Saturday, May 26, 2007

Custom stone lintols in less than 24 hours

lin·tel [lin-tl] -noun
horizontal architectural member supporting the weight above an opening, as a window or a door.
Also, British, lintol. (from dictionary.com)

There are several methods for spanning an opening in a masonry wall. Arches are the most elegant, but angle iron is probably the most common. Rather than employ either of these methods, the stonemason suggested that I look for stones large enough to fabricate "lintols." I liked his idea because lintols would do a better job (than iron or an arch) of tying together the columns beneath them. Using the backhoe, we dug out nine of the biggest (longest) stones from my pile of rocks, and carried them to th
e front yard. I laid out the 9 stones and selected 3 that were nearly the same thickness. If we screwed up, or if the rocks just wouldn't cooperate, we had 6 more chances to get it right.

The collage to the right illustrates the sequence of events. The upper left picture shows the stones laid out for inspection the evening before. The next morning, the stonemason's son started pitch-facing one of the stones, and I started on another. The upper right photograph shows the stone that I worked on first. The face looks almost finished, but I had to spend about 30 more minutes on the face of this rock after taking the photo, in order to chisel off all of the orange iron deposits. After the younger mason finished facing his stone, we discovered that it was about an inch thicker than mine, so, using a chisel, he split an inch from it to make it the correct thickness. Fortunately, sandstone splits easily along the horizontal grain. After we made 3 lintols of the same thickness (6 1/2" + - 1/2"), it was necessary to cut them to the proper length and depth. The lower left photo shows the younger mason sawing the lintol to the correct depth (8"). The smooth saw-cut face will not be seen because it will be turned to the back of the wall. The lower right picture shows one of the lintols on the end of the crane, being flown to its final destination above the window.

By lunch, we had fabricated the three lintols (with all six spare stones left intact!) and the mason had set them above the windows. Fabricating three lintols from scratch and setting them in the wall was a big effort, but not a lot of square footage of wall space. Being paid by the square foot, the older mason was definitely not ready to stop for the day! I helped by selecting and cutting stones, and they were able to lay two more courses before the end of the day. Each of these next two courses required special consideration as well. The course directly above the lintols contains three keystones to relieve the weight on the three lintols, and to help hold the wall from collapsing should the lintols ever crack. (admittedly redundant, but it just "looks right.") The next course up has corbels that cantilever 4" out from the stone wall. The course above the corbels (not yet built) will extend out yet another four inches. Every old tower I've studied (in pictures) has a wall that steps out near the top... presumably to avoid the embarrassment of dribbling boiling oil on your walls as you pour it upon marauding Visigoths and other unwelcome house guests.

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