Vicor deck flashing or similar, is just for this type of situation. For extra protection, you could use sheet metal flashing, bent for each joist combination.

Mark

I'm wondering if your fears concerning future repairs are unfounded. I'm not a builder, but to replace a rotted joist, you'd just need to cut it off at the house, and depending on whether you're replacing all the deck joists or just one or two, you'd add blocking or an entire rim joist and a ledger and hang new deck joists off the ledger. You'd need to add posts outside to support the other end of the joist: I'm assuming that now the joists are cantelievered. So, should your deck joists become unsafe someday, you might consult with a builder for the best solution before tearing up floors inside the house.

Bill

Some very good thoughts Bill. If a person uses .40 acq lumber any " protection " is not needed, its already been installed by the Treater.

Using any of the target/market products on line now is a waste of time and money and will probley work in the Neg. for a lot of reasons. J.

Sometimes an attempt to keep water out only serves to trap it in. Water may eventually get under the material, through nail holes for example and then sit, unable to evaporate. There was an article in Fine Homebuilding last month, volume 196, "Smater Deck Framing" and it didn't mention capping joists, though the builders did use an "isolation membrane", self sealing flashing tape from Grace called Deck Protector, to isolate any joist hangers from wood. This is because they're afraid any treatment product, (ACQ), will speed corrosion of the metal in the joist hangers. The material was just wrapped around the ends of the joists where they sit in the hangers.

Seems to me if you use anything to cap a joist it should be something like this "Self-sealing" product. Just a guess.

That is what the Vikor is. It is a self sticking, self sealing membrane, from Grace. Others make similar products.

The only question that I have is their UV protection. Light passes between the deck boards and can fall on the membrane. Some of these membranes will fail if exposed to direct sunlight for any length of time.

For the most part, we only use it for the tops of sandwiched joists or occaisionally as a isolation membrane if we can't find the correct finished hardware.

Mark

Imus Cap is a deck joist cap made of bonderized metal with a butyl rubber waterproof tape sealant. It is easy to install, can be painted to match the decking color, and will keep water away from rotting deck joists.