Wednesday, January 30, 2008

Traditional Roofing Magazine

Joe Jenkins, author of "The Slate Roof Bible," publishes a nice magazine called "Traditional Roofing Magazine." His book is awesome, so when he asked me to write a short article for his magazine, I was honored to try. To my excitement, the latest issue of the magazine (with my article) arrived in the mail last week. (I can't help but to think of the scene in "The Jerk" when Steve Martin gets his name published in the phone book.)

Joe Jenkins makes .pdf's of his magazine available for free on is web site, so if you're interested in the story of our slate roof (or of other slate roofs!), you might want to check out his rag... Traditional Roofing Magazine. When you get to that page, you can browse all of the articles in that issue or jump straight to my article.

Saturday, January 26, 2008

Flashback to the Rock Pile

All of the stone for our house has come from our farm. Most of it was "free stone," which around here manifests itself as nice rectangular chunks. In other words, I picked it up from the ground, out of the creek, and from the hillsides where natural erosion and uprooted trees uncovered the layers that had been hidden for millions of years. One day late last summer, I decided to be more deliberate at my attempt to acquire some of this stone.

I began my experiment by choosing a neglected corner of a pasture where I thought I might like to have a small pond and where I was fairly certain that several layers of stone lay within 4 feet of the surface. Even though the grass barely grew in this location, I was careful to stockpile (with a backhoe) all of the top soil I could before digging into the subsoil. In case the pond didn't hold water, I could reclaim the hole by filling it up in reverse order... rubble, subsoil, then topsoil. After digging about 4 feet down, I hit a layer of stone which I carefully uncovered and swept with a broom. Most self-respecting pond diggers would utter a series of expletives upon discovering stratified rack at the bottom of their pit (it's a notoriously leaky foundation for ponds), but I was thrilled. My initial goal was to get as large of slabs as possible... since you can always make them smaller. I cut a rectangle in the stone with the Stihl chop saw, careful to note where the natural cracks in the stone bed already existed. Then with much anticipation, I pryed my first bit of stone free from the ground.

Cutting stone with the saw was noisy and dusty, and the exhaust from the saw lingered in the shallow pit with me when the breeze died down. At one point, I could feel the fumes or Carbon Monoxide getting to me, so I climbed from the pit for a breath of fresh air. As my mind cleared up, I remembered that local history is littered with stories of well diggers who suffocated from gas in the pits they were creating... and of more stories of the would-be-rescuers that succumbed in the pits as well. Whereas they had the innocent, if not ironic, misfortune of discovering natural gas, I was creating my own pollution and could do something about it. I made a mental note to run the saw as little as possible and to wait for a strong breeze. If my body decided to take a dirt nap in this pit, it would be midnight before anyone came looking for me. Although more labor intensive and less precise, using the spud bar to exploit natural cracks in the stone became my preferred method of liberating the stone.

Much to my disappointment, due to natural faults, most of the chunks were not coming out of the ground as large as I had hoped. I was really searching for large monolithic material that could be used for window sills and book shelves (rarely do you find it laying in this condition on the forest floor). But I had expended tremendous effort to create the hole in the ground, so I pressed on. I knew that I would be able to use this stone somewhere and I wanted to finish the experiment. If nothing else, these stones were unique (among those on our farm) for their thin yet consistent thickness. I could probably use them for stone flooring, if not inside the house, then at least for patios and walkways.

I manually wrestled quite a few stones from each of the layers until I reached the lowest layer. Beyond this last layer, I could find nothing of value. From there on down it was a mixture of hard-packed blue shale and clay. Useless for my building purposes, but harder than even the stone for the backhoe to dig through. I persisted through about 18 inches of this stuff, before I quit probing. Bummer... I had hoped to find more layers of stone to reward the work I had invested in removing the "overburden." At least this blue clay/shale makes a good pond liner.

With mixed feelings about the results of the experiment, I proceeded to remove the rest of the stone with the two foot bucket of the backhoe, wasting very little time to preserve large chunks. What I got from the final hasty backhoe process was rock less suited for flooring, but still usable in stone walls if faced or shaped with a chisel. In fact, the thin stones earned in this gamble have been proving very useful in composing the dry-laid puzzle that forms my fireplace.

To summarize, my previous experience of unearthing thicker rock from a hillside was considerably more productive than this attempt at digging thin stones from a pit. I invested about ten hours of equipment time ($40/hr x 10hrs = $400) and two days of hard labor (priceless), for which I produced about six tons of usable stone, with a new watering hole for my livestock as a positive byproduct. No doubt a life enriching experience, but my first preference will always be to look for rocks that have been exposed by natural forces.

Friday, January 25, 2008

Brick Tricks (Fireplace VIII)

Yesterday, the mason started on the brick arch that will line the ceiling of the wood cook stove alcove. Other than a few of the firebrick in the firebox, I've left all of the brick laying up to him. I thought I would show his nifty secrets in this blog posting. First the form... it was his brainstorm to use masonite to line the arch. The 1/8th inch peg-board can be found at just about any hardware store, and it bends easily. It's lightweight, strong, and is full of holes that you can run drywall screws through. When we're done with the form, he's going to use the masonite to hang tools in his garage, so you could even say that it's recyclable. This form is actually two forms in one. Because the brick ceiling will be two inches higher than the stone facade, the bricks must span 48 inches, while the stones will span only 44 inches. The mason cut 2" off of the height of 2x6's in order to incorporate the smaller stone form into the larger brick form.

Earlier that morning, we stopped at the farm store and picked up 50 feet of 3/8" rope. After the form was in place, the mason proceeded to cut the rope into 20" strips. He then laid bricks edgewise on the form, using the rope as gauges to keep the bricks evenly spaced. I then cut some 7/16 plywood shims that he pushed into to cracks between the tops of the bricks. The wooden shims helped keep the bricks in their proper orientation. Before mortaring anything, the mason laid all of the bricks on the form. It's a good thing he did a dry run, because he discovered that the spacing wasn't going to work out perfectly. No worries though -- we decided that by turning the final course of brick sideways, the spacing did work out. In fact, bricks turned in this fashion matched the spacing for the light box that had to be mortared in at the top of the arch.

After he was satisfied that everything would work, the mason filled his grout bag and started mortaring the joints. He looked like a persnickety baker putting the final touches on an elaborate wedding cake, pulling out the wooden shims as he went. After I cut and place the stone arch, and after we have the next 24 inches of flues in their proper places, we'll pour concrete over this brick arch. A day later, we'll wreck the forms and pull out the rope spacers from below. Then the mason will tuck-point the joints with mortar and make everything look neat. Finally, the 6th and final arch will be finished.

Thursday, January 24, 2008

Rumford Fireplace Part VII

Each day we plod forward on the fireplace project. I can get really fired up in the morning and think that I'm going to get a lot done that day, but it never seems to turn out like that. So, I just chip away every day and progress happens slowly. I'm excited to be done with 5 of the 6 stone arches that will be contained within this structure. I think I'm getting better at it, but it still takes about one day to design and cut an arch, regardless of the size of the arch or the number of stones. This first picture shows (from left to right) "the pizza oven arch," the "great room wood storage arch," and the "Rumford fireplace arch."

In this picture you can see that we've reached an elevation of 5 feet 2 inches, and poured the interior volume of the stonework with concrete again. It took 36 bags of quickcrete and two bags of portland cement, plus some sand and stone chips (I have plenty of stone chips!). All totaled, I think we poured about a cubic yard in this last lift. I am somewhat amazed that the stone walls don't blow out when we pour the wet concrete inside of them, but we are careful to keep the mixture thick and do not use a vibrator.

The pizza oven is going to get very hot and expand when fired to 700+ degrees (mmmm... 3 minute pizzas!), so there is a danger that the oven could push and weaken the concrete and sandstone around it if room for expansion is not built in. For a while, I was puzzled at how to maintain a compressible layer of fireproof insulation around the pizza oven. I considered using fiberglass, since it is not flammable, but I read on the internet that it contains some kind of binder that can give off gas when heated. Perlite mixed with cement is not as compressible as I first thought when I started this project, so I didn't trust it for this application. Loose perlite is very compressible and has a much higher insulation value than perlite mixed with cement, but how to get loose perlite to stay in place while pouring concrete around it? The stonemason had an idea of parging a wire-mesh armature surrounding the pizza oven, being careful to leave a gap into which we could pour perlite. I liked his idea and ran down to the farm store to get some wire mesh. When I got back, we came up with a better idea - line the wire mesh with aluminum foil and pour the perlite into that without parging anything. It worked great. Where ever the perlite leaked through the aluminum foil, I poured water on it and it stopped flowing out the leak. As we poured concrete against the perlite insulation, I ran my hand down into the insulation and made sure it was at least an inch thick everywhere. By the way, use a dust mask if you work with loose perlite. Unlike vermiculite, it does not have trace amounts of asbestos so up to this point I had considered it somewhat inert, but it is very irritating, and possibly harmful, to breath the dust that inevitably comes from working with it. Put the mask on before you start coughing!

The rumford fireplace kit came with a cast iron damper and a clay smoke chamber to place on top of the fireplace throat. The two-piece smoke chamber appears to be two normal 16x20 flue liners (if a 16x20 flue liner can be called normal!) that have been cut so that when placed together they form a smoke chamber which tapers from 36x16 to 20x16. (the height is about 19") The factory cuts aren't perfect, and could be made more perfect with a grinder or chop saw, but the stone mason and I said "heck with it." We assembled them as tight as we could which left a gap that varied from zero to 3/8ths of an inch. (3 years ago, this would have drove me nuts!) We will be pouring concrete around the smoke chamber, so even if the fireclay mortar cracks and falls out of the seam, no smoke should ever be able to escape.

I took this last picture from above the fireplace. It shows the cast iron damper that the mason mortared into place before we placed the smoke chamber above it. The 8.5" x 8.5" flue at bottom left is for the wood cook stove and the flue at the bottom right goes to the basement in case I ever put a furnace there. Ideally, there would be a little more separation between these flue liners (and there will be further up in the chimney), but it wasn't possible to separate them at this point.