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what is under your egg?

WileECoyoteWileECoyote Posts: 516
edited November -1 in EggHead Forum
I am just finishing my custom table and I fired the egg up for the first time inside the table to test it out last night. The egg was sitting on a high quality 16x16 ceramic floor tile with a PEI rating of 4 (very dense) and the tile was sitting directly on a 19/32" sheet of project grade plywood, which in turn was supported by three 2x4 rails underneath. I didn't use the feet under the egg because I assumed that the ceramic tile would serve the same purpose, and in fact I thought it would provide even better protection since it would support the full base of the egg.

Well I fired the egg up to 380 and all seemed fine for the first hour. Then I reached in with my gloved hand to adjust the draft door and the tip of my glove just barely brushed the ceramic tile, at which point the tile literally exploded into 4 even pieces with such force that each piece was pushed out about 1" away from the center of the egg. I cooled the egg to 330 and finished cooking for another hour then shut the egg down completely. I went out to check the results today and here is what I found:
bustedtile.jpg
I believe the dense tile actually made a better conductor for heat and thus it absorbed a lot more heat than the three small egg feet would have. There was also a lot of pressure on the center of the tile because my egg has a very slight raised bump on the bottom near the center, I assume from the original casting. You can't see it but you can feel it when you run your hand across. So the tile got very hot and was under high pressure in the center from the weight of the egg, then when I bumped the tile with my glove this was enough to release the pressure and explode the tile. Also, the wood under the tile was scorched black on the stained surface but thankfully it did not catch fire and there doesn't seem to be any real damage to the wood.

So I now think the reason that the BGE feet work so well is that they allow air to get under the egg and cool the bottom by carrying the heat up and around the sides of the egg. Air is a good insulator so this keeps the heat down and prevents it from scorching the table under normal conditions. By using a solid tile you are actually absorbing much more heat and channeling it down to the table unless the tile base is porous and thick enough to act as an insulator rather than a conductor. I believe a secondary factor is that I had just switched from a ceramic fire grate to a cast iron fire grate, which I believe allows more air in but also allows more heat to reach the bottom of the egg.

So my question for all of you that have egg tables: what is under your egg, and have you ever scorched the table under or around the egg? I know that some people are using concrete paving stones or fire bricks and a thick base of these would be ideal from a safety perspective, however the lip of my egg is already at 40" above ground due to my table design and I don't want to raise it another 2-6" or rebuild my table so I am hoping I can just use the egg feet directly on top of the wood shelf.

I did some searches on the forum and found a few posts but not that many. Any comments would be appreciated.

Comments

  • NibbleMeThisNibbleMeThis Posts: 2,295
    Here is our set up
    100_8135Medium.jpg

    I did decide to go with the three egg feet in addition to the floor tile, just for extra measure. Now that I've seen what yours did, I'm glad I did!

    We've done searing temps with no problems.

    My dealer told me most people just use large patio stones, but I thought the tile/feet combination would work and it has so far.
    Knoxville, TN
    Nibble Me This
  • WileECoyoteWileECoyote Posts: 516
    Thanks Chris.

    I just got done browsing all the table photos at TNW's site again. Seems that most people are using the same setup as you: a ceramic tile or paving stone of some sort, usually about 1/2-1" thick, then the egg feet. A smaller number of people used very thick fire bricks, stones, thin slate, or steel plates.

    So I think I will get a new porous ceramic tile or a thin fire brick of some kind and place it under the egg feet and then I should be all set. I just wonder if the tile will still transmit too much heat to the wood under the tile. Have you ever checked under your tile to see if the wood is scorched? I have a digital infrared surface thermometer so I am going to take some measurements of all the interior table surfaces while the egg is cooking at various temps. I want to do enough testing to be sure I can trust it before I take the egg up to the nuclear levels. I had always assumed that most of the heat would be on the top half of the egg and I figured the bottom would be relatively cool since the lump is suspended above the bottom but I can see that I was way off.
  • Mike in AbitaMike in Abita Posts: 3,302
    You bring up a very good point about heat transfer. One of eggers from up north has had a table catch fire and burn his house pretty bad. I'm hoping he will see this and respond. My egg is in it's nest and a good 20 feet from the house. Most don't realize that although the egg is a good insulator and can maintain some low even cooking temps, the lump actually burns at 1900 deg and anything in direct contact with that much heat will eventually burn.
  • stikestike Posts: 15,597
    tile plus feet will still transmit less heat to the wood than tile alone or feet alone.

    fishless has a picture of a scorched deck, when just using the feet. and we all know what happens (sometimes) when the egg sits only on tile.
    ed egli avea del cul fatto trombetta -Dante
  • DSCN1775.jpg
    I have garnet under my Egg.
    My Best,
    Ross
  • big green egg recommends this on the table plans page:
    "Make sure you use a concrete paving stone underneath your EGG in the table as a safety precaution."

    the green feet are not necessary under the egg if you use the proper paving stone. (that's the way i understand it, contact big green egg for the definitive answer)

    thinner tiles may be sexier, but they all crack from what i've seen here. the bottom of the egg will get hotter than the sides because the charcoal radiates heat down through the charcoal grate and burning particles will fall through and lay directly on the ceramic in addition to the ceramic firebox being in direct contact with the egg bottom.
  • A single paving stone is a recipe for disaster IMHO.

    I have seen severely burnt wood underneath single stones and even scorched wood under two stones.

    Using the egg feet prevents this.

    I use the feet plus rest them on a piece of aluminum flashing on top of plywood.

    Spacey.
  • "Sparky""Sparky" Posts: 6,024
    All I use is a paver or two.I use two under the small so it's the same height as the medium.The wood under the stones is not scorched.I have been using this set-up since 2004 without any issues.

    002.jpg
  • SundownSundown Posts: 2,980
    If I knew where the camera was I post a photo of 'what's under my Egg'.

    When I bought my Egg and table in 1998 or 1999 the dealer said to put the feet under it, that's all. Since then that's all that's been under my Egg. Two years ago, maybe three I took the whole rig apart to tighten a few things up. I half expected to see some scorching under Eggie but, to my surprise, there wasn't any.

    No pavers, no metal, no tile. Just the feeties under Eggie.
  • I am surprised that people are using only tile as a stone.
    Use the feet and a stone (or metal I guess) surface. I would not use anything less than 1" thick and even then if it's the wrong kind of stone (like slate) it could still fail.

    This was with 3/4" slate. Lasted less than a year before this.
    stonecrack-1.jpg

    I replaced it with 18" x 18" x 1.25" bluestone, which seems to be working.
    newstone-1.jpg

    Thickness is the key. With different materials there are different thicknesses that are appropriate. I know lots of folks use the thick conc. pavers like Doug uses.

    Unless you know of a tile that has already proved itself under an Egg in a similar environment, I would stay away from tile and use your feet.
  • The Naked WhizThe Naked Whiz Posts: 7,780
    I use the egg feet on top of a 1" piece of slate. The slate sits on four pieces of 1x4 which are on edge. So, in other words, most of the slate is not resting on anything. I don't know if you can see in this image, but it shows the opening in the bottom shelf for the slate and the four 1x4 cross pieces that support the slate: page3.gif

    In 7 years, I have had 2 pieces of slate crack doing this. After the second one, I stopped replaceing it and just push the two pieces of slate back together. It has never cracked any further.

    Also in 7 years, I have never had the wood beneath the slate scorch or discolor. I'd have to guess that the slate gets hot, but most of the heat is radiated away since it isn't resting on a solid wood surface.
    The Naked Whiz
  • TomM24TomM24 Posts: 1,364
    I have similar looking tile in my bathroom it is porcelain I think that might be part of the problem.The darn stuff is very hard it took seven drill bits to drill 6 holes for the shower door.
  • I just love your smokehouse set=up. What a good idea. I have the xtra large egg for turkey but am planning on getting a smaller one for smaller fare.
    Thanks.
  • TRexTRex Posts: 2,714
    Wow - I bet you could sell that as some kind of "exploding tile art."

    Glad nothing was damaged, including yourself!

    Befriend the feet. The feet are your friends.

    Jason
  • fishlessmanfishlessman Posts: 25,901
    mine was set up like that on the feet on 2 inch thick boards, no problems for a few years, then poof into flames during an overnight while i slept. no more egging on the deck for me, hope your egg is in a safe area away from the house. this burnout was during a low and slow, not a high temp cook, the egg was teatering when i found it in the morning.

    2005_0104Image0008.jpg
  • Whoa!!

    I'm going out to check just in case! That's scary on a good day. Maybe I'll fix it before my luck runs out. Thanks for that heads up.
  • WileECoyoteWileECoyote Posts: 516
    Scary pics fishless. Here is what I have learned based on all of my research and testing thus far:

    If the egg is set on wood, set on feet alone on top of wood, or set on thin material supported by wood, then there is too much heat directly transfered to the supporting material which will be hot enough to crack tile, crack slate, and burn wood. In fishless' case it seems that the wood must have been slowly scorched over time until it eventually burnt clear through his deck.

    The logical conclusion is that it is critical to use the feet on top of a tile, fire brick, or some other fire and heat resistant surface. This introduces an air gap which serves as an insulator and allows some heat to radiate out and up around the sides of the egg. The question is what material to use, and what is the minimum thickness. BGE recommends a concrete paving stone and those are about 2" thick. A number of people are using thinner, more dense tiles like porcelain or slate or stainless steel with mixed results, although I would bet that most of these people will have some scorched wood under the supporting material if they check it.

    So now I am going to get a fire brick or concrete stone which is at least 1" thick and put this under my feet. If this raises the egg too high then I will just cut out the support shelf and rest the stone directly on the wooden support rails similar to what is shown in TNW's table design.
  • BeliBeli Posts: 10,751
    I might add, that the 3 egg feet are invaluable under the drip pan when cooking indirect.
  • WileECoyoteWileECoyote Posts: 516
    Yeah, I have seen a lot of people using the feet to cook inside the egg which is another reason I was hoping to just use tile under the egg. So now I ordered a second set of feet and will use those to cook when needed with the original feet remaining under the egg. An option would be to use some other fire bricks or tiles under the egg like the feet but to me the feet are ideal and a replacement set was only $11.95 including shipping so why not pickup a spare set and keep the egg safe?
  • pop-a- toppop-a- top Posts: 184
    My dealer gave me extra set of feet just for the asking.
  • i was simply repeating what i've seen an employee of big green egg post here, what their website says, and what the manual says.

    if you feel strongly that placing an egg directly on the proper concrete paving stone is a serious safety concern, i suggest you contact big green egg directly and work to have their instructions changed.
  • ILL--EGGERILL--EGGER Posts: 478
    Stone paver with feet. Not the best view but best I have ATM.
    eggtable.jpg
  • BrocBroc Posts: 1,398
    I made the same mistake when I first built my Egg-Home. I had spruce 2x's laid horizontally, then capped with the 16x16 tile, then the Egg, without feet. ;)

    Blammo! :ohmy: :ohmy: :ohmy: :ohmy: :ohmy:

    I thought someone had a 22... really! :angry:

    It didn't occur to me it was the Egg... until the 2x caught fire. :blink:

    Oh, yeah! B)

    Here I am, broken neck :whistle: and crushed back, :silly: completely disabled, :S with a 20 lb lifting limit, putting on a winter jacket [for insulation] and picking up a fully loaded Medium :side: :side: :side: and hauling it 6' to concrete blocks.

    Then running like a bat-outta-you-know-where :evil: to get water to put out the fire.

    Live-'n-learn!

    ~ Broc

    :laugh: :laugh: :laugh:
  • WileECoyoteWileECoyote Posts: 516
    Rick's Tropical Delight wrote:
    i was simply repeating what i've seen an employee of big green egg post here, what their website says, and what the manual says.

    if you feel strongly that placing an egg directly on the proper concrete paving stone is a serious safety concern, i suggest you contact big green egg directly and work to have their instructions changed.
    Rick: I don't question the info that you shared. BGE's table instructions do include the following statement:

    "Make sure you use a concrete paving stone underneath your EGG in the table as a safety precaution."

    They do not specify whether the feet should also be used between the paving stone and the egg but I think that is a given. Based on my testing and research and the posts on this forum I believe it would be unsafe to do otherwise, although many have reported using only a paving stone or other thin tile with mixed results. To each his own.

    My table is enclosed and it will sometimes be positioned close to the house so I don't want to take any chances. I contacted several brick and concrete dealers today and they all recommended using firebrick instead of the concrete paving stone or any other brick and tile materials.

    I am headed to a firebrick dealer tomorrow morning to pick out something that will work. A "split firebrick" measures 9" long x 4.5" wide x 1.25" thick so I am thinking that 8 of these will make a nice 18x18 square to sit under the egg and then I will test the temps with and without the egg feet on top just to be sure. If I can run the egg at nuclear level for several hours and the firebricks don't get too hot then I will go without the feet, otherwise the extra set of feet I ordered will be put to good use on top of the firebrick for extra protection.

    I will share my results when I get the firebrick installed.
  • WileECoyoteWileECoyote Posts: 516
    Dang Broc! I can't imagine trying to move a fully loaded egg while it was lit. You are lucky it was only a medium! I am a pretty big and healthy guy but I can barely move the large and I certainly wouldn't be able to do it with the egg lit. I have done some more testing and the egg gets very hot on the bottom and sides, even at modest temps like the 380 degree fire which made my support tile explode. Now that my egg is inside a table it is not possible to remove it unless I first take out the interior parts and remove the lid, and even then I have to be careful not to scratch the sides while lifting the bottom out of the table.
  • whatever, man.

    what i am telling you is BIG GREEN EGG themselves state in both the new (page 10) and the old (page 13) versions of the manual the green feet can be discarded if you put the egg in a wooden table and use the appropriate paver stones. a BIG GREEN EGG employee (namely Bobby-Q) has posted the same information on this forum.

    i never said using the feet AND a stone was a bad idea or unsafe or anything like that. feel free to use the feet and a stone if you want.

    what i find dangerous is soliciting ideas and recommendations from untrained and novice people that really have no idea what is and what isn't and then trusting their recommendations with the safety of your home and family.

    please contact BIG GREEN EGG directly to get the corporate response and if you feel the instructions in the manual and the website are in error, please work directly with them to make a change if you feel necessary.

    have a great evening ;)
  • WileECoyoteWileECoyote Posts: 516
    Rick: I want to thank you for your suggestion about contacting BGE. This has led to an ideal solution which I will post here and in another similar thread to help others with this issue.

    Per Rick's suggestion, I did recently contact John Creel at BGE corporate (R&D Dept.) and we traded info about our testing and results. We both came to the same conclusion:

    BGE recommends using the concrete paving stones between a wood surface and the bottom of the egg, primarily because they are relatively cheap and easy to find at almost any major hardware store. They have found this solution to be adequate during their testing, however John also agreed with my research that the concrete paving stones are prone to cracking and breaking over time since they absorb moisture and they are not designed to take the high heat generated by the bottom of the egg. John also agreed with me that it would be better to use the three ceramic feet on top of the concrete paving stone as an additional buffer to keep the temp of the concrete stone down and reduce the risk of charring the wood under the stone, and that the best solution would be to use a layer of split firebrick under the egg in lieu of the concrete paving stone, with the three ceramic feet used on top of the firebrick for the air buffer.

    John also wisely pointed out that using a cracked stone or no stone under the egg is a hazard because if the bottom of the egg ever cracked then super-heated air or coals would hit the wooden surface and cause a fire in no time. So over the past week I have done a lot of research about stones and firebrick. I called close to 50 brick yards, masonry suppliers, hardware superstores, brick manufacturers, construction firms, and contractors. Everyone agreed that the split firebrick was the way to go, however most places either didn't sell the split firebrick or they only stock it during the winter. The split firebrick is most often used as a replacement part for repairing the lining of cast iron wood stoves and pellet stoves, so it tends to be a seasonal item. It is 9" x 4" x 1.25" compared to a full firebrick which is 9" x 4" x 2.5". I didn't want to use the full firebrick since it would be overkill and raise my egg too high. I could have cut the full brick in half but I don't have a wet tile saw and I didn't want to pay to have it done.

    After a few more days of digging I found three good solutions for purchasing split firebrick that should work for just about anyone in the USA.
    [ol][li]Visit your local Tractor Supply store and ask the manager if they have any split firebricks in stock (item # 3112783). Most of the time they will tell you no since it is a seasonal item but if they check their inventory on the computer then they will see that they usually do have at least 10 bricks on hand. They can even check inventory at all other stores for you instantly in the computer. Most stores take this stock off the floor in the summer so you have to ask them to go back in their warehouse and find the firebricks for you. After calling a few stores I did find one store that was able to scrounge up enough bricks for my project. The best part is that the price is lowered to clearance level in the summer so I got my firebricks for $2.08 each.[/li]
    [li]Another option is to order a 6-pack of firebricks from AceHardware.com and you can opt to have them delivered to your local store for free. You just pay $20 plus tax which comes out to about $3.60 per brick in most places. Costs almost twice the Tractor Supply option and it can take a few weeks for shipping to the store but it is convenient and still cheaper than the other options.[/li]
    [li]The last option is to contact a local fireplace or wood stove retailer. If they are a big shop then they will probably have at least a few split firebricks on hand. The problem I had with this option was that most places only had 2-3 bricks in stock and their prices ranged from $4-6 per brick plus they were further from my home. Surprisingly about half of these places also did not stock the bricks and they wanted even more to special order them.[/li]
    [/ol]
    So to each his own regarding the proper base for the egg. My conclusion (which BGE supports) is that the best and safest solution is a full layer of split firebrick (4 bricks wide by 2 deep will form a 16"x18" square) and then use the BGE ceramic feet on top of those. It is also best to keep most of the bottom of the firebrick open to the air so they won't transfer as much heat to the wood. You can do this by cutting out your shelf and using a few narrow support beams or metal rods similar to how TNW's plans show. I am modifiying my table tomorrow and will post pics when it is done. I will also take temp readings with my digital infrared laser thermometer and I think many will be surprised how hot the firebrick and surrounding table surfaces can still get even with a proper solution. Err on the side of caution lest you have a tragic fire.
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