Sunday, February 24, 2008

Fireplace stonework is done! (Part X)

Completed: Six stone arches and approximately 250 square feet of dry-laid stone, using only rocks found here on our farm. It took way too long, but now that part is finished and my life can go on. In retrospect, I think it would have been cheaper and faster if I had taken a job frying burgers at McDonalds for 3 months and paid the stone mason to do all of this with artificial stone veneer. But that wouldn't have been nearly as satisfying. This photograph is of the south-west corner, taken from the near the kitchen door. The contraption on the right is a gas powered winch (attached to a special ladder) that the mason brought to the job so we would not have to lift the buckets of concrete that we placed inside the stone walls.

I wanted to have power available to the mantle without always exposing an ugly electric outlet, so I came up with this way to hide the electric box when not in use. This small stone will remain in place unless something on the mantle requires power. Presumably, the doo-hicky requiring power (a clock or Christmas decoration?) will cover the ugly outlet when the stone is not there. This will have to suffice until wireless power delivery becomes more feasible! My father-in-law recently made the walnut mantle from a piece of stock we found in one of my barns. The 3x8 stock was to be used for making corner braces in the house, but I had culled it long ago because one side had numerous bug holes. (we turned that side down for the mantle). In fact, this same piece of walnut served as our lunch table a couple of years ago when we were cutting the beams for the house frame.

Here's a picture of the North-East corner of the fireplace structure. The shelf is already proving to be a nice place for books and random clutter to accumulate. I cut the stones for this arch a little bit differently. I made it easier to work the regular field stones into the arch, by cutting the arch stones with corners on them. I think this is more commonly done when mixing stone arches with brick work, but because my stone work is coursed and the field stones are rectangular in nature, the effect worked nicely here too.

The 2-by-4 "crown molding" at the top of the stonework is temporary. I intend to replace it with an oak trim board and dental molding. Placing trim here eliminates the requirement that the last course of stone exactly match bottoms of the timbers.

Here's a peak inside the stone walls. There's a lot going on here! To keep the hot flue surfaces safely away from the timbers, to make room for the wood cook stove alcove, and to get the flues to line up with the yet-to-be-built chimney, I found it necessary to cant the flue liners 25 degrees for a small distance. The tiny pizza oven flue at the top of the photograph is tilted 30 degrees, which is the absolute maximum suggested by fireplace guidelines and code books. The white powder near that flue is more of the perlite insulation on top of the pizza oven. On top of this I placed some leftover firebrick and aluminum foil to keep the concrete from mingling with and/or displacing the perlite.


Finally, here's a picture of the finished stonework, taken from the great room. The green rebar protruding above the loft will be contained within the cores of concrete blocks used to build the chimney. These cores will be filled with grout (concrete with small aggregate) to tie the blocks and the rebar together. This type of reinforcement is only required in areas of high earthquake probability, but I thought it sounded like a good idea for a chimney that I hope will last several hundred years.

You might notice from this photograph that the fireplace is neither symmetrical nor centered in this hammer beam bent. Although centering the fireplace might have proven more aesthetically pleasing, we had several reasons to keep the fireplace off-center... the primary reasons being: 1) I didn't want a chimney sticking up through (or shading) any part of the south roof, which is covered with photovoltaic solar panels, and 2) there will be a bar to the left of the fireplace that will allow conversation, food, and dishes to flow between the kitchen area (the pizza oven area!) and the great room. Were the fireplace centered, there would not have been enough room to incorporate the bar. Even with these solid justifications, I still occasionally find myself second guessing the decision to off-center the fireplace. Oh well, there it sits... all 30,000+ pounds of it, literally etched in stone!

8 Comments:

Blogger Cliff said...

Amazing fireplace, the electrical outlet is an awesome idea.

February 24, 2008 at 11:16 PM  
Blogger oldmilwaukee said...

Cliff,

I just scanned your log blog... your log home project looks awesome! It might possibly be even more labor intensive than timber framing. When I get more time, I want to go back and read your whole blog.

February 25, 2008 at 8:42 AM  
Anonymous Tom said...

What great work you do - I'm so amazed at the skill you've got. This house is going to be a true work of art. I love the fireplace.

February 25, 2008 at 2:43 PM  
Anonymous Anonymous said...

Ok, I read the whole blog. First off, exceptional work and dedication! The thing I can’t figure out is how are you allowing the fireplace to breath? As the fire gets hot, the masonry will expand. It seems you poured mortar right up to the firebrick and backfilled the stonework. Is any of the fireplace hollow (like around the flue liners) or did you use a more sophisticated component like ceramic fiber paper? How did you handle this?
Chris

March 2, 2008 at 6:44 PM  
Anonymous Anonymous said...

Thomas, your cousin Matthew Brothers here. I follow your blog more or less religiously, which is to st, when the spirit moves me. I love your house. My brother Eva, having gotten very involved in the local produce movement (he spent the last six months volunteering for heifer international) and myself, desiring to have a small farm where my son can spend his summers, are looking for some property in Lewis County. When we're inthe area, we were wondering if it would be ok to stop by to visit. Rather than discuss details in an open forum, you can reach me at thematthewbrothers@yahoo.com. I look forward to hearing from you.

March 3, 2008 at 2:50 PM  
Blogger oldmilwaukee said...

Matthew - Thanks! and definitely stop by - I will send you an email this evening.

Chris, great question. I struggled with this decision. On the back of the firebrick and around the throat of the fireplace, I mixed up perlite and cement which is a little bit compressible (300psi instead of 3000psi), but still dicey. Above that, I said the heck with it and poured cement right to the flue liners. What will happen - I do not know. If those flue liners crack, I don't think they'll fall out. If they do fall out, I'll remove the rubble and the cement will be the liner. (someone is gasping reading this right now... sorry. those same people probably gasped when they saw me roofing w/o any felt or tar paper under the slate) I might be making a horrible mistake... but I hope not. ceramic fiber paper (the stuff I could find) was ridiculously expensive. It can't be that many people ever use that stuff. I bet most masons not on the internet have never even seen the stuff.

The flue liners will have an airspace around them once I get a little higher where they have no tilt. But every once in a while (my mason-dude recommends at all the joints), the flue liners will still have that airspace filled so they have lateral support. I think maybe the second reason for the airspace is to allow the flue liners to come up to temperature w/o having to bring the surrounding masonry up to temperature, so less creosote will build up, and the surrounding masonry will not get as hot. Oh well.

FWIW, in the course of building this house, I have discovered several "best-practices" that I want to follow but find that they just aren't feasible. For instance, you're allowed to slant a flue liner (and many fireplace designs have this), but what keeps the flue liner in place when it has 1000 pounds of flue liners stacked on top of it? BTW, when flue liners get hot, do they poke up higher out of the chimney?

I promise to report back on this topic after building a few fires in the fireplace. It's probably wise (for any fireplace) to bring the fires up to temperature slowly.

-Thomas

March 4, 2008 at 10:39 AM  
Blogger oldmilwaukee said...

Tom,

Thanks. I think the key is using natural materials and just taking it one step at a time... not necessarily any profound skill. I think almost anyone could do it if they had the time. Professionals can do it in a lot less time. I wish I had more time or skill!

Chris,

The shorter answer to your question would have been... you are right, what I am doing with the cement around the flues is not recommended by most references on the subject. Ceramic paper would be insurance against the differential expansion of the flue liners vs. the masonry surrounding them.

March 4, 2008 at 7:29 PM  
Blogger oldmilwaukee said...

OK, here's another way to maintain the gap between the flues and the masonry...

I have a friend who told me today that he built his chimney of cinder-block, with flue liners inside. He wrapped the flue liners with cardboard, then filled the space between the cardboard and cinder-block with brick. Presumably the cardboard will some day catch on fire and burn out (if it hasn't already), but this does not seem to bother him at all because he has a layer of brick and cinder-block between the cardboard and whatever abuts his chimney. Hmmm. Interesting approach - but I doubt you could ever get an inspector to sign off on putting flammable material in the chimney, so I'm not recommending it - I just think it is clever.

March 5, 2008 at 5:17 PM  

Post a Comment

<< Home