More About Insulating Plastics in Exterior Wall Construction

Quality construction is more than just meeting code. This article looks at issues related to Foam Plastic Insulation (FPI) that go beyond the code and the simple sustainable goal of increasing energy efficiency.

Regarding Sustainability
As with any plastic, FPI is inherently flammable. Manufacturers formulate the FPI with fire-retardant additives which go a long way to improving their performance in fire situations. The sustainable problem is that the fire retardants usually contain bromine. The type of bromine used in FPI, Hexabromocyclododecane (HBCD), is known to be somewhat persistent, bioaccumulative, and toxic to human beings. It's considered a borderline case requiring more research subsequent to more regulation in Europe. The call is out to look for replacements. You can find an articles addressing the issue here on BuildingGreen.com.

Regarding Fire
Fire-retardant additives go a long way to improving the performance of plastics in fire situations as quantified by ASTM E 84. It's conceivable you could light a match to a sample of insulation and see absolutely no fire propagation. But what about real building fires? Large-scale fire tests such as NFPA 286, FM 4880, UL 1040, and UL 1715 expose 20-30 foot high corner assemblies to a burning crib that is more akin to a real fire, and observations and measurements are taken. In these tests, the fire-retardant additives have negligible effect.

And it's borne out by experience. In a 21-year recent study, FM Global determined that 80 percent of the damage in fires involving plastic construction materials was caused by FPI. In May 2008, they issued new guidelines for cavity walls (Data Sheet 1-12) as follows:

Protect new exterior cavity walls using one of the following methods:

1. Use FM Approved Class 1, expanded glass insulation in cavity walls, or
2. Use FM Approved Class 1, foil-faced polyisocyanurate insulation in cavity walls, or
3. Use combustible insulation over a noncombustible substrate, but eliminate the air space so the thermal barriers are in direct contact with the insulation on both surfaces, or
4. Use combustible insulation over a noncombustible substrate in conjunction with fire stops to divide the wall cavities into areas not exceeding 2000 ft2 (186 m2).

In all cases, ensure the exterior wall veneer and the substrate for the insulation are noncombustible. Do not directly attach combustible insulation to wall studs.

What's not immediately obvious to those who are not familiar with the entire Data Sheet is that non-combustible insulation (such as mineral wool) is the preferred insulation.

In existing buildings, the FM Global recommendation is to install sprinklers around the perimeter to control the fire should the exterior wall somehow be compromised and the insulation catch on fire.

Regarding Thermal Barriers
Thermal barriers are also a tricky thing. If the barrier is not in direct, continuous contact with the plastic, then there is no telling how the assembly will perform in a fire. Therefore, 1/2-inch Type X gypsum board or 3/4-inch FR-treated plywood should only be used as a thermal barrier when in direct contact with a smooth insulation such as an insulating board. For spray-applied polyurethane, a thermal barrier that conforms to the contours should be used (such as Carboline Pyrocrete L/D or W.R. Grace Monokote Type Z-3306, or 1/2-inch Portland cement plaster on metal lath). Metal (0.016 in. steel or 0.32 in. aluminum) is effective as a thermal barrier in factory-formed sandwich panels because it allows a properly-formulated core to char, protecting the rest of the core.

LEED 2009 Specifications

Here are sample green specifications for LEED 2009, following CSI MasterFormat and SectionFormat.

It addresses the following MasterFormat Sections and LEED credits by providing commentary and sample specification language:

• Section 01 14 19 – Use of Site for requirements related to LEED SS Credit 5.1: Site Development—Protect or Restore Habitat and IEQ Prerequisite 2: Environmental Tobacco Smoke (ETS) Control.
• Section 01 32 13 – Scheduling of Work for requirements related to Scheduling requirements of Chapter 3, “Control Measures,” of ANSI/SMACNA 008 referenced in LEED IEQ Credit 3.1: Construction Indoor Air Quality Management Plan—During Construction.
• Section 01 33 29 – Sustainable Design Reporting for requirements related to Sustainable Design Submittals and LEED Online forms.
• Section 01 56 00 – Temporary Barriers and Enclosures for requirements related to Pathway Interruption requirements of Chapter 3, “Control Measures,” of ANSI/SMACNA 008 referenced in LEED IEQ Credit 3.1: Construction Indoor Air Quality Management Plan—During Construction.
• Section 01 57 23 – Temporary Storm Water Pollution Control for requirements related to LEED SS Prerequisite 1: Construction Activity Pollution Prevention.
• Section 01 66 00 – Product Storage and Handling Requirements for requirements related to LEED IEQ Credit 3.1: Construction Indoor Air Quality Management Plan—During Construction.
• Section 01 74 13 – Progress Cleaning for requirements related to Housekeeping requirements of Chapter 3, “Control Measures,” of ANSI/SMACNA 008 referenced in LEED IEQ Credit 3.1: Construction Indoor Air Quality Management Plan—During Construction.
• Section 01 74 19 – Construction Waste Management and Disposal for requirements related to LEED MR Credit 2: Construction Waste Management.
• Section 01 74 23 – Final Cleaning for requirements related to LEED IEQ Credit 3.1: Construction Indoor Air Quality Management Plan—During Construction and IEQ Credit 3.2: Construction Indoor Air Quality Management Plan—Before Occupancy.
• Section 01 81 19 – Indoor Air Quality Requirements for requirements related to LEED IEQ Credit 3.2: Construction Indoor Air Quality Management Plan—Before Occupancy.
• Section 01 91 13 – General Commissioning Requirements for Contractor’s obligations related to LEED EA Prerequisite 1: Fundamental Commissioning of Building Energy Systems and EA Credit 3: Enhanced Commissioning. The Commissioning itself is not in contract.
• Divisions 02 through 09 for requirements related to LEED Materials & Resources and Indoor Environmental Quality credits.
• Section 07 30 00 – Steep Slope Roofing and Section 07 50 00 – Membrane Roofing for requirements related to LEED SS Credit 7.1: Heat Island Effect—Nonroof and SS Credit 7.2: Heat Island Effect—roof.
• Section 07 55 63 – Vegetated Protected Membrane Roofing for requirements related to LEED SS Credit 6.1: Stormwater Design—Quantity Control, SS Credit 6.2: Stormwater Design—Quality Control, SS Credit 7.1: Heat Island Effect—Nonroof, and SS Credit 7.2: Heat Island Effect—Roof.

The PDF file is read-only. Send me an email if you would like an editable format.

What's different about LEED v3? The answer is both "Not much," and "A whole lot."

From a technical point of view, not much has changed. The credits are all very similar to LEED NC 2.2. There have been tweaks with the language as part of the "harmonization," and some of the targets have been upgraded.

However, the new credit weightings make such a difference, it may feel like an entirely new system.

Case in point: under LEED NC 2.2, I used to affirm that an architect could make every building LEED certifiable just by adopting the following credits as standard practice:

• SS Prerequisite 1: Construction Activity Pollution Prevention
• SS Credit 6.1: Stormwater Design: Quantity Control
• SS Credit 6.2: Stormwater Design: Quality Control
• SS Credit 7.2: Heat Island Effect: Roof
• SS Credit 8: Light Pollution Reduction
• WE Credit 1.1: Water Efficient Landscaping: Reduce by 50%
• WE Credit 3.2: Water Use Reduction: 30% Reduction
• EA Prerequisite 1: Fundamental Commissioning of the Building Energy Systems
• EA Prerequisite 2: Minimum Energy Performance
• EA Prerequisite 3: Fundamental Refrigerant Management
• EA Credit 1: Optimize Energy Performance (21% / 4 points)
• EA Credit 4: Enhanced Refrigerant Management
• MR Prerequisite 1: Storage & Collection of Recyclables
  
• MR Credit 2.1: Construction Waste Management: Divert 50% From Disposal
• MR Credit 4.1: Recycled Content: 10% (post-consumer + 1/2 pre-consumer)
• MR Credit 5.1: Regional Materials: 10% Extracted, Processed & Manufactured Regionally
• MR Credit 7: Certified Wood
• EQ Prerequisite 1: Minimum IAQ Performance
• EQ Prerequisite 2: Environmental Tobacco Smoke (ETS) Control
• EQ Credit 1: Outdoor Air Delivery Monitoring
• EQ Credit 3.1: Construction IAQ Management Plan: During Construction
• EQ Credit 3.2: Construction IAQ Management Plan: Before Occupancy
• EQ Credit 4.1: Low-Emitting Materials: Adhesives & Sealants
• EQ Credit 4.2: Low-Emitting Materials: Paints & Coatings
• EQ Credit 4.3: Low-Emitting Materials: Carpet Systems
• EQ Credit 4.4: Low-Emitting Materials: Composite Wood & Agrifiber Products
• EQ Credit 5: Indoor Chemical & Pollutant Source Control
• EQ Credit 6.1: Controllability of Systems: Lighting
• ID Credit 2: LEED Accredited Professional

These points are all relatively easy to achieve, relatively inexpensive to implement, and gave you 26 out of 69 points - good enough for LEED certified under 2.2.

Now, those same credits only give you 31 out of 110 points - not even close to LEED certification. In the whole scheme of things, those credits were low performers. After all, is adding a bike rake really equivalent to providing public transporation access? We all knew it wasn't, and now the new system has made it official.

The question now comes, what are the credits that are relatively easy and inexpensive for the Owner to adopt? I submit the following:

• SS Credit 2: Development Density & Community Connectivity (good for 5 points!)
• Credit 4.3 alternative transportation—Low-Emitting and fuel-Efficient vehicles (3 points)
  
• Credit 4.4 alternative transportation—Parking Capacity (2 points)
  
• Credit 5.1 site Development—Protect or restore Habitat (1 point)
  
• Credit 5.2 site Development—Maximize open space (1 point)
• Credit 1 water Efficient Landscaping—No Potable Water Use or Irrigation (2 additional points)
• Credit 1 optimize Energy Performance (go for 30% / 6 additional points; if the Waxman-Markey bill passes Congress, we may be required to be at 30% reduction in five years anyway.)
• Credit 3 Enhanced Commissioning (2 points)
• Credit 5 Measurement and verification (3 points; USGBC is now requiring Owners to submit operational performance data on a recurring basis as a
  precondition to certification under v3, so why not go the whole way?)
• Credit 1.1 Building reuse—Maintain Existing walls, floors, and roof (3 points)
• Credit 1.2 Building reuse—Maintain interior Nonstructural Elements (1 point)
• Credit 7.2 thermal Comfort—verification (1 point)

Total: 61 points, a LEED 2009 Gold Building, and we haven't even taken into account the regional bonus credits.

Here is my LEED 2009 Scorecard for these credits.