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UnderBlock™ Rubber Floor Underlayment

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UnderBlock Rubber Flooring Underlayment

It's a bird! It's a plane! No... it's UnderBlock! The floor soundproofing solution that will give a wedgie to footfall noise and a giant uppercut to airborne noise passing through your floor-ceiling assembly. Don't let a noisy upstairs ruin your day. Bring in some super help with an UnderBlock flooring upgrade.


Product Information

  • Subflooring / underlayment for reducing impact noise, airborne noise, and vibration reduction
  • Post-consumer recycled rubber
  • Flat and semi-smooth surface
  • Excellent improvement in STC ratings (airborne noise), FIIC and IIC ratings (impact noise) --- typically 50 to 70 for both depending on specific construction
  • Easy installation and compatible with most floor finishes and assemblies

UnderBlock - 3/8"

  • 3/8" thick black recycled rubber
  • Each roll is 4' x 25' (100 sq ft)
  • Weight: 120 lbs
  • Recommended for most floor-ceiling assemblies

UnderBlock - 1/2"

  • 1/2" thick black recycled rubber
  • Each roll is 4' x 20' (80 sq ft)
  • Weight: 145 lbs
  • Recommended for open joist ceiling (unfinished ceiling underneath the floor)


UnderBlock Flooring Underlayment Bulk Discounts

For large orders that can take freight delivery, we offer significant discounts off the listed price. You must be able to take a FREIGHT delivery to be eligible for the BULK discounts. 


 Roll Thickness   Sq Footage   New Price   How to Get Bulk Discounts 
 3/8"  500+  $2.30 / sq ft + FREIGHT   Request a quote via "Add to Quote" button on this page or call us! 

 1/2" 500+  $3.13 / sq ft + FREIGHT   Request a quote via "Add to Quote" button on this page or call us! 



Product Uses

  • Homes, apartments, home studios, recording studios, condos, hotels, conference rooms, offices, music practice rooms, band rooms, houses of worship, hospitals, malls, retail stores, theaters, schools, restaurants, and bars
  • If you've got a floor, UnderBlock will make it a soundproof floor. UnderBlock rubber underlayment stops all impact noise while also blocking airborne noise.
  • The floor's soundproofing should be considered equally along with soundproofing walls and ceiling sound insulation when deciding how to soundproof a room.
  • To completely treat all 6 surfaces in thee room, sound proof doors and sound proof windows will be needed for any rough openings.


Installation Instructions

  • Roll out UnderBlock to cover the subfloor. Adhesive is optional. UnderBlock is heavy and will not move around.
  • Use a metal straight edge to make any cuts with a sharp utility knife.
  • Leave a 1/8" gap between UnderBlock and any obstacles (walls, columns, posts, drains, pipes, etc). Fill this gap with acoustic sealant caulk.
  • For perimeter walls, you can run UnderBlock directly to or under the wall instead of leaving the 1/8" gap and sealing it.
  • Roll out the UnderBlock in rows, keeping the factory seams tight and flush. If the seams are flush, acoustic sealant is not needed. Joints and seams can be taped if desired.
  • Install your chosen flooring on top of UnderBlock rubber flooring underlayment.


If you have any questions about your type of flooring for your project, call us and we can walk you through it!

  • Floating floors do not require additional adhesive. They just lay on top of UnderBlock.
  • Mechanically fastened floors (nail down) should have a subfloor glued to the top of UnderBlock. Use our recommended rubber adhesive when required.
  • Glue down floors should use whatever adhesive is recommended by the flooring manufacturer that is compatible with attaching to rubber.

Contact us if you have questions!

For large construction jobs with specific IIC requirements, contact us for additional information.




Shipping Cost:
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Project Category:
Material Type:
Room Soundproofing