Hardwood floors are one of the most popular flooring options in new homes. They add warmth and classic beauty and it can work with virtually any style of home—from a simple, tiny house to a mega mansion, from a sleek, contemporary to a rustic traditional, and everything in between.
This week’s mini lesson will cover hardwood flooring and the flooring layers that support them. It’s great to have pretty hardwood floors, but hardwood flooring that's well-constructed will help you avoid squeaking, creaking and premature wear.
This week we’ll be talking about what types of materials and construction are best for floors and subfloors. We’ll compare solid hardwood floors and engineered hardwood floors. And I’ll give you some secrets on how to prevent hardwood floors from squeaking and creaking.
Let's start with two quick pro terms: Planks and Strips
Flooring boards that are 3 inches in width or greater.
Flooring boards that are less then 3 inches in width.
As you can imagine, the wider, hardwood planks are generally more expensive than strips. Planks have become increasingly popular over the last several years.
Let’s start today’s lesson by talking about the different flooring layers.
Floors are made up of 3 different layers. From bottom to top, those layers are the subfloor, the underlayment, and top or finish floor. The finish floor is the visible, top part of your flooring that you walk on, and the underlayment and subfloor support the finish floor. Hardwood flooring, ceramic or porcelain tile, vinyl and laminate are all examples of finish flooring.
We"ll to talk more about the finish hardwood layer towards the end of the lesson, but first let’s learn about the bottom most supporting layer.
The subfloor is the bottom layer of flooring. If your house is built with a crawlspace or basement, instead of a slab, the subfloor will be attached to the floor joists. Pop Quiz: True or False? Joists are framing elements used to support the floor and they are comprised of beams, set on edge and arranged in parallel.
The answer is true. We learned about joists in episode 16 where we talked about advanced framing. The floor joists support the layers of the floor. The subfloor rests directly on the floor joists in crawlspace or basement foundation homes.
Plywood is the material often used for the subfloor. Plywood is an engineered structural element that’s made from thin strips of wood, called plies or veneers, that are layered at right angles to one another. Those wood veneer plies are compressed and bonded together. This gives the plywood significant strength and stability.
The advantages of plywood are that it’s widely available, although not water-proof, it is resistant to changes in humidity and moisture. CDX plywood is the grade of plywood most often used for subflooring. This type of plywood is rough on each side and has some imperfections.
"A" is the best quality plywood you can buy. It’s smooth and without any noticeable knots, holes, or repaired defects. B grade plywood is the next best in quality, then, there’s C and D.
The plywood used for subflooring can be rough and ugly, so using CDX plywood is perfectly fine. The X, in CDX plywood, stands for exposure and it means that it’s ok if the plywood has some outside exposure.
In addition to CDX plywood, OSB, or oriented strand board, and particleboard are other options for subflooring. But many experts say you should never use OSB or particle board, because, over time, nails will loosen from these materials and that will cause floors to squeak. So ideally, CDX plywood subfloors that are 3/4 inch thick should be used for traditional framing. You’ll need 1 inch thick plywood if you’re using advanced framing techniques.
There is no particular brand of plywood that you should buy for your subfloor, however, if you live in a particularly humid climate or if you are concerned moisture penetration, you may want to consider a plywood product called Dry Ply. Dry Ply is a plywood made by Georgia-Pacific that has a water resistant coating. Dry Ply come in 4 by 8 foot panels.
Another good option is CDX plywood in a tongue and groove configuration. Tongue and groove subfloors are ideal because they fit together snugly and prevent the edges of the plywood from moving. Construction adhesive is used to tightly seal the tongue-and-groove joints. This makes tongue and groove sub flooring smoother and less likely to squeak when compared with standard 4x8 foot plywood panels.
Wood floor doctor.com says that plank (tongue and groove) subflooring should be laid diagonally to floor joists. Then the finish floor should be laid perpendicular to the floor joists. This will give you an extra strong floor. So, if the floor joists are going up and down (or north to south, if you want to think about it that way), then the subfloor should be installed diagonally on top of the joists, and the finish floor boards should be installed left to right (or west to east).
If you decide to use 4x8 panels of plywood instead of tongue and groove plywood, make sure that there are gaps between the panels to allow for expansion. Professionals suggest a 1/4 inch gap between each sheet of plywood and 3/4 inch along the walls.
Ok, so what if you have a slab foundation?
SUBFLOORS WITH CONCRETE SLABS
If the house has a concrete slab foundation, a subfloor can be attached to the slab. But often, the slab itself serves as the subfloor.
Concrete is stable and firm, so it won’t bounce. In addition, the concrete won’t contract and expand with changes in temperature and humidity like a wood subfloor would. So, for those reasons, using the slab as the subfloor a great choice. But, if you want to install hardwood flooring on a concrete slab, without an added subfloor, you have to choose engineered hardwood, not solid hardwood. Engineered hardwood is a product made with a hardwood veneer top layer, glued to a plywood core.
Whether you install a subfloor or finish floor directly on a concrete slab, it’s very important that the slab be tested for moisture before any of the flooring layers are installed. Minimum moisture levels must be achieved before flooring is installation.
A new slab is naturally moist, but will dry as the concrete cures. You can speed up the process with heat and ventilation. Slabs less than 60 days old are generally too moist to install floors.
After the appropriate curing time, make sure your foundation contractor or flooring contractor actually tests the moisture level of the slab with a moisture meter. Don’t just assume that moisture levels are low enough for floor installation.
Moisture levels of the slab will decrease significantly as the slab cures, but the moisture level may never reach zero, so to decrease the risk of any residual or future moisture from extending through the slab and reaching the finish floor, a vapor barrier must be installed. Flooring installers may wish to use a liquid vapor barrier or polyethylene sheeting over the concrete to control moisture. The flooring manufacturer should list their vapor barrier recommendations.
So, in crawlspace and basement homes, you have the floor joists, then the subfloor and in homes build on slab foundations, the slab usually serves as the subfloor. Ok, so what’s next?
Above the subfloor, and just under the finish floor is the underlayment.
The underlayment material varies pretty significantly based on the type of finished floors you choose.
Some contractors say that you don’t necessarily have to install an underlayment, but the underlayment makes the overall quality of the floor better. And it decreases the chances of squeaking.
The underlayment provides a smooth surface for the finish floor. For hardwood flooring, the most common underlayment choices are felt paper, foam, particleboard, OSB, cork and plywood. The manufacturers of your finish floor will most likely recommend the best type of underlayment for their flooring.
If you choose rigid underlayment material like plywood, look for shiplapped, meaning overlapping, or tongue-and-grooved joints. Those shiplapped and tongue-and-groove joints allow for cleaner, smoother seams between the boards. It’s not completely necessary, but it’s nice. And it’s important to both glue and screw down rigid underlayment to prevent squeaks in your floor.
Alright, now let’s get to the fun stuff. The finish floor--the part that you will see and walk on everyday.
FINISH FLOOR— SOLID HARDWOOD VS ENGINEERED HARDWOOD
The two main types of hardwood flooring are engineered hardwood and solid hardwood. Engineered and solid hardwood floors are both made from 100% real wood, but there are significant differences in their overall construction.
Solid hardwood is just what it sounds like. Each flooring board is made of a single piece of solid wood that has the same composition throughout the entire thickness of the board. Boards are usually about 3/4 inch thick. You can choose a thinner, less expensive floor, but your floors will be more prone to warping.
Solid wood can be purchased as pre-finished or unfinished. Pre finished floors have the stain applied at the factory. The majority of solid wood purchased today is pre-finished.
Unfinished flooring, also called site-finished, is shipped to job site and then stained and finished on-site. One advantage of site finished floors are that you can you can custom mix a stain to get a very specific color. In our upcoming hardwood flooring 102 show, we’ll go over the pros and cons of pre finished vs site-finished flooring.
Solid hardwood flooring can be glued, nailed or stapled to a subfloor. But, be warned, if you staple the flooring or glue it without also using nails, the floor is more likely to squeak. The ideal installation for most solid hardwood floors is gluing plus nailing them in place.
The price of hardwood floors varies considerably based on the type of hardwood you choose and the type of installation you request. Materials can cost from
$2-over $12 per square foot. The installed price of hardwood floors range from
$5 to over $18 per square foot.
Solid hardwood floors are beautiful, but they are prone to shrinking or expanding due to changes in humidity. And they are susceptible to denting and dings, especially if you choose a softer wood variety. More about that in the Hardwood flooring 102 show.
Makers of flooring classify finish flooring by grade, which refers to the number of surface defects, such as knots and color variations, and the length of the boards. Fewer defects and longer boards mean a higher grade and higher price. All grades are structurally sound, but if you look at the knots and irregularities in the wood and see defects instead of charm and character, you should probably choose higher grade flooring.
Because it’s 3/4 inch thick, solid hardwood can be sanded down and refinished
6-10 times. This is an advantage over engineered wood which can only be refinished 1-3 times, at most.
Solid wood floors can be installed at ground level or above ground level, like on the second floor of a house, but solid wood should not be installed in basements. Because basements are below-grade, they are prone to problems with moisture and humidity. So solid wood is not an option for basements, but engineered wood is.
Engineered hardwood is made of genuine wood, but it's not a solid piece of wood. Instead, it’s a core of plywood that’s covered with a top layer hardwood veneer. The criss-cross, sandwich-like construction of the core increases the stability of the flooring and allows engineered floors to be installed in basements and over concrete slabs, where solid wood cannot be installed.
The cost of engineered wood is about the same unfinished solid wood, at about $2 to $12 per square foot, but with engineered wood you will save on labor costs since it is easier and faster to install. Engineered wood planks range from 3/8 of an inch thick to 1/2 inch thick.
Installation of engineered wood is a great project for do-it-yourselfers. Engineered wood floors can be nailed down and/or glued down. They can also be installed as "floating" floors, in which the boards attach to each other and "float" above the subfloor. Most solid hardwood floors cannot be floated.
Although choosing a floating engineered hardwood floor allows for quick, easy installation, floating floors have a greater tendency to do you know what…squeak.
Engineered wood usually comes with a factory finish, but a few companies sell unfinished products so they can be stained and finished on-site. To judge the quality of engineered wood, check the thickness of the top layer, called the ”wear layer," plus the thickness and number of layers in the plywood core. The thicker the better.
One last note about engineered hardwood. I talked to a high end builder at the Tulsa Parade of Homes and she told me that she overwhelmingly prefers engineered wood over solid hardwood because of its easy of installation and overall performance. In this very upscale house that I visited, the builder had installed unfinished engineered wood floors that they stained on-site. That allowed her to do some interesting inlay designs in the flooring. That floor was so beautiful. It looked exactly like solid hardwood. So, before you completely write off the idea of using engineered hardwood, go take a look of some samples at your local flooring store.
Finally, let’s go over...
HOW TO PREVENT YOUR HARDWOOD FLOORS FROM SQUEAKING, CREAKING AND MAKING OTHER EMBARRASSING SOUNDS.
Squeaking, creaky and popping floors can prevented by constructing a firm, stable floor system that minimizes movement and decreases wood-on-wood contact.
To prevent those unwanted, haunted-house like sounds from emanating from your hardwood floors, consider the following tips.
These first tips are for floors installed over floor joists (remember you’ll have floor joists with crawlspace or basement construction). Consider all of the following to prevent squeaking.
1. Use floor joists made of engineered wood, instead of dimensional lumber, so you get stronger, straighter framing elements. This will greatly minimize squeaky and bouncy floors.
2. Ensure that joists are sized and spaced to meet, and preferably to exceed, building code requirements. That way floors are rigid or less likely to move and squeak.
3. Use plywood for your subfloor, instead of OSB or particleboard, since plywood holds finish floor nails in place better. If nails stay in place, floor boards will stay in place, and there will obviously be less unwanted movement.
4. Space subfloor panels with a 1/4 inch gap to allow for expansion. We don’t want planks to move, but we do want them to be able to expand with changes in temperature and humidity.
5. Make sure the subfloor is properly glued and fastened to floor joists with either screws or spiral nails, which kinda look like screws. Conventional nails can loosen over time, especially with contraction and expansion of wood. Nails can pull up and out, but screws and spiral nails stay in place. You should glue and screw. Glue holds the materials together and screws, or spiral nails, lock the materials in place.
6. Make sure there is an expansion gap between the perimeter of the finish floor and wall. Follow the instructions of the flooring manufacturer, but usually the gap is around 1/4 to 1/2 an inch.
7. Choose a glue-and-nail floor system. With this system, the finish floor is both glued and nailed in place. Again, less movement so less squeaking.
Although engineered floors resist gapping and are less like to move around after installation, if not properly installed, engineered floor installed over concrete slabs can squeak and creak too. Here how to avoid that:
1. Make sure the slab is fully cured before installing the flooring system. Usually the slab needs at least 60 days of curing before the moisture levels are low enough to install flooring. The only way to know for sure is to get the slab tested for moisture levels. Insist that your foundation contractor or flooring contractor use a moisture meter to test the slab for moisture before flooring is installed.
2. Ensure that the proper adhesive is used to adhere the finish floor to the slab. Follow the flooring manufacturer’s recommendation, but usually they will recommend a good quality rubber-based mastic adhesive (a mastic adhesive is a very strong adhesive often used in construction).
3. Allow for the appropriate drying time for the adhesive before you lay down finish flooring. This allows the adhesive to get a little tacky before installation.
4. Make sure that the slab itself is fairly smooth and is free of high spots and low spots. You can have high spots ground down and low spots filled in.
5. Once installed, the new finish floor must be rolled with a 150 pound floor roller to get all the boards to contact the adhesive.
Phew, this lesson had quite a bit of information, so you may want to listen to it again to make sure you get all of the important points.
If you are enjoying the podcast, you can share this episode with your social media community or anyone who might be interested in hardwood flooring. Just look for the subscribe and share icons. In iTunes, tap the 3 small dots at the bottom right of the screen.
Now, let see how you do on this week’s quiz
1. True or False? Flooring boards that are 5 inches wide are considered strips.
The answer is false. Strips are flooring boards that are less than 3 inches wide. Flooring boards that are 3 inches wide or wider are planks.
2. True or False? Engineered wood can be refinished up to 10 times.
This is also false. Because engineered wood has a relatively thin top layer of wood veneer, it can only be refinished 1 to 3 times, at most. Solid hardwood flooring can be refinished multiple times.
Please remember that the purpose of this podcast is simply to educate and inform. It is not a substitute for professional advice. The information that you hear is based the only on the opinions, research and experiences of my guests and myself. That information might be incomplete and it’s subject to change, so it may not apply to your project. In addition, building codes and requirements vary from region to region, so always consult a professional about specific recommendations for your home.
Thank you for joining me this week. I hope you’ll come back for the next episode of Build Your House Yourself University (BYHYU).
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