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What Paper Goes Under a Hardwood Floor?


The installation of paper underlayment between a hardwood floor and the subfloor is something that dates back well over one hundred years, and it’s a tradition that seems to have stuck even as modern housing standards and regulations have continued to develop.

In this article, we will look into why paper underlayment can be a beneficial part of the hardwood floor installation process, and we’ll also explain which types of paper work best.

Not every hardwood floor is suitable for use with paper underlayment, with glued floors being incompatible. For nailed or stapled floors, two common types of paper are rosin paper and felt paper, although you should always opt for the type recommended by the manufacturer of your hardwood floor.

Read on to learn more about the specific benefits of paper underlay for your hardwood floor and find step-by-step instructions for installing both rosin paper and felt paper underlayment.

Do You Need Paper Under a Hardwood Floor?

Not every type of hardwood floor is suitable for use with paper, with glued floors being incompatible given that the underlayment tends to stick to the bottom of the hardwood boards.

For other types of floor, for example, those that you nail or staple down, there’s no shortage of claims about the particular benefits of installing paper underneath the hardwood floor.

Speak to a flooring expert or spend some time researching on the internet, and here are some of the reasons you’re likely to find:

  • To stop air flowing through the floor assembly and prevent annoying drafts from coming up through the floor.
  • To act as a moisture barrier and slow down the moisture flow, allowing the hardwood floor to breathe such that expansion and contraction and damage from excessive moisture are minimized.
  • To provide a smooth surface to make it easier to slide and maneuver boards during the installation process.
  • To increase the level of adhesion between the hardwood floor and the subfloor to minimize squeaking and annoying noises.

For us, the most logical reason for installing paper under hardwood flooring is to regulate moisture levels.

The use of paper underlayment as primarily a moisture barrier is something that the National Wood Flooring Association (NWFA) appears to agree with, too:

Install a vapor retarder over wood panel or board subfloors prior to installing nail down solid strip or plank flooring.

NWFA

When used, this paper underlayment will still let moisture through, but it significantly reduces the rate versus omitting the paper layer.

Too much or too little moisture can cause the floor to expand or contract to various extremes.

By regulating the amount of moisture that can reach the underside of the hardwood floor, the paper helps minimize the potential for moisture-related damage such as warping or mold growth and rot.

Ultimately, we’d recommend following the manufacturer’s guidance regarding installing paper under a hardwood floor, as doing so can avoid potential warranty issues in the future should something go wrong.

Where no specific guidance is provided, installing a paper layer could be beneficial given the relatively small material and additional installation cost, as doing so can provide considerable peace of mind.

You should always contact the flooring manufacturer first to confirm the compatibility of the paper layer, though, to prevent potential warranty issues should a problem arise.


What Kind of Paper Goes Under Hardwood Flooring?

Whatever paper you choose to install under a hardwood floor must be sufficiently permeable. In other words, it needs to let a sufficient amount of moisture and air through.

While this might sound counterproductive, it’s important to remember that the paper is there to primarily serve as a vapor retarder, not as a vapor barrier.

So, in most cases, you should avoid completely impermeable materials unless the manufacturer has specifically recommended these. For example, some polyethylene films could trap moisture in the subfloor, potentially leading to damage.

It’s important to choose paper that is specified for use with hardwood flooring.

Two of the most common types of paper are rosin paper and felt paper, although you should always opt for the type recommended by the manufacturer of your hardwood floor.

Should a type not be recommended, following the NWFA’s guidance could be a suitable alternative option.

Here’s what the NWFA recommends:

Before installing wood flooring place 15 lb. asphalt saturated felt paper that meets ASTM Standard D4869 or use a building paper with an equivalent permeance over wood subfloor. Refer to manufacturers recommendation before proceeding.

NWFA

We would echo the NWFA’s recommendation of contacting the flooring manufacturer to verify that the proposed paper underlay material will be suitable, so as to avoid any potential warranty issues should a problem occur.

It would also help if you also avoided paper containing excessive toxins, for example, roofing paper, which could create health risks over time.

Rosin Paper

In building construction, rosin paper is used to help reduce air and moisture flow through the floor. It also creates a ‘slip sheet’ that allows the different materials to expand and contract easily.

Another benefit of rosin paper is that it can act as a barrier to prevent the dust from coming up through the floor and also stop it from infiltrating down to the subfloor.

Rosin paper tends to come in rolls of various lengths, and you would lay it just before installing the hardwood flooring.

Many flooring installers opt for rosin paper because it is more economical, covers up the rough subfloor, and makes maneuvering the floorboards easier during installation.

It’s important to note that the National Wood Flooring Association (NWFA) explicitly recommends not using rosin paper with hardwood flooring. The reason is that rosin paper does not function well as a moisture inhibitor. Rosin paper instead readily absorbs water, which can lead to moisture-related issues should excessive moisture gather under the hardwood floor.

Felt Paper

Felt paper is an alternative underlayment option that is suitable for hardwood flooring. It helps increase insulation and, like rosin paper, prevents dust from rising from the subfloor.

Often referred to as asphalt-saturated felt paper, felt paper is a potential option for hardwood flooring that is nailed or stapled to a wooden subfloor.

When installed under hardwood flooring, felt paper also provides an extra layer of moisture protection and sound dampening.

Certain brands of hardwood planks have a padded felt layer already attached, in which case you wouldn’t need to use a felt paper underlayment because you could install it directly on top of the subfloor, previous floor, or plastic sheeting.

The NWFA recommends using either 15-pound or 30-pound felt paper as a hardwood flooring underlay in the construction industry.

When using 15-pound felt paper, unroll it across the floor, overlap the seams by 3 inches, and staple together.

30-pound felt paper, on the other hand, is too thick to have an overlap, so instead, the edges need to be flush with one another.

It is up to you whether you opt for 15-pound or 30-pound felt paper, though we would recommend 30-pound for upstairs flooring to help increase the sound insulation.

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Be careful not to confuse felt paper with roofing paper!

Even though they might look similar, roofing paper is typically coated with tar or asphalt and wouldn’t make a suitable floor underlayment paper.


How Do You Install Paper Under Hardwood Flooring?

There are a few different methods for installing paper under hardwood flooring, each of which will depend on the type of paper you use.

This article will focus on felt paper and rosin paper because they are the two most common types of flooring paper used today.

Always refer to the manufacturer’s guidelines and recommendations to ensure you use the correct building paper for your floor.

Many warranties will tell you what kind of flooring paper to use, so in those cases, it’s important you adhere to the terms and conditions to avoid breaking your warranty agreement.

How to Install Rosin Paper Under Hardwood Flooring

While installing rosin paper is not recommended by the National Wood Flooring Association (NWFA), there could be situations where the installation of rosin paper is deemed suitable or preferable.

Here’s a step-by-step guide for installing rosin paper where a hardwood floor manufacturer specifically recommends it:

1

Prepare the Substrate


Measure the size of the room to roughly work out how much rosin paper you’re going to need.

The subfloor must be smooth and flat before installing the rosin paper. Check for any nails that are sticking up out of the subfloor. If you come across any protruding nails, either hammer them down or remove them with pliers.

Sweep up the subfloor to remove any dust or debris that has accumulated over time.

Carefully remove any base molding with a crafting or utility knife and put it aside for later. You may also wish to take the door off its hinges so it is out of the way.

2

Lay the Rosin Paper


Staple along all of the edges of the rosin paper every 12 inches, then put a few staples in the middle to ensure it is entirely secure.

If there is excess rosin paper at one end, use a utility knife to cut it to size, making sure you trim it as close to the wall as possible.

Roll out the second row of rosin paper and overlap it with the first sheet by a couple of inches.

Once accurately aligned, staple the two rows together before fixing it in place securely with more staples along each edge.

Repeat the last few steps until the rosin paper fully covers the floor. Check there aren’t any staples sticking up and all the edges are securely in place.

Reattach the door and base molding if you took those off in the previous step.

How to Install Felt Paper Under Hardwood Flooring

Here’s a step-by-step guide for installing felt paper under hardwood flooring:
1

Prepare the Substrate


In newly built homes, you will find the substrate should be relatively straight and even and therefore won’t require too much preparation.

However, older homes are more likely to have an uneven and crooked substrate full of humps, dips, and the odd raised screw.

You should take some time to fill any dips with flooring-leveling compound and smooth any humps by sanding them down or fastening them tighter if they have become loose.

Skipping this step could misalign the finished hardwood flooring and prevent the boards from slotting together correctly, so you must ensure you prepare the substrate thoroughly before continuing.

2

Roll Out the Felt Paper Roll


Most brands of felt paper can tear easily, so very carefully unfold the first roll and run it along any wall in the room.

Cut the felt with a utility knife, making sure you leave a little material for excess.

3

Fasten the Felt Paper to the Subfloor


The most common way to secure felt paper to the subfloor is to staple it using a heavy-duty staple gun or flooring stapler.

Align the felt, so it is flush with one of the walls. Staple along the edge to keep it in place and add more staples to ensure it lies flat.

Once you are happy that the first roll is sufficiently secured, roll out the subsequent rows and fix them, in the same way, using the staple gun. If you are using 15-pound felt paper, make sure to leave an overlap of around 3 inches between each row.

4

Tidy Up


Once you’ve covered the entire room with felt paper, you may need to carefully cut any excess material along the edges to tidy it up.

You can carefully use a utility knife for this, cutting as close to the walls as possible.

Check all the staples to make sure they are all sitting flat. Use a hammer to tap any that may be sticking out too much.


Can You Use Roofing Paper Under Hardwood Flooring?

Roofing paper, also known as tar paper or roofing felt underlayment, is often mistaken for flooring paper.

Roofing paper is a heavy-duty paper used as a waterproof layer in roof construction.

Unlike felt or rosin paper, roofing paper is typically coated with asphalt or tar, which will emit harsh chemical odors that can be harmful if enclosed in your home.

If installed under hardwood flooring, there’s a chance the harmful fumes would be released up through the floorboards and rise into the room.

Therefore, we’d highly recommend that you opt for flooring-specific underlayment paper, such as felt or rosin, rather than roofing paper.

Can You Use Rosin Paper Under Hardwood Floors?

Rosin paper has been a staple material in the building industry for years for use as flooring underlayment.

When installed under hardwood floors, rosin paper will help reduce air and moisture flow through the floor.

Many floor installers also claim that rosin paper can minimize squeaking between the hardwood boards and the underfloor layer.

As mentioned above, the National Wood Flooring Association (NWFA) explicitly recommends not using rosin paper with hardwood flooring. The reason is that rosin paper does not function well as a moisture inhibitor. Rosin paper instead readily absorbs water, which can lead to moisture-related issues should excessive moisture gather under the hardwood floor.

Can You Use Felt Paper Under Hardwood Floors?

Often referred to as asphalt-saturated felt paper, felt paper has been used by flooring installers for years and is, therefore, a suitable underfloor paper option for hardwood floors.

Like rosin paper, it helps prevent dust from rising from the subfloor and acts as a moisture retarder to slow down moisture flow.


Final Remarks

Not every type of hardwood floor is suitable for use with paper, with glued floors being incompatible given that the underlayment tends to stick to the bottom of the hardwood boards.

For other types of floor, for example, those that you nail or staple down, there’s no shortage of claims about the particular benefits of installing paper underneath the hardwood floor, with perhaps the most significant advantage being the reduction of moisture flow through the flooring layers.

Ultimately, we’d recommend following the manufacturer’s guidance regarding installing paper under a hardwood floor, as doing so can avoid potential warranty issues in the future should something go wrong.


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