Water Is Construction’s Worst Enemy

I have a water phobia. When I was very young I fell into a pool and nearly drowned. Consequently, I never learned to swim out of sheer fear. Despite my attempts to avoid it, water continues to haunt me. (See an article I wrote about my Chicago condo’s construction defects for some background.) It’s ironic I now live along the nation’s southernmost glacial lake. I love the view from our home, but the lake’s recreational opportunities are lost on me.

To further substantiate my negative feelings toward water, 2015 was an especially wet year for the Midwest. In mid-December, my Iowa town received 5 inches of rain in a day and a half. Our basement—where my office is located—flooded (for the second time since August). My husband bought the house (which he planned to make his lifelong bachelor pad) knowing the basement might leak during heavy-rain events. He never planned to have anything down there. Then I came along.

As this issue was coming together—around the same time our basement was soaked—I read a line in “Tech Point” that really resonated with me: “… water is construction’s worst enemy, so when it goes where it shouldn’t, it’s causing damage—seen or unseen.” I shared that line, which was written by Armand T. Christopher Jr., AIA, with my husband. The next week we hired a basement waterproofing contractor to solve our ongoing water problems.

Christopher’s story likely will resonate with you, as well. He and his team had recently installed a PVC roof system on a high-profile government building in central New Jersey. Six months after the install, a three-day nor’easter exposed numerous leaks in the building, which the client thought were coming from the new roof. The ensuing “detective work” Christopher’s team completed was tedious but uncovered the cause of the leaks and made Christopher and his colleagues heroes.

Christopher points out a nice feature of the roof’s thermoplastic cap sheet is areas where water had pooled within the roof system were dried and resealed with heat-welded target patches. Thomas W. Hutchinson, AIA, FRCI, RRC, CSI, RRP, builds upon this idea in his “From the Hutchinson Files” article. Hutchinson notes today’s “new age” roofs may not require removing all system components during reroofing. Instead, it may be in the customer’s best interest to consider restoration; roof-cover removal, enhanced with additional insulation; using the existing roof membrane as a vapor retarder; or membrane removal before installation of a new roof cover.

My husband and I seem to have found the best solution to our basement water problems. Although we’re not looking forward to the construction ahead, we are excited about all the things we can do with a dry basement. Right now, we’re envisioning a mini spa in which we can relax after a stressful workday—another welcome upgrade my husband never imagined for his “bachelor pad”.

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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Stop Leaks Around Vent Pipes

The Perma-Boot is a gasket-less, high-performance pipe boot system designed to permanently repair the most common type of roof leak—the leak around the vent pipes that penetrate the roof.

The Perma-Boot is a gasket-less, high-performance pipe boot system designed to permanently repair the most common type of roof leak—the leak around the vent pipes that penetrate the roof.

The Perma-Boot is a gasket-less, high-performance pipe boot system designed to permanently repair the most common type of roof leak—the leak around the vent pipes that penetrate the roof. Perma-Boot slides over an existing boot, preventing future leaks. Installation takes a few minutes; no tools are required. The product is designed for all standard roof pitches: 3:12 to 12:12. It is made of durable TPO and guaranteed for the life of the shingles.