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Weather Barrier & Stucco Durability Seminar Notes 3.5.14

  I’ve gotten involved recently with the Austin AIA Chapter’s Building Enclosure Council (a Building Science group), and they had a great seminar today at the University of Texas JJ Pickle Research center.  The seminar was mainly given by David Nicastro, PE (with Building Diagnostics ) where they gave an overview of a joint private/public research project about the durability of Stucco and the related assemblies behind Stucco facades.  David and his associates (a group of Engineers & Consultants) do all kinds of cool things in their work including diagnosing building failures/issues related to waterproofing, expert witness & litigation consulting, and plan reviews to ensure buildings will work well from the start. 
  The main focus of the seminar I thought was going to be stucco related, but it turns out I found their research into durability of WRB’s (weather resistive barriers, ie Tyvek, Tar Paper, Fluid Applied Prosoco, etc) fascinating. 

  I took 4 pages of notes today and it was a tough 4 hour presentation to boil down; here’s my highlights then I’ll get into some test rack photo’s which is what I was REALLY excited to see at the end of the presentation.
Notes: ________________________
-Durability is the essence of Sustainability
    Reduce waste and keep building materials out of landfill longer
    Select product with longest service life
Durability Concepts:

  • Average Expected Useful Life
  • Whole Building Design Life
  • Institutional Buildings – Should last over 100 years
  • Commercial Building / Residential Buildings 60 years???? No definition
  • Products Design Life – Env Life Cycle

Types of Building Materials:
Permanent – (e.g., Glass)
Maintainable (masonry)
Replaceable (roof)
You can have durability issues in all these categories!

Design Life vs Service Life
Average Commercial Roof Design Life = 15 years
Service Life = Actual Duration
     Affected by many variables: Design/use, Product Quality, Climate

If Service Life = Design Life then Normal Duration = Durable! 
    The only thing that matters is your expectation of longevity. 

Primer for Durability: (Caulks/Peel&Sticks – Many products say they are primerless)
Better adhesion w/Primer
Priming Improves Durability! 
    -Solvents in primers clean the substrate
    -Binds Debris in the surface to be adhered. 
In General:  If you can use a primer, YOU SHOULD USE  A PRIMER!

Clear Sealant isn’t suited for Construction (talking about silicone).  But it’s the most common sealant!  Different chemistry to make it clear, needs color to make it durable. 
Also, Sealant needs a gap to work!  Tight gap, no sealant will actually seal.  You see this all over in Construction…

Sealant Durablity improved by:
Premium Product
Trained Installers

Building Envelopes:  The four barriers (interesting to note they didn’t list this in order of importance like Joe Lstiburek does! I ordered my notes in the correct order of importance)

  1. Water Resistive Barrier – WRB
  2. Air Barrier
  3. Vapor Barrier
  4. Heat Barrier (Thermal)

NO vapor barrier at all in the wall section for our climate greatly enhances durability!  (I’ve seen this mistake in many remodels where they used Polyethylene (plastic) sheeting behind sheetrock for a “code mandated” vapor barrier in the 90’s.  

Changing topics now to the durability racks outside and WRB’s
Many new Liquid-Applied WRB’s on the market today. 
Crowded Market!  Some products will die.
Survivors will likely:
-Permit long UV exposure (1 year +)
    -A decade from now we won’t see products that only have short UV time (short meaning less than 3-6 months)
-We are interested in products that last 6 mo or longer
-Want ones that self seal fasteners! 
-Have low total system costs – How many components does the system take?

Practical Questions for WRB Product
-How easy was it to use?
-Are the instructions ok?
-How long can it be exposed?
-Ho does it work on Typical Details?
-How durable is it?


We find window jambs leak at little fish mouths (maybe sealed originally) that are small!
-Using a joint/seam sealant at the joints/edges makes a HUGE difference.  This affects durability.  This even makes a difference in the short term (3 years). 
We call this termination caulk at the seams “Stitching the edges”

Nail Sealability
-There is no standard for sealing nail holes in WRB’s. 
Water + Heat is extremely damaging to WRB’s in real life. 

Tapes/Flashing/Seams are the biggest source of damage we see in building failures. 
   Not fastener penetrations…
Stucco has a TON of penetrations through the WRB.  Lath staples! 
WRB’s that don’t self seal will exit the market eventually. 
 End of the Presentation Notes… Now we went outside to see the test racks! 

12 different WRB’s being tested!  They have been outside about 3 months (winter) now.

Asphalt impregnated paper WRB.  (I’m not a fan)

The standard Tyvek homewrap is looking faded after this time with UV exposure, that’s why I like the commercial version.

I’m looking forward to seeing how the Zip tape holds up.  I don’t like how it’s mis-lapped. 

Carlisle’s Fluid Applied WRB.  Looking rather Blue but other wise in perfect shape.

This foil faced WRB is Polyguard’s Peel-n-Stick.  I have two trusted builder buddies who swear by this stuff.  It has alot going for it. 

Zoomed in on the Tar Paper “Window Flange” detail that’s looking bad after a short period of time.  Not good.

I didn’t include pictures but I also saw Grace and Prosoco fluid applied on some test panels.  This should prove to be very interesting.  This is in the early stages of testing so I hope to be invited back in 6mo or a year to see how things are going.  The plan is to cover the top half of these WRB’s with Hardi-Plank to protect them from UV while the bottom half keeps getting beaten by the sun.  I think the results from this will be very telling.  Overall I think this test panel and their choices of product for Round 1 shows what they think will be the most common players in the next 5-10 years.  The future is definitely Fluid Applied and Self-Adhered Sheet Applied WRB’s.
  Thanks for hanging with me on this long/geeky post everyone.  I’d love to hear your comments.  Drop me a line below and I’ll respond quickly.
Matt Risinger
Risinger Homes in Austin, TX

Risinger Homes is a custom builder and whole house remodeling contractor that specializes in Architect driven and fine craftsmanship work. We utilize an in-house carpentry staff and the latest building science research to build dramatically more efficient, healthy and durable homes.
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