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How Much Underlayment Do I Need to Buy?

Dear Bob and Betsy,
I’m getting ready to install my flooring in my living room but I still need the 3-in-1 underlayment. The room is about 350 square feet, maybe a little bit less. Do I need to cover the entire floor? How much underlayment do I need to buy?
– James K.

Dear James,

This is a common question. Since underlayment isn’t actually seen, many homeowners think that they might be able to get away with leaving a little room on the sides of the flooring, and not buying the full amount needed. That’s dangerous and it could decrease the life of your flooring.

As a rule, we suggest buying as much or more than you need. If your room is about 350 square feet, you will probably want to buy four rolls of 100 square foot underlayment. Most underlayment is sold in packages that cover 100 square feet, so the math is easy.

Here’s why you’ll want to ensure your underlayment covers the entire subfloor when you install.

1. It’ll reduce the amount of noise in your room.

Because you’re buying 3-in-1 underlayment, you want to get the maximum benefit of the noise reduction. Without the 3-in-1, your floors might echo, making your house a little noisier than you’d like. To get the full noise reduction, make sure you install the underlayment throughout the room.

2. It’ll decrease your risk of moisture damage.

Moisture and laminate flooring don’t mix very well. That’s especially true when moisture is found underneath the floor boards. To prevent warping caused by leaks or cracks in the subfloor, you need to cover the entire room with underlayment.

3. It’ll extend the life of your floors.

The underlayment is there to stabilize your flooring and make it more comfortable. If there are sections without underlayment, you risk your floors becoming damaged from the bottom up. This can cause serious harm to your flooring over time. Although laminate planks are easy to replace, you don’t want to have to go through that burden if it’s not necessary. Install your subfloor throughout the entire room, from corner to corner, for the best results.

About Bob and Betsy

Bob and Betsy
Bob and Betsy are the dynamic duo that have all the answers for your flooring related questions! Don't hesitate to submit a question to them at support@bestlaminate.com!

8 comments

  1. Alana Kane

    Hi Mike, thanks for the question. Yes, you will let it go up the wall a bit and cut off the excess before adding the moldings.

  2. Avatar

    When installing underpayment do you butt it up 1-2 inches up your room walls with the intent to eventually cut away that exceeds at the base later??

  3. Alana Kane

    Hi Kathy, the number of rolls will depend on how much the underlayment roll has. We sell 100 sft rolls to 500 sft rolls. A great LVT underlayment is this one: https://www.bestlaminate.com/bestlaminate-pro-line-premium-lvt-underlayment-15mm-100sf/. If you go with that one, you will need 22 rolls. I would recommend making sure your subfloor is level before installing your vinyl. If it is a floating vinyl, it could dip into areas that are lower, causing issues with the joints. An underlayment will help with a slight imperfection, but if it has many high and low spots, it could be an issue down the line.

  4. Avatar

    how many rolls of underlayment do I need for a 2135 sq ft house?
    And what is a good underlayment that isn’t the cheapest but not the most expensive?
    Where do I buy the underlayment?
    If my floors are uneven, is it o.k. to still install the vinyl plank flooring?

  5. Alana Kane

    Hi Robert! Great question. We typically recommend sound suppression for 2nd or higher floors, so the sound doesn’t transfer to the floor below. If you’re looking for the sound under your foot to be quieter, you could invest in a sound dampening underlayment. A basic cushion underlayment will provide some sound dampening, but it depends on your preference here!

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    Thinking about pulling up carpet in the basement. Carpet is already floating on a plywood subfloor. Would I gain anything by spending more money and buying an underlayment with sound suppression?

  7. Avatar

    Hi Margaret! Yes, you can definitely add an insulating underlayment underneath your laminate floor to make it warmer. We recommend Roberts Super Felt Premium Underlayment. This underlayment also comes with a vapor barrier, which you need if you are installing over a concrete sub-floor. Good luck with you installation and feel free to call us if you have further questions! 1-800-520-0961!

  8. Avatar

    we are thinking of pulling the carpet up in our living room. The floor is cold in the winter due to the basement is concret. Will laminate flooring the floor ever colder or there a way to put a warm under layment to help keep some of the cold out.

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