A subfloor is the bottom-most structural level of your floor. A good subfloor needs to be durable, level, at least 1 ⅛ inches thick, and free from residue. If it is not, it won't support tile well. Even the smallest cracks or depressions in a concrete floor could cause your tile to break early.
1/2'' ply is ok if your subfloor is in good shape - flat and sturdy. 5/8'' or 3/4'' is better if it's dodgy. Think about transitions to other flooring in the house though.
Plywood is the correct substrate for a bathroom floor really - it has the best moisture resistance. While, ideally, your subfloor shouldn't actually get wet, there is always a puddle that seeps past a compromised mastic joint or something somewhere that gets it wet eventually.
As a rule, floor tile is typically 1/2-inch to 3/4-inch thick. Wall tile tends to be thinner and available in squares (3 inches to 6 inches). Mosaic tiles are usually the smallest tile, available in 2-inch squares.
The code requires 1 1/4" floor thickness (overall) unless it is tongue and groove plywood in which case 3/4" is adequate. Will 1/4” plywood over 1x10 plank subfloor be thick enough t ...
A good subfloor needs to be durable, level, at least 1 ⅛ inches thick, and free from residue. If it is not, it won't support tile well. Even the smallest cracks or depressions in a concrete floor could cause your tile to break early.
Joist Spacing
For instance, if the joists are 16 inches or less apart, a 1/2 inch of subflooring may be enough. In older homes, where the joists may be farther apart, you will need thicker subflooring for stability. This will require at least 7/8 inch plywood and 1 inch thick of OSB.
Plywood. WBP Ply, which is a type of plywood, is a perfect underlay for bathroom floors, especially wet rooms, as it is of the utmost quality and provides a durable base with a moisture barrier.
Standard residential thickness between (1/4 inch / 6.5mm) and (3/8 inch / 9.5mm) works great in most homes, while the thickest vinyl plank flooring at (5/8 inch / 15mm) provides maximum protection and sound reduction.
In terms of withstanding moisture and humidity, luxury vinyl tiles (LVT), vinyl roll, and porcelain or ceramic tile are the best bathroom flooring options. Each of these flooring options is water-resistant and able to withstand humidity and temperature changes in a bathroom.
Both plywood and OSB are effective choices for your subfloor needs. Plywood is a better option for projects that require a lot of cutting and molding, while OSB is a good option for those who need to cover areas where moisture exposure may be an issue.
Cement-Based Backer Board
It is generically called cement-board or backer board, or it can also be referred to by one of the common brand names, such as DensShield, Hardiebacker, and WonderBoard.
The National Construction Code (NCC) requires all wet areas in a home, including bathrooms and laundries, to be waterproofed.
Rather than nails, screws are best to use for subfloors — these fasteners are convenient, easy to remove and capable of providing torque that nails lack. Because of their structure, screws can penetrate plywood more easily and improve the connection, whereas nails can weaken the plywood.
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.
A thicker subfloor offers greater structural support, preventing sagging, squeaking, and unevenness. This is particularly important for heavier flooring materials like tile and stone.
DuraLux® Waterproof Luxury Vinyl
With a rigid stone-based core, your floor is not only 100% waterproof but scratch and dent-resistant. 5mm DuraLux® Performance Plank with built-in foam backing is a great flooring choice that is quick and easy to install!
Thinner vinyl, such as 2mm, is ideal for low-traffic areas like bathrooms or laundry rooms. On the other hand, thicker options like 8mm provide better insulation, and soundproofing, and are suitable for heavy foot traffic areas like kitchens or living rooms.
Now it's time to apply waterproofing membrane. Make sure your chosen membrane is suitable for bathrooms. Apply the first coat in the same way as the primer coat, ensuring that the layer is approximately 2mm thick.
And it says to use (per page 4) a minimum of 19/32-inch (5/8-inch nom) tongue and groove subflooring.
Subflooring in the kitchen and bathroom may also be pressure treated since water leaks are common in these rooms and subflooring is inaccessible to the residents.
Luxury Vinyl Tile (LVT) is a superstar when it comes to small bathroom remodels. Why? Because it offers the look of natural stone or wood, without the high maintenance or cost. LVT can be waterproof, durable, and incredibly easy to clean—a must for any bathroom.
Generally speaking, OSB absorbs moisture slower but plywood dries faster. When plywood gets wet, it typically swells consistently across the sheet and then shrinks back to its normal dimension as it dries out. OSB tends to swell along the edges and will retain a portion of that misshapen edge after it dries out.
Flooring joist spacing affects subfloor plywood thickness. Closer joists (16 inches apart) can use thinner subfloors (1/2 inch), but wider spacing in older homes may require thicker materials (7/8 inch plywood or 1 inch OSB). Proper thickness of subfloor ensures floor stability and comfort.