Locating the Source of Water Intrusion Can Be Tricky

The building in question features one whole face that is an aluminum-framed glass curtainwall. The curtainwall extends up above the roof lines, slopes up (from the vertical) forming a peaked skylight, which then slopes back toward the roofs that were holding water.

The building in question features one whole face that is an aluminum-framed glass curtainwall. The curtainwall extends up above the roof lines, slopes up (from the vertical) forming a peaked skylight, which then slopes back toward the roofs that were holding water.

As architects/roof consultants, there is nothing we hate more than to get a call from a client who says, “My new roof is leaking.” Yet, that is exactly what happened to us not long ago. My firm had put a new thermoplastic PVC roof system on a high-profile government building in central New Jersey. The owner was my long-time client, and I ran the project, so I was intimately familiar with it and utterly shocked to get this call about six months after the project was completed. We had just experienced a three-day nor’easter that began on Thursday night and ran straight through to Monday morning when the client arrived at the building to find numerous leaking areas.

I responded by immediately going to the building. I was accompanied by the roofing system manufacturer. As the client led us around the building, water was dripping through suspended ceilings all over, which gave us the sinking (almost apocalyptic) feeling you hope to never know. However, when we went up to examine the roof, much to our surprise, there was no blow off; no seams torn; in fact, no apparent defects at all. Our thermoplastic cap sheet looked perfect on the surface.

On the upper roof, aluminum-framed sawtoothed skylights were dripping water when the team first arrived. This gave the only clue to where the “smoking gun” may lie.

On the upper roof, aluminum-framed sawtoothed skylights were dripping water when the team first arrived. This gave the only clue to where the “smoking gun” may lie.

What we did find, however, was large amounts of water trapped between this cap sheet and the 90-mil bituminous base sheet underneath. This was creating large water-filled blisters on the roof that looked like an old waterbed as you walked up to and around them. No matter how hard we looked we just couldn’t find defects in the membrane surface or at any of the flashing connections or terminations that could be causing this. There was, however, a likely suspect looming adjacent to and above our roofs. The building experiencing the roof leaks has one whole face that is an aluminum-framed glass curtainwall. It extends up above the roof lines, slopes up (from the vertical) forming a peaked skylight, which then slopes back toward these roofs that were holding water. On the upper roof, sawtoothed skylights of the same construction were dripping water when we first arrived. This gave the only clue to where the “smoking gun” may lie.

METHODOLOGY

Water was dripping from the saw- toothed skylights into a planter in the 4-story atrium. The client said that was typical with all hard rains. Armed with this clue, and no other apparent explanation for such a large amount of water intrusion, the owner engaged us to find out what indeed was the root cause of this problem.

On the upper roof, aluminum-framed sawtoothed skylights were dripping water when the team first arrived. This gave the only clue to where the “smoking gun” may lie.

On the upper roof, aluminum-framed sawtoothed skylights were dripping water when the team first arrived. This gave the only clue to where the “smoking gun” may lie.

In a couple days, the dripping subsided and most of the water blisters had dissipated or at least were reduced and stabilized. In the interim, I assembled a team consisting of a roofing restoration contractor (this is not a rip and tear production contractor but one especially geared to finding problems and making associated repairs), skylight restoration contractor and testing agency capable of building spray racks onsite to deliver water wherever it’s needed. With this team, I embarked on a systematic investigation that would make any “detective” proud.

First, we plugged the roof drains and let water pool on the roof until the en- tire surface was wet. Meanwhile, “spot-ters” inside the building were looking for any sign of water intrusion using lights above the dropped ceilings. When this showed nothing, we began constructing spray racks and running water for set intervals on every adjacent surface rising above and surrounding the lowest roof in question. We first sprayed the exposed base flashings, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Then we would move laterally to a new position and start again.

The team first sprayed the exposed base flashings with water, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Testing moved laterally to a new position before starting again.

The team first sprayed the exposed base flashings with water, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Testing moved laterally to a new position before starting again.

This proved painstakingly tedious, but we knew that making the building leak was not enough; we had to move slowly and systematically to be able to isolate the location to determine what exactly was leaking and why. It is important when applying water this way to start low and only after a set period move upward, so when water does evidence itself as a leak, you know from what elevation it came.

After an entire day of spraying the rising walls surrounding the first (low) roof area, we could not replicate a leak. Somewhat frustrated—and rapidly burning the testing budget—we began the second day focusing on the adjacent peaked skylight, which is more than 75- feet long.

The team first sprayed the exposed base flashings with water, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Testing moved laterally to a new position before starting again.

The team first sprayed the exposed base flashings with water, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Testing moved laterally to a new position before starting again.

Again, we started low, where our base flashing tied into the knee-wall at the base of the skylight, below the aluminum-framed sill. Still no leaks. Late in the day, when we were finally up to the glass level, we sprayed water from the ridge and let it run right down the glass onto our roof below. Finally, we found some leaking occurring at a skylight flashing to wall connection. OK, that was reasonable to anticipate and easy to correct.

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The Success of Your New (Replacement) Roof Depends on Adjacent and Connected Elements, including Masonry

Although the name of this publication is Roofing, the roofing/waterproofing/construction industry recognizes more and more that the building envelope is a fully integrated and interrelated assembly of systems.

masonry cracks due to freeze thaw

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As such, I feel the need to discuss the importance of water resistance and structural integrity in existing wall surfaces, which are adjacent and connected to your project’s new (replacement) roof system. The focus of this article is not how to design a replacement roof system but how to address adjacent masonry to ensure it doesn’t work against the success of the new roof.

These principles actually apply to any wall system that connects, generally above and adjacent, to your roof, but masonry poses some distinct concerns. Water intrusion, thermal movement and structural integrity of this masonry, along with locations of embedded flashing, all come into play as the new roof system is properly integrated into the adjacent rising wall, parapet wall or even perimeter edge wall beneath the roof.

COMMON MASONRY ISSUES

Thomas W. Hutchinson, AIA, FRCI, RRC, a regular Roofing contributor, has said, “long-term service life is the true essence of sustainability”. Moreover, designers specify (for owners to buy) warranties of 20, 25 years or more with new roof systems. It’s just good common sense that you can’t allow a new roof to be jeopardized by water intrusion from an adjacent system because of an oversight in the original analysis of the situation.

Many of us have been called by an owner who says his or her new roof is leaking, only to find roof-mounted equipment or an unrelated system is actually leaking. However, if the leak is stemming from another aspect of the building envelope, such as an adjacent parapet or rising wall, which is now jeopardizing the investment made on a new roof, that you (the designer) should have foreseen, it makes for a very difficult position. The roofing system manufacturer, who holds the warranty, and the owner are going to look at you as being responsible.

masonry

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Let’s examine three common occurrences using actual case studies. All three situations, which occurred on schools in the Northeast, exemplify the condition of adjacent masonry was deficient and had to be corrected, adding a significant degree of scope and cost to the project to guarantee a roof design that would perform over the long haul. These three cases cover:
1. Repairing the masonry and covering it.
2. Altering the masonry to change the location of embedded flashings.
3. Replacing structurally unsound/failed masonry with another material.

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System Combines Flashing and Counterflashing

FlashCo's FlashCap System

FlashCo’s FlashCap System

FlashCap’s innovative design and easy one-minute installation provides contractors with a fast, high-quality option for flashings. The FlashCap System from FlashCo combines the flashing and counterflashing, completely sealing the penetration without compromising the integrity of the protrusion. With FlashCap, venting capacity is maximized while the pipe and flashing are allowed to naturally expand and contract.

The purpose of the prefabricated part is to save the contractor field fabrication and installation time and provide a quality part fabricated in a controlled factory environment. The FlashCap system eliminates the need for a hose clamp and caulking. Compared to the universal boots in the market, FlashCap does not need to be cut down to fit the penetration. The FlashCap system is made to size and is customizable for a snug and secure fit. When utilizing FlashCap the seal is complete and simply needs to be heat welded to be secure. The FlashCap is available in TPO, PVC and lead.

The mission of FlashCo is to save the roofing contractor time and money by providing quality products that are easy to install.