Decks, Patios, Porches and Docks - Waterproofing under a 2nd story deck

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07-23-00, 05:10 PM
I plan to build a 2nd story deck over an enclosed porch. What's the best way to water proof the porch under the deck?


08-14-00, 10:03 AM
I have been trying to figure this out for 8 years! The guy who built my upper deck skipped town, and it began to leak like crazy. It is 16' x 36' and we have tried everything to keep it from leaking, but it eventually fails. Kote-deck was our last choice, but the heat ended up cracking it. Please let me know if you find an answer-
Thanks,
jwmgs@flash.net

08-14-00, 02:03 PM
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by jwmgs@flash.net:
I have been trying to figure this out for 8 years! The guy who built my upper deck skipped town, and it began to leak like crazy. It is 16' x 36' and we have tried everything to keep it from leaking, but it eventually fails. Kote-deck was our last choice, but the heat ended up cracking it. Please let me know if you find an answer-
Thanks,
jwmgs@flash.net
<HR></BLOCKQUOTE>

To date I have not. What infor I have obtained from publications and/or people who "think" they know, is that when building such a deck, one must create a waterproof layer (e.g. a plywood surface covered or coated with some kind of sealing layer) first, then lay stringers in the top of that (waterproofed with sealant), followed by the deck surface attached to the stringers. I think this would be a very difficult 'retrofit' to an existing deck.


08-14-00, 06:55 PM
Hi Guys!
I built a second-floor "waterproof" deck over my boathouse when I built it 1995 here on the Albemarle Sound in Northeastern NC. We custom-designed this thing, and built it up in stages. First, after installing the boatlift, I built-in a corrugated aluminum roofing layer over it just like you do any metal roof (screwed roofing sheets to 1 X 4" p-t boards), only I sealed (silicone) the overlapping edges because the angle only dropped about 4" over 12' width. You can custom order extruded aluminum roofing to any length that you want to the inch. I ran the ends of the roofing out through one side of the boathouse for drainage. Built a deck (w/joist hangers, 2X6's, and 5/4 decking) over it. Keeps my pontoon boat bone dry from above (of course, it gets a little damp through the open end of the boathouse when we have a little blow like Fran, but hey). I think that you could build a similar sealed roofing structure, even with plastic roofing, and raise it up and bolt it place under an existing second-floor deck. Works for me. Good Luck!

08-14-00, 09:06 PM
This is something that has to be designed from the beginning, and done from the bottom up. One key is to install a roof that will require no maintanence. We have done it using Weatherbreaker II roof panels (4' wide and available in lengths up to 30' that lock together and seal) for the porch roof. Over that, install the deck. However, you don't want to project too far from the house. Whatever you use for joists has to be able to free span over the roof, and any joist that can freespan over 10 feet or so will get pretty pricey.