Hi, I wouldn't. I would think that because moisture saturates hypertufa well, it would be too porous, and explode if any moisture was in the 'tufa'. Sealing I would also think, could wear away or burn from the heat. I would line the firepit with 'fire brick" and at a distance away from the heat use tufa for decor..... Just my 2cents worth. Marcia

My fire pit is about four feet in diameter similar to those in the link. The steel is about 1/8 inch thick and rusty, but will not rust away in my lifetime. It is made in three sections and bolted together. It is intended to sit right on the ground, but we decided to make a ring of concrete stones intended for retaining walls, the smallest size, and we set the fire pit ring on that. Al

eyoung- Here's a link to the store where I purchased the bowl. I don't think they deliver but any nearby outdoor specialty store should have a selection of outdoor bowls to chose from. Just make sure it is a clay fired bowl so it can withstand the heat and tell them what you are using it for so they can make recommendations. http://www.cornercollectiononline.com/gsb.htm The fire ring kit and feather rock was purchased from fire pit outfitters per link below. They do deliver and I ended up with one of the manual spark ignition kits instead of the electronic ignition kits. When you see the pricing, you'll know why! There is also a match lit kit if your budget is tight and you don't mind manually opening the gas valve and lighting the fire ring with a match. Note, the manual kit does not have any flame out protection, so if the flame does go out, the valve will have to be shut off manually to prevent gas from flooding the area and creating a hazardous situation. Both the direct spark ignition and electronic ignition kits have flame out protection. http://firepitoutfitter.com/index.asp?PageAction=COMPANY I then converted the manual kit over to an electronic kit using the components below. Note, you can also buy the electronic ignition kit directly from firepit outfitters but it will cost a lot more than the conversion components I describe below. The advantage, of course, is you won't have to hassle with the conversion and you'll know that the kit will work out of the box if installed properly. Here's the electronic conversion parts. These parts can be found online or at a local HVAC Center or Appliance Parts Center. Gas Valve - Electric Direct Spark Ignition Control Module with flame out detection Flame Sensor - Electric The manual spark ignition kit already has a spark ignitor included in the kit but the flame sensor with the kit is a mechanical one so it needed to be upgraded to electric. The ignition control module will be controlled by our pool automation system and turn the fire pit on/off with the hand held pool remote. Also very important, allowances for air flow are critical to ensure the temperature does not exceed 175 degrees F where the electronics and gas valve are housed to avoid damage to them. This includes adequate intake openings at the bottom of the bowl to allow cool air in and adequate openings around the pan to allow the hot air to escape upwards without restriction. If any of this does not make sense, I would recommend consulting with a local professional such as an electrician, plumber or HVAC technician who has experience making these parts work together safely. Hope this helps!

Trying to make curved, round or perfectly circular things does not work well with backerboards. They tend to bend irregularly, especially at the ends. I'll tell you how I would attack something like this. It may sound complicated until you understand it, but it's actually a fairly simple process that guarantees a perfect, or near perfect circle. First, I'd find a cylinder of some sort that was close enough in size to my desired inner diameter, that I could use for an inner form. Like an old trash can. I'd create a hole in its bottom, allowing it to be slipped over a post that is embedded in concrete below the ground (below the fire pit bottom.) Once the cylinder is slipped over the post, add wooden supports in a triangular arrangement, coming from the center post to the inside edge of the cylinder, so as to center the vertical post within the cylinder. The post should project upward beyond the top of the fire pit cylinder as a means of attaching the rotating screed/guide board and stabilization for it. Temporarily, wood spacing strips are placed vertically around the outside of the core cylinder, for the purpose of allow a wire mesh cylinder to be embedded within the final concrete core. As concrete is troweled onto the inner form, adjacent to the temporary wooded strips, and begins to harden, the strips are removed and their cavities filled will troweled concrete. One trowels concrete onto the enlarging concrete cylinder using the rotating screed/guide board to determine that the limits of the concrete cylinder have been achieved. The final surface of the cylinder should have a rough texture in order to be ready for applying cultured stone. For the top ring of the fire pit, I'd use a similar radius point post to screed a form out of damp sand (the mold. If you want the top ring of the firepit to be smooth like stone (similar to the picture) you'd need to grind smooth its finished surface with carborundum stones. If you want it to be polished, you'd need to grind it with an ever-diminishing size of grit, which would probably require that you take it to a polishing expert. I'd suggest trying the people who install polished stone counter tops as they would have the resources. I would not make the top ring any less than 4" thickness ... for looks a durability. It would need steel reinforcement embedded within. It's going to be heavy so gravity will easily hold it in place on top of the base cylinder.