Today the Pole Barn Guru answers reader questions about pre-drilling steel panels, the proper use of house-wrap and weather resistant barriers, as well as concern for the effectiveness or fresh concretes ability to withstand compression.
DEAR POLE BARN GURU: What size hole should I predrill in panels for the #12 diaphragm screws? Thanks! JOSEPH in KIOWA
DEAR JOSEPH: From Hansen Pole Buildings’ Construction Manual, Chapter 2:
“For pre-boring nail holes, 7/64” and 1/8” bits are required. Same size bit can be used for pre-drilling steel roofing and siding.”
DEAR POLE BARN GURU: Having read all of the info relating to insulating and am still confused. Main question is my entire 40×48 was wrapped in Tyvek including the roof. Now am trying to figure out if and how I can install a vapor barrier for the roof? Am planning to put in a ceiling with blown insulation above it and would like some options for the vapor barrier. Not sure if the roof Tyvek is a help or a hindrance. KEVIN in MALAD CITY
DEAR KEVIN: I’d like to find builders who are using Weather Resistant Barriers (WRB) under roof steel on post frame buildings, thinking they are installing a vapor barrier, and slap them silly. They have totally wasted their client’s hard earned money and, as in your case, have created a hindrance. Your only real solution is to remove Tyvek from under roof steel and replace it with an actual vapor barrier (one with a thermal break). You might see if a local spray foam installer would be willing to flash spray two inches of closed cell foam on underside of your building’s WRB.
DEAR POLE BARN GURU: My contractor poured concrete in each hole for a 30’ x 32’ pole shed and about 4 hours later started setting poles and put the entire frame up yet that same day. Can the concrete actually cure that fast or should I be concerned? PAUL in MITCHELL
DEAR PAUL: I am guessing you are talking about concrete poured for a footing pad under the columns.
Concrete gains its strength with time after casting. The rate of gain of concrete compression strength in higher during the first 28 days of casting and then it slows down. The compression strength gained by concrete after 24 hours is only 16%!
For practical purposes, a four hour old concrete footing is virtually worthless. Yes, you should be concerned.