MasterSeal 550: Flexible, cementitious waterproofing membrane

Formerly: Flextight

How does MasterSeal 550 work?

Flextight is an acrylic-modified, portland cement-based flexible, waterproofing membrane for concrete and masonry. Use it above or below grade on interior or exterior surfaces.

Recommended uses:

  • Walls and floors
  • Tiled pools and fountains
  • Plaza decks
  • Balconies
  • Mechanical rooms

What are the features of MasterSeal 550?

  • Waterproof membrane
  • Creates a flexible membrane
  • Breathable
  • Ready-to-use kit

What are the benefits of MasterSeal 550?

  • Protects against soil moisture and water seepage; extends life of structural slabs and underlayment
  • Accommodates substrate movement; prevents cracks from telegraphing; provides excellent underlayment for thin-set tile applications
  • Allows interior moisture vapor to escape
  • Easy to mix and place
  • Low odor

US / Canada Product Information 

Data Guide

Certification Letter

Safety Data Sheets (SDS):

MasterSeal 550 - Part A

MasterSeal 550 - Part B

MasterSeal 550 - Gray

MasterSeal 550 - Powder

Direct contact

Master Builders Solutions Technical Support

Construction Systems


Safety Data Sheet (SDS)

Find all available safety data sheets for this product.

Product Certifications

Generate a free certificate of conformance for a specific BASF construction product.

Related Literature

Certification Letter

pdf (55.32 Kb)

Data Guide

pdf (260.33 Kb)