now the building code for years had a requirement if you had an outdoor requirement, you must put venlation. -- ventilation so that moisture does not >> one of the rules in all waterproofing design is everything leaks. every wall leaks. and you have to put in a weed to put the water out. if you do something like this, you're going to trap the water because you let the water in are the top and you don't let the water out. so the cardinal rule, you always allow a weep to allow the water to escape. >> what do you mean by a weep? >> a hole or a track with preforracings to allow things to breathe. -- preforations to allow things to breathe. >> so what are the normal places that you would look for failure in this kind of a deck? >> for myself, typically the underside of the surface, the plywood on the bottom. where the post attach. anywhere there's an attachment with two pieces of wood and it's not concealed, water's going to get attached there. and the surface. i'm assuming this is some sort of a deck coding of walk-on surface. we look at that to make sure it's not worn. >> here's your -- that's