Is Underlayment Necessary for Hardwood Floors?

Are you considering installing hardwood flooring? Ripping out the old carpet or lino and slapping down some wood planks to enhance your home is an excellent DIYer project. But what about the subfloor? Are you wondering, is underlayment necessary for hardwood floors?

Underlay can reduce hardwood floor echo and footfall noise, decrease sound transfer between rooms and floors, prevent moisture from concrete floors from damaging the wood, and extend the lifespan of your investment. A quality underlay is an important and necessary addition to any hardwood floor, and in many regions, it is building code required.

In this article, we’ll explain what underlayment is, why it is necessary, and how it will help with different types of flooring. We’ll identify different types of underlayment, their costs, which is considered the best, and why. By the end of the read, hopefully, you’ll have a better understanding of why underlay is necessary for hardwood flooring.

What Is Floor Underlayment?

Underlayment is a thin barrier installed between the subfloor and your new hardwood flooring. These underlayments come in different composites that protect and extend the life of hardwood flooring from the elements, such as moisture seeping up from a cement floor to sound deadening and insulation on single-story and multi-floor buildings.

Is Underlayment Necessary for Hardwood Floors?

Building codes vary from area to area, and in my location, I was required to put a vapor barrier on the cement slab floor, and to take out a permit to install the wood flooring. It may be different in your city or county, so it is important to ask your local building department what their requirements are.

On a cement slab, it is always recommended and usually required by the building code to install a vapor barrier underlayment. Foam with a vapor barrier or a polypropylene type barrier to keep the wood floor from wicking moisture up from the cement. Moisture can cause mold or warping issues in the wood.

A moisture barrier or similar underlayment should be installed, per the manufacturer’s recommended installation guidelines, to meet their warranty requirements. When a wood floor is installed in a multiple-story building, it is advisable to install an underlayment that will provide elements such as soundproofing, acoustics, insulating qualities. It not only improves the sound, but improves the longevity of your investment.

If you have done your research and are still unsure which underlayment is suitable for your hardwood floor, it is advisable to ask a home improvement specialist. This will ensure nothing has been overlooked in your situation. A hardwood floor is an expensive home improvement project that will last for years, if not decades into the future.

Why underlayment is a good idea and the benefits you will receive are many. A good quality underlayment will eliminate moisture infiltration, make the room warmer and quieter when walked on, increase its longevity, and reduce energy bills.

It is not a pleasant experience to walk into a room and it sounds hollow, or you hear every footstep echo as you walk, or the wood flooring squeaks as it gives a little under the pressure of your footsteps. More than likely this is due to using a sub-standard acoustical underlayment. A few extra dollars spent installing the floor can make a substantial difference in the sound and feel of your floor.

Sometimes a subfloor is not level and has ridges, swells, or other imperfections which require a quality underlayment installion to correct them. If the subfloor has large ridges, swells, or defects, an epoxy leveling compound may be required to make the subfloor level before installing the underlayment and hardwood flooring. Preparation of the subsurface is the first rule of any flooring project, and it makes a significant difference in how the finished product turns out.

Is there a difference between Solid Hardwood and Engineered Hardwood?

• Solid Hardwood Floor – First of all, both are extremely durable floors. Solid hardwood flooring is just like it sounds. It is a solid piece of wood with an overall greater strength based on the wood type. You will want to consider your climate when installing solid hardwood as it is not suggested for use in areas of high heat, humidity, or moisture and will tend to warp due to expansion and contraction. A benefit to this flooring is the ability to sand it down and refinish it as needed since it is not a veneer.

• Engineered Hardwood Flooring – Built of layers bonded with waterproof glue, it is a better choice for moist climates, basements, or any area that is not climate controlled, since high heat and moisture do not affect it as much. This type of flooring can be installed in basements, bathrooms, and kitchens with excellent durability. The finish of this design can not be sanded down though, or have a new coat of stain applied since the veneer on top is not of a thickness that will allow sanding. If you try, you may go through the veneer and ruin the flooring plank.

• Laminate Flooring – Some may consider a Laminate Flooring to be a hardwood floor; however, it is not. It has an image of wood applied to it, which is why the cost is relatively inexpensive compared to Hardwood and Engineered flooring. A significant amount of laminate flooring is produced with the padding or underlayment already attached to the plank. Never use additional underlayment with this product as it will make the floor unstable and possibly result in joint separation with use. Laminate flooring does not have the durability of solid hardwood or engineered hardwood flooring. When using the less expensive flooring, it is a good idea to choose a premium underlayment if required. Many manufacturers recommend using a heavier felt for this type of flooring, depending on your budget.

Different Types of Underlayment for Hardwood Floor

There are various underlayments designed for different applications for use when installing flooring:

• Rosin Paper – Flooring installers sometimes choose this paper as it costs less and is good for covering a rough wood subfloor. This paper is not a vapor barrier; therefore, it should only be used on a wood subfloor where moisture will not be an issue.
• Felt Paper – You have a choice of 15lb or 30lb paper; however, this should not be confused with roofing paper. The felt paper should only be used under hardwood flooring that is going to be secured to the subfloor with nails or staples. It is not a vapor barrier but will cover minor imperfections and prevents the floor from squeaking.
• Foam – Standard foam is a thin poly foam padding that is usually no thicker than ⅛”. It is the most common type of underlayment used by contractors as it is the least expensive. This is suitable for areas that have no issues with moisture wicking up from cement slab foundations or basement floors. Excellent for floating floors.
• Film-Foam Combination – This combination is the same as the standard foam padding; however, it has a vapor barrier attached to the bottom. This forms an actual vapor barrier when installed properly and will keep moisture from entering the wood from underneath. It is lightweight and inexpensive if you are on a budget. Excellent for floating floors.
• Modified – These types of underlayments are constructed of dense foam, rubber, polypropylene, and closed-cell foam to mention a few. These are high-end underlayments and can be very costly depending on how large an area you are covering.
• Cork – Cork underlayment can have a preservative incorporated into it, so it is well suited for cement subfloors that may have moisture. Cork is warm, quiet, and easy to lay flat since it is available in sheets and does not curl up like the others. Cork comes in three thicknesses; 3mm (⅛”), 6mm (¼”), and 12mm (½”), and it is more expensive as you get to the thicker sizes. If you are using it on a cement floor, make sure it is impenetrable to moisture.

Do All types of Hardwood Flooring Require Underlayment?

All hardwood flooring and laminate flooring should have underlayment installed, even if it is not a building code requirement. You may think you will save money by skipping this step, but a quality underlayment will protect and extend the lifespan of your expensive hardwood floors. Solid and engineered hardwood and laminate floorings are relatively easy to install, and the most expensive part of the project could very well be the labor. If you are handy and watch a few YouTube videos, you can install it yourself, use high-quality materials, and enjoy your investment for many years to come for a reasonable price. Always do it right beforehand rather than regretting doing it the least expensive way.

How Much Does Underlayment for Hardwood Floors Cost?

(Shown as Cost Per Square Foot)

• Rosin Paper – $0.06
• Felt Paper – $0.10 to $0.15
• Foam – $0.22 to $0.30
• Film Foam – $0.30 to $0.45
• Modified – $0.70 and up
• Cork – 3mm (⅛”) = $0.50 per sq ft / 6mm (¼”) = $1.00 per sq ft / 12mm (½”) = $2.00 per sq ft

What is the Best Underlayment for Solid Hardwood Floors?

According to the pros, the best underlayment for cement and wood subfloors is cork. With the correct selection, cork adds moisture protection, superior acoustical properties, comfort, and warmth, plus it’s an eco-friendly product. Throughout the world, condo associations choose cork as the underlayment of choice to minimize noise and moisture transfer between levels.