A new outdoor Rocket system

[boo]

WOW......beautiful work Matt.........maybe I need to have a crack at one of those!

[matt walker]

Thanks much guys. I've sure been enjoying it. I think I've gained 10 pounds in the last two weeks! Not really, but I'm doing a good job of clearing last fall's hogs out of the freezer thanks to this thing.

[Mikimble]

Hey Matt,

How does the cob hold up outside? I had to use mostly bentonite clay for my cob, and am concerned about how it's gonna handle rain.

Mike

[pa_friendly_guy]

Matt will give you a better answer than I will, but since it is raining very hard and I can't get outside right now I will give you my 2 cents worth, Once cobb is very dry and hard it is fairly durable, but it is still mainly Dirt and it will be effected by wind and rain over time. If you look at Matts outside stove you will see in the pictures that he covered the top of the bench with very large, very flat, very thin stones. So he made a Hat for the unit. The larger the stones the less joints between stones to let the water through. The flatter the stones the better they feel on your behind when you sit there. The thinner the stones the easier they would be to lift and set them in place. As I looked at his video and pictures I thought to myself, WOW Where did he find those stones, they are perfect for the application he used them for. Just perfect stones for the top of his bench. I have to say that I was envious, I do not have any stones like that at my place. I love stone work and Matt does nice work when it comes to selecting and using the stones he has available on his property. When building with straw, and I would apply this same theory to cobb as well, I have always heard that you need a good Hat and you need good boots. In other words you need a good roof and you need a good foundation. I don't think the boots are as important with cobb since it is basically dirt sitting on dirt, but the Hat is a very important item if you want it to last for years and years to come. Having said all of that, I think you can paint the cobb bench with a Glaze and bake it on to give your bench a hard more or less water poof surface that would add many years to the project. I personally like the large stone idea much better. They are beautiful, they last forever, and they are cheap if you have the stones handy. The glaze would give the bench a bit of a shine, and I believe you can get it in different colors so it would give a different look that some people might like better than stone. If you make an outside RMH like Matt has I would make some sort of a Hat for it to make all the work you do last longer.

[matt walker]

Guy, I have to admit in a not-permaculturally-enough moment I bought those flat pieces I have on top of the bench.

Mike, so, I agonized over the thought for a while, and got lots of feedback online. Most of that said "it won't work." I didn't care much, since I was experimenting, and still am. What I discovered over the summer was that while I was using the system, it could get wet and then dry out again when I used it with no ill effects. The rock covering made it so we weren't sitting in mud when it was wet, and for other spots I'd just throw a piece of scrap wood over it when I wasn't using it.

Fast forward to now. This system hasn't been run since October, and we get about 30" of rain annually, mostly between late October and May. So, it's seen a LOT of rain. Guess what? It's fine. Like, totally, completely fine. It's wet, but I'm pretty sure I'll just dry it right back out again once I start using it. I'm going to do the rocks over the whole thing sometime this spring. I think it looks nice and it does make the bench more functional since it's not muddy when wet. And they dry quickly once it's lit. So yeah, no problem. Even the hollow chamber held up with those little sticks is totally fine, which I expected to be a mud pile at this point. Keep in mind I'm referring only to a system with an internal heat source. I wouldn't expect a cob monolith bench with no internal heating to ever dry.

[pa_friendly_guy]

Matt, do you think that painting the cobb bench with a glaze would seal it enough so that it would not get muddy? I know that there are many different glazes available with different sealing properties. If you fire the stove hot after painting on a glaze I would think it would bake on and harden pretty well. Boiled linseed oil is used to seal concrete, it might work for cobb as well.

PS. I still love those flat stones, I think they make a wonderful Hat for your stove. If you bought them by the Ton getting the thinner stones makes them cover a lot more area than thick heavier stones would cover.

[matt walker]

Yeah, the stones really didn't cost very much at all. There's maybe $30 worth on top of that bench, at most.

As for the glaze or some sort of sealer, I dunno, maybe. I'm not terribly interested in trying to find out at this point though, to be honest. I have seen some beautiful linseed finishes on outdoor cob benches in the past. The difference, as far as I can tell, is that if it's a regular unheated bench, you can't use stones because they trap moisture underneath.

And,the big one for me, once you seal a cob bench, you can no longer stick new cob to it or reuse the cob with the stuff on it.

So, I'm just going to stick with the rock top, which works great for a heated bench. I can pressure wash it. I can lift 'em up and change it around. They look nice. They are cheap, and durable. It's not permanent. There are no chemicals. I can recycle the cob into a new design if I make changes. They are pretty nice to sit on and get nice and warm. I could go on, but I think it's a pretty good solution for what I am trying to do. I think a person could also use wood, or tile on a piece of backer board, or bottles, or any number of things. If someone wanted something truly permanent, then a freestanding roof over a cob bench, or a masonry skin are both options.

[Mikimble]

Hey Matt,

What I did for seats was go to the local Habitat for Humanity store, and bought some 12 inch tiles for fifteen cents each. I just laid then on top of the wet cob. Makes a great seat.

Mike

[matt walker]

I've always thought that would be a great seat top Mike. If you feel like posting pics at some point I'd love to see them. I think there's a lot of potential for nice finishes with tile, indoor or out.

[pa_friendly_guy]

I think the ceramic tiles will make a great hat for your bench. Ceramic is hard, durable, and water poof. It sounds like you found some at a wonderfully affordable price , while helping out a very worthy cause. I have bought a number of things from our local habitat for humanity store, I like the fact that the profits go to a Great cause, and the stuff is normally really reasonable in price, its a win , win, as far as I am concerned.