Hearth size

[JRPizza]

Totally stuck on hearth size, and forum problems are keeping me from looking at some images that I think might help me. I have laid out a 70X70 corner base, but space is at a premium so would like to shorten to a 62.5X62.5. I have a sketch but am not sure about how much room the vent/landing need. I am showing 4.5 + 13 for vent/landing - will I have enough room to build a 36" igloo? Let me know what you think or if you need more information to help me out.
Thanks - John

[JRPizza]

Well, I went ahead and poured the cores in my 70X70 stand, so the question on stand size is moot!

[RandyJ]

70"x70" will be good. I did that same size for my 40". I was feeling a little cramped when I did my vent. So make sure that you are very careful when you lay everything out as space runs out faster than you would think, but I made it all work just fine and could have moved back a little if I had thought about it.

Randy

[RandyJ]

You might want to make the front of the stand a little wider. I think I was at 32.5" and that was barely enough.

Randy

[JRPizza]

Any comments on these dimensions would be appreciated. The layout is for a vent for a 36" oven. I think I have the inner arch dimensions correct - 19 inch opening and 4.5 thick. I show the inner arch width at the base @ 28" assuming these are half bricks sitting on edge. Is this correct? The vent area is shown at a similar 28 wide at base, but I didn't correctly space the opening to provide a lip for the door to stop against - is one inch about right for this dimension? If yes I would open the vent outer dimension to 30". I am showing the depth of the vent to be 1.5 bricks long (~13.5) with 3 inches deep for decorative arch. I'll update the sketch with the enlarged vent opening and any other suggestions I get and repost.

Thanks - John

[JRPizza]

I cleaned up the layout a little and corrected the vent width to provide door stop. Comments appreciated. I am framing my hearth and want to get my landing sized right.

[DavidApp]

Hello JRPizza

I have a 36" oven.
My stand is 59" wide and 63" from front to back. It is a bit tight, mainly front to back.

My inner arch is 19" by 12" and my vent is 21" by 13 1/2" and outside the vent columns is 37"

It has worked out well for me but I could have had more area outside the front of the oven.

David

[RandyJ]

1" will work for the reveal but you might be happier if you went up to 1.5" that just gives you a little more room to work and makes it a little easier to get a door in and out. So if you can find the room it would be a good idea. Other than that I think you have a good plan. You are pretty much laying it out as I did. We'll except for the part where I just eyeballed where I thought the oven should sit and went from there.

Randy

[Gulf]

I agree with Randy about the wider reveal. The wider, the better, imo. Build the reveal real wide enough, and it will offer the working room of a "flared entry" without the "intimidation". My reveal is 3".

I show the inner arch width at the base @ 28" assuming these are half bricks sitting on edge.

That is partially true, but the inner arch brick are not exactly "half brick". Their length is determined by the distance from the vertical outside face of the arch to where they intersect with the inside curve of the dome. That distance will change depending on how high the arch brick is from the floor. They should reach further into the dome from the vertical face as the arch gets higher. At the very apex of the arch those brick will be very close to a whole brick in length. From your drawing it appears that you need to shift your inner arch back a little to make that work. It will also give you a little more room. I think as much as 1.5".

Also, leaving a little reveal on the decorative arch will allow for an easy to fit storm door. I'm not sure if you are including any type of heat breaks in your build. but, do consider a space behind your decorative arch.

[JRPizza]

Thanks for all the help. I am sweating this as I want to keep as much room in front of my stand as possible. My next move is to cut the backer board at a 45 degree and want to make sure I have enough room without too much sticking out. A question for you all - did you use common brick for the vent arch or firebrick? Looking at pictures it looks like folks have done it both ways. I believe Forno recommends using common bricks which would seem to be more durable if the heat resistance is not needed. Since they are different dimensions which brick I use will change my landing size.

[Gulf]

I recommend firebrick for the entry. The rear and upper section of the entry will receive extreme temperatures. The lower and front of the entry will not. If you go with a "common brick" make sure that it is a true clay paver. A clay brick made with no other material in it. And definitely, make sure that it is not a concrete paver. Not all commons are the same. Since you are sweating this as you say, I think that it is time for a full size template drawn on poster board.

[JRPizza]

Thanks Gulf, firebrick it is then. I'm drawing a full size template on a large piece of stiff cardboard. I'm a little puzzled at your comment about setting the first inner arch brick. I obviously don't want my arch to be bigger than one full brick at the top, so how do I know in advance where to set the base brick? Looking at your mod to my picture, do I set the outside corner of the first arch brick to intersect the circle representing the outside of the dome? On on my full size layout, that lets me move the arch back almost 2 inches. Does that sound about right?

[Gulf]

On your original drawing, your reference line for the face of your inner arch protrudes about 1.5" to maybe a full 2" from the outside of the dome. It doesn't have to protrude any. But, 1/2" to 3/4" is fine. It looks to me like 1/2" to 3/4" would bring it to about the inside diameter line of your dome at the floor. Look at the green dotted line in the photo below. On the backside of your cardboard template, you can do a full size profile of the inside arch and the inside curve of your dome to see how far the inner arch will reach. Don't sweat it, though. Having the inner arch reach full length into the dome just makes it a little easier later on in the build. There are plenty of inner arches on this site that don't. Probably, most of them. I hope this helps.

EDIT: I think that you edited your post after I started working on the reply. But, I think that my answer clarified that anyway. If not let me know.

[JRPizza]

Gulf, I notice you built your inner arch first. Did you use an IT or similar tool to help you "widen" your arch as it gained height? Is that what you meant by having the arch a full brick into the dome? It looks to me like on some builds they just used a constant arch thickness all the way up, and had to compensate for it with some tricky cuts.

[Gulf]

Yes, I used the IT to mark my cuts. But, I set my inner arch too far forward. I had to splice the upper four inner arch brick to extend them in to meet the inner curve of the dome. I don't really advise that. But, it is not near as difficult as compensating for extending the dome courses out to meet the arch. I did not get many pics of that part of my build. I was too busy scratching my head and "sweating it" lol. I did complete my arch first, but I tied it in with a couple of courses of the dome brick at the bottom. If it is not tied in, it will fall over to the inside under its own weight. Below are two pics. The first is of my arch. Though, they are not completed courses, you can see where I laid enough of the bottom two courses to keep it from falling. The second pic is of Kbartman's. KB, built his arch as he laid his dome courses. You can see how he tied the arch and dome in in at the bottom. You can also see a very good example of another trick on the inner arch to make the cuts for the dome brick a lot easier.But, that is not important right now to get the foot print of your oven for the template.