Fol­low­ing the blind - un­til now


Dur­ing the sum­mer of 1992, while as­sist­ing the Pue­blo of Zuni sta­bi­lize the old stone ma­sonry homes in Mid­dle Vil­lage, I was struck by the need to de­velop a method for un­der­pin­ning build­ings that would pro­vide the nec­es­sary me­chan­i­cal sup­port and not dam­age the nearly thirty feet of arche­o­log­i­cal and reli­gious de­posits be­neath. I had ac­tu­ally be­gun “in­vent­ing” the needed sys­tem when I dis­cov­ered that I had been beaten to the task by a blind Ir­ish­man a hun­dred and fifty years ear­lier.

Alexan­der Mitchell, the Ir­ish­man, de­vel­oped what he called the “screw pile” as a means of an­chor­ing light­houses in mud, sand, and sim­i­lar un­sta­ble for­ma­tions. The screw pile soon came to be known as the “he­li­cal pier” and has been in wide­spread use world wide ever since. The ap­pli­ca­tions of he­li­cal tech­nolo­gies are prac­ti­cally end­less: they are equally ef­fec­tive at hold­ing things back as at hold­ing them up and so are used as tie-back an­chors for lean­ing walls; they can be in­stalled in spa­ces as small as the cham­ber of a kiva fire­place; their bear­ing and ten­sion ca­pac­ity is re­mark­able— even the light­est pier we in­stall will han­dle a load of 25 tons and, im­por­tantly in places like Zuni, the pier does not dis­place the soil, can be re­moved as eas­ily as it is in­stalled, and does not need bol­ster­ing with con­crete or ad­di­tional steel.

Within a few months of dis­cov­er­ing them, I be­came a cer­ti­fied he­li­cal pier in­staller and dis­trib­u­tor. Bum­mer that my bright idea had been hi­jacked by a blind man a cen­tury and a half be­fore, but I still saw the po­ten­tial for de­vel­op­ing new hard­ware to ac­com­mo­date a niche in­dus­try— the sta­bi­liza­tion of build­ings con­structed of soft ma­te­ri­als like adobe, and build­ings of any de­scrip­tion that had been built with­out a foun­da­tion or on col­lapsi­ble soils.

In pur­suit of so­lu­tions for un­der­pin­ning build­ings whose foot­ings have ab­so­lutely no span strength, I in­vented “adobe bas­kets.” In re­sponse to adobe build­ings whose walls had be­come so coved at the base that col­lapse was im­mi­nent, my son Jess in­vented “adobe cages.” Both are struc­tural el­e­ments that can be sup­ported with he­li­cals. Along the way we be­gan solv­ing seis­mic retro­fit prob­lems us­ing the piers in con­junc­tion with polypropy­lene strap­ping to tie build­ings off in con­trol­lable blocks. In short, we em­barked on a pe­riod of cre­ative think­ing that pro­vided el­e­gant, ef­fi­cient, and af­ford­able so­lu­tions to struc­tural is­sues in his­toric build­ings. We found that im­prov­ing on a bril­liant idea with a spe­cific goal in­mind is al­most as sat­is­fy­ing as in­vent­ing the core tech­nol­ogy. Ah, but to have had that first patent...

It was a log­i­cal pro­gres­sion that the so­lu­tions we de­vel­oped would have ap­pli­ca­tions in con­tem­po­rary set­tings. By the early 2000s, we were un­der­pin­ning far more non-his­toric build­ings than his­toric ones. The rea­son for that is many-fold: build­ings are be­ing per­mit­ted on marginally build­able sites; own­ers and ar­chi­tects are of­ten loathe to spend money on a geotech­ni­cal as­sess­ment (or ig­nore the rec­om­men­da­tions pre­sented when they do); and con­trac­tor er­ror and short­cuts are a ma­jor con­tribut­ing fac­tor as is the fail­ure of in­spec­tors to de­mand com­pli­ance when short­com­ings are found.

In the last twenty-five years, we have in­stalled thousands and thousands of he­li­cal piers in­many hun­dreds of lo­ca­tions in three states and Great Bri­tain. And that’s enough. We have fol­lowed the blind man’s lead as far aswe care to take it, and are very sat­is­fied with the re­sults. We at Crocker Ltd have de­cided that hence­forth we will no longer take on he­li­cal pier or mois­ture-re­me­di­a­tion jobs un­less they fall into a spe­cial cat­e­gory. We em­phat­i­cally will re­tain and con­duct our preser­va­tion busi­ness, and use piers and solve mois­ture prob­lems in that con­text. In short, we will be lim­it­ing our ser­vices to build­ings that are his­toric, ar­chi­tec­turally im­por­tant, or that demon­strate par­tic­u­larly dif­fi­cult tech­ni­cal chal­lenges.

We thank our long list of clients and col­leagues, as well as the legacy of a vi­sion­ary Ir­ish­man who gave us the hard­ware to be­gin.

Ed Crocker’s com­pany, Crocker Ltd., spe­cial­izes in the restora­tion of his­toric build­ings and im­por­tant ar­chi­tec­ture. The com­pany has won nu­mer­ous awards from the Na­tional Trust for His­toric Preser­va­tion, the City of Santa Fe and the State of New Mex­ico. Ed is a Fel­low of the In­ter­na­tional Coun­cil on Mon­u­ments and Sites. More in­for­ma­tion can be found at crock­

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