I'm rebuilding my rear deck and intend to screen in part of it. I am going to put screen wire under the screened in portion to keep out bugs. Will fiberglass screen work under those deck boards, or should I use aluminum?

I have used both but there are pro's and cons. Dirt and "stuff" gets caught in the cracks and is hard to get out. Aluminum is, or can be, a one man job since it is more ridged and can be pushed in place and then stapled. Fiberglass is harder to install since it is so flexible. Last one I did was fiberglass and was a 2 man job. Are you going to staple to joist or floor?

My plan is to staple the beginning of the run, and then pull it tight over the joists and staple the other end using four foot wide rolls. I'll then just put the boards over the top and screw them down. My only concern about fiberglass is durability.

What is the Difference Between Aluminum and Fiberglass Window Screens?

Difference Between Aluminum and Fiberglass Window Screens

Fiberglass is generally less expensive as compared to aluminum. It also does not dent when pushed or hit. Fiberglass however, is somehow darker than the aluminum mesh, this means that it gives it a darker external appearance and therefore reduces the amount of light getting into the room. Another disadvantage of fiberglass over aluminum is that it tends to degrade with time due to long exposure to UV light. This quality also makes it break and fray easily and hence does not last as long as aluminum. Fiberglass screens are sold in 100 foot rolls of varying widths ranging from 18 to 120 inches. Aluminum screens are also purchased in 100 foot rolls; however, the range available is limited as compared to fiberglass, according to Wire Screen.
As evidenced in the difference between aluminum and fiberglass window screens, both make good options it all depends on personal preferences.
Related Resource: Different Types of Window Screens

Window Screen Mesh Types Explained - Quality Windows Screens - Quality Screen Co, LLC (LP)

What kind of bugs do you have in your region? We have gnats and they lay eggs on screens and reek havoc when they hatch INSIDE the screen.

Got pets?

Screen doors and screen repair - you've found the source

Not trying to complicate your project, there's just a lot of stuff out there.

Mainly concerned about flying insects such as mosquitoes, or things like ants, spiders, etc. Doing this proect for wife, and she is not a fan of bugs. With the screen under the decking, I don't think UV would be a consideration. Now when we screen in the porch, then that is a different story.

My front deck is completely screened in and we don't have any screen under the decking. We have essentially no bugs, I honestly don't think bugs are smart enough to come up the floor. We get more from the kids holding the door open for too long. If bugs do get in that way, its so few and far between they're easy to manage. I live in the mosquito capital of the world too btw. The dirt and crap that will build up on that screen, to me, is worse than the odd mosquito getting in.

EDIT: My bad for resurrecting an ancient question!! Haven't been in here in a while and hadn't noticed.

No problem. Thanks for your input. I finished the deck about a year ago. So far so good. I did put the screen under the deck. It turned out to be fairly simple to do so it was no big deal. I used fiberglass. What was really surprising was how easy it was to screen in the deck openings.