Chapter 5

A LONG established method of preparing a subfloor before laying resilient or textile floorcoverings is to overboard the area with a suitable grade of plywood or hardboard. Here in the land of half-assed-conversion-to-metric (Canada), our plywood and OSB are manufactured in millimetre thicknesses, despite being 4′ x 8′ in the other two dimensions. With a floor in place, you won’t have another opportunity to add insulation in this part of the attic. Installation is crucial, you must get good coverage of thinset and have a floor within the specified strength. Some engineered hardwoods with plywood base layers are not recommended for radiant heat.

There is always an odd number of layers in plywood panels so that the panel is balanced around its central axis. Fill dips, low spots and gouges with a cementitious leveling compound, which may also be called floor patch. I just poured it directly from the can to the floor and I used a 10” 100% lambskin applicator to apply the finish. They have used a high quality 5 ply birch plywood and, while you still wouldn’t want to lay any type of plywood in a high traffic area, it works really well in a bedroom. Extra stuff that ends up exceeding the design limits of the suspended floor count as a big minus, not the plus you imply.

Typical constuction debris on the subfloor includes drywall compound, bits of insulation, expanding foam and drill debris from plumbing and electrical operations. If there is a great deal of damage to the floor or it dies not meet the manufacturer standards, it’s probably best to call in a professional contractor and replace the entire sub-floor. Your customer may not see what is beneath the beautiful wood floor, but what you do below determines how the floor will look above. The most commonly used thickness range is from 0.14 to 3.0 inches (0.36 to 7.62 cm).

There are some products mentioned here and probably many others but I would advise against plywood for what you’re considering. So the simple answer is that if you reduce plywood thickness and make up the difference with fiberglass laminate, you get not only a more flexible panel, but one that weighs a lot more. These materials can break down over time, leaving a void between the underlayment and the subfloor.

Following extensive consultation with industry experts we have detailed some suggested procedures to help achieve a professional and reliable installation of plywood in the subfloor preparation process. Porcelain or Ceramic Tile: If the Ceramic Tile is well secured and flat then you could install a Laminate or Engineered Floating wood floor over it using the recommended underlayment pad. I used 2” Green exterior screws with T-20 star drive heads to secure the plywood to the 2X4s. Prior to installing, a moisture test should be carried out on the plywood and a reading taken.

After I have all my floor down I will go back and double the screws around every seam. Apart from load and span, designers must consider the type of floor covering or roofing, the effect of colour on cavity temperature, seasonal conditions, wind effects and the intended use of the building or surface that will determine exposure to moisture and sun radiation. Plywood flooring with tongue and grooves on the long edges eliminates the need for noggings. I loved the super wide, raw planks & built in headboard from Hindsvik, and I also loved the worn look & durability from Picklee’s floor.

During the flooring installation stage, layers of 15- or 30-pound asphalt felt will be applied over the subfloor panels as an additional vapor barrier. We have a log home with 6×8 floor joists 24″ on center with 2×6 tongue and groove spruce subflooring (very solid, no deflection issues). Perhaps the biggest thing plywood has going for it is the perception of higher quality among homeowners. Installation requirements prescribing the use of H-clips on roofs, blocking on floors and allowance of single-layer floor systems are identical.

Again great step by step painting instructions make this another essential plywood flooring article. I’ll give you the smart JOBSITE WORD answer: the grade stamp that says it’s floor rated. When you add in the extra flex from 5/8″ plywood on top of 1″ EP, i foresee issues down the line. However, wood tends to shrink/expand much more across the grain than along the grain and the cross – laminated structure of plywood means that the longitudinal veneers in one ply tend to restrain the perpendicular veneers in the adjacent ply.


It’ll make up for any minor floor imperfections and also help with sound insulation. There wasn’t enough difference between the floor that was under the cabinets versus the rest of the shop floor, only a color difference so I didn’t bother adding pictures to this article. It was finally time to start clearing out the rest of the floor and making some repairs. My thinking was that screws would be overkill, take longer, and might split up the plywood (its very thin plywood). Because we’re laying the plywood onto the existing floorboards, we didn’t want anything that was too thick so that we’d create a step. We have an old bathroom, floor is about 4′ X 9′. It’s been covered with carpet.

When properly installed on your floor it is an ideal tile substrate for a quality and lasting installation. I hope this makes things easier if you’re deciding if you want to install your own plywood floor. Osb and plywood are equals structurally, but flooring manufacturers make different recommendations regarding their use as a substrate. Our bathroom tile installation dealt with placing HardieBacker over a wood subfloor that was composed of two layers of plywood approximately 7/8 inch thick.

The only time thickness may be a problem is when the plywood sub floor is weak or flexes when you walk on it. If this is the case, then ideally you should either opt for a thicker board or introduce an additional thin layer of ply (around 0.5cm thick) to stabilize the floor and give you a better laying surface. Make sure it is screwed and fixed at appropriate points, usually a minimum 300mm centres.

This myth is quickly dispelled when a piece of each material gets thrown into a pond of water and the fiberglass sinks like a stone while the plywood floats. Like the project from Remodelista above, this floor was created by painting directly onto the plywood subfloor. Constantly stepping on that spot will, over time, loosen the screw and your floor will move.

Once you put your attic stair in, the 2’x8′ isn’t bad, you just have to lay them down to get them spun around the right way. This void can allow noticeable movement, floor squeaks or cause fasteners to poke through. When used as a roof sheathing, this tendency to hold moisture means it can degrade faster than plywood when exposed to chronic leaks. A popular plywood is lauan, because it has a good history of performance and is available virtually at any supplier.

Plywood is rated for use, based on whether it’s for interior or exterior applications, and what type of material you plan to use for the finished floor. And if this question is asked because thicker panels are not available, the answer is to use a double thickness of plywood rather than attempt to make up the difference with fiberglass. According to Capital Hardwood Flooring, the recommended minimum thickness of OSB is 3/4 inches, over joists spaces 19 inches or less apart. The row of slits must be wider than the curved object you plan to lay your floor around.

Hmmm, you would either have to install a subfloor underneath to have something to nail to (and to keep moisture from seeping up from the concrete to the wood) or you could possibly glue the planks down with a solid layer of flooring glue (to double as a moisture barrier). Before doing anything we are going to stabilize our floor from below, however, we are still very limited on our flooring options. There’s no equivalent of the weak spots that can be left in plywood when knotholes in adjacent plies overlap.

To keep an equal distance between the boards (we still wanted to be able to see that they are planks of wood and not one solid piece of floor) we used some old credit cards as spacers. Most plywood panels are overbuilt to cover the statistical range that guarantees each sheet of plywood meets the minimum standard. Now that I look at the article there is actually 6 pieces touching the plywood when it’s laid down parallel and not 4. And 7 pieces if the center is included but my instructions didn’t include that part.

It is also used to raise one area up to be even with another floor or used to provide a suitable substrate for tile (like Hardi Backer Board) and to stiffen the subfloor. If you want to run your floor parallel (in the same direction) as the old boards, you should introduce a layer of ply (as above for plywood sub floor). The downside to this is that there is nothing between you and the ground and without any protection other than the paint you might damage the subfloor and need to replace it (not something I wanted to do). More to the point, the modulus of elasticity (stiffness) is actually much higher for plywood than fiberglass for the same thickness.

DIY Dork – If you want the plywood diy installation guide to end all diy guides then head on over and visit Kevin at (great name!). To my knowledge, there has not been a problem of similar scale associated with plywood siding. The first is the thickness of the overall board and the second is the thickness of the solid wood lamella or top layer. All the recommended adhesives and tools in this section are available to purchase here For rooms larger than 15sq m, or which have heavy traffic, we recommend that you fully adhere the entire floorcovering to the sub floor.