Underlayment substitution request

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Author Message Russ Hinkle, AIA, CDT, LEED BD+C Senior Member Username: rhinkle Post Number: 127 Registered: 02-2006 Posted on Tuesday, October 28, 2014 - 09:05 am:    We have a senior living housing project, 3 stories, concrete plank floor. After the stud walls are installed, a gyp / concrete floor underlayment will be installed. We specified a 4000 psi product. Owner wants to entertain cost savings options and they are interested in looking at 3000 psi options. It's been a while since I have done this type of overlay and feel like this is not a good idea, but need technical reasons why. Russ Hinkle Nathan Woods, CSI, CCCA, LEED AP Senior Member Username: nwoods Post Number: 606 Registered: 08-2005 Posted on Tuesday, October 28, 2014 - 09:56 am:    4k products are kinda rare. They are usually in the 2-3k range. I have specified and installed this one on many Multi-family and office building floors, with no problems: Hacker Industries Firm-Fill 3310 Scott Piper Senior Member Username: spiper Post Number: 10 Registered: 08-2014 Posted on Tuesday, October 28, 2014 - 10:07 am:    I have limited recent experience with this type of underlayment as well but in my experience this was typically a 3,000 psi type product in our area. Justatim Senior Member Username: justatim Post Number: 61 Registered: 04-2010 Posted on Wednesday, October 29, 2014 - 07:18 am:    If the facility's operation requires rolling medical equipment (with those itsy bitsy wheels and heavy load) along the floor, I would insist on cement type with high psi. The lower strength products (usually gypsum) can rut from the concentrated rolling loads. One hospital that I trouble-shooted had this problem; the solution was to remove all the sheet flooring and replace the underlayment. For predominantly residential loading, the lower psi should be OK.