Under Decking Roofing Concerns

[KennyG]

I have a deck (no roof) over a walkout, similar to this. I put treated wood strips under the joists to lower the mounting surface about 2 inches and installed regular 29 ga. metal roofing under the decking. The deck is Azek composite and the structure is normal treated wood. It has worked very well and was simple to install. There doesn't appear to be significant debris buildup after several years and no moisture issues. I ripped the mounting strips to give me 1/4" per foot slope and there is plenty of open space for air circulation.

 

[AnotherBueller]

Yes, I would but the lower pitch will only help when we had to wash out the acorn hulls the squirrels left us. The lower pitch lets the slower water speed float things out.

 

[forgeblast]

I am looking at doing the same thing, but we are thinking of going with aluminum decking that has the channels built in. Figured it would save the wood and I would not have to stain it ever again.

 

[MGH PA]

Can you share if you were able to resolve the issue? I have a similar problem. I have inherited a house with a deck. I have no idea how my grandparents dealt with it if at all, but our deck has the same issues. We put furniture there, not knowing what was going to happen. We get furniture here outdoor bar furniture because it is affordable and we literally cannot afford any more of the same furniture that has been ruined by a really strong rain that made us realize that we had problems with our deck at all. We wanted to make an outdoor dining area under the deck, but dealing with this is quite the challenge. Please share any progress if at all!

Sorry about the delay. I was waiting for lumber prices to drop and they finally did in late July around here. I essentially built a drop ceiling suspended from the existing joist framing of the deck. Imagine an inverted "T." This gave me the pitch I needed while also maintaining air flow under the deck. We just finished the metal this weekend and got the gutter installed. I still have a lot of trim work to do and I have to close of the ends of the deck. I'm considering venting the front rim joist before I enclose it since I have about a 4.5" drop from the existing rim joists to the top of the gutter. I think if I do this, I should have a pretty well bug/bird proof system with good ventilation.

I haven't been taking many photos, but here's a couple:

You can't see it in the picture, but we flashed above all of the posts to divert the water into the deeper groove about 10" away from the post to help eliminate leaks around there as well.