Can I make Fire + Wood Deck = Safe?

August 16, 2013 3:51 PM

We will be building a deck in a few weeks, and another aspect we would like to have with our new outdoor environment is a nice small fire to sit around for the cooler Minnesota evenings. What are our options without risking burning the deck (and/or the house) down?

I'd like to hear from any MeFites that have experience with any of the following being used on a wood deck:

- Gas fire bowl or table
- Wood burning Chiminea
- Wood burning table fire pit

My biggest concern is safety, seconded by not messing up my deck. Are any of the above viable options for our deck? Or should we pursue a ground fire pit? Other options? I'm leaning towards gas (propane) just from a safety perspective, there's no embers or sparks to worry about. Some woods produce some nice bug-repellent smoke, but this would tend to infiltrate the house and we can probably get the same effect from some citronella tiki torches mounted to the railings.

My favorite is the gas table, but even with gas, do I risk damaging my deck, either from heat, or the unit itself? (stains, dirt collecting underneath, etc.)

Possibly relevant details: This is a cedar deck in MN; will be sealed / stained in the spring. The deck will be 12'x12' raised deck about 10 feet in height, and adjoin a screen porch; I would probably locate this in the corner furthest from the house and porch as possible while still allowing for chairs all around. Cooking is not an issue; I'll have a separate BBQ.

We'll opt for a fire pit in the backyard if we need to, but I'd really like to have something on the deck where it will be much more convenient to use. Thanks in advance!

posted by SquidLips to Home & Garden (11 answers total)

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.
posted by raspberrE at 4:11 PM on August 16, 2013

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.
posted by straw at 4:30 PM on August 16, 2013

What about using a large grill mat under whichever option you choose?
posted by PorcineWithMe at 4:37 PM on August 16, 2013

The best thing you could do since you mentioned several different options would be to choose something you like and talk to the vendor for that item. The fire features you are talking about will have specific installation requirements which take into consideration that people want these on or near decks. A stray spark is unlikely to light your deck on fire. Very unlikely.
posted by amanda at 4:47 PM on August 16, 2013

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.
posted by amanda at 4:51 PM on August 16, 2013

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.
posted by mareli at 5:10 PM on August 16, 2013

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.
posted by beagle at 5:36 PM on August 16, 2013

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.
posted by rtha at 5:37 PM on August 16, 2013

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.
posted by Good Brain at 12:39 AM on August 17, 2013

Watching for cinders that land on the deck is one thing. One much smaller but much more serious risk is the cinder that will fly up and land, not on the deck, but into the space between planks on the deck, falling below the deck... where it could ignite dry leaves and other detritus that have accumulated there over years...

All manufacturers of portable fire pits warn against using them on wooden decks.

If you choose to do it, make sure that you put about 3-4 inches of sand at the very bottom of the pit, for further insulation.
posted by megatherium at 5:15 AM on August 17, 2013

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!
posted by SquidLips at 7:10 PM on August 18, 2013