Blog Viewer

The CSI-Connect Community Forum is a go-to resource where architecture, engineering, construction and owner (AECO) community professionals can connect with each in real-time and ask each other for advice about specific projects. Here are three timely conversations you may want to follow—and contribute to—right now.(The comments have been edited for length, so please log in or create a new profile to read them in their entirety.)

Moisture In Slab on Grade

Where does the moisture in concrete go? Hopefully it evaporates and leaves the slab. So, what happens when you take a slab on grade and put in a very efficient vapor barrier on top of a well-drained subbase? Now let’s cover it all with a continuous floor covering that is vapor impermeable. You have a moisture sandwich. Slab edges can still wick out to some extent, but they could be a long distance from the center. Expansion joints are sealed, so it won't happen there. Partition walls? Not a lot of exposure to atmosphere there.

Now let’s ask why the water-based adhesives on this slab don't bond or cure. Is it the adhesive? The installation process? Or is it because the moisture in the slab has nowhere to go? Thoughts?

Clint Newton III, CSI, CDT®

I would argue it’s the installation process. Flooring (or any vapor impermeable product) should not be installed until the moisture content in the concrete has lowered. This can take months and does not equate to the 28-day cure time. Portland Cement Association (PCA) Engineering Bulletin (EB) 119, Concrete Floors and Moisture, says normal weight concrete will dry to 75% RH in 3 months, and lightweight structural concrete takes 6 months (based on an 8-inch slab, not rewetted, with 2-way drying potential). Of course, there is the issue of how to measure the moisture content and what RH is acceptable. Many contractors will use the plastic sheet method to test for moisture content (ASTM D4263), but this test is unreliable. The NRCA, for example, no longer considers the plastic sheet test viable (and hasn't for many years). Instead in-situ probes should be used to measure the moisture content (ASTM F2170). Often a 75% RH is used as an acceptable threshold, but really what is acceptable will depend on the product/adhesive being applied to the slab. 

Nicole Byl, CSI, CDT®

Join the conversation: https://www.csiresources.org/discussion/moisture-in-slab-on-grade?ReturnUrl=%2fbrowse%2fallrecentposts 

Does Anyone Pre-Qualify Bidders or Subcontractors Anymore?

Earlier in my career, it used to be pretty common that we would pre-qualify bidders for some portions of the work, especially if we wanted something that was visible (or a featured item) in the finished project. Wood veneer casework was a common restricted bid list, and sometimes precast concrete was another one. This was for bid projects back in those days. We now have "experience" requirements written into some spec sections, but sometimes we are precluded from even doing that. Does anyone pre-qualify bidders anymore?

Anne Whitacre, FCSI, CCSI, LEED AP

In NH and Massachusetts mainly, I have seen plenty of prequalified subcontractors being required. In Massachusetts, on the public projects, all main/large subs need to be prequalified via a special state agency. On private projects, of course owners and the owner's reps can do what they want for the most part. But, in general, I would say that prequalifying subcontractors is a fairly smart idea.

Ken Lambert CSI

Join the conversation: https://www.csiresources.org/discussion/does-anyone-pre-qualify-bidders-or-subcontractors-anymore?ReturnUrl=%2fbrowse%2fallrecentposts

Specifying Custom Millwork

Our office does work that includes a lot of custom millwork and metal work, and I typically have things spread out between finish carpentry, architectural woodwork, casework, decorative metal, etc., but some of the custom work doesn’t fit neatly in any of those sections and we typically see it in the millworker’s scope. I was wondering what others do when it comes to millwork specifications. When it comes to custom ceilings or column wraps, super custom doors, and hanging decorative objects, how do you write those into your specs? We do a lot of details and information on our drawings, but I wish I had a “millwork” spec section or something that was more inclusive of lots of built-in custom pieces than just wall panels or trim or case goods.

Jessica Saravia CSI, AIA, LEED AP

I’m coming from the millwork end of this, not metal, so I’ll speak to things that have wood or laminate finishes. I would use a separate spec section for that type of work; in the 06 area for paneling, ceiling wraps, hanging decorative objects, etc., and in the 08s for doors. Metal substructures would be included in the section if they're integral to the finish, so there’s one sub responsible. That will help avoid coordination issues and finger pointing. The other standard cabinet, door, and millwork sections should be referenced in the “related sections.”

One thing to watch for is coordination with the standard millwork items. With wood and wood veneers it’s critical to have one finisher do all of the work if it’s supposed to match. I would put the requirement for one finisher into each related spec section and make sure it doesn’t get dropped, as I have seen multiple projects where things didn't match even with the same veneer flitch.

Mitchel Taylor CSI

Join the conversation: https://www.csiresources.org/discussion/specifying-custom-millwork?ReturnUrl=%2fbrowse%2fallrecentposts