Step 22 - Subfloor

How to Install Underlayment

Underlayment provides cushion, reduces noise, smooths minor imperfections, and makes floors more comfortable. The final prep step before installing your beautiful new flooring.

Time needed

1-3 hours

Cost

$0.50-2/sq ft

Difficulty

Easy

Types of Underlayment

Foam Underlayment

Most common. Cheap ($0.25-0.50/sq ft), easy to install, provides basic cushion.

Best for: Laminate, LVP on any subfloor

Cork Underlayment

Premium option ($1-2/sq ft). Excellent sound dampening, natural antimicrobial properties.

Best for: Condos/apartments, noise reduction priority

Rubber Underlayment

Heavy-duty ($0.75-1.50/sq ft). Superior sound blocking and cushion, very durable.

Best for: High-traffic commercial areas, gyms

Felt Underlayment

Dense felt ($0.50-1/sq ft). Good for hardwood, very quiet, slight moisture protection.

Best for: Engineered hardwood installations

Installation Steps

1. Check Your Flooring First

Important: Many LVP products have attached underlayment. Using additional underlayment makes floor too spongy. Check packaging before buying separate underlayment.

2. Roll Out Perpendicular to Flooring

Install underlayment at 90 degrees to the direction your flooring will run.

  • • Start at one wall and unroll across room
  • • Don't overlap seams - butt edges tightly together
  • • Cut with utility knife at walls
  • • Some types have moisture barrier attached (shiny side down)

3. Tape the Seams

Use underlayment tape or duct tape to seal seams and prevent shifting.

Pro Tip: Only tape seams as you go - don't tape entire floor at once. Tape row, install flooring on that row, then move to next. This prevents underlayment from shifting during installation.

4. Cut Around Obstacles

Trim underlayment carefully around doorways, vents, and protrusions.

Leave small gaps around obstacles - underlayment doesn't need to be perfect since flooring covers it. But avoid large bunching or gaps.

Common Underlayment Mistakes

Overlapping seams: Creates bumps and high spots. Butt edges together tightly.
Double-layering: If flooring has attached pad, don't add more. Floor becomes spongy and planks unlock.
Wrong side down: Moisture barrier side (usually shiny) goes DOWN toward subfloor.

FAQs

Do I need underlayment if my LVP has attached padding?

No. Using additional underlayment over attached padding makes the floor too soft and planks won't stay locked together. Only use separate underlayment if your flooring is rigid with no pad attached.

Can I reuse old underlayment?

No. Old underlayment is compressed, damaged, and dirty. It costs so little ($0.25-0.50/sq ft for foam) that reusing isn't worth compromising your new floor. Always use fresh underlayment.

Which underlayment is best for sound reduction?

Cork and rubber underlayments provide the best sound dampening. Cork is natural and eco-friendly, rubber is more durable. Both significantly reduce noise transmission between floors - essential for condos and apartments.

Subfloor Prep Complete!

Your subfloor is now ready for flooring installation. The foundation is solid, level, dry, and protected. Time to install your beautiful new floors.

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