The National Tile Contractors Association and the Resilient Floor Covering Institute both recommend plywood for subflooring and underlayment, because it doesn't have the risk of swollen edges that OSB does. Plywood also has a slight advantage in stiffness, which means that subflooring panels need not be quite as thick.
This evolved plywood may claim an overall advantage over OSB, since plywood is a stiffer, longer-lasting subfloor option. It will also hold up better under flooring accidents like leaks or flooding, and has greater nail withdrawal strength to hold the nail in under stress.
Plywood has been a standard subfloor material since the 1950s and remains the preferred subflooring for many builders. Standard plywood can be used for subfloors, but a better material is 3/4-inch tongue-and-groove plywood subflooring.
Most local codes allow OSB to be used for subflooring. It's always best to check with your local permitting office before using OSB for your subfloor. One advantage that OSB has over plywood is its larger formatting. For plywood, 8-foot and 10-foot long sheets of plywood are standard.
Plywood is considered the most popular material used for subflooring, it has been used since the 1950s and remains one of the top choices for contractors. Standard plywood works perfectly fine as a subflooring material, but the best option is ¾” tongue-and-groove plywood subflooring.
Good shear strength.
“OSB is stronger than plywood in shear,” says a report by the Building and Construction Technology program at University of Massachusetts--Amherst. “Shear values, through its thickness, are about two times greater than plywood. This is one of the reasons OSB is used for webs of wooden I-joists.”
Best for Durability and Maintenance: Plywood
As subfloor materials, both plywood and OSB should last as long as the house itself if the subfloor has been properly installed. There is no maintenance required, except to keep the subfloor as dry as possible.
The minimum thickness of plywood for subflooring is about 5/8 inch. Since it does not hold fasteners as well as plywood, OSB must be a little thicker, or at least 23/32 inch. There are several factors that determine what subfloor thickness is optimal for added benefits like insulation.
Common Subfloor Materials. There are four primary materials used as subfloor: plywood, oriented strand board (OSB), concrete, and high-performance panels. There are other subfloors materials out there, but they are used in more niche situations.
Things You'll Need
Before finish flooring is installed on top of a plywood subfloor, you must waterproof the subfloor, especially in a bathroom. If you do not waterproof the subfloor, moisture can make its way under the subfloor and cause mold growth or other damage.
OSB won't be completely destroyed by water, unlike MDF or similar interior laminate materials; however, like any wood product, it will swell and shrink as it absorbs and releases water, so you should typically avoid more than casual contact with water.
OSB takes longer to get wet than plywood but also takes longer to dry out. When used as a roof sheathing, this tendency to hold moisture means it can degrade faster than plywood when exposed to chronic leaks.
For subflooring, you use tongue and groove plywood. The tongue and groove are only along the 8 foot edges. On the four foot edges, your seams will fall on joist tops, so no need for tongue and groove. But to start off, we will need to remove the tongue so the plywood is tight with the exterior ICF walls.
Underlayment
The underlayment material is installed below the floor covering and placed on top of a subfloor. Under the visible covering, there is a layer made of soft or foam-like materials with a thickness of between 1/4 – 1/2-inch.
One of the benefits of removing the old flooring is it allows you the chance to fix any loose subflooring or squeaks by re-securing the main subfloor to the floor joists prior to installing the new flooring. With all that being said though the answer is YES you can install New Wood Flooring over the old.
But plywood's softer surface has a tendency to chip and dent, making the final application of a hard top coating vital to the success of your floor. Plywood floors are suitable for any room where you'd otherwise install hardwood, though kitchens and bathrooms are less desirable since frequent water spills are likely.
Glue is sprayed between each layer and the sheet is hot pressed. CDX plywood should be a minimum of 7/16 inch thick. The thicknesses are as follows: 7/16-, 15/32- and 1/2-inch-thick panels require joists spaced 16 inches on center; 19/32- and 5/8-inch-thick panels require joists spaced 20 inches on center.
For decades, 23/32″-thick OSB has been the most commonly used thickness of OSB subflooring. But a simple switch to 7/8″ panels offers several advantages for accommodating a home's energy efficiency and for ensuring the performance of finish materials and the overall feel of the floor.
Basically, subfloors are a structural part of your home that provide strength and rigidity to your home's flooring. Underlays, on the other hand, protect your floor covering from moisture, help soundproof your floor, and offer cushioning and comfort underfoot.
Yes, you can use pine subfloors as primary flooring. In many older houses, the pine subfloor was the only floor and it held up well. Uncovered pine subflooring appeals to recycling enthusiasts as well as fans of distressed wood.
There are six main reasons: Versatility – Unlike plywood, OSB can be engineered in special formulations for different types of climates and projects. Moreover, a layer of fire-resistant material can be added to OSB in the mill, which is how LP FlameBlock Fire-Rated OSB Sheathing is manufactured.
Durable wood also lasts longer. Since it lasts longer, manufacturers will sell fewer boards over time. To ensure they don't miss out on future profit, they need to price their boards at a higher price point. OSB is expensive because it's durable and requires more resources and processes to make it.
OSB is less expensive than plywood. To build a typical 2,400-square foot home, OSB may cost $700 less than plywood. OSB is considered by many to be a “green” building material because it can be made from smaller-diameter trees, such as poplars, that are often farmed.
Staggering a Subfloor
Stability is more important than aesthetics when laying a subfloor, so it isn't important to make the pattern random. When laying the plywood, install a full sheet along one edge of the floor, then start the next row with a half sheet and use a full sheet for the third row.
It is usually correct to lay sheet material across the direction of the joists, this ensures even distribution of loading on joists, however, plywood is cross laminated so each layer is of different direction providing a strong floor covering.