flashing problem, rotting under deck


  #1  
Old 07-06-22, 07:58 PM
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Question flashing problem, rotting under deck

Found some damage under my deck (this is against the garage wall). I want to make sure I donít need to do this again in 20 years. The t-11 didnít get much sun, so it looks nice, and I hadnít gone under here to check further in many years. The messed up wide cement frost wall (forms split during the pour) makes this weird to flash, and obviously the water wicked back up. Thereís about 20í of this T-1 under here, above the ledgerboard is vinyl. I believe there will be celotex foam behind this, but it might be plywood or a combination. Could anyone advise how to flash this right, and what material would work better down here?

thank you for any advice!

G






 
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Old 07-06-22, 08:17 PM
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You probably want to cut that siding out about 6" high.... slip a z flashing behind it and put a pvc 1x6 along the bottom. Won't rot again.

Here is an illustration to give you the idea. (Except you don't have clapboard siding.)


image credit: building advisor dot com.

One other problem you might have... that aluminum flashing on the very bottom of your photo looks like crap and is probably not doing what it's supposed to do. I'd remove it and replace it, but this time run a heavy bead of sealant (Like Loctite S10) under it so that no water can ever run back underneath that flashing.
 
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Old 07-07-22, 07:44 AM
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Thanks. Yeah, the flashing is not angled enough and the water isn’t running off the cement. I’m thinking the siding should be shorter and new flashing be angled and maybe run all the way to the edge. ? I’m unsure how to do that and still have things sealed from critters. It seems like everything being tightly fit down here was more of a problem than a help. I think I’ll have to rip out all the T-11 and starting over because it’s really hard to work under here. The t11 is only 18” tall, and was installed before the deck went up. Is there some kind of vinyl planking or maybe composite board that would be better to use? I appreciate your help.
 
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Old 07-07-22, 10:47 AM
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I don't think i can improve on what I already said.

Tearing it all out will open a can of worms you didn't count on. They hosed you by putting those posts in front of the siding so you will have a nightmare if you tear it out.
 
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Old 07-07-22, 01:00 PM
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Actually, the siding was pieced to fit after the ledger board and deck posts were attached to the wall. I was just really good with a jigsaw back then.
 
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Old 07-07-22, 01:08 PM
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I see... if you never want to mess with it again, the best thing to use would be a 4x8x3/8" sheet of Azek, cut to fit.
 
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Old 07-07-22, 01:09 PM
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This is whatís behind there. The T11 was along the left after the deck supports were up. Looking back I realize I shouldíve flashed it differently and used rot-proof siding.


 
  #8  
Old 07-09-22, 07:33 AM
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I found a roll of aluminum flashing in my shed, but I don’t have a brake to bend it. Is there a cheap way to bend it without it being too ugly? It’s wide enough that I could get over the cement curb. Would cutting a 1” strip of pvc board and putting it down first with sealant, then flashing angled down, then siding above that make sense?
 
 

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