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September 2012
Utah's Art Magazine: Published by Artists of Utah
Page 6  
A bungalow style house in the Westminster Heights area of Salt Lake. Photo by Jared Christensen.
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Architecture & Design
Stone Timber and Steel
The Logic of Structure


Standing on the tee box of a local golf course I saw a peculiar sight. A nearby house sported a second-storey deck, clearly a cantilever as there were no support posts, and rising from its corners to carry the safety rail were two stone columns.|1| The carpenter side of my brain kicked in: “Those must be steel or timber posts clad in faux stone, they’re far too skinny to pass the Drunken Allen Test.” My partner Jeff and I have jokingly applied this rule for decades while repairing yet another failed deck rail: got to make the connections strong enough that Allen could lurch his 230-pound frame into our product without going through it like a Hollywood stuntman.

It was only later that I was struck by the inherent silliness of placing a stone structure, any stone structure, floating by itself on the second- storey. Since frame construction has come to dominate housing and light commercial building, materials once used as structural components have been reduced to decorations, applied as siding or embellishments with less and less thought given to their original structural roles. As I started looking for these architectural non sequiturs they popped out like spring mushrooms: second-storey stone dormers,|2| massive timber columns supporting tiny entry porch roofs; constructs no self-respecting mason or master carpenter would have considered sixty years ago.

Builders in the Craftsman era reveled in their use of materials, cobblestone foundations and broad tapered porch newels, timber trusses and deep wooden beams;|3| they wanted to display their structural thought process. As aesthetically pleasing as this style can be, it’s also pretty spendy. And as the nail gun replaced the well-swung hammer, master carpenters gradually were replaced by nail-gun operators. The structural rules of thumb once passed down from master to apprentice faded as the masters retired, and we are left now with timber arches spanning openings in stone walls.

Why shouldn’t you span an arch with timber? Why doesn’t a 6-inch column look right in the middle of a 2-foot stone base? The answer lies in the physical properties of the materials.

An overview: Stone is heavy, resistant to rot and oxidation, weak in tension and strong in compression. Timber is light, vulnerable to rot, and possesses considerable tensile strength. Steel is heavy, vulnerable to oxidation, and hugely strong both in tension and compression.

Obviously, stone is an ideal material for foundations. The more you load it, the stronger it gets, it won’t rot, and the bugs won’t eat it. As the Plains Indians said, “Only the stones last forever.” Its low tensile strength makes it less useful as a beam to span openings, but masons long ago devised the masonry arch as a practical and visually pleasing workaround. This assembly redirects loads down and sideways along the compressive paths around the opening. This loading places all the involved stones under compression and can actually increase their individual strength.

Timber’s greater tensile strength allows it to perform well as a true beam, transferring loads from the center of a span to point loads at the sides of the opening. Picture a timber as the proverbial bundle of sticks, gaining strength through the multiplication of many relatively weak members. The “members” here start out as thousands of cellulose tubes in the cambium layer, the living outer sheath that conveys water and nutrients to the tree’s crown. Each year the innermost layer dies and solidifies while the tree adds a new layer on the outside. We count these layers as rings on the stump of a felled tree.

This cross-section of the tree, which shows the “grain” as rings, is the hardest and is fairly resistant to crushing; the sides of the trunk, which become the sides of the timber, are far softer. When you lay a timber horizontally to form a beam you concentrate the load on small sections of these softer sides, which will crush if not sufficiently large in area. While timber is well suited to carry the vertical load of a living crown, it is also designed to flex under lateral loads. Trees that are too rigid break when the wind gets high. Timber columns must either be thick enough to resist this natural tendency to bend or need proper bracing. A single 2X4 can carry thousands of pounds, so long as it is prevented from bending under the load.

Steel can be used for almost any structural need, so long as it is kept out of the weather or coated to prevent rust. It is often used in modern structures for columns, beams, roofing and siding, but not commonly used in the sort of traditional style buildings that so often violate proper use of stone and timber. We see it most often in the gusset plates connecting larger timber members.

So the basic rules of thumb? Stone belongs on the ground or on top of other stone. Masonry chimney “stacks” can obviously raise two or three storeys so long as the footprint at the bottom is large enough to carry the apparent weight. Stone or masonry columns must start with large enough footprints to carry their apparent weight without “post holing” down into the earth. While they can taper, they need to maintain enough cross section to resist lateral loads and thrusts, to which their low tensile strength and rigid mortar joints are vulnerable.

Wood columns that rest on masonry columns should have the largest practical footprint in order to place all the base stones or bricks under compression thus increasing their strength, both individually and as an assembly. Timber columns should be thick enough to resist bending under their loads but not so thick that they suggest a wasteful carpenter. Wooden beams should appear to be deep and broad enough to resist deflection (bending) under their loads and rest on large enough beam pockets or columns that their bearing surfaces don’t crush over time.

Steel gusset plates are so much harder and stronger than the timber members that they connect that their main structural consideration lies in the placement of the bolts that tie them to the timbers. Any bolt hole drilled through wood severs the fibers, or “grain.” Loads placed on these cut fibers can tear them out, particularly close to the end of the timber. The old rule of thumb was to place them at least seven nail or bolt diameters from the end of the wooden member.

The sum of these rules is nicely demonstrated in the typical two-storey masonry house of the turn of the nineteenth century, the kind commonly found in Salt Lake’s older neighborhoods, like the Avenues. Rising out of the ground on a large block sandstone foundation, the brick walls extend to the eave lines of its roof slopes.|4| The roof and gable end wood structures place the brick walls below under compression, lending strength to the upper courses which otherwise would be unloaded and fragile. The bottoms of window openings are dressed with massy stone sills (to place the brick courses beneath under compression); the masons show off their artistry in the brick arches that span the window openings at the top.|5| The front porch roof is supported by wide wood columns, which terminate either on broader masonry columns or transfer their load through the floor framing to the sandstone foundation below. The beams spanning between columns appear to be at least 12 inches tall and 6 inches deep.

Other examples of the authentic use of traditional materials are on display in the Westminster Heights neighborhood above Westminster College. There, several Craftsman-style homes built in the 1920’s and ‘30s recapitulate the bungalow style, with overhanging roofs that cover the front porch, and deep eaves on the gable end sides of the building to add shading and weather protection for the shingle siding.|6| These houses most commonly are frame construction resting on cobblestone foundations, with robust timber brackets to support the barge rafters of the deep eaves and broad tapering cobblestone or wood columns that rise to the beams supporting the porch overhangs.|7| Often a tapered cobblestone chimney stack will embellish one gable end; the final impression is a composition in functional structures and materials.

The contrast between these authentic buildings |8| and the new, faux traditional, business that I pass every day on my way to work strikes me every time. This building is stone clad, but the stone siding covers the gable end to its peak. Were the stones actually structural, those running up the rake and at the apex would be relatively unloaded, not locked by weight into the structure and easily loosened. Two-piece timber arches span the windows, joined at the peak by small steel gusset plates. To cut these curved shapes out of straight timber would have cut every fiber of grain, and placing weight on them would have split the cut fibers apart, assuming that the bolts attaching the gusset plates at the top of the arches didn’t pull through the end grain first.

And just to confirm that the bold elements applied to the building were false, the 10-foot-wide car passage through one stone wall is spanned by what looks like a deep timber arch. The curve cut in this arch is deep enough so that in the center, where bending forces would be greatest, the timber has tapered to a mere 5 or 6 inches. The ends of the “beam” are, in contrast, so massive that they could support a timber spanning twice the opening, were the beam of even depth.

This all may seem like quibbling, the stones and timbers used are attractive enough, if you ignore the lies they are telling about their functions.|9| But the structures are built to last, and for the next fifty years or so no competent builder or architect will glance at them without at least a snicker.



Hints & Tips: Plein-air painting
5 + 1
A recipe for critiquing your own paintings



Critiques are interesting animals; some are big and hairy while others can seem small and cuddly. Like judging in an art competition, they are all dependent on the artistic paradigm of the person doing the critique. Sometimes the best critiques are the simplest ones, like when my wife Teresa walks into my studio and says, “I love it!” as opposed to, “It’s nice.” I can usually tell right then and there the painting is going to be snapped up right away, rather than sitting on a gallery wall for a while.

There are two basic categories of critiques. A simple expression of how eye-catching a piece is, like Teresa’s critique above, is a good indication of a piece’s salability. I call these critiques type B. Type A critiques are more complicated. They are the ones dealing with the aesthetic merits of a painting. For years I wondered what made one painting seem so “right” while other paintings just didn’t have that same magic. Type B critiques, which looked at the whole, were not much help and I would often frustrate Teresa and myself by pressing the issue for more information on what went wrong. (By the way, Teresa is also good at type A critiques, but it was a skill that took years to develop, for both of us - nowadays she can pretty much tell me not only which paintings won’t be hanging around too long, but also give me valuable insight when something is not working in a painting. How good is that!)

My basic problem back in the early days of my work was to find a way to break down the painting process into its component parts and be able to assess a work artistically based on how all the areas come together. I used to devour “how to books,” attend demos and workshops, gallery hop, museum hop, attend critique groups, enter shows and hang around with seasoned artists in my area in an attempt to gain understanding. In my studies, I found that artists all had their pet systems, some quite elaborate, to explain the nuts and bolts of a good work of art. The job was to find a way to approach all this information and distill it down into a format that I could relate to. And one I could use on my own. What I found was that even though everyone had their own way of approaching this complex subject, there were basic fundamental principles that ran through each. The 5+1 system of self-critique is what I finally came up with.
John Hughes discusses the 5 + 1 system of self-critique in his studio. Photo by Simon Blundell.
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Without having a starting place, direction, and a logical concluding point, it is a daunting task to pinpoint what is and what is not working in a painting. Something like the 5+1 system gives you a structure to do just that. The information presented here is nothing new; I did not invent it by any means. The 5+1 system is only one artist’s approach to understanding knowledge that has been around since the beginning. It comes down to five basic areas:

1: Drawing
2: Color
3:Value
4: Edges
5: Brushwork, or Texture.

The Plus 1 refers to Drama. More on that later.

The logical place to begin is where a painting begins: Drawing. The category of Drawing encompasses line, placement, size, direction, composition and design. In other words it’s a category for all of those things related to laying out the basic design of the painting. For some artists this may be quite extensive and for others the drawing might reside mostly in the mind. Either way, at this stage in the critique you are asking yourself, “Are there any problems with the drawing?” Questions like – Are the proportions right? Does the linear movement of the painting flow? Are there annoying parallel lines? Is there a certain amount of oppositional lines for balance? Is there variety in my spacing? Is there variety in size and shapes of objects? Is there a certain amount of continuity of shapes to hold the painting together? -- are a good place to start.

Color – Questions in this grouping might include: Is the color beautiful in the painting? Do I have a balance between neutrals and more saturated colors? Do my colors clash? Do they seem real? Do they portray the mood I am after? Do my colors transition into other colors effectively? Again, not all the questions that could be asked. There are many possibilities.

Value – Is my painting too light or too dark? Do the values seem real? Are they effective? Have I fractured any of my masses by having too many value jumps? Is there a simple value structure to the painting? Are my values representative of the way light behaves? Etc. Etc.

Edges- Are the edges in my painting too hard, too soft? Are my edges juicy? Do they transition well? Do they depict the way light behaves? Are they interesting? On and on . . .

Brushwork or Texture – Is the brushwork exciting? Is it expressive of the things being depicted? Are all my brush marks the same and therefore dull and boring? Am I using the full range of brushwork from a simple wash to heavy impasto? Is there continuity in my handling of the brush? Some of these questions may even seem contradictory, but it’s all in what you want to say in any given painting. Sometimes continuity in your brushwork might be the answer and at other times a little more variety might be just the thing. Only you can decide that, but it either works or it doesn’t and that is what you need to be sensitive to it.

Finally, drama. Drama is that certain something that each painting needs to make it exciting enough to hold the viewer’s attention. It could be a spotlight on the horizon created by an opening in the clouds or just a fleck of raw paint in a strategic place in the painting that captures the eye. Whatever it is, it’s the hotspot or icing on the cake that says, “Look at me.” Each painting needs a certain amount of drama. Sometimes it will be very dramatic and at other times very subtle. But it should be there.

One final word, lest the reader think that a painting can be broken down to a few simple formulas. It’s not that easy, if it were all the mathematicians and accountants would be the artists and the rest of us would be chopping rocks in Sing Sing. It’s the heart, mind and spirit that make an artist, and when they all work together great art can be the result. And when a painting doesn’t speak to your heart or spirit, it’s time to use your mind to figure out why.




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