Canadian Contractor


Caulking video response: Polyurethane is great stuff, but it is not the easiest to work with

Joe White cautions against trying to the same type of caulking bead shape with different types of caulk.

A post in response to our Backer Rod and Bond Breaker video re: exterior caulking…

Thanks for the info. Polyurethane is great stuff… but it is not the easiest to work with. It would have been interesting to have more info on how to also finish the bead (top, visible surface). I believe urethane and other hybrid caulks and the popular “Mulco Supra” are NEVER to be tooled nor applied like an acrylic latex, etc. The former require a convex bead, while the other calls for an “ hourglass” type bead (this is per manufacturers’ technical instructions).

Most info about using backer rod says it works to create the “ hourglass” bond, which works with this video’s instruction of doing “1/2 of joint width for joint depth.” BUT how well does this work with the polyurethane and Mulco Supra requirement for a convex (bubble-like) bead ?

Finally, new installations are far easier to work than replacement caulking jobs o older material. On old insulations material gaps, bad workmanship, etc. require using caulk just as much for visual detail (and cover-up) as a sealant. These cases seem to always require tooling to get WIDE gap coverage. Is this not a problem for non-toolable calks like polyurethane or using backing rod? I’d also like to see a follow up video on these contradictions between caulk tooling/beads with backer rod and a video on real-world “ cheating” that is called for on wide gaps where backing rod won’t work (lack of depth, etc.) No, this is not the right way. But customers on many jobs refuse the “expensive”correct fix.

Joe White


Stories continue below

Print this page

Related Stories

Leave a Reply

Your email address will not be published. Required fields are marked *


This site uses Akismet to reduce spam. Learn how your comment data is processed.