David A. Bandel
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The contents of this site are original material (copyleft) from the deranged mind of David A. Bandel -- all rights (and lefts) reserved. If you are as of unsound mind as I am and actually want to quote anything here, be my guest, but I would appreciate attribution (a link back to the original text would be even better). Thanx for your support.
The Panamanian firm Hopsa is using our house to promote a product they call "TejaGala". They have been doing so without our approval, in fact, we talked to the folks at Hopsa in David and demanded they stop using our house for their advertising (first appeared in La Prensa "Compras" section 15 Dec 2010). They haven't. Don't know why. But they need to pay us, either in cash or, preferably, with a new, properly installed roof. (How do I know the house was ours when the photo was taken? Because the day after we signed for the house, I installed the lights on the columns out front.)
The problem with the roof is that it leaks like a seive. They should have called it TejaMala or TejaLeak. And while they didn't install it, contractors for Constructora Tia Maria, did, they have been aware of problems with the installation of this roof for many months, and the have allowed the poor installations to continue on new Tia Maria constructions. Personally, because of this knowledge and their lackadaisical attitude about it, I consider the problem at least 50% theirs.
After buying our new house and finding out we had a problem with the roof leaking, we of course complained to the builder, Constructora Tia Maria, who guarantees their construction. They have sent their contractor out here several times trying to fix the roof. They have glued, screwed, riveted, and painted. In fact, the roof now looks like a complete disaster. Between untrained contractors, and even more clueless "engineers" (I find the more these so-called engineers insist on being addressed as engineer, the more clueless they are), no one can figure out why the roofs leak so badly -- read on for the answers.
So I went down to Hopsa, David, and asked about their roof TejaGala. A very nice salesgirl talked to me and even offered to get me trained on the installation. I asked if she just had an installation manual. She asked me to wait and printed out the slideshow they use to train installers. The slide show is written so even complete morons can understand exactly how to properly install the roof. (Assuming complete morons can read their own language.)
As I read through the slides, I came to one that was _very_ simple and just as explicit. You use two-inch screws pushed to one side of the bottom of the wave. Another slide showed that the wave was two inches high. I questioned the girl about the placement of the screw and she insisted this was correct. (Scan of their slide).
I've looked at length at the sheets of TejaGala installed on my house and have determined exactly why we have water pouring in the house. If installed per Hopsa's instructions, the roof would seal hermetically. No water would ever be able to penetrate. It is a good design. The screws would only penetrate one sheet (ever), and would be held down to the carriola with no space between the carriola and the sheet or (more importantly) between overlapping sheets. Solid contact -- no leaking, no deformation of the sheets.
Now to explain what happens when the manufacturer's instructions are not followed. Imagine you have two perfectly round half tubes (like a can cut in two). But these two cans are designed so that one slips perfectly into the other i.e., one is slightly larger than the other.
Remember I told you that following the manufacturer's instructions, no screw would penetrate two sheets of zinc at a time? This is not the case if you install the screws in the top of the wave. The two sheets overlap by 2/3 of a wave. That is, these two perfectly formed waves mate precisely allowing no light, water, bugs, or anything else to enter when not deformed by untrained installers.
But the contractors for all the houses built to date don't follow the manufacturers instructions. They are forcing three-inch (not two-inch) screws into the top of the wave. In order to quickly penetrate these two sheets, workers push down _hard_ on the drill-point screws. This force deforms the waves downward. The sheets slide against each other. As the screw pops through one, then later (with continued force) the next, the holes don't allow the sheets to relax back up to their original position because if you removed the screw you'd see the screwholes are displaced side to side. The workers now have to torque the sheets down hard further deforming the overlap to force the sheets back together and making the overlap look horrible, as well as flattening the previously round wave. But the flattening out of the wave is only part of what allows gallons of water to stream in during torrential rains.
What happens next is the workers move up the slanted roof to install the next screw. Imagine the above scenario all over again, but this time, the workers don't take the time to ensure the screw is entering the zinc at an exact 90 angle to the sheets. What happens is that both sheets deform down again. The screw pops through the top sheet, which starts to ride up the screw. More pushing down to get the screw to penetrate the second sheet which is separated from the first by as much as an inch or more. And because the drill hasn't been held at exactly 90 degrees to the slope of the the roof, when the second hole is punched through, the two holes don't line up perfectly. The distance from the first screw to the two just-made screw holes is different for each one -- perhaps as little as half the width of the screw.
Some of you may now begin to see what will happen. The installer continues pushing the screw through the cariolla and has to use a good amount of torque to bring the two sheets together again. Forgetting the defomed wave, think only of the very small offset between the two new holes and the first hole. The holes in the top sheet are just a few millimeters off from the holes in the bottom sheet as measured from the first screwhole. By torqueing them down, the installer is forcing the two sheets together and also the two offset screwholes. But as the sheets are made of zinc and don't either stretch or shrink, something has to give.
At this point, I'd like to direct your attention to a wooden yardstick. If this is lain on a counter, one end is held firmly in place by the palm of your hand, and the other end is moved ever so slightly in the direction of the first end, you'll see a seemingly large loop form in the center of the yardstick. Any real engineer can tell you that you will get a lot of bow in the yardstick with only a little bit of initial movement. But zinc isn't a wooden yardstick. However, it will bow. And so with a very small offset between the holes in the second screw, we wind up with a gaping maw opening between the two sheets as the longer sheet moves rapidly away from the shorter sheet (the sheet measured as the distance between the holes in each sheet). And that's where the water comes pouring in. Perhaps you can also identify at least 5 areas in my neighbor's roof where water will pour onto his gypsum ceiling?
Note: it is _impossible_ to create this gaping maw when the manufacturer's instructions are followed. Water only pours into a house through TejaGala when it is installed by untrained installers. Does Hopsa know this? If they don't they should. They supposedly designed the roof and definitely wrote the installation manual. They should insist that a roof this difficult to install properly (despite the "easy to install" claims in their ad) be installed only by installers trained by them. And while they offer this training, they hide when confronted about issues with their roof insisting they only sell "materia prima" (new materials).
The local vendor came out to my house with an engineer from Tia Maria. When I confronted him with the installation manual and the improper installation and crushed waves, he said all was OK, using three-inch screws on the upper part of the wave as "an approved alternate installation method". The salesman also claimed to be a certified engineer. Saying this in front of the Tia Maria engineer is tantamount to him certifying, as a Hopsa representative, that they could keep installing the roofs improperly.
We are insisting Tia Maria remove and install the roof properly (of course using new materials now that these are so full of holes). I doubt this will happen out of good will, it will likely take a lawsuit. Either way, there's a good chance any number of folks with leaky houses will demand the same. But it's what they get for going with the cheapest, most poorly trained labor on the market. If I were the builder, I'd be looking at Hopsa and demanding they foot at least half the bill. Hopsa should have known and pointed out the problem from the beginning. Their David agency has been well aware of this for many months now.
David-TejaGala -- a horror story
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