Can I make Fire + Wood Deck = Safe?

Essentially the procedure is the same as if you were putting a woodstove inside a house. You want a fire resistant surface below, extending at least 18 inches out as Marell said. I would lay down a piece of sheet metal underneath those pavers, just for insurance. And, all around the pit or chimenea, keep a clearance of at least 36 inches to the nearest combustible surface in all other directions. Don't overdo it, no roaring fires. Burn seasoned hardwood only so as to minimize sparks. Put the fire to bed properly.

Put some concrete pavers or bricks under it and for 18 inches out all the way around. I saw a chimenea burn through a deck once, no fun.

Since the deck hasn't been built yet, could you incorporate fire-pit-accommodating materials into the part of the deck where the pit will go? Like, that section would have space to set bricks or similar so that they're flush with the deck, with an adequate margin for stray embers or small coals to fall on.

Not sure why I didn't think to contact customer service on some of these places. Duh! I'm going with a gas table. It's made by a subsidiary of Blue Rhino, and I e-mailed them and got a very quick response, which was it should be fine - it's just like using a gas BBQ on the deck anyway (another point I somehow never considered) - but they do recommend keeping it 10 feet from any structures. I'm assuming that's a cover-their-ass kind of statement, and as long as I'm sensible and take obvious precautions (including having an extinguisher at the ready) I'll be fine. It got really good reviews so I'm hoping it rivals a nice wood fire. Thanks for the comments!

Just last week we took our wood burning fire pit over to my parents' house and used it on their (very old) wooden deck. We simply set it on top of a piece of concrete backer board (like what you put underneath tile), which is apparently fireproof... or at least fire resistant. I got this idea from googling. Obviously, that's not a permanent or attractive solution, but we had no problems whatsoever. I would think as long as you are not leaving the fire unattended you would notice any sparks or cinders and be able to extinguish. People use fire pits all the time near grass/trees/plants [I'm not saying they should, just that they do] and people don't often burn their yards up.

I got a bunch of wood from the seconds pile at a high-end deck place (which is, alas, now defunct). This included a variety of South American hardwoods that tend to not float, and the guy who was giving me the guide through the scrap pile was telling me about their fire resistance relative to concrete. All were factors greater than 1. (And these woods are a pain in the tailfeathers to machine, they're full of silica and dull bits and blades super fast.) Anyway, that's one approach: Build your deck out of fire resistant wood. But in any case, last time I was in Costco they were selling a metal "fire pit" that put your fire up in a steel basin on legs, and had a screen to keep the flaming bits of ash contained. A reasonably fire-resistant deck (for when those little sparks do escape) and something like that, or the insulated (by concrete blocks) surface (the concrete backer board) that raspberrE describes above should be fine. I'd keep a fire extinguisher and a few large buckets of water handy, just in case, but I do that any time I've got an open fire anyway.

What about using a large grill mat under whichever option you choose?

I will say, those metal fire-pits on a stand are probably not really meant for a deck. We have one that we fired up sitting on the grass and it dried the grass underneath dead. So, it could likely discolor and maybe damage the deck surface. I don't think it's a hazard necessarily but I'd opt not to put something like that on the deck itself.

I think it is doable, but I'd be very cautious about protecting any wood under any sort of wood-burning fire-feature you have on your deck. A friend had their wood fence catch fire becaue the night before, their neighbor used some sort of of fire-pit with legs on a patch of ground covered with woodchips. The radiant heat from the thing managed to start a small, smouldering fire in the woodchips which burned slowly under the surface all night and into the next day when it managed to set fire the fence. Even then, the top layer of woodchips appeared undisturbed. A deck would be less likely to burn, particularly without giving a sign, but all it would take is not snuffing the embers one night and by the next morning, some of the boards below could get hot enough to burn, and, it being a deck, I imagine it would burn nicely once it got started.