Wednesday, February 29, 2012

It's all in the details... - Part I

I found this interesting little detail the other day while peer reviewing a set of drawings. On this job, I am serving as waterproofing consultant to the Architect of Record (AOR). This detail was found in the Landscape section of the drawings.

A brief aside from the detail to talk about lines of communication. While it may be easier for me to call the Landscape Architect (LA), my contract is with the AOR. I need to bring this to the AOR's attention and he can decide to approach the LA about revising this detail.

Back to the detail. While it is not a big issue, there is a problem with this detail. Click the "read more" link to see the answer.

The problem with this detail is that the sealant joint is too deep. Maximum sealant depth should be one half of its width. In this instance, because the joint is 3/8" wide, the max sealant depth should be 3/16" In other words, the maximum ratio of Depth to Width should be 1:2 , this detail's ratio is 1:1.

A proper repair for this is to continue the expansion material another 3/16" higher. At that point, the backer-rod can be inserted and a sealant joint can be gunned.

A final point - because this is a sidewalk installation with concrete that is susceptible to high expansion, a Hi-Mod (High Modulus of Elasticity) sealant should be specified. A good product, and one of my favorites, would be Sika 1a.