Will Screw Piers Pass Inspection?
I got excited reading about using Techno Metal Post screw piers for deck foundations ("Building a Freestanding Deck," 12/11). This seems to be a simpler alternative than using a concrete pier. I did some research but could not find a prescriptive code for helical piers nor any listings with the ICC Evaluation Service for the technology. While the method looks viable, I wouldn't want to consider it if I can't get a permit and pass inspection. What are the additional costs for soils reports and engineering?
Steven Ward
Kansas City, Mo.
Bergen, N.J., deck builder Greg DiBernardo responds: Until recently there wasn't even an ICC category for helical piers. The code body has finally defined the test specs, but at this point only a couple of brands have gotten approval, because it's expensive and - since the legitimate companies already provide job-specific engineering for every installation - somewhat redundant.
We've become Techno Metal Post installers as part of our deck business. Here's how it works. The installer monitors the torque required to drive the pier, and takes it beyond the needed bearing capacity (we have a chart that relates torque psi to soil bearing capacity). This recorded data is sent to the engineer to be verified and stamped, and the sealed report is delivered to the building department for inclusion in the permit folder (see sample report, above). No inspections are required, and the piles can be built on immediately. We always load-test our piles right after installation to verify the capacity; if one sinks beyond 1/4 inch, we drive them deeper. In some cases, the torque reading is meaningless because slippery clay soils don't have enough friction to cause the reading to increase with depth, but the load test confirms bearing capacity.
Some old-school inspectors treat this as alien technology, but most, once they see an actual installation, are on board. There's nothing to argue with - you get a quantified load test. Try that with a concrete tube pier.
Quick Tune-Ups for Tight Miters
JLC does a good job covering specialty tools. One of my favorites over the years has been the benchtop belt and disk sander, which I use when running trim. Recently I was hanging prehung doors in a new starter home. Even though the casings were machine-mitered, they still needed finetuning, so I set up my sander on a portable stand, put a 120-grit disk on it, and did a light sanding on the cuts to get perfect joints. It went very quickly.
You can use the disk sander to clean up a rough cut, or to take a few thousandths off the heel or toe of the miter so it closes tight. You can relieve the back edge of the cut so the front closes tight. Using a sander takes much less time than trying to do the same job on a miter saw and doesn't change the length noticeably. Also, if one piece of trim is slightly thicker, you can use the belt sander to remove material off the back for a flush fit.
If you happen to get a sander that has some wobble in the disk, take it to a machine shop and have them flatten it. The last one I had machined cost me $8, but most of the sanders I've bought are fine right out of the box.
Jim Glover
Pierre, S.D.
Cross-Bracing Decks
Regarding "Building a Freestanding Deck" (12/11): In the Bahamas, it's common to build both homes and decks on 8x8 pressure-treated yellow-pine posts, usually placed on 8- to 10-foot centers. These posts are more flexible than you might think - even a house only 6 feet off the ground will sway when someone inside jumps, unless the posts are cross-braced.
Here, of course, the primary purpose of the cross-bracing is to withstand wind loading, and typically decks are attached to the house, or the ends of the deck are cross-braced from the top of one post to the bottom of the other. The cross-braces are usually hidden by lattice.
Chris Dowd
Abaco, Bahamas
