Proper installation of a self-adhering membrane system

Exactly what should you look for in a crack isolation membrane warranty? There are many answers to this question. By definition, the warranty is the membrane manufacturer’s statement that its product(s) …

Will be free from any warranted defects in materials or workmanship

…Meet approved industry performance standards …

Will perform as stated provided that the installation procedure was correctly followed and a compatible mortar was used…

For the defined warranty period.

In the tile and natural stone floor setting world, the common goal of the specifying architect, membrane supplier, installer and building owner is a beautiful, long-lasting crack-free floor. There are millions of installed square feet where this goal has been achieved.

Such outcomes, however, are not always the case. Tile and natural stone floor failures, while rare, do happen. Generally, failure of the crack isolation membrane and subsequently the floor is a combination of one or more of the following:

•Membrane design and construction

•Improper sub-floor surface preparation

•Insufficient membrane bonding to the substrate

•Moisture vapor transmission

•Use of an incompatible mortar, or incorrect mortar application

•Movement of the structure beyond the membrane’s stated performance capability

This article takes a look at current crack isolation membrane warranties, as well as the development of a new breed of warranties that will result in a solid “win-win” for the membrane manufacturer, specifying architect, installer and building owner.

Membrane warranties differ widely. They need to be more consistent. Take a detailed look at the warranties for the different brands of crack isolation membranes and you’ll discover that each is different. Different in terms of …

Protection from reflective joint cracking (generally from 1/16 to 1/2-in.)

Length of time the membrane material is covered for defects

Length of time the floor should remain fracture-free

Type of tile or stone and mortar the membrane is compatible with

Tile or natural stone that is defective or cracked, or not suited for intended application

Powdering or discoloring of the grout joints

Application – indoors or outdoors

Required installation methods as well as what constitutes improper application or installation

Substrate conditions – defects, vertical displacement and lateral movement, hydrostatic pressure, moisture vapor transmission

Defects or failures of the tile installation materials, floor leveling/patching materials, grout, sub-flooring, or other products that can affect floor performance

Abrasion from external forces or damage by acts of negligence, accidents or misuse

Walking on or moving heavy equipment over the tile and membrane systems before it is cured, dropping heavy objects on the floor, construction within the building causing damage, etc.

Natural disasters – acts of God, earthquakes, floods, substantial shifting of the substrate

Failure of the building owner, installer and/or distributor to comply with the terms, conditions and limitations of the warranty

As such, if you are looking at different crack isolation membrane options, it is important to compare warranties as to exactly what is, and isn’t covered, and for how long. What, if any, are the protections for the architect/specifier, you the installer and your customer, the building owner?

What are the remedies if there is a problem? Specifically …

What will the membrane manufacturer replace if there is a problem?

What will they pay for – their products? Finishing materials? Labor for replacement? And, how will the amount of payment be determined?

What won’t they pay for?

What are the “we’re not responsible” exclusions? Such as …

Workmanship not performed in accordance with the manufacturer’s instructions.

Failure to follow industry standard guidelines.

Incidental damages or consequential damages, including losses due to delays incurred by the purchaser or any other party.

If you are not careful in your review of warranties, exclusion loopholes can relieve the membrane manufacturer from up to 60 percent of the liability for tile and natural stone floor failures. Bottom line - carefully read the warranty of the membrane system you are considering using.

After 25-years of long-term crack isolation membrane installation success, we have found that the key to no “call-backs” is using mortar that is compatible to the membrane, tile or natural stone being installed. And, it is critical that the membrane manufacturer’s substrate surface preparation and installation instructions be followed to the letter.

Written vs. unwritten (implied) warranties

ECB anti-fracture membrane installation in The Monte Carlo Hotel & Casino

Should there be a floor failure, who gets called? Chances are it’s you, the installer. In turn you call the membrane manufacturer. Membrane warranties generally have a section titled “How to Make a Claim.”  The wording is usually something like, “To make a claim, you must notify us in writing within 30-days of the defect discovery.” Often you are also required to supply proof of product purchase and use. Most large jobs have a project specific membrane and system performance warranty in place for a stated period of time.

But what if the problem is in a “fuzzy” non-warranted area? Then what? When you made your membrane decision, did the manufacturer’s sales person say, “if there’s a minor problem down the road, don’t worry, we’ll stand behind you.” It’s too late to find out whether you’re covered when a problem occurs several years after your install. In all businesses, and especially in this one, reputation is everything. Manufacturers of high-quality crack isolation membranes are proud of their products and the installation success they have enjoyed over the years. Before you make your final decision as to which membrane system to use, check the manufacturer’s reputation with your peers and your distributor. Do they stand behind their product even when the trouble spot is a bit fuzzy warranty-wise?  

Key considerations beyond the warranty

Make-up of a self-adhering crack isolation membrane

Many ceramic tile and natural stone floor failures that can be traced to improper membrane placement, poor membrane composition and the use of primers that causes re-emulsification and breakdown of the membrane. Hence, it is extremely important to make a detailed evaluation of the differences in membrane design/construction and the recommended installation procedure before you make a final decision on which membrane system to use.

Evaluating membrane design/construction



There are two basic types of sheet membrane systems. One type has an asphalt adhesive base and uses a primer to provide a “tacky” surface for “peel-and-stick” installation. These also have some type of top fabric layer for tile setting.

A second type of sheet system utilizes a proprietary primer formulation that, combined with the adhesive formulation of the membrane, bonds to the substrate. This membrane/primer combination eliminates moisture vapor transmission (up to ten lbs. per thousand MVT). It also provides a “matched” surface for the adhesive pre-applied to the bottom of the membrane. This membrane has a coating that protects the fabric from lime deterioration from the cement and the mortar. And, the fabric is “locked-in” to the membrane with adhesive.

Your detailed look at membrane system differences should include the following:

Overall construction and make-up of the membrane

Is the fabric top layer positively locked in place?

Will the fabric layer prevent lime deterioration?

Can the membrane absorb movement; yet stay rigid enough to protect the tile/stone from movement?

Types of floor primers and adhesives



What is the chemical composition of the primer? Water-based latex primers that are generally used with “peel-and-stick” membrane systems can re-emulsify when water vapor is present, causing the primer to break down to the point where the membrane loses its initial bond strength. The resulting curling or warping of stone will create tensile stresses that exceed the bond strength of the membrane, and as a result, a loss of adhesion can occur between the membrane and substrate.

The proprietary primer used with “self-adhering” sheet membrane systems is formulated to rapidly “cure” in place and provide a surface that permanently bonds with the polymer adhesive of the membrane. Once the primer is cured, it cannot re-emulsify. The result is that the membrane and its self-adhering co-polymer system become an integral part of the floor substrate.

The materials used in membrane construction and their chemical make-up differ widely

What is the chemical make-up of the membrane? There are varying amounts of rubber, asphalt, elastomers and fillers used.

How high a percentage of asphalt is in the composition? A large percentage could lead to a tendency for the membrane to crack over time.

Evaluating membrane installation procedure



For a successful installation, the membrane and primer composition is critical to achieving the sheer bond strength required to securely bond the membrane to the floor. For long-term floor performance it is important that the membrane retain its elasticity and the primer not re-emulsify when water vapor exceeds three pounds per thousand pounds per day.   Key questions include …

What surface preparation is required before the install? How thorough and exacting is it?

How is the substrate sealed?

What type of sealing primer is used?

How does the membrane installation allow for lateral movement, but hold the tile/stone layer rigid?

It is important to note that natural stone and some agglomerate marbles are more susceptible to expansion and warpage from moisture than their ceramic and porcelain counterparts. Consequently, they have a tendency to expand and/or warp due to their sensitivity to moisture unless they are securely bonded to a substrate or membrane system.

When a membrane fails, or loss of adhesion occurs, it is generally traceable to the use of “peel-and-stick” membranes that lack an adequate bond to the substrate or a sufficient chemical bond between the tile setting material and the membrane’s fabric. The curling or warping of natural stone, for example, will create tensile stresses that exceed the bond strength of the membrane, resulting in a loss of adhesion and failure of the composite system.

Does the membrane meet all performance standards?



New ANSI performance standards for crack isolation membranes were introduced in 2005 as ANSI A118.12. Long-term tile installation success directly depends on the ability of the crack isolation membrane system to meet or exceed all of the standard’s ten tests because of the complexity of the various membrane systems.   

Floor failures – particularly with natural stone installations – can be avoided if you pay particular attention to the results of the two most critical tests. These are shear strength after accelerated aging and long-term water emersion. Poor performance or failure of these two tests indicates that the membrane will not provide the adhesion necessary to hold up under a natural stone installation. To help you avoid a potential floor failure, membrane manufacturers must make the results from all ten performance tests available. Unfortunately, most do not. Questions to ask include …

Does the membrane manufacturer provide test data for all ten ANSI A118.12 tests?

Does their membrane system pass all ten tests?

How does their system fare on the two most critical tests – shear strength after accelerating aging and long-term water emersion?

Based on their test performance, how long a performance warranty do they offer?  

What is the membrane manufacturer’s success track record/reputation?

Membrane and floor failures are a direct result of putting other factors before quality. Importantly, crack isolation membranes do work when installed correctly.  Ask …

What is the manufacturer’s reputation for backing up their warranty?

Do they go the extra step if necessary?

Does the membrane manufacturer train and/or certify installers with its products for different tile/stone and mortar combinations?

Do they provide references and referrals?

Have they had problems that required a court settlement?

The ideal system warranty



To make it a true “win-win” for all parties involved, your project needs to be covered by a combination of two warranties:

The crack isolation membrane manufacturer’s warranty, and …

A total system compatibility warranty for the thin or medium bed mortar that is to be used with the membrane.

A total system performance warranty that ensures compatibility between the mortar used and the crack isolation membrane is the only way to assure the specifying architect, you the installer, and your building owner customer that the newly installed floor is protected against reflective cracking and delamination between the substrate and floor surface for a very long period of time.