In a message, [log in to unmask] writes: The material that separates sidewalk concrete from buildings, light pole footings, etc., should not be tubular. My guess is that the "tubular stuff" that you mention is backing rod (often called backer rod". Backer rod just will not function properly in this application. No, it's not backer rod, I described it carelessly. I think it is just the occasional newly-installed rubber installations that were put in a bit too high, and were abraded off in strips that I interpreted casually as backing rod (hitherto backer rod). Control joints can also be sawn into sidewalk and other concrete flatwork. I won't go into that unless you insist, and maybe not even then. Had you written that last week, I wouldn't have believed you. But on Monday I saw just such sawing going on in a new sidewalk installatin at 1040 Park Avenue. I have never seen it before. I would think that these control joints would freeze/thaw. As always, thank you, S. J. I think you should be able to get college credit for reading the BP posts. Christopher ************************************** See what's free at http://www.aol.com. -- To terminate puerile preservation prattling among pals and the uncoffee-ed, or to change your settings, go to: <http://listserv.icors.org/archives/bullamanka-pinheads.html>