True, point well taken Paul. While I did concede that a hollow-core block might take longer to install somewhat, but I don't know that it would be that much greater if any when costs are considered.
On the flip side:
#1 at least as far as my block go, the cost of the block, because we produce it right here is less and many times can help to ease that extra labor cost. Less cost because of less concrete being used. I don't know that I could say that if it were in CA paying the wages that Bill has to pay?!?
#2 is would you rather have your worker carrying 1 or 2 blocks at a time? 2 blocks at a time increases your productivity right? Labor savings right? With hollow-core I can carry one in each hand. Even with a Versa-Lifter it's hard to carry two at a time, safely and I sure can't carry a Rockwood or Keystone two at a time. While that doesn't't matter for the base course cause it depends on how fast the guy laying them can get the base course done and level, it will make an impact on tiering up the next courses.
#3 is Angle of Friction. Take a solid block for example. When you stack, for practical purposes you have 2 pieces of smooth concrete resting on each other and can be slid easily cause there is not much friction. Hollow core have a higher angle of friction because the drainage stone inside is all locked together from course to course.
Please don't take this as an argument, just various opinions. As others have said, that's what is cool about this site, no arguing. As with anything, there are pro's and con's. It always goes back to what works best for you. This is fun and your responses (Paul) help to keep me on my toes for any rebuttal I might get around here from contractors. I need to have an answer for everything!!!
