Florprufe™ 120

Integrally bonded vapour protection for slabs-on-grade

Product Description

Florprufe™ 120 is a high performance vapour barrier with GCP’s Advanced Bond Technology™ that forms a unique seal to the underside of concrete floor slabs.

Comprising a highly durable polyolefin sheet and a specially developed, non-tacky adhesive coating, Florprufe 120 seals to liquid concrete to provide integrally bonded vapour protection.


Florprufe 120 is engineered for use below slabs-on-grade with moisture-impermeable or moisture-sensitive floor finishes that require the highest level of vapour protection.

Florprufe complies with the latest recommendations of ACI Committees 302 and 360, i.e. for slabs with vapour sensitive coverings, the location of the vapour barrier should always be in direct contact with the slab1.

The membrane is loose laid onto the prepared sub-base, forming overlaps that can be either mechanically secured or taped. The unique bond of Florprufe to concrete provides continuity of vapour protection at laps. Alternatively, if a taped system is preferred, self-adhered Preprufe® Tape can be used to overband the laps.

Slab reinforcement and concrete can be placed immediately. Once the concrete is poured, an integral bond develops between the concrete and membrane.

Product Advantages

  • Forms a powerful integral seal to the underside of concrete slabs

  • Protects valuable floor finishes such as wood, tiles, carpet and resilient flooring from damage by vapour transmission

  • Direct contact with the slab complies with the latest industry recommendations

  • Remains sealed to the slab even in cases of ground settlement

  • Ultra low vapour permeability

  • Durable, chemically-resistant polyolefin sheet

  • Lightweight, easy to apply, kick-out rolls

  • Simple lap forming with mechanical fixings or tape

Health & Safety

Refer to relevant Material Safety Data Sheet. Complete rolls should be handled by 2 persons.

Florprufe 120 can be applied at temperatures of -4ºC or above. Membrane installation is unaffected by wet weather. Installation and detailing of Florprufe 120 are generally in accordance with ASTM E 1643-98.

Prepare substrate in accordance with ACI 302.1R Section 4.1. Install Florprufe 120 over the leveled and compacted base. Place the membrane with the adhesive coated side facing towards the concrete slab. Remove and discard release liner. End laps should be staggered to avoid a build up of layers. Succeeding sheets should be accurately positioned to overlap the previous sheet 50mm along the marked lap line.


Florprufe 120

Supplied in rolls

1.2m x 35m

Roll area 42m2
Roll weight 37kg approx.

Ancillary Products

Preprufe Tape is packaged in cartons containing 4 rolls that are 100mm x 15m.

GCP’s Liquid Membrane is supplied in 5.7 L pails.

Physical Properties

Property Typical Values Test Method
Colour White  
0.5mm ASTM D 3767 Method A
Water Vapour
0.03 perms ASTM E 96 Method B
Tensile Strength 65lbs / in. ASTM E 154
Elongation 300% ASTM D 412
3300gms ASTM D17091
Peel Adhesion to
>4lbs / in. ASTM D 903

*Test methods that comprise ASTM E1745 standard for vapour retarders.


  1. Mechanical fastening method – To prevent the membrane from moving and gaps opening, the laps should be fastened together at 1.0m maximum centres. Fix through the centre of the lap area using 12mm long washer-head, self-tapping, galvanised screws (or similar) and allowing the head of the screw to bed into the adhesive compound to self-seal. It is not necessary to fix the membrane to the substrate, only to itself. Ensure the membrane lays flat and no openings occur (See Figure 1). Additional fastening may be required at corners, details, etc. Continuity is achieved once the slab is poured and the bond to concrete develops.


  1. Taped lap method – For additional security use Preprufe® Tape from GCP Applied Technologies to secure and seal the overlaps. Overband the lap with the 100mm wide Preprufe Tape, using the lap line for alignment. Remove plastic release liner to ensure bond to concrete.


Mix and apply Liquid Membrane from GCP Applied Technologies liquid detailing compound to seal around penetrations such as drainage pipes, etc. (See Figure 2 and refer to the Liquid Membrane data sheet).

Concrete Placement

Place concrete within 30 days. Inspect membrane and repair any damage with patches of Preprufe Tape. Ensure all liner is removed from membrane and tape before concreting.

gcpat.my | For technical information: asia.enq@gcpat.com

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We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

Florprufe and Preprufe are trademarks, which may be registered in the United States and/ or other countries, of GCP Applied Technologies, Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

© Copyright 2017 GCP Applied Technologies, Inc. All rights reserved.

GCP Applied Technologies Inc., 62 Whittemore Avenue, Cambridge, MA 02140, USA 


This document is only current as of the last updated date stated below and is valid only for use in Malaysia. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on www.gcpat.my. Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2021-02-05