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Foundation

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  • Foundation

    Just signed up first post and have a ton of questions. Might as well start at the bottom. Living in Ct. with frost and freezing what do you do for foundation of stove? Footing code here is 42 inches this seems like overkill for a stove. Is it ok to dig down 8 inches or so and do a pad? I have a wood 15 X 12 shed in my back yard that weighs quite a bit on a 6 inch pad with no problems. This is not going to be inspected.

  • #2
    Re: Foundation

    Mike, I remember going through the same thought process. I grew up in Maine and currently live in Michigan. I know what frost can do to even the heaviest of items. In the end, I decided to put the full foundation under the oven. I didn't want to put all the time and effort into the oven only to find it attacked by a winter's frost. Here is a link to photos that I took of the foundation process: Picasa Web Albums - Daniel Woodruff - Wood Fired Oven. Another great resource can be found here: http://mainewoodheat.com/downloads/L...nual_Small.pdf. Go to the bottom of the .pdf document. It includes some help on how to build a proven foundation for a wood fired oven.

    Comment


    • #3
      Re: Foundation

      There have been many discussions on this topic, Mike, so you can find a bunch of information in old posts, such as this one. Do a search for "floating slab" or "frost line."
      I went a similar route as tusr18a, with a 60" deep foundation, but many people in "the north" have had success with floating slabs. It depends to some extent on the soil type and drainage conditions. Good luck!
      Daren
      Picasa web album
      Oven-building thread

      Comment


      • #4
        Re: Foundation

        I build three-foot-down one-foot-thick footings, but I was planning a two story chimney attached to a building, so I was building to masonry fireplace code. It's generally accepted that for freestanding ovens that aren't going to be much taller than you are, a 4 inch reinforced slab on six inches of well drained crushed rock is all you need. The theory is that if you aren't sitting in water, frost heave won't be a problem.
        My geodesic oven project: part 1, part 2

        Comment


        • #5
          Re: Foundation

          I live in Maine (where are you from tusr18a?) and have the same question. A lot of our soils are clay and I have the added issue that the location I have chosen for my oven is where they pushed out the material from our in-ground pool. Probably not a real stable area in which to rely on a 6 inch pad for something where so many hours of work are going to be invested.

          In speaking with the local masonary supplier this weekend, he suggested digging down 4 + feet and putting in 18 inches of compacted gravel and then pouring a 3 foot deep by the dimensions of the slab block of concrete. I figure that it will take about 5 yards which at about $100 a yard delivered is a good chunk of change. I guess I will have to weigh that against the time and effort of pouring a deep footing and building up to grade with block. I was hoping that all of my block work could be dry stacked. Once you brought the blocks up to grade, did you fill the center of the block cube with dirt tusr18a before pouring the base (across the top of the foundation blocks)?

          I may just excavate the hole down the 4 + feet, fill it with compacted gravel for stability and drainage and then pour an 8 inch reinforced slab. Does this seem reasonable?

          BTW tusr18a, you get the award for the most intricately engineered form.

          Comment


          • #6
            Re: Foundation

            Everyone that I talked thought that I overbuilt the foundation. I simply did it for a piece of mind. I went down to a depth of five feet. I poured a 1 foot thick footing. Then I built a cement block wall up to grade. I did not dry stack. Never having done any masonry work, I decided to learn the trade on the part of the oven build that would ultimately be buried. It was a very frustrating process. Definitely gained a whole new respect for the masonry trade. With that said, through trial and error, I started to get the hang of it. By the time I was ready to build the dome, I had the needed masonry skills to pull it off. As to buying pre-mixed cement or hand mixing it, I ended up going w/pre-mix because I was never confident that I would be able to mix up all the cement before some of the pour started to set on me. For the footing, I had the cement truck come to the yard. For the slab at grade and for the slab on the top of the stand, I found a vendor that sold pre-mixed cement by the trailer load. I attached the trailer to my SUV and dragged it home. A lot cheaper.

            I grew up in Central Maine in a small town called Pittsfield. My dad still lives there. My mother lives down on the coast in South Bristol. Get back a few times a year.

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            • #7
              Re: Foundation

              I grew up in Central Maine in a small town called Pittsfield. My dad still lives there. My mother lives down on the coast in South Bristol. Get back a few times a year.
              I know exactly where you are from. I live just south of Portland, in Scarborough. I am a transplant from Los Angeles though. Thanks for the additional thought on the base.

              Comment


              • #8
                Re: Foundation

                Hi Mike, I live in Southbury Ct. and poured a slab over 6" of stone, but I also did some 42" sono tubes that got filled with concrete. I will let you know in the spring how it fared! LOL I know that won't do you much good now. Here is a couple of pics of my progress. Good Luck!
                John
                Attached Files
                Last edited by Aegis; 10-12-2010, 05:59 PM.
                Build Thread:http://www.fornobravo.com/forum/f8/i...ome-15521.html
                Photos: http://groups.yahoo.com/group/brick-...67884/pic/list
                Oven Blog: http://johns-brickoven.blogspot.com/...ven-folly.html

                Comment


                • #9
                  Re: Foundation

                  Couple more pics of the "finished oven" LOL
                  Attached Files
                  Build Thread:http://www.fornobravo.com/forum/f8/i...ome-15521.html
                  Photos: http://groups.yahoo.com/group/brick-...67884/pic/list
                  Oven Blog: http://johns-brickoven.blogspot.com/...ven-folly.html

                  Comment


                  • #10
                    Re: Foundation

                    In speaking with the local masonary supplier this weekend, he suggested digging down 4 + feet and putting in 18 inches of compacted gravel and then pouring a 3 foot deep by the dimensions of the slab block of concrete. I figure that it will take about 5 yards
                    Wow. Wow. Wow. I think "masonry supplier" is the key phrase in that sentence. Here's what code is for masonry fireplaces, which is overbuilt by most backyard builders standards:

                    The footings should be below the frost line (three feet here) and extend six inches beyond the footprint of your oven. It should be consist of twelve inches of reinforced concrete, and be poured on undisturbed soil (no gravel). It can either be a ring below the oven walls, or a solid slug, whichever is easier. On these footings, you build your walls upward.

                    I think the guy who's trying to sell you a three foot block of concrete on a foot and a half of crushed rock is trying to make a big sale. It sounds like the anchorage of a mid-sized suspension bridge to me.
                    My geodesic oven project: part 1, part 2

                    Comment


                    • #11
                      Re: Foundation

                      Aegis looking good. After the feed back here and thinking about it a bit I think im just going to set mine on a 6 or 8 inch deep pad. I noticed your pad ontop of your cinder blocks sits ontop of the block. Alot of these builds I see they use rebar to suspend that pad between the block with a 1inch gap between the block and pad. Is there any differance to these two methods?

                      Comment


                      • #12
                        Re: Foundation

                        Hi Mike,
                        I am following the forno Bravo Pompeii oven directions. The reason for the suspended pad in a bread builders Allan Scott type oven is to isolate the heat transfer from the oven to the stand. I am using 4" of foamglas under my oven which, from what I have read will be enough insulation on the bottom of my hearth. The cold weather is arriving here, so I will finish the patio pavers and wait till spring to start the actual oven. This will be good for me to finish the details of the oven construction. I was shooting for a 42" round oven but will end up with a 38 or 40" dome instead. I could use the side space for extra insulation. Good Luck on your build, another oven is being completed in Oxford Ct. by Bob, I can only hope my dome comes out half as good as his did! He did a FANTASTIC job! Here is a link to his posts http://www.fornobravo.com/forum/f8/p...uild-7155.html He has great pics and documentation to boot!
                        Build Thread:http://www.fornobravo.com/forum/f8/i...ome-15521.html
                        Photos: http://groups.yahoo.com/group/brick-...67884/pic/list
                        Oven Blog: http://johns-brickoven.blogspot.com/...ven-folly.html

                        Comment


                        • #13
                          Re: Foundation

                          Alot of these builds I see they use rebar to suspend that pad between the block with a 1inch gap between the block and pad.
                          This is really bad masonry construction practice. Rebar should be completely buried in the concrete, or it will rust, swell, and break apart the slab. It's also not very good for thermal isolation because steel conducts heat better than concrete.

                          Please, for your own sake, read the FB pompeii instructions. They are based on the actual experience of multiple builders, not one persons ideas.
                          My geodesic oven project: part 1, part 2

                          Comment


                          • #14
                            Re: Foundation

                            I should have added I would never suspend concrete with rebar. It may last the builders lifetime, you maybe (with a big fork lift) move it with you to another house. But it will fail much, much sooner than the pompeii build. It is just not a good engineering practice to put such a relatively weak link in the structure. Thermal isolation and expansion/contraction issues included, this does not adhere to safe engineering design. because when it fails, the possible safety and damage could be significant. Hot oven with hot coals and someone getting wood out of the bottom to feed the fire... you can get a sense of the inherent dangers.
                            Sorry for not posting this, as it would have been negligent on my part for omitting it.
                            Thanks
                            John
                            Build Thread:http://www.fornobravo.com/forum/f8/i...ome-15521.html
                            Photos: http://groups.yahoo.com/group/brick-...67884/pic/list
                            Oven Blog: http://johns-brickoven.blogspot.com/...ven-folly.html

                            Comment


                            • #15
                              Re: Foundation

                              Originally posted by Aegis View Post
                              Hi Mike,
                              I am following the forno Bravo Pompeii oven directions. The reason for the suspended pad in a bread builders Allan Scott type oven is to isolate the heat transfer from the oven to the stand. I am using 4" of foamglas under my oven which, from what I have read will be enough insulation on the bottom of my hearth. The cold weather is arriving here, so I will finish the patio pavers and wait till spring to start the actual oven. This will be good for me to finish the details of the oven construction. I was shooting for a 42" round oven but will end up with a 38 or 40" dome instead. I could use the side space for extra insulation. Good Luck on your build, another oven is being completed in Oxford Ct. by Bob, I can only hope my dome comes out half as good as his did! He did a FANTASTIC job! Here is a link to his posts http://www.fornobravo.com/forum/f8/p...uild-7155.html He has great pics and documentation to boot!


                              I have read all 19 pages of that thread

                              Comment

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