Post Number: 9
|Posted on Friday, June 27, 2008 - 12:14 pm: ||
Walter- Thanks! Looked for your contact info first- you're referring to the slate edge in a valley damage to copper? Is it erosion/corrosion, erosion and corrosion or ? ; erosion being an abrasive or mechanical process ? Yes, I was aware of copper being unfavorably soft in some applications and especially in a particulate environment w/ acid rain- sometimes so destructive by abrasion that painting the copper seemed like a great and immediate idea to retard replacement- I've been concerned/cautious about broaching this topic in light of the general good favor copper seems to have- high-quality, maintained galv. steel has struck me as a competetive material if one was going to have to paint anyhow- some choices of s/s don't hold paint well? or I'd spend my money up front on it- painting in this result being for appearance as s/s is a bit bold and untraditional looking
Post Number: 89
|Posted on Wednesday, June 25, 2008 - 03:43 pm: ||
the CDA refers to it as "erosion corrosion "
Post Number: 8
|Posted on Wednesday, June 25, 2008 - 11:24 am: ||
Kurtis- we hear you, amen .. copper does have a coefficient that's perilous to ignore. As an adjunct, I observed copper performance in valleys such that I'd much prefer cold-rolled, tempered copper sheet(10 ft max?) that's brake-bent and fastened to allow for movement w/ only the scarce minimum of slates being nailed through it. I've seen a few valleys done with soft roll copper that often ran the whole length, were not brake-bent but apparently "formed" on the roofdeck and were subject to ripping width-wise at certain wrinkle points from repeated thermal effects of stretch and shrink. These effects seemed to be multiplied by the extreme length of the copper- I imagined that the cold-roll would do better, if similarly treated, for its linear, tempered integrity, and its reduced length(joint-like form). The soft-roll looked like 2nd-hand aluminum foil from the start. Electrolysis science might further advise to felt w/ strips between the slate layer and the metal for a crude but reasonable attempt at isolation- maybe more so for galvanized than s/s or copper(I think copper appreciates it in the long haul, too- ever seen copper rotted out right at the valley edge?) It's that "dang" acid rain, don't you know?
Post Number: 57
|Posted on Wednesday, June 25, 2008 - 01:18 am: ||
I know it's been said over and over, but I'm tired of seeing homeowners who paid someone good money to do copper box gutters, only to have it re-done 20 or 30 years later if they're lucky.
Please please please remember to follow the SMCA or CDA guidelines. They write those specs for a reason. Rivets or lock seams and expansion joints are crucial! If your leave them out your work will fail.
If you claim you've done them for 30 years without that stuff and it's never failed, you are lucky. But that doesn't reverse consensus of the peer-reviewed engineering community who wrote the specs for the SMCA and CDA guides. I'll side with their findings thanks. I've also heard old-timer argue that they never used them with terne gutters, but that theory is shot because terne has a different expansion factor than copper, and most of the terne gutters where installed in 18" sections with lock-seams. The multiple seams would help to relive some tension much like a flat-lock roof. 10' long pans in 16 or 20 ounce copper are a much different animal than terneplate.
Sorry for the rant, hopefully this will help someone.
If you are a homeowner commissioning box gutter work, make sure the contractor is following these guidelines or you are throwing your money away.
Everyone stay safe of the roofs, and keep cool this summer!