I have 3/4 inch thick plywood screwed to joists already and I am going to add secondary 1/2'' plywood underlayment on top of it for more stiffness because I am going to tile marble floors. Additionally as mentioned, drywall screws are not rated for flooring application. 4 x $40 = $160. I am about to lay 1/2" APA Underlayment rated plywood down as an underlayment over 3/4" plywood subfloor for 1/2 strand woven bamboo. For hardwood, tongue-and-groove CDX plywood rated AC with a 1/2- to 3/4-inch thickness is ideal; ceramic or porcelain tile does best with 3/4-inch AC plywood; and stone should use 19/32-inch tongue-and-groove plywood. Resultant finished height (5/8" + 1/4") does not equate the same strength as a solid piece of material at the stated thickness. Do not 1/4 turn the underlayment direction from the subfloor. • Nail-down subfloor: 5/8 -inch or thicker plywood panels are fastened every 12 … 1-1/8 x 4 x 8 Sturd-I-Floor Tongue & Groove OSB Subfloor (Actual Size 1.069" x 47-1/2" x 95-7/8") Model Number: 1242922 Menards ® SKU: 1242922 The span rating for 1/2 inch plywood is 32/16. It typically comes in 4 x 8-foot sheets. A single 1/2" alone isn't good enough regardless of the finish flooring you choose, with the exception of hardwood. Tags: installing plywood underlayment, plywood underlayment The pilot hole is … However, on one of my very first houses using plywood, we had a giant downpour during construction when the frame was open. Panels classified as Exposure 1 are intended to resist the effects of moisture on structural performance as may occur due to construction delays, or other conditions of similar severity. • Glue-down subfloor: 5/8 -inch plywood panels are glued in a staggered joint pattern directly to the slab. Used 3 boxes of 1 5/8" Deckmate screws. Exposure 1 : Plywood suitable for uses not permanently exposed to the weather. Place your plywood pieces so their joints don’t go directly over the joints of your wood subfloor. For touch-sanded grades such as C-D Plugged, C-C Plugged, UNDERLAYMENT and APA RATED STURD-I-FLOOR (marked PS 1), see Table 2. Plywood comes in 4-by-8-foot sheets with thicknesses ranging from 1/4 to 1 1/4 inches. Direction As a sub-floor, I prefer to install the plywood sideways as the finish flooring will be installed lengthwise on top of that. The two layers together made up the subfloor. It is fastened to the subfloor and sits below the finished floor, providing a suitable base that is as smooth and flat as possible. Removed this floor down to the joists and replaced the 1/2" plywood :bonk: . We’re comfortable slightly exceeding the recommended subfloor spacing. For optimal and long-lasting results, consider all three components when installing a new floor. These panels feature a built-in underlayment that allows the convenience of using only Sturd-I-Floor® under certain finish flooring, especially carpet and pad. Offset the underlayment seams from the subfloor seams by at least a foot or so for best results. For the plywood, I’d need four 4’x8’ sheets total, and I should have a 4’x2’ piece left over. For screws, a 1 lbs pack of 3 inches long #8 coated screws will cost around $10, I’ll use these for the framing. Subfloor plywood is extremely strong and can support most floor types including plywood and treated plywood. If you intend to put down carpet or hardwood flooring, that won't be necessary. The combined height is between 2-1/4″ and 5-1/4″ compared to 1″ for a DRICORE ® Subfloor R+ panel. Re: 1/2" plywood subfloor Nearly every house I framed in the 70s and early 80s was 1/2" subfloor with 5/8 particle board over in the carpet areas and 5/8" ULCX ply at the vinyl areas. Is the extra 1/4 inch really needed? I could just have well been parquet. If you are using 1/4 inch plywood, and you are going through 3/4 inch subfloor, I would go with a 1-1/2 to 2 inch screw. That’s 32” when plywood is sheathing for a roof (not much expected weight on it), and 16 inches as a floor (lots of expected weight on it). 3/4 inch pressure treated CDX goes for about $40 each where I am. 16 inch on-center joist spacing with single layer OSB or plywood subfloor; 19.2 inch on-center joist spacing with single layer OSB or plywood subfloors; 24 inch on-center joist spacing with double layer OSB or plywood subfloors; 24 inch on-center joist spacing with single layer OSB or plywood subfloors; Each configuration has specific guidance for: Foolishly, the tile guys wanted to mud base over just the 1/2" so the tile wasn't so much higher tha the hallway and bedroom carpets. If additional force is needed, always use a block of wood against the groove edge to minimize damage to the panel, and always allow a 1/8-inch gap between panels. Removed all original flooring down to the 1/2" subfloor. See our complete plywood underlayment installation video at www.InstallSurePly.com. Plywood is the most common type of subflooring. A plywood subfloor generally uses 1/2-inch to 3/4-inch-thick sheets of plywood that have one rough side (which faces down) and one smooth side, which faces up. A conventional subfloor includes 2×4 sleepers, vapour barrier, 1″-2″ rigid insulation, 15/32″ plywood, and a lot of fastening. The half inch (actually 15/32 inch) thick plywood that I use, adds another 73.5 lbs to the conversion. Step 3: Secure your plywood pieces in place using 1-inch decking screws. Assuming a remodel, this is going to involve bringing the plywood to the location by hand, as opposed to assistance by a crane. I am thinking #8 length 1-1/4 inch, but I am really not sure. When your house was built the subfloor system was 1/2" ply with 5/8" (probably) over it. It was 1-1/8-inch plywood we should have glued to framing but just nailed it. 9. Make sure you predrill the hole through the 1/4 inch plywood, use a bit the same diameter as the outside thread of the screw. The addtional underlayment should be glued and screwed down over 3/4 inch thick OSB subfloor to add stability. It should not be so long that it penetrates the combined thickness of the plywood underlayment and subfloor. Leave a 1/4-inch expansion gap around walls and joints. This will be necessary if you're going to lay down resilient (vinyl) flooring. Some people have told me it is not needed, but I want more opinions. The right type of plywood for your bathroom's subfloor will vary based on the type of floor you are placing over it. The sheets are generally 4 x 8 or 4 x 12 feet in size. Be careful! Hide screw heads below the surface of your plywood pieces to … For best results, you'd then apply 1/4 inch lauan underlayment plywood over the repaired subfloor to make it perfectly level. The thickness that builders use most often for subfloors is 3/4 inch… Installed 16 sheets (very pricey) of 3/4" sanded plywood directly over the 1/2" subfloor. The floor system is not dependant upon receiving any strength from the hardwood floor to meet this requirement. Had water damage under the halfbath floor (1" mudbed). The thickness needed for subflooring depends on the type of floor that will go on top and the primary purpose for the subfloor. When installing engineered, solid or floating floors that are less than 1/2" thick we highly recommended you add an additional layer of 3/8" or 1/2" thick plywood underlayment. Flooring underlayment comes in a variety of different forms, ranging from 1/4-inch plywood to cement board to carpet padding or foam material. The manual says you need 3/4 inch CDX plywood subfloor. Sturd-I-Floor® is an APA designation that is a combination subfloor-underlayment produced from OSB or plywood. I have 1/2 CDX plywood subfloor. Plywood comes in a variety of thicknesses, beginning at 1/8 inch and increasing to 1 inch. What size number and length of screws should I use to screw 1/2 plywood underlayment to subfloor? Forgetting to check your work. Table 1 applies to unsanded plywood and is based on APA RATED SHEATH-ING (marked PS 1) grade. BTW, 1/2 + 1/4" does NOT equal 3/4", strength wise. Additionally, underlayment plywood is a middle layer that keeps moisture from reaching the surface. I'm going to install tiger wood 3/4 inch hardwood floors in my house. 10 Posts . 1/4" plywood does not add structural integrity to a floor application and does not have the nail holding capacity. This resulted in a ton of edge swell. The fasteners should not protrude out of the bottom side of the subfloor. Do I need to remedy my subfloor before I put down carpet? Steps to Install 3/4 Inch Plywood Subfloor. This provided a nice stiff floor and eliminated my squeak issues. Answer. A 3/4 inch sheet of plywood weighs approximately 75 lbs. Plywood, or even OSB, has its strength running with its length. Your new layer of underlayment needs to be perpendicular to the joists just like the subfloor is. Filled a 20 yard dumspter. Plywood continuous over two or more spans and face grain perpendicular to supports.Unsupported edges shall be tongue-and-groove or blocked except where nominal 1 / 4-inch-thick wood panel-type underlayment, fiber-cement underlayment or 3 / 4-inch wood finish floor is used.Fiber-cement underlayment shall comply with ASTM C1288 or ISO 8336 Category C. Allowable uniform live load at … Discussion Starter • #1 • Apr 25, 2012. Re: 1/2" SUBFLOOR Bill, If the joist are ok and the 1/2 plywood subfloor is rated 16/32 which it probably is, the it meets the minimum requirements of the code. Table 3 applies to sanded grades such as A-D and B-D. The system is designed for use on all of the most commonly used subfloor materials—plywood, OSB, concrete and gypsum-based screed. Step 1: Get the plywood to the right level of the house. Prior to finished floor installation, walk the subfloor to check for squeaks, missing fasteners, improper nailing, etc. The uncoupling membrane is adhered to the surface being tiled using a layer of thinset adhesive applied with a 1/4-inch V-notch trowel. The panels should be staggered every 2 feet and spaced 1/8 inch between ends. Most plywood underlayment is about 1/4 inch thick and has square edges and a smooth, knot-free top face. 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