher | Typically lower |
Does Thickness Matter?
Yes. Thickness affects stiffness, and stiffness affects how the finished floor holds up.
Thicker panels flex less between joists. That matters most for tile, which will crack at the grout lines over a subfloor that moves. The right thickness depends on your joist spacing. The APA – The Engineered Wood Association publishes span and thickness guidelines that are worth reviewing before you order. Your finished flooring manufacturer may also have a minimum thickness requirement.
Remodels vs. New Construction
In new construction, you start clean. The framing is level, panels go down on known spans, and you control moisture during the build. The subfloor conversation is mostly about material and thickness.
Remodels are more complicated. You are often working over an existing subfloor with years of moisture history, old repairs, or soft spots that were never fixed. In crawl space homes, which are common in older parts of Metro Atlanta, vapor barrier condition and air flow directly affect subfloor moisture.
On a remodel, look at the subfloor before you choose a finished floor. What you find changes the scope of the job. Skipping that step usually costs more time in the end.
What to Check Before Work Starts
Walk the floor before you order materials.
Look for soft spots or bounce. That usually means a fastening failure or damage below.
Check for high spots at panel edges. Swelling from past moisture is common and needs to be addressed before anything goes over it.
Check moisture levels if there is any reason to suspect a problem. Crawl space homes, slab-on-grade construction, and rooms with a water history are worth checking.
Review what the finished flooring manufacturer requires. Some products have specific prep steps that affect what you need to do first.
Jobs get delayed when this step is skipped. The materials arrive, the crew is ready, and the subfloor is not. That is a much easier problem to solve before the job starts.
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Frequently Asked Questions
What thickness of subfloor panel do I need?
It depends on your joist spacing. A common starting point for 16-inch on-center joists is a 3/4-inch tongue-and-groove panel. Wider joist spacing may need a thicker panel to reduce flex. Confirm with your finished flooring manufacturer and local code before ordering.
Can I install a new subfloor over an existing one?
In some remodel situations, yes. It can help level the surface and add stiffness. The trade-off is added height, which affects how the floor meets adjacent spaces. Check door clearances and transitions before you decide.
How do I know if my subfloor has a moisture problem?
Look for discoloration, soft spots, swollen panel edges, and squeaking that shifts around. A moisture meter gives a more exact reading. In crawl space homes, check the vapor barrier condition and look for staining on the underside of the panels.
Does Georgia's climate affect which panel I should use?
It does, especially when the building is open to weather during construction. Plywood tends to handle moisture exposure better than OSB in those conditions. If panels may sit exposed during the build, factor that into your choice.
What causes subfloor squeaking after install?
Most often, panels were not fastened tightly enough to the joists. Too few fasteners or some joist movement before fastening are common causes. The fix is usually adding fasteners from below or screwing down from above before the finished floor goes down.
