2850930 Mapeguard UM Underlayment Membrane - 323 sq. ft. Roll

SKU: 2850930
Manufacturer: Mapei
MPN: 2850930





Mapeguard UM Underlayment Membrane - 323 sq. ft. (30 m²) Roll by Mapei

Mapei's Mapeguard UM is a lightweight uncoupling mat for use under ceramic tile and stone installations and can also work as a waterproofing and vapor-pressure-equalizing underlayment. This versatile underlayment membrane can perform on the most challenging substrate surfaces, such as young concrete and single-layer 3/4" plywood floors, in both commercial and residential applications. The unique engineered tri-layered design of Mapeguard UM absorbs lateral stress from the substrate without transferring this force to the tile or stone, which maintains exceptional bonds.


  • Prevents transmission of in-plane substrate cracks up to 1/8" (3 mm)
  • Recommended for use with polymer-modified mortars
  • Fast Track Ready - approved for use over young (green) concrete and mortar beds
  • Time-saving: Embed membrane then install tile immediately
  • Engineered cavity design allows easy single-pass filling of surface core with less mortar
  • Uncoupling, waterproofing and water vapor membrane up to 25 lbs. (11,3 kg) MVER and 100% relative humidity
  • Compression resistance to support rolling loads
  • Approved for radiant-heating applications
  • Light green, translucent color shows mortar coverage under membrane
  • Reduced “roll memory” and unique tri-layer construction keep membrane flat
  • Easy to cut with standard utility knife
  • Chalk and laser lines easily visible on surface
  • Mesh-fabric top layer makes it easy to fill cavities with mortar

Suitable Substrates

  • Concrete
  • Cement mortar beds, self-leveling underlayment and leveling coats
  • Young (green) concrete
  • Industry-approved exterior-grade plywood and APA Sturd-I-Floor, Exposure 1 OSB (interior, dry areas only)
  • Approved backer units – see manufacturer’s installation guidelines
  • Cement terrazzo (properly prepared interior only)
  • Existing ceramic tile or stone (properly prepared interior only)
  • Radiant-heat systems
  • Existing, properly prepared vinyl flooring – vinyl composition tile (VCT), non-cushioned paper-backed/felt-backed sheet vinyl, luxury vinyl tile/plank (LVT/LVP)
  • Epoxy terrazzo (with appropriate bond testing – interior only)
  • Gypsum underlayment or lightweight concrete

Questions & Answers

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Ratings & Reviews

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The best.


In my opinion this membrane is by far the best one out.
1. By using a grey mortar you can see the coverage.
2. It has all the features that schluter has but you can use modified mortar.
3. It has all the features stratamat has but...its also waterproof which stratamat is not.

I've been using this product for years but often settled for stratamat because I was getting umguard at a higher price. Now that CD stocks it...it will always be my membrane.

Mapeguard UM . Game changer!


Awesome product and super fast shipping because I am near Connecticut. I made the switch from 1/4 hardy to mapeguard um. I am on my 4th roll in a few weeks. Absolutely game changer all though it’s .34 cent more per sq ft it make up for itself in time and labor. I would have had to go pick up and load 86 sheets of cement board, drop off at the job, carry it in up stairs, cut and nail off or screws off. These rolls are delivered right to my door and are easily carried to the truck and brought to the job. And cuts with a razor knife.