I’m sure everyone remembers the adage “measure twice and cut once”. Its purpose was to stress the importance of correct measurements. The Inca’s, the Mayan’s, and the Egyptian’s must have thought precise measurements were very important. The builders of the great cathedrals also knew that all measurements had to be accurate. The beauty and longevity of these structures prove how important precise measurements truly are. We have progressed tremendously from the most rudimentary devises. We have come from using body parts in repetition, to standardization, such as cubit, rod, and square. In my lifetime, we have progressed from the use of water levels, plumb bobs, and steel tapes, to the use of transits, building levels, retractable single-user measuring tapes, and on to lasers and GPS. Yet, we still can’t seem to get it right.
All of our materials have built in tolerances. Our measurements also have some allowable variations. As an example, masonry is considered ‘PLUMB’ if it is within ¼” in 10’-0”. The wood industry is so detached, they prefer not to deal with tolerances. Locally I know of wood framed buildings that are as much as four stories high, and 2” to 6” out of plumb. As for light gauge steel and structural heavy steel, many installers believe everything is fine as long as the structure stands when bolted together and doesn’t fall over. Do not let the iron workers install shelf angles. They just don’t understand level and plumb as necessary for a masonry installation.
Masonry contractors with our unyielding tolerances, some as small as 1/16”, have to work around, within, and over some of these framing systems. The concrete folks have larger tolerances than masonry, even when the masonry and concrete beams, columns and slabs are tied into the same wall. The slab edges frequently wander, the footings are wavy, the columns are twisted, and the beams wobble around. However, the masons are expected to bring it all together as a finished wall. A CMU corridor wall with wall washing light is expected to have no shadows. Drywall can’t do that and it comes in sheets, not hand placed individual units.
We give plumbers and electricians a 5 ¼”X 5 ¼” core opening in the CMU’s to get their PVC and conduit in, and yet they cannot seem to get it into an 8” wall. They wonder why we get mad when we have to thin down the face shell of the CMU. DUH!
Come on back next month and we will discuss who has the responsibility to get it right the first time. Until then, measure twice and verify, verify, verify.
Raise the line and come on around the corner!