Do indoor / outdoor carpets rot wood decks?

A combination of wet wood and carpet over the wood is a double whammy. With the arrangement, nature gets involved -- wood that is at 20% or higher moisture levels is susceptible to rot. And, at least in this wet maritime climate, the question is not"whether" the wood will rot, the question is simply "when" will rot occur in this wood that stays wet almost all of the time.

It is my suggestion, when building decks, that structural components such as posts, joists, beams and ledgers (where possible) should consist of pressure-treated lumber. And the decking, especially wood boards, should be installed with rain gaps or spaces between the planks -- so rain does not collect on the surface. Of course, carpeting should not be tacked over the wood, doing so defeats the purpose of the rain gaps and leads to rot.

Some can. I used a AstroTurf remnant on my last deck...when it wore out I painted the deck.

I wouldn't glue a carpet down. You don't want anything that will hold the moisture there. I'd suggest removing them in winter and picking them up after wet weather so the wood can dry.

We have a screen in porch .it has a wooden deck boards .sit on a hill does rain in .went to home depot bought a piece of carpet .they even cut the size I needed .my boards are spaced rain has not hurt my boards .the carpet is the kind they use on boats . Dry easy .we used staples in corners .furniture sits in middle .I love it makes my porch looks so much brighter .Good luck .

The turf won't cause rot, however if it is not properly sealed to the deck water may seep underneath and cause rot.

It shouldn't. Not if the wood is treated with a sealer first.

Anything that holds moisture will cause breakdown. Even if the deck is "finished wood", in time there will be an opening which will let in moisture. Sealers are great, but deck boards are rarely as polished as a piece of furniture.

providing the deck is properly sealed no it will not rot the deck