Terra-Petra Presents “Principles of Building Enclosure Systems” Lunch & Learn for Johnson Fain

Terra-Petra’s Forensic Waterproofing Expert, Barry Taheri, presented his tenth lunch and learn seminar for global architecture, planning and design firm, Johnson Fain, at their Los Angeles Chinatown offices on Broadway on March 6, 2019.

In this small group* presentation, “The Principles of Building Enclosure Systems,” Taheri provided info on the importance of building waterproofing and the benefits of investing in mock-ups, along with a live demonstration of dangerous wicking.

Thanks to Greg Keating who asked many relevant questions and added to the lively discussion. And a special thanks to Nicole Villamin for organizing our event.

Contact Terra-Petra for more information on how to schedule a Lunch and Learn Program for your organization.

*Lunch and Learn Programs are available to all group sizes. 

Lunch for the group was once again catered by Mendocino Farms.

Highlights from the Lunch & Learn program…

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Terra-Petra’s Blindside Waterproofing Project featured in Waterproof! Magazine

Terra-Petra Building Waterproofing Division Project Featured on the Cover of Waterproof Magazine, Fall 2018



Blindside waterproofing systems are among the most difficult to design and install.  These waterproofing and drainage systems are placed before the structural walls are poured, which means they must be installed over a soil retention system rather than concrete or masonry.  That retention system—whether it be lagging beams, sheet pilings, shotcrete, or compacted native soils—is typically rough, uneven, and subsequently requires extensive detailing.

Additionally, blindside applications are usually part of massive projects that extend far below a water table where, in some cases, hydrostatic pressure can be extreme. Here, the workmanship must be flawless, as once the structural wall is in place, it is extremely difficult to repair any leaks that develop.

While blindside waterproofing is a considerably more complex below-grade solution, sometimes it’s the easiest—or only—way to get the job done: Applications of this waterproofing methodology can be found in bored tunnels and deep foundations where over-excavation isn’t possible, for example. Blindside techniques are also optimal when property lines and/or nearby structures limit excavation and access, such as “zero lot line” foundation walls.

This was the case at 1840 N. Highland Ave., a luxury multifamily complex constructed in the heart of Hollywood, California, steps away from the world-famous Hollywood Bowl and Hollywood Boulevard.  Typical of many projects in high-density, built-up areas, the 118-unit complex is sited on a tight lot, and extends three stories below grade to create space for mechanical systems and tenant parking; an ideal scenario for blindside waterproofing techniques.

As the schedule moved forward, it transpired that there were several unique complexities, which made the project even more challenging.

The entire lot was excavated to more than 30 feet below grade, with soldier piles, wood lagging, and rock bolts used to keep the surrounding soil in place.

“There were some real twists to the project, including two fault lines under the cantilever of the building and the water table, which sat at different levels,” says Josh Heidt, with Terra-Petra, the company contracted to provide waterproofing consulting services.

Terra-Petra brought in Epro Services, a Kansas-based waterproofing company with a long history of success on blindside jobs in the state, to provide a solution. Heidt says, “Epro has the kind of case history we were looking for from a manufacturer on a multi-faceted project like this.”

Construction began with a major earthmoving project.  The entire 8,144-square-foot lot was excavated to more than 30 feet below grade.  Soldier piles and wood lagging were used as a retention system, augmented by tiebacks and soil nails. On one wall, massive tubular steel rakers—more than three feet in diameter—were used to ensure that the foundation of the adjacent seven-story building stayed in place.

To ensure optimal waterproofing, the system had to seal tight despite the irregular substrate and needed to be durable, too. The structural walls would be placed with shotcrete, which would be applied directly to the membrane without a protection course.

The underslab barrier extends up the wall two feet higher than the water table. The mat of reinforcing steel will be encapsulated in the four-foot-thick foundation

The architect worked closely with the geotechnical consultant and the waterproofing supplier to ensure the specified system would perform as designed.  Architect Ronald Rosell, representing the project architect Arquitectonica, says “Epro helped us and the geotechnical consultant work through the issue regarding the north face of the building where the fault line divided the water table.”  He continues, “The fault acted like a subterranean waterfall, and Epro gave us recommendations for how best to prevent that hydrostatic pressure and constant flow of water from impacting the structure.”

The general contractor, Frymer Construction, was also brought into these discussions to ensure the design would be buildable.  “We collaborated with Terra-Petra regarding the usual qualifications, review of transitions, and fastening and drainage considerations,” says David Frymer, company president.

The bottom of the excavation was about 10 feet below the water table, so crews poured a “mud slab,” then installed the underslab waterproofing system:  Epro’s E.Protect+ Underslab, which features built-in layers of redundancy.  It’s achieved by combining different types of waterproofing materials to leverage the positive attributes of each, a technique they call “Redundant Field-Installed Composite Design.”

Tubular steel rakers more than three feet in diameter provide support for the lagging and simplify the detailing.

In this particular application, E.Protect+ Underslab was comprised of a layer of 16-mil HDPE thermoplastic membrane with heat-welded seams, over which the team spray-applied a 100-mil layer of polymer modified asphaltic membrane.  Finally, this was topped with an HDPE-reinforced bentonite sheet which will expand to seal any leaks that may develop in the future.

This triple system was installed across the slab and up the walls two feet higher than the historic high water table level.   Then the structural slab was poured, four feet thick with a double mat of reinforcing steel running 12 inches on center in both directions.

Above the water table, Arquitec-tonica specified E.Proformance Shoring, a blindside waterproofing system used for non-hydrostatic conditions. It’s comprised of a 30-mil HDPE dimpled drain mat installed against the lagging, which was then sprayed with a 60-mil layer of the same asphaltic membrane used in the underslab waterproofing.

The spray-applied coating is formulated so that the heat generated by curing concrete will chemically bond the product directly to the structural wall. The dimples in the drain mat also help prevent delamination between the membrane and the concrete.

E.Proformance was used all the way up to grade level, where it was transitioned to a hot rubber horizontal waterproofing system that was used to seal beneath the planters and the above-grade stucco wall system.

In total, the project used 70,000 sq. ft. of waterproofing.

EPS “geofoam,” reduces the effect of seismic movements on the building’s structure and create a smoother substrate for the waterproofing.

Experts say the key to quality in any blindside application is the ability to detail around the soil retention system.  This project used an ingenious solution to resolve that dilemma: A two-foot-thick layer of EPS “geofoam,” installed between the retaining wall and the shotcrete structural wall.

Provided by Insulfoam, this rigid insulation arrived in giant blocks and was installed between the retaining wall and the dimple membrane.  The geofoam will reduce the effect of seismic movements on the building’s structure and creates a smoother substrate for the waterproofing.

Crews fastened the geofoam directly to the lagging. Then the dimple drain sheet was fastened over the foam, with the waterproofing layer spray-applied to the dimple sheet. The same spray-applied product was also used to detail around the many pipe penetrations, the pits for elevators, and utilities.

“My experience with Epro has been outstanding,” says Mostafa Sobhi, president of BM Builders and the certified Epro applicator responsible for the installation. “Their quick turnaround in answering any concerns and providing details due to changing field conditions has been a huge factor on how jobs like this can be successful, while also maintaining schedules.”

Heidt reports that Epro representatives were “on the site a great deal of the time” to ensure the workmanship was flawless. Despite the high level of complexity and the presence of hydrostatic conditions, working closely with the project team enabled Epro to provide a 15-year no-dollar-limit warranty to the developer.

The project at 1840 N. Highland Ave. is scheduled for completion in 2019.

The 1840 N. Highland Ave. apartments are on schedule to be completed in 2019.  The development shows that despite the difficulties blindside work presents, with the right materials and know-how, contractors can get excellent results.

The Principles of Building Enclosure Systems: Lunch and Learn Program

Terra-Petra’s Forensic Waterproofing Expert,  Barry Taheri,  recently presented a lunch and learn program for global architecture, planning and design firm, CallisonRTKL at their downtown Los Angeles offices on Hope Street on August 22, 2018.

In his presentation, “The Principles of Building Enclosure Systems,” Taheri provided info on the importance of building waterproofing, and the benefits of investing in mock-ups along with a few live demonstrations.  He plans to present more of lunch and learn presentations in the months to come.

Contact Terra-Petra for information on how to schedule a Lunch and Learn Program for your organization.

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The Terra-Petra Waterproofing Division team will be exhibiting at the RCI Trade Show Exhibit in Houston

Terra-Petra Waterproofing Division Exhibits at RCI International Convention & Trade Show

The Terra-Petra Waterproofing Division team exhibited at the RCI International Convention & Trade Show at Houston’s George R. Brown Convention Center on March 24-27, 2018.

Our group of professionals provided information and further insight on our BUILDING ENVELOPE CONSULTING * ELECTRONIC LEAK DETECTION * CERTIFIED AIR & WATER TESTING  * INSPECTION & MONITORING services.


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The annual RCI, Inc. International Trade Show offers attendees the chance to meet and learn from representatives from over 130 manufacturers of roofing, waterproofing, and exterior wall products. 



Terra-Petra Waterproofing Division provides inspection services for new Trammell Crow Residential project in West Hollywood

Domain, a mixed-use development from Trammell Crow Residential, is now complete in West Hollywood. Terra-Petra Waterproofing was called in to provide building waterproofing inspection services prior to final close of project.

Located at 7141 Santa Monica Boulevard, just east of La Brea Avenue, the property features a seven-story building containing 166 apartments atop 9,000 square feet of ground-floor commercial space.  The newly opened mix of studio, one- and two-bedroom apartments.

Architecture firm Studio One Eleven designed Domain, which features a three-story opening along Santa Monica Boulevard.  Building heights gradually step down as the property approaches the lower-scale residential neighborhood to the north, creating space for outdoor decks.  Other amenities are located within a central courtyard, including a swimming pool.

The Use of Electronic Leak Detection (ELD) on Waterproofing Membranes over Concrete Surfaces

Waterproofing membranes are a key element in building enclosure systems—a key element that ultimately gets covered up by a variety of finish materials including landscaping, green roofs, topping slabs, pavers and so on. As most of us know, excavation to expose a failed waterproofing membrane for repairs can be prohibitively expensive and in some cases impossible. For this reason, many designers are choosing to specify integrity testing to verify that the waterproofing membrane is free of discontinuities and penetrations through the membrane prior to the installation being permanently covered. When integrity testing is not specified, many contractors are often performing this type of testing voluntarily to avoid future problems or “call-backs.”

The most common integrity testing method is the flood test. Flood testing is typically performed by flooding waterproofed horizontal surfaces with at least two inches (50 mm) of water for a period of up to 48 hours. Temporary dams are often constructed to partition the test areas, provide an up-turned plaza edge and control the depth of the flood testing. During the flood test, access to the underside of the flooded areas is necessary for a visual inspection of water leakage. However, in the case of a membrane failure (leak), flood testing indicates only where water is penetrating through the entire assembly within the test area, not the location above where water is breaching the membrane. In addition, flood testing cannot be performed on vertical surfaces or at locations where the underside of the slab is not accessible.

The aforementioned restrictions and lack of conclusive data associated with flood testing has enabled Electronic Leak Detection (ELD) to gain momentum as a viable alternative to traditional flood testing. This article will focus on the different types of ELD and the applications where ELD is or is not well-suited.


Terra-Petra ELD information

Detec Systems Training for the Terra-Petra Team

Certified ELD Field Testing Crew, from left to right: Diego Saucedo, Project Coordinator Andrew Alvarran, Anthony Avina, Alvaro Arellano, Director of Field Operations Daniel Valdez and Chad Herrick of Detect Systems.

Certified ELD Field Testing Crew, left to right: Diego Saucedo, Project Coordinator Andrew Alvarran, Anthony Avina, Alvaro Arellano, Director of Field Operations Daniel Valdez and Chad Herrick of Detect Systems.

Detec Systems visited Terra-Petra’s Los Angeles office this week to conduct a comprehensive education and training session to promote their innovative product line of leak detection technologies. Detec provides leading-edge technology in the field of electronic leak detection (ELD), by way of membrane integrity testing and scanning, and automated structure monitoring. The training session included a classroom like session followed by field training on a jobsite.


The Terra-Petra Waterproofing Division is certified to conduct ELD testing throughout Southern California for numerous types of fluid-applied waterproofing and roofing systems in compliance with ASTM 7877-14. This includes any thermoplastic roofing system, any asphalt based waterproofing, traffic coatings, hot and cold fluid applied membranes and some bentonite systems (as long as they have thermoplastic reinforcement).

Terra-Petra employs the use of the Detec Systems Roof Membrane Integrity Scanner (RMIS) to accurately identify breaches in new and existing membrane systems. Many contractors are using a 24-48 hour flood test to check for breaches in these types of waterproofing assemblies. While this method can identify water leaks, it is time consuming and less cost effective. The benefits of the RMIS technology is that breaches and other imperfections can be identified, repaired and re-tested the same day, saving valuable time, resources and money for any project.

Please contact us for a quote.

Terra-Petra Inspector Anthony Avina being trained to perform ELD Testing on vertical surface.

Terra-Petra Inspector Anthony Avina being trained to perform ELD Testing on vertical surface.


ELD Testing at penthouse pool using the Detec RIMS System

ELD Testing at penthouse pool using the Detec RMIS System

See more photos here.

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