What’s that smell? I worked in one of the first planned ecologically correct communities done by the Controlled Environment Corporation, a collaboration of Dartmouth College, The Society for the protection of NH Forests, and a couple of financial institutions that have been renamed so many times they don’t deserve mention. It was called the Eastman Community comprising land in Enfield, Grantham, and Springfield, NH. It was the mid seventies and better building products through chemistry was in full swing. Cabinets and carpet underlay were made with particleboard which was essentially sawdust doused with urea-formaldehyde. One had to air out the rental units before showing them because of the burning formaldehyde in the air. And we thought this was business as usual! Shortly after that, Borden, and a few other intrepid chemical providers (and you thought Elsie the Cow produced only milk?) came up with a shaving cream consistency urea-formaldehyde home insulation that could be injected into wall and roof cavities to provide superior insulation. Just then the oil embargo of the early seventies hit and we were off to the races. Poly on the outside (or aluminum foil under the vinyl siding) and urea-formaldehyde inside. I was told by my boss at the home manufacturing facility where I was working to look into it, but to be wary of the word on the street which was “shrink and stink”. Prescient to say the least. A call to Borden got some enthusiastic reps to the plant who would foam up a demonstration panel for me. I said, “Let me test it in our environmental test facility before we sign up for production.” I took the panel to the south side of the barn and leaned at the appropriate latitude inspired angle and screwed a cover sheet of plywood over it. The mixture shrank away from the stringers initially- I was told to expect 3% and got it. But the mixture of good and bad news was that it continued to shrink linearly over the next year. So the bad news was that it was out-gassing formaldehyde in quantities that could be irritating, but the good news was that in thirty years it would be all gone! Talk about a zero sum game- but you would have to fork out $3500 to save a little on the next winter’s heat bill, and open the windows to be able to live inside. Other points for the day:
- If you are going to use a “No VOC” product, make sure it has the performance necessary for the application. We can’t think we are saving anything by putting on a coating that will peel off in six months and have to be re-applied: all those trips to Home Depot, puttering about with ladders and brushes and brush cleaner can amount to more damage to the environment in toto than a carefully applied, long lasting product containing VOCs.
- Avoid those VOCs that are not or do not have a progression of oxidation into naturally occurring products. Formaldehyde is formed in outer space as well as by chemists on earth! CH2O is a pretty simple molecule, smelly, but ready to be oxidized.
- Take a look at the list of compounds on the global warming potential list. CO2 is the benchmark at 1, while some of the Freon’s can rank in the 10’s of thousand times worse. Interestingly enough, Sulfur Hexafluoride, used as a tracer gas in sophisticated building air leakage studies is 32,600 times worse over a 500 year period than CO2. Think twice before you squirt! I always thought cigarette smoke or an extinguished match would do for a ventilation test, and then of course there is the ultimate test of the bath vent, a sheet of toilet tissue lofted near:
- It’s not rocket science!
Green side up. I reminded myself of the old sod installation story a few days ago and in searching for today’s topic I thought outside the box, or building, as it were. That pristine, natural site we have disturbed to create a building or home. What obvious wisdom can I impart today, (aside from the green side up when putting in the sod)?
- Slope away from the building. How many foundation grade lines have I seen below the roof drip and exterior existing grade lines? Too many. I have seen property with slabs on grade seeping at the sole plate from rain and surface water that was ponded around the building. We are not building boats, thank heaven, or many properties would have floated away like so many manufactured home parks built in flood plains. (It is somewhat counter-intuitive that the disaster assistance funds are used to rebuild the parks in the same flood plain!)
- Keep expansive and frost prone fill away from the foundation walls. Backfilling with clay will lead to cracked or buckled concrete walls.
- Remember the landscaping plants will grow. Putting an oak next to a building or sidewalk is great for the first 20 or so years and then the roots and trunk wreak havoc with the work in place.
Factories. Assembly Lines. Manufacturing Systems! Quality Control? Continuous Improvement? Feedback? Transportation Cost. Bulk Materials. Cookie Cutter Design. Lots of hot buttons and points to ponder when you talk about creating our dream home in a big old factory.
I used to run a company called Yankee Barn Homes, may it rest in peace, another casualty of Wall Street not Main Street stimulus. During my tenure there, literally rebuilding the facility from its ashes I discovered a few things about manufacturing and manufacturing homes:
- If you think about the sequence of construction and what materials will need to be where and when, you tend to minimize a lot of standing around time waiting for the GC to get back from the hardware (after stopping for the obligatory coffee and fixing the world’s problems) with those washers you need to keep the support rods from pulling through the sky bridge over the lobby. If you read Profit Beyond Measure: Extraordinary Results Through Attention to Work and People about the Toyota manufacturing process, you can learn lots that can be applied to any manufacturing process. Get the pieces to the right place at the right time, with the right people (electricians and plumbers don’t have to bore the holes for their wires and pipes) and you will profit.
- “When was the last time you saw a Volvo manufactured in a field in Sweden?” Weather ruins much, and has been know to preload materials with enough moisture to cause problems down the line; and the corollary, could you pick up a stick-built home and drive it down the Interstate at 75 m.p.h. and not have sticks all over the road?
- Waste is intolerable when you have to pay to truck it away. Any manufacturing line that accumulates piles of items that are usable somewhere else will be refined. It costs too much to dump things, especially construction materials. We used the plywood window cut-outs for the roof panels. Scrap is defined as smaller than the smallest necessary piece. Finger jointing is cheaper than the dump.
Now that’s a mouthful for a Wednesday morning, geotechnical, or soils mostly has to do with the first line of defense keeping buildings against gravity. Know your geotech and build your house upon the rock, sometimes literally. Ignore it, or assume, and you end up with the Leaning Tower of Pisa, or worse. For instance, in many areas of the country, the underlying clay soils expand (a lot) when wet: foundation irrigation under the building is the only way to build, and better get them away from the exterior walls or they will be cracked like a lobster. And where are they? Check out this map, pretty random pattern.
So what common sense can we apply:
- Know what you are building upon, I have seen buildings on old landfills that had sunk 4″ in the width of an apartment. I have seen a six by six jacked 18′ down into an old stump dump. I have found shingles 6′ down on a sandy point. So it’s not just Love Canal anymore, if it has a questionable past don’t ignore it. I have seen a warehouse built on a peat bog where the slab, at the time, was 18″ thick, because every time it sank, they placed another layer on top- kind of like looking at the sedimentary rocks along the interstate highway cuts.
- Test. Test. Test. But remember, until the entire excavation is done, you can not breathe easily. I say a quarter acre lot where they dug all four corners and the middle to eight feet with no refusal (our way of saying we didn’t hit a big rock or ledge- a.k.a. mother earth), and yet there was a huge ledge cap with a six foot crack in the middle of the lot!
- Water changes everything- what feels firm underfoot when dry can turn to soup or worse when wet.
Getting plastered can have positive and negative connotations. I won’t deal with the latter cheap shot, but as we have completed our building foundation, frame and mechanicals hanging sheetrock is the harbinger of building finish! Exciting stuff, only two weeks to completion, (two weeks is a highly evolved spacetime concept used by general contractors when asked how long a project will take- “Two weeks, two weeks. You sound like a canary!” [watch The Money Pit, you will understand]) So what does an engineer have to share about Gypsum Sheet Rock (GSR).
- Know your gypsum. The Chinese high sulfur GSR mess happened because everyone thought gypsum is gypsum. There used to be asbestos in some veins or added purposefully to strengthen joint compounds.
- Use the appropriate facing for the application. Since common sense is so uncommon, manufacturers are trying to develop a “one size fits all” fiberglass faced product for use everywhere. The greenboard works for wet location, although cement board is the material of choice for shower and spa backer board. Paper faced will work in all other locations–if you control moisture migration. That is a big if, and subject of learned tomes like my friend Lew Harriman’s ASHRAE published guides.
- Green side up. My mentor, Emil Hanslin used this phrase to explain in simplest terms how to lay sod. I have seen building complexes where the gypsum stucco backer was installed with the wire lath inside while they tried to plaster the backing. Not a pretty site or sight.
Conserve, combine, create. That is the hierarchy. Why is it so difficult to adopt this attitude? Dawkins and Dennett, two authors of evolutionary tomes ask the question when a new species has developed: “Who benefits?” . A friend asked, “Why is it so hard to make conservation of resources a way of life”. Short answer: because the non-use of something is hard to market, the answer to the “Who benefits?” question; and because we have yet to establish a “meme”, a piece of cultural DNA that will float through our societies and reproduce prolifically, the Nike “Just do it.” moment. I used to say “we conserve energy, because it is the right thing to do”. No reproduction to my knowledge.
- We have to see ourselves as a system. Our activities are a direct result of our forebears and will influence our heirs. A pump manufacturer said to me once, “We are pretty great at understanding pumps from flange to flange, but we need to expand that.” Building fluid networks are a system that includes the pump, but is not just the pump. So is our generation on earth!
- We have to look at conservation as saving our species, not the planet. The planet will be just fine. I cut my thumb, it hurt, it will heal in about two weeks, and little evidence of it will be there next year. Mankind, in proportion, is cutting the biosphere in a smaller slice than on my thumb, and will heal in less than 1o,ooo years, far less than my 1/70th of my tenure. (Watch “Life after Man”, the National Geographic movie! Our activities are of little impact or duration, except to ourselves.)
- Look to where small changes can redirect large consequences: Malvina Reynolds was singing about the faucets that drip in New York in 1962 in Town Hall, today we are running out of fresh water! Take responsibility. (GK Chesterton responded to the question posed by the London Times at the turn of the 20th century, “What is wrong with the world?” with a simple “I am.”. Tom Shadyac made an eponymous movie about that, and the solution? We are!
I was privileged to meet Buckminster Fuller in my grad school career at Dartmouth’s Thayer School of Engineering and listened to his random musings and wisdom. I still recall his dicta when it came to structural engineering: no structural engineer was ever sued because a bridge or building was too heavy, but mechanical engineers have do design airplanes that will actually fly; and, if you want structural analysis, give some shapes to a three year old and watch them manipulate them, they will get to know that anchored triangles are the simplest self supporting structure– then build on the triangles!
- Indians knew their tepees and lodges would work with posts in the ground and connected at the ridge or apex. We westerners adopted that in the A-Frame and the Cape. The Cape roof is a marvelous triangle, anchored at the eaves to the second floor joists, and compressed along a ridge board at the peak. Then came the bad old days, which I attribute to carpenters who knew the rules being killed in the Civil War. The builders forgot the triangle and tried to get more headroom in the second story. Knee walls. Unreinforced with strongbacks or hammer braces were lofted above carriage sheds in the Victorian era. Every one of them is swaybacked on the ridge because those knee walls are pushed outward.
- Collar ties. So we want to triangulate those rafters and are sure “a collar tie or two on four or eight foot centers will pull the walls back in”. First of all you are trying to resist a moment at the short end of a lever, and second, you are applying a bending moment to a point where the rafter is already at designed maximum bending. Not a pretty sight. Ridge beams to eliminate the bending or designing the knee wall studs to cantilever and the top plate to act as a beam will do. Better think about it and ask for help.
- Cantilevers: when we carry a beam over multiple supports, or to float a load in space we are cantilevering (horizontally, usually in the case of pop out closets and windows; vertically in the case of the above mentioned knee walls). This bending moment becomes obvious through failure when we see an old mill building with beautiful first growth southern yellow pine beams (Pinus palustris, long leaf yellow pine, used for ship’s masts and warehouse buildings. I salvaged hundreds of thousands of these timbers for recycled post and beam “Yankee Barn Homes”. A truly magnificent material, we would see 30 growth rings per inch where a modern yellow pine has 3 or 4, and they would still smell of turpentine when resawn; drive a nail in and it would break before it could be pulled), which are coming apart halfway between top and bottom: excessive moment from cantilever bending shears the top and bottom halves.
The Ides of July! Beware moisture! It’s not just March with Ides. During the hot summer months, thoughts of condensation are not always with us, but our life giving Aitch to Oh (H2O) can come into view in awkward places where warm moist air comes into contact with cold surfaces. Before we start just a quick commentary on the difference between water and water vapor. We sometimes think that what we see rising off a pond in the morning as water vapor, the white plume from the teapot, or clouds- if you can see it, it is water drops, water vapor is clear. Most important, water vapor does no harm- it is liquid water of which we are to beware.
- Avoid overall humidity analysis- it is at the exceptions the problems arise- when a channel of uncontrolled air hits the cold surface you have a problem, especially if that cold surface is sheet rock paper. Mold needs three things, spores (which are practically everywhere-note the Kurds in the desert making “sourdough” bread by leaving a pan of flour and water in the open for a few hours), liquid water, present through our poor planning or analysis, and food: cellulose is choice, although good old household dust can be quite nutritious.
- Remember that heat transfer is orders of magnitude faster during evaporation and condensation: a heat pipe is that because of these phenomona- moisture issues are huge heat highways.
- If you don’t ventilate you will suffocate and compost your structure. Cooking and bathing are prime culprits. Recirculating stove “vents” are the bane of the building scientist and fodder for forensics!
Happy Bastille Day, also brother Bill’s birthday-big celebrations for him in Paris every year. I was going to call this Concrete Commonsense but it seemed redundant. Concrete, that Roman miracle of burned limestone that enabled the Pantheon to stand with the largest masonry dome in the world for 2000 years is truly gravel superglue. That being said, what more can I add?
- One never “pours” concrete, one “places” concrete. If it is so soupy that it “pours”, it is too watery to be strong. Adding water has to be precise, because the mixture is one of cement (often used incorrectly to describe, synechdotally, perhaps, the whole compound; and yes it is a compound, not a mixture, where the water has to be precisely enough to hydrate without extra to make it too slippery, or as aforementioned, soupy), water, and washed sand or gravel. If you don’t get the mix right, you will have cracks and breakage. And let it cure properly, usually in a 28 day time frame (there must be a parallel with rehab programs there, but I won’t touch it here!). Sun, rain, and uneven evaporation (particularly caused by those pesky “vapor barriers” of poly under) will curl the final product.
- Wash your sand or gravel. I have seen large lumps of sod and dirt in finished concrete walls when the forms were stripped, how embarrassing. Avoid cold joints, if you schedule your placement around noon, and the driver for the second load stops for lunch you may spend a lot of time grouting, or worse, re-“placing”. I have seen 40′ gravelly seams across the back of a basement wall- fortunately not a retaining wall. (And if you are using your basement wall as a retaining wall, design it that way! Spend the money on a structural design with all that #5 rebar, counterfort footings, and 30 times the diameter laps.)
- Formwork is where the money is. I remember Doug Gay, a local hero concrete man discussing having to “get physical” with the formwork in complicated multi faceted designs. Each corner adds a minimum of 3% to the overall cost (and that runs right up through the building, and no, that does not mean that a round building costs 12% less). Rectangular foundations are what is to be expected, everything else is optional- and those 30 degree angles can be the bane of construction progress and commonsense! Allons enfants!
Mark Kelley, a partner at the Hickory Consortium formed under DOE’s “Building America” program was one of the first mechanical engineers of my ken who started the mantra of “looking at buildings as if they are systems”. As if! Of course they are, as Hafiz pointed out in the 14th century, (paraphrasing), “you will finally understand what every atom and universe understands, when one of us wiggles, we all wiggle.” I used to design jet engines. And yes, today, I am happy to fly with those engines keeping me in the air. Everybody knew that a jet engine was a system, that you could write an equation for the airflow and fuel supply and determine the thrust and then optimize the fuel consumption for a given thrust. But for a building? For the energy related parts a resounding “Yes”; and you could write it so that you could optimize the cost of ownership. Who knew? Better to ask “Who knows?”.
- Today we call the practice “Building Energy Performance Analysis”, BEPA (gotta love those acronyms). Usually we use some type of spreadsheet to do the dirty work of equation formation, but when we are done we can “simulate” the building performance before we build it.
- Using this tool, we can make trade offs for insulation thickness, window quality, mechanical system type, fuel, and efficiency; as well as exterior shading (trees!), orientation to the sun, window size and configuration, and so forth and arrive at an “optimized” design.
- But remember, and this is the commonsense part: The building is not the model, and doesn’t even know about the model- it will perform as it was built. It is up to the construction delivery team to build and verify that the model design intent was executed properly. Henry Gifford has said that the building performance awards so proudly displayed in the lobby should be attached with screws that will allow removal if the building doesn’t perform according to the model predictions. There have been too many examples of buildings not performing as designed, not having equipment as specified, and just plain not even having the equipment installed to corroborate Mr. Gifford’s reservations. For example, we used to think that R-19 insulation in a wooden stud bay gave an R-19 wall. Tests have shown that between the conduction through the wood studs, gaps where the insulation doesn’t touch the studs, and air leakage that we are lucky to get the equivalent of R-11.