Waterproofing Concrete: Crack Size Matters, Crack Bridging Capacity

Blindside Waterproofing: Swellable Membrane Limitations: Cracks, Voids and Poor Consolidation Matter

In concrete, there are voids and cracks that waterproofing systems must compress against to be functional. This is relevant, particularly regarding poorly consolidated substrates which is inherent to shotcrete.  Swellable membranes such as Bentonite often do not achieve the 24 lbs. of compression per square foot required to achieve watertight functionality, when installed in conjunction with shotcrete.

When it comes to saving construction costs by using shotcrete at below grade vertical conditions, in lieu of cast-in-place concrete, we advise using some of those consequential savings towards a waterproofing system that can accommodate the inconsistencies inherent with blown concrete. Even the best nozzlemen cannot guarantee that voids will not be left behind.

A High-Density Polyethylene (HDPE) membrane with taped seams, used in conjunction with a bentonite option (that has the capacity of bridging in a watertight manner the poor compaction and consolidation areas that are acceptable structurally but inherently problematic from a waterproofing standpoint), is a predictable way to get watertight performance results with shotcrete applications.

Contact Terra-Petra today for a consultation on our waterproofing consulting, testing and inspection services.

IIBEC Technical Advisory No. 018-2019 (updated 2021) Electronic Leak Detection

Re-post from iibec.org

TITLE: Electronic Leak Detection

DESIGNATION: IIBEC-TA-018-2019 (updated 2021)

OBJECTIVE: To provide information on the methods and qualifications for electronic leak detection testing used for installed roofing and waterproofing systems.


This Technical Advisory is intended to serve only as a general resource and to identify potential issues for consideration by industry professionals. Each person using this Technical Advisory is solely responsible for the evaluation of the Technical Advisory in light of the unique circumstances of any particular situation, must independently determine the applicability of such information, and assumes all risks in connection with the use of such information. The materials contained in this Technical Advisory do not supersede any code, rule, regulation, or legislation and are not intended to represent the standard of care in any jurisdiction.


With the desire to improve the service life of roofing and waterproofing systems, a need has arisen to improve both quality control (QC) and trouble-shooting techniques of these systems. The introduction of nondestructive electronic leak detection (ELD) testing has provided additional options to meet this demand. Since QC is an increasingly important aspect in today’s construction projects, ELD is becoming a commonly specified and utilized procedure to determine watertightness in roofing and waterproofing assemblies. The introduction of ELD technology occurred around 20 years ago in the North-American market and has led to increased confidence in the performance of roofing and waterproofing systems. In recent years, questions have arisen regarding differences in technology and training required to provide accurate results using ELD. This technical advisory will provide information related to ELD on the following:

  • History and development of equipment currently utilized
  • Current ASTM standards and how they apply
  • Basic principles needed to conduct testing
  • Characteristics and limitations of the different technologies
  • Training and proper implementation
  • Recommendations


The origins of ELD began with high-voltage (holiday) testing equipment. This equipment was originally designed to test corrosion-resistant coatings applied on metallic pipes and was later modified to test geomembranes, waterproofing membranes, and low-slope roofing assemblies.

Moving into the 1990s, low-voltage testing made its way slowly into the German market as a means of troubleshooting existing roofing assemblies. It quickly became evident that low-voltage equipment was also suitable for integrity testing on exposed membranes.

Low-voltage electric field vector mapping also has the ability to assist with the troubleshooting of roofing and waterproofing through different types of overburden covering the membrane, although these tests are much more difficult and challenging than testing exposed membranes and have significantly reduced reliability.

In the 1990s, low-voltage testing—electric field vector mapping—was introduced in the North American market. While ELD was first promoted as a troubleshooting tool, as it was in Europe, it quickly became apparent that many individuals in the industry were interested in using the technology as a QC tool during installation of roofing and waterproofing systems.[i] Several developments have been made in the equipment over the years to allow for QC on numerous types of roofing and waterproofing systems. Within the last ten years, conductive grids, conductive primers, and other materials have also been introduced into the market to act as alternative grounds. These are incorporated into systems to allow for testing conventional insulated roofing systems. ASTM D7877–14, Standard Guide for Electronic Methods for Detecting and Locating Leaks in Waterproof Membranes, specifies that the alternative ground be installed directly under the membrane when the electrical path to the conductive deck is interrupted.

While there are several forms of equipment utilized for ELD—such as high-voltage broom, scanning platforms, electric field vector mapping—the basic electrical theory of either high or low voltage is similar.


ASTM D7877ii was introduced in 2014 and specifically explains the various pieces of equipment in use and the conditions required to perform a test. While this standard outlines the terminology and methodology associated with current electronic test methods and equipment variations, it does not address training and experience of the individual performing the tests.

Equipment Addressed in the Standard

ASTM D7877 outlines two methods of low-voltage ELD for horizontal surfaces, one method of low-voltage ELD for vertical surfaces, and one method of high-voltage ELD for horizontal and vertical surfaces, further described in the following.

Pendry Hotel and Condo Complex Opens on Sunset Strip

Re-post of original article from labusinessjournal.com

The long-awaited Pendry, a large hotel and condominium development positioned on the Sunset Strip at the site of the former House of Blues, has partially opened.

The property’s 149 hotel rooms started taking reservations April 2 while its 40 condos are slated to open in June.

Clad in digital billboards, the eye-catching complex is located at 8430 Sunset Blvd. in West Hollywood and holds two restaurants from Wolfgang Puck, Ospero and Merois, which are also open.

Marcy Schulte, a principal with Cuningham, which executed the project, said Pendry is benefiting from rising vaccination rates. “There’s a lot of pent-up demand and energy around getting back out,” she said.

Schulte added that the property’s residences are also seeing a lot of interest. “We’re expecting that, with vaccines coming online, and the more and more we know about it, that it will start to look more familiar in terms of the way people are socializing,” she said.

Even though the project was erected during the height of the pandemic, it didn’t have to undergo many changes in terms of land-use and design. “There’s some adjustments in terms of intensity and density of usage but really pretty minor,” Schulte said.

Read the complete article on labusinessjournal.com

Terra-Petra is thrilled to have been a part of this fabulous The Pendry Hotel project. Terra-Petra served as the Quality Assurance/Quality Control Waterproofing Inspectors throughout the entire construction process. We are also in the process of completing the QA/QC Fenestration Testing at the Residence in compliance with the project’s performance specifications.

Read more about Terra-Petra’s work on the project here

The Importance Of Waterproofing and Site Integrity – Keeping Priceless Works Of Art Safe

Terra-Petra has been selected to perform Electronic Leak Detection (ELD) testing by BEST Contracting Services for the project improvements at the Orange County Museum of Art in Costa Mesa. Testing will take place at the podium planters, with an estimated 4 move-ins where Hot Rubberized Asphalt Waterproofing will be installed as part of the site renovations.

Terra-Petra’s Waterproofing Division provides full scope building envelope consulting, design, testing and inspection services to our clients. Our goal as always is to make our clients’ lives easier by providing expert, unbiased and practical waterproofing consulting services in a highly responsive and cost-efficient manner.

While our current testing at OCMA will take place in the landscaping around the building rather than the interior of the structure, we can’t stress enough the importance of waterproofing and site integrity tests. How important?  Potentially saving priceless art collections, as noted in the 2015 article below.  A cautionary tale about the Isabella Stewart Gardner Museum in Boston where leaks in the building jeopardized multiple rooms in the museum holding priceless art.

The Gardner Museum’s Roofs Are Leaky, Jeopardizing Art

Re-post of original article on artnet.com by Cait Munro

It’s been a tough year for Boston’s Isabella Stewart Gardner Museum. Just days after longtime director Anne Hawley announced her resignation (see Hate Your Job? Gardner Museum Seeks Director), a security guard observed water dripping into the third floor Chapel Room.

The Boston Globe reports that the Tapestry Room, which lies one floor below, also had leaks later the same evening. Buckets and rubber mats were brought in, and jeopardized works were either removed from the area or draped in plastic.

Several days later, the Little Salon, which lies adjacent to the Tapestry Room, was also discovered to have leaks. It currently remains closed to the public, in addition to the Chapel Room.

“We are extremely cautious when a leak is detected and will drape and de-install art as a preventative measure,” said Hawley, who acknowledged that the leaks have been an ongoing problem for the past month. “We err on the side of caution and leave the plastic covering up until we are certain that any leak in the area has been stopped since water often travels. This is not always an ideal visitor experience, but protecting the collection is our top priority.”


This Is A Robbery – Netflix Documentary on the Isabella Stewart Gardner Museum

Interestingly enough, there’s also a documentary on the 1990 Heist that took place at the Isabella Stewart Gardner Museum currently streaming on Netflix.  It’s a four-part crime series on this amazing $500 million heist at this historic and beautiful building, and worth taking a look!