Hey, all you roofers! I was asked to put a corrugated Lexan roof over an existing plastic lattice roof on a lanai. The roof has on 1/4″ slope per 10′ that I warned the HO about before it was built. I told him the Lexan panels would probably leak due to no slope, but he insisted. So, after the first leaks were found to be occurring in the overlapping seams, I went back and put in a silicon based roofing caulk between the panels at the overlap. The leaking has come back after a year, I think that the individual panels expand and contract too much when the clouds pass over. You can hear the movement all day long. I went over during a heavy rain recently and saw that water was coming through the valleys of each panel, so we (the HO) and I decided to try screwing the valleys also with a new type of caulk. Are there any very flexible caulks or other materials that may work between the Lexan panels?
Thomas Jefferson
3rd president of US (1743 – 1826)
Replies
Tell the HO the panels aren't going to work. Go order white steel panels, they are hard to get and will take a little time to come in.
Then replace them, hook them up so rain water is collected by his cistern.
All that caulk and junk can't be good for his water storage. I would show him the warnings on the side of the tubes of caulk that say not to be taken internally.
Woods favorite carpenter
The pitch is the problem, not the material. Steel won't perform a bit better at that low pitch
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Material is part of the problem, he is posting about being able to hear the panels move.
Steel is more rigid and stable than what he posted, Lexan I believe.
Don't they make a foam tape that goes between the sheets where they overlap?
Steel is commonly used in his area for water recollection into cisterns. That much I know, never heard of Lexan being used.
I wouldn't want all that caulking and what not if this is tied into my recollection system.
Woods favorite carpenter
Edited 12/29/2007 10:13 pm ET by MattSwanger
Butyl caulk or tape is what we used to use. It is like chewing gum only worse - to get off of something - and it is not clear. geocel was developed to replace butyl.Steel has a higher rate of thermal movement than Lexan does. If he can hear clear Lexan move, then steel will drive him batty!!!I'm going to assume that any water he is drinking off the roof is being treated and filtered anyways, but I can't vouch for the toxicity long term of butyl or Geocel, but most caulks danger stuff is only in the VOCs and stuff that off-gasses in the first few weeks. Lexan itself is used for the shelves, drawers, and liners of refrigerators and freezers so if it is a toxic problem we are all in trouble.
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I have never heard of Lexan being used as roofing in Hawaii, only things I have heard was the wide spread use of steel. And I haven't heard any issues with that moving on the big island from my uncle that lives there now.
I guess I am making some assumptions without any feedback fromt he OP. It may not be tied into a cistern and once again I am talking about something that doesn't matter.
Is Lexan an Geocel compatable? Having never worked with Lexan I wouldn't know the answer to that.
And it was Butyl tape we used to use, that stuff was a bear to work with. Made for a tight overlap though.
Woods favorite carpenter
I've used Geocel on a polycarbonate that is a step down from Lexan, and on some sort of polyvinyl stuff. Also with vinyl cladding on windows and with cellular PVC.It sticks to all of the above well and I've never seen it cause any deterioration."it was Butyl tape we used to use, that stuff was a bear to work with."LOL, I haven't ever heard anyone say they just love to play with butyl;)
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I keep trying to picture what this Lexan panel looks like.
All I keep seeing in my mind is that translucent fiberglass barn siding. Used just under the eaves for cheap day light in the barn.
Woods favorite carpenter
These panels are called Suntuff, and are now carried by Cheapo Depot. They look the same as corrugated steel roofing and are just a little thicker. The lack of slope is the culprit, but the expansion and contraction of the panels is what caused the first caulk to fail. The Geocel sounds like the way to go. These panels are unbreakable and are very clear to look through, so what you get is light, with no UV, (90% filtered) almost no weight, and with proper slope, no water intrusion. I have had them on my lanai roof for 10 years with regular winds of 50+ and gusts once to 92 mph. Not a problem. I have also bent one completely back on itself as a test and then just kicked it back out, left no mark or crease, really impressive. Was carried by a local guy for awhile, then came Cheapo Depot and they picked up on it, now he does not sell it anymore. They are about $37 for a 24" x 12' panel and come in colors: bronze, clear, green. Anyway, I'll try a tube of the Geocel on one area next week and set a hose sprinkler up there and see what it does. No H20 collection involved.
Mahalo and a Hau 'ole makahiki hou to everyone!Never fear the want of business. A man who qualifies himself well for his calling, never fails of employment.
Thomas Jefferson
3rd president of US (1743 - 1826)
Edited 12/29/2007 11:13 pm by Hoohuli
That description is what I found in my google search.
Looks like a great product. Especially in a Lanai situation.
I was picturing something very different, thats why I suggested steel.
Woods favorite carpenter
"Mahalo and a Hau 'ole makahiki hou to everyone!Never fear the want of business. A man who qualifies himself well for his calling, never fails of employment.
Thomas Jefferson
3rd president of US (1743 - 1826) "I didn't realize Jefferson spoke the hooli-hooli language!;)
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Jefferson also didn't have to type out his responses and hit return!Never fear the want of business. A man who qualifies himself well for his calling, never fails of employment.
Thomas Jefferson
3rd president of US (1743 - 1826)
He said corrugated, so it probably is shaped about like that.Lexan is tough and can be formed in any shape you want it.A lot of those signs that have lights inside them are made of Lexan also - you see hundreds of them when you drive the interstate. It can really take a lot of temperature change is the reason why. Holds its shape well from triple digit temperatures down to way below zero without becoming pliable nor brittle.
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Silicone is definitely not good for this sort of application.
I like Geocel if it is available out there. It sticks to about anything clean and gives about 800% plasticity. I did an addition to a house that I had built after about three years and had to remove window trim i had caulked in place with Geocel. I was blown away by what I saw. I had to cut it with the utility knife and any place that had stringer still stuck stretched like a rubber band when I pulled things apart.
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I just did a quick google search and I think I was picturing an entirely different product than what you are talking about.
Find out if Geocel is compatable with it because it is a good material to use.
Whether or not it's tied into a cistern would be my only other concern.
Woods favorite carpenter
Big Stretch also really holds like Piffen said regard Geocel.
I live in the mountains of California 6000 ft elev. and have used Big Stretch almost exclusively. Weathers great; and have to cut it also if need to remodel etc.
That one isn't easy for me to get, but I have sampled it. I agree it should do the job too. Matter of fact, I had it in the back of my mind as I first responded, but was not sure if it comes in a clear or not.
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