Paint finishes in Natatoriums

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Author Message Kathleen Alberding Senior Member Username: kalberding Post Number: 7 Registered: 06-2004 Posted on Friday, July 07, 2006 - 03:59 pm:    I am working on specifing a paint system for an unfinished CMU wall in a natatorium. The wall has a vapor impermeable air barrier system on it's exterior face with insulation outboard of the barrier in the air cavity. Epoxy paint has been recommended for the interior face but I am concerned about trapping moisture in the block. Does anyone have experience with this type of wall assembly? Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 139 Registered: 10-2002 Posted on Friday, July 07, 2006 - 04:33 pm:    What “vapor impermeable air barrier” are you specifying??? ......air barriers are intended to be permeable; vapor retarders should be impermeable. Is the project located in the deep south? How much insulation [R-value] and what type of insulation? Has the location of the dew point been determined? Vapor drive is very high in natatorium type applications. You are justified in being concerned about the proper design of this type of wall. But there are a whole host of questions that need to be determined before a “correct” answer is selected to include the design of the HVAC system, what type of siding/veneer is to be used on the outside of your CMU wall, ventibility [sp?] of the cavity, etc. Wherever coating you use on the inside face of the CMU wall should, as a minimum, be cleanable, imperious to moisture and have high elasticity to bridge current and future hairline cracks in the CMU. Ron Russ Hinkle, AIA, CCS Senior Member Username: rhinkle Post Number: 8 Registered: 02-2006 Posted on Friday, July 07, 2006 - 04:38 pm:    Don't forget to address the ceiling/roof as well. It can be as big and issue as the wall design. Last pool I did, I worked with my paint rep. to specify High performance coatings; primer, 1st coat and 2nd coat were all high performance the was applied to the walls and ceiling. The coatings on the inside of the wall were our vapor barrier (located in Michigan). Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 140 Registered: 10-2002 Posted on Friday, July 07, 2006 - 05:11 pm:    Russ is correct. In my haste, I did not mention the roof. On one project a while back we had a research facility with large vats of frogs, fish, and seaweed with a roof system consisting of pre-engineered wood trusses, plywood roof sheathing, vented insulating panels [with an internal 1" air space], and a standing seam roof. We used a high-end air barrier [Blue Skin] and we also coated the exposed galvanized gussets plates with an asphaltic based coating before painting the wood trusses and underside of the plywood roof sheathing. On another project we used HP coatings for both the exposed steel joists and metal deck. The last few projects had lots of glass walls which makes calculations as lot easier. <g> Ron Ken Moore, FCSI, CCS, SCIP Intermediate Member Username: kjmoore Post Number: 4 Registered: 06-2006 Posted on Saturday, July 08, 2006 - 05:23 pm:    If roof construction is metal deck and trusses, suggest metal deck be galvanized; trusses be primed with a zinc rich organic primerer. Spec deck be mechanically fastened to steel framing, not welded. Welding will burn off galvanized coating and acellerate rusting. Spec a spray applied epoxy coating that will go over galvanized deck, zinc rich organic primer, galvanized duct work, conduit and roof drainage system. Be selective, not all epoxies can be applied directly to galvanize. Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 141 Registered: 10-2002 Posted on Sunday, July 09, 2006 - 01:44 pm:    Ken: In applications such as this, I use a urethane zinc-rich and epoxy primers, polyurethane intermediate coats, and a fluoropolymer polyurethane finish coatings. Translation: “Series 90-97 Zinc Primer,” “Series 161 Fascure Primer Coat,” “Series 1075 Endura- Shield,” and “Series 1070 Fluoronar Finish Coat” all by Tnemec. Ron John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 550 Registered: 03-2002 Posted on Monday, July 10, 2006 - 08:44 am:    Ron, Just a note that it is not necessarily true that air barriers should be permeable. Here in Massachusetts, it is very common to use a vapor impermeable air barrier with outboard insulation. (I don't know where Kathleen's project is.) Thus, the air barrier is also the vapor retarder. By putting the insulation outside of the air barrier, you have a much simpler condition regarding vapor drive and dew point such that the one product can perform both functions. However, Kathleen is right to have some concern due to a natatorium's high RH, and perhaps that's the reason for your comment. Acrylic paints tend to be quite permeable, so if the determination is that the wall needs to dry towards the interior, though with high humidity I'm not sure how it would, I'd look at this type of paint. Kathleen Alberding Senior Member Username: kalberding Post Number: 8 Registered: 06-2004 Posted on Monday, July 10, 2006 - 09:15 am:    The project is in Texas, but the architect has detailed the wall similar to how we would here in the Northeast. The air/vapor barrier is "Blueskin". There is a 2 inch airspace and then a Stucco skin. My thinking is that epoxy would trap moisture but with acrylic paint the wall humidity has a chance of breathing or "equalizing" with the space. In either case, I am worried about leaching, paint peeling, mold, etc... Kenneth C. Crocco Senior Member Username: kcrocco Post Number: 57 Registered: 04-2003 Posted on Monday, July 10, 2006 - 11:48 am:    There are manufacturers promoting the use of exterior vapor permeable air barriers only. (Recommending against the use of vapor impermeable air barriers.) Contact Prosoco to hear what they have to say about this application.