High Performance Walls: How Stucco and Continuous Insulation Work. Nick Brown VP, SMA Ex-President, Merlex Stucco President, Build Smart Group

Transcription

1 High Performance Walls: How Stucco and Continuous Insulation Work Nick Brown VP, SMA Ex-President, Merlex Stucco President, Build Smart Group

2 Defining Stucco Terms Standard 3-coat stucco 7/8 thick R coat stucco 2 coats CI stucco ½ thick + foam 1 foam is 1- ½ thick R-4.2

3 What Was Wrong with Batts in Cavity? Thermal Bridging Sometimes shoddy installation We care about performance

4 Batt Rating Wall Performance Impact of Framing on Wall Insulation Performance Effective R w/ R-4 CI Effective R Cavity Insulation 2x4 wood 2x4 wood 2x6 wood 2x4 metal 2x4 metal 2x6 metal Cavity Insulation Effective R Effective R w/ R-4 CI Source: CEC Title 24 Reference Appendices, JA4.3.1, JA4.3.3

5 Adding CI Reduces Heating/Cooling Energy Use 7-23% Biggest impact in cool coastal climate zones, but significant impact in all zones

6 Current Residential Wall Standards

7 Assemblies that Meet Standards

8 Other Alternatives to Comply HERS Measures Advanced Framing Air Sealing Quality Insulation Installation (QII) More efficient HVAC systems, water heaters, windows, etc. High performance attics Reduced glazing, window shading PV credit (except CZ 6 & 7 Coastal SoCal)

9 How to Build with Traditional Walls Status Quo: what other measures in home would it take to compensate for not meeting prescriptive standard for HPWs? To use traditional 2x4 R-13 walls, a typical production home in Irvine required: 16 SEER HVAC QII HERS verification Many other combinations of measures builder could use All costly

10 How to Build with High Performance Walls CI wall construction One Coat Stucco Siding over foam board SIPs/ICFs not yet mainstream Concrete block w/ interior insulation EIFS systems One Coat Stucco Same hard cement stucco that is dominant in California over lath, WRB, just with 1 to 1.5 of EPS foam sandwiched inside assembly

11 One Coat Stucco Differences from 3-coat stucco Foam board attached to studs with metal lath attached through foam to studs Foam board is T&G with WRB under it Windows are 1/2 deeper to account for foam thickness Trims are 1/2 deeper (weep screed, expansion joints, Milcore) Manufacturers ICC reports provide full specification for application Established standard method in many markets (AZ, NV, Sacramento)

12 Benefits of One Coat Stucco Significantly reduces thermal bridging Eliminates need for scratch coat Shortens construction cycle for plasterer by 2-7 days Fibers in 1-coat products add strength Factory blends improve quality of plaster Available pre-sanded for greatly improved quality, no sand piles Improves building comfort Does not sacrifice building square footage to achieve insulation goals

13 How to Specify One Coat Stucco Dictate use of one-coat window nailing fins Dictate use of foam board EPS, Graphite EPS, XPS, Polyiso, Mineral wool Dictate use of 1-3/8 weep screed and other trims Work with plasterers on best practices for foam and lath installation Work with framers to ensure straight surface to leave plasterer

14 Barriers to Adoption of One Coat Stucco Inertia Higher plasterer bids Easier Title 24 compliance options in 2013 energy code Many removed by 2016 code Assembly fire test (NFPA-285) required over 3 stories with one-coat Not required with 3-coat stucco Need for Field Training

15 Best Practices Develop a detailed specification for CI stucco Get framer and plasterer together in a meeting Scrutinize first few houses with each new contractor for proper application of foam Mark studs, electrical, and plumbing on paper, foam 17 gauge wire is good upgrade over 20 gauge Let help

16 More Best Practices Check inside after stapling lath for missed studs & caulk Keep Economics Reasonable by lining up windows & stucco in the same plane Fully bury lath with brown coat Plan for penetrations and seal: plumbing, electrical, control joints Use scraps with no groove at base of walls, above windows and doors Use scraps with no tongue at top of walls, under windows Soffits: use 3-coat details for rib lath and outside corner drainage

17 Windows & CI: Practical Concerns How do I use the regular 7/8 flange windows I already bought? Furr out with picture frame Other alternative is to hang window as normal and return plaster in to window frame Same method for thicker CI when window flange cannot accommodate thickness

18 3-coat over CI also possible Table appears in CEC s Residential Compliance Manual Specifies how to fasten lath over foam sheathing Various cladding weights 11 psf = 3-coat stucco Other tables for metal framing, furred assemblies You can have your 7/8 stucco plus CI

19 2019 Residential Code Sneak Peek 1 ½ inch foam is coming to an inland valley near you Window bucks on every window Thicker trims, longer fasteners Fire-rated assemblies pending, not yet defined in ICC reports PV credit may disappear CI will become low-hanging fruit Learn it now

20 Contact Us Mark Fowler, Exec Dir Nick Brown (213) (714)