What type of plywood should I use under vinyl plank flooring in the kitchen?

As usual, the answer is: It depends. Not enough info in the question to provide a definitive answer, so here are a couple: IF you intend to have any vinyl type material GLUED down, you want to make sure (as you wrote) that the existing boards are SCREWED down and are solid (replace as you find it necessary), then sand the surface to get it all as FLAT (level and flat are two different things and "level" is not required for warranty purposes, FLAT subfloor IS (although YOU may require a level subfloor, this is merely a personal choice), and then install (screw down with the heads of the screws BELOW the top surface) 6mm (1/4") 4ftx4ft sheet plywood underlay available for this exact purpose, including in the box stores, with the location of the future screws (or nails) already marked on them (we used to use 1" "ring" nails but screwing them down will make it more secure), sand and patch all of the joints with a sand-able material such as Mapei Planipatch. Then sand that also to end up with a solid, smooth surface, because if you don't do this (although all of this IS required for warranties to apply should you need to or want to ever claim for whatever reason, it isn't mandatory otherwise, understanding that if you don't provide a smooth subfloor) ridges you leave will telegraph through the glued down vinyl on top and THAT visual may or may not be acceptable to you, but by then it is too late. IF you plan on installing a "FLOATING" (Click or Loose lay type) vinyl floor, after the securing of the existing subfloor as you mentioned, it is enough to install (screw down!) a new construction grade 3/8" (9.5mm) plywood subfloor with the new joints sanded to, AGAIN, end up with a smooth subfloor. I hope the above detailed comments will be helpful. If YES, please Like it below.

Hi, for kitchen with vinyl plank flooring, use AC exterior-grade plywood or a knot-free, exterior-grade plywood, as it offers moisture resistance and durability. The subfloor should be level, properly prepared and at least 6mm thick. We would also recommend OSB (Oriented Strand Board) as a durable option.

For installing vinyl plank flooring over an existing subfloor of older, uneven wood boards, the best practice is to first address the stability of the subfloor. You should secure or replace any weak boards to create a solid foundation. When adding a layer of plywood on top, a good option is to use an underlayment-grade plywood, such as a sanded A-C or B-C grade plywood, which provides a smooth and stable surface for the new flooring. Plywood Grade: The grade of plywood refers to the quality of the veneer on the face and back of the panel. For underlayment, a smooth, sanded face is important to prevent imperfections from showing through the vinyl flooring. Thickness: A thickness of 1/4 inch or 1/2 inch is commonly recommended for underlayment. Marine Plywood: Marine plywood is designed for use in environments where it will be exposed to moisture for long periods, such as in boat building. It is not necessary for a kitchen subfloor and would be an expensive over-specification for this application. Exterior-Grade Plywood: Exterior-grade plywood is made with waterproof glue, but its surface may not be as smooth as underlayment-grade plywood, and it is not designed to be a finished surface

Standard spruce 3/8” is typically enough and ensure to secure each and every skateboard to a joist prior plywood install

Use 1/4” or 3/8” exterior-grade plywood (AC or BC grade). This is the correct underlayment for vinyl plank flooring Exterior-grade plywood (AC/BC) is strong, smooth, and moisture-resistant.Marine plywood is NOT necessary — it’s expensive and only needed for boats or constant water exposure. Secure the old wood boards first, then install the plywood tightly with screws, and make sure all seams are smooth. This will give you a stable, flat base for your vinyl plank flooring.

We use mostly engineered strand board made specifically for subfloor applications. Can get materials with up to 200 days exposure to the elements warranted.

First secure all loose boards and fill in any missing gaps to reassure underlay has solid substrate. A 1/4 or 3/8 plywood would work fine. To assure nothing moves where it’s old boards beneath I would use a construction adhesive under the plywood any places where you think a screw may not grab the best. Make sure to screw your plywood off on a 4”x4” screwing pattern to ensure there will be no movement overtime(squeaky floors). You could even use a floor levelling compound on top of your plywood if your floors aren’t perfectly level for a pro finishes floor.

1. Replace and secure old original floor boards. 2. Place extra floor screws (every 2" or so along the entirety of the joists to prevent squeaking) on the original floor boards that are 1/2" longer than the thickness of the floor (e.g., if it's a 2x6 floor board, you will need a 2.5" floor screw to secure the board). 3. Use 5/8" plywood (thickness matters more than the type of plywood) or OSB (oriented strand board), which is cheaper than plywood but still does the job. Glue and screw this down as well to prevent squeaking.

Depends on thickness, if it were my home id reinforce, screw, ulay would be final layer before any vinyl was laid

All answers I've seen so far in this thread are wrong to some degree. Exterior grade plywood is not an acceptable substrate for vinyl plank, as it contains knot voids (core voids) in the inner layers of the plies and can be punched through. OSB is also not acceptable as an underlayment because the adhesive from your LVT can react with the adhesive holding the wood strands together in the substrate and cause them to de-bond and bubble. The ONLY acceptable substrate is a product rated as "underlayment", which could include products such as Tolko Fir underlayment or a manufactured underlayment product such as Enstron Ulay. These need to be STAPLED down with narrow crown staples (following the marked x's on the panels), not screwed down, and joints should be together but not super tight, then smoothed with a cementitious filler such as Ardex Feather Finish or Mapei Planipatch. Underlayment panels have no core voids, unlike other grades of plywood.

Good grade "one sided" plywood. there is less prep time. The floor should be smooth and perfect for the vinyl to adhere 100%

For vinyl plank flooring in an Ontario kitchen, the plywood you use depends on whether you're installing over joists or overlaying an existing subfloor, but here’s exactly what the top contractors in the province specify in 2025 to stay 100% code-compliant and warranty-approved: (A) Over bare joists (new build or full gut): minimum 23/32″ (18.5 mm) tongue-and-groove subfloor-grade plywood, CSA O121 Douglas Fir (DFP) or CSA O151 Canadian Softwood Plywood (CSP), stamped Exposure 1 or Exterior, with T&G on all four edges. Ontario Building Code 9.23.14.5 requires at least 19 mm (3/4″) when joists are 16″ o.c. (B) As an overlay on top of an existing subfloor (most kitchen renos): 1/2″ or 5/8″ premium sanded underlayment plywood (Russian Baltic Birch or high-grade Lauan/Meranti) with exterior glue. Russian Birch 5/8″ is the #1 choice in Ontario right now because it’s perfectly flat and void-free. (C) For glue-down LVP/LVT: the subfloor must be APA-rated Exposure 1 or better, sanded smooth, and flat to within 3 mm over 3 m radius. Most pros use 5/8″–3/4″ Russian Birch or marine-grade plywood for zero telegraphing or adhesion issues. (D) Floating click-lock LVP: any of the above work as long as the surface is flat, securely screwed (not nailed) every 6″ in the field and 4″ on edges, and moisture content is under 12%. ADDITIONAL ONTARIO MUST-DO'S: (1) On or below grade, lay 6-mil poly vapour barrier (joints overlapped 200 mm and taped) beneath the plywood; (2) Always screw (never nail) the underlayment; and (3) Check flatness with a 3 m straightedge before installation. Follow this spec and you’ll never have a vinyl failure or warranty claim in an Ontario kitchen.

or vinyl plank in a kitchen, you don’t need marine plywood — unless you’re planning to park a boat in there. 😄 What you do want is 3/8" or 1/2" exterior-grade plywood (marked as “Exposure 1” or “Rated Sheathing”). It handles normal kitchen moisture just fine and gives you a stable, smooth surface for the vinyl. Your plan is right: tighten or replace any loose boards first, then add the plywood, screw it down well, and make sure seams are flat. A quick skim coat over the joints makes the finish even cleaner. Marine plywood is great, but it’s overkill (and overpriced) for a kitchen unless you expect the Titanic to visit. Exterior-grade is the standard, reliable choice.

For a kitchen, you don’t need marine plywood. That’s overkill and expensive. Use ½" or ⅝" exterior-grade plywood (CDX or better) or AC plywood. The key is that it’s exterior-rated (glued for moisture resistance) and flat, not the label “marine.” Make sure you: Secure all loose boards first Screw the plywood down well (not just nail it) Stagger seams and avoid lining them up with the boards below Sand or patch any seams so the surface is smooth That will give you a solid, stable base for vinyl plank or tile and save you money