Safer Alternatives

How to Use This Page

This page is the companion to Materials to Avoid. That page explains what to eliminate and why. This page explains what to specify instead. Both pages use material categories, not brand names — the $79 Build Package includes specific product examples with the disclaimer that equivalent products meeting the same criteria also comply.

Every alternative listed here is evaluated against two questions: does it reduce VOC exposure compared to the conventional option, and does it reduce mold risk by being either inorganic or capable of drying? Some alternatives achieve both. Some address one but not the other. The trade-offs are noted.

Sheathing & Structural Panels

Instead of OSB (Oriented Strand Board)

OSB is the most common residential sheathing in the U.S. It is also organic, absorbs moisture readily, and becomes mold food when wet. Formaldehyde-based binders in standard OSB add chemical exposure during and after installation.

Magnesium oxide (MgO) board: Inorganic, moisture-resistant, non-combustible. No formaldehyde binders. Suitable for sheathing, tile backer, and interior substrate. Trade-off: heavier than OSB, requires corrosion-resistant fasteners in some formulations, quality varies by manufacturer — verify the board does not contain organic fillers or chloride compounds that cause fastener corrosion. Specify boards tested to ASTM C1658.

Exterior-grade gypsum sheathing: Fiberglass-faced (not paper-faced) gypsum board designed for exterior use. Inorganic face resists mold growth. Lower structural capacity than OSB — typically requires supplemental bracing. Trade-off: not a structural panel, so wall bracing must be addressed separately. Suitable for non-structural sheathing applications.

Cement board / fiber cement board: Portland cement with cellulose or fiberglass reinforcement. Moisture-tolerant, dimensionally stable, will not support mold growth on the surface. Trade-off: heavy, requires specialized cutting (dust control required), some formulations contain silica that requires respiratory protection during installation.

Insulation

Instead of Spray Foam (Open-Cell or Closed-Cell)

Spray foam involves chemical off-gassing during and after installation, traps moisture (closed-cell) or absorbs it (open-cell), and eliminates cavity inspectability. See the full spray foam evaluation.

Mineral wool batts and boards (rock wool / slag wool): Inorganic, non-combustible, vapor-permeable, does not absorb moisture, does not support mold growth. Available as cavity batts, rigid exterior boards, and loose-fill. The primary insulation recommendation across all Good Air Standard build options. Trade-off: denser and heavier than fiberglass batts, higher material cost than fiberglass, requires friction-fit installation (no adhesives needed in cavity applications).

Why the Good Air Standard specifies mineral wool over sheep wool — including binder chemistry, mold substrate risk, and what both manufacturers omit: Mineral Wool vs Sheep Wool Insulation.

Mineral wool continuous exterior insulation: Rigid mineral wool boards installed outboard of the sheathing. Vapor-permeable — allows the wall assembly to dry outward through the insulation. Critical for thermal bridging reduction in steel-frame assemblies. Trade-off: requires mechanical fastening or adhesive compatible with the system, rainscreen detailing required over the insulation.

Instead of Fiberglass Batts (Standard Kraft-Faced)

Standard fiberglass batts are low-VOC but kraft paper facing is organic and mold-susceptible when wet. Unfaced fiberglass is acceptable but performs poorly if compressed, gapped, or moisture-exposed.

Unfaced mineral wool batts: Higher density than fiberglass, better friction-fit retention, inorganic throughout (no paper facing), better sound attenuation. Trade-off: higher material cost, slightly more difficult to cut (denser material).

Interior Wall & Ceiling Surfaces

Instead of Paper-Faced Drywall

Standard drywall uses paper facing on both sides of a gypsum core. Paper is organic and becomes mold food when moisture reaches it — which it does, from both interior humidity and wall cavity moisture. Paper-faced drywall is the single most common mold substrate in residential construction.

Fiberglass-faced gypsum board: Same gypsum core, fiberglass mat facing instead of paper. Inorganic face does not support mold growth. Drop-in replacement for paper-faced drywall — same dimensions, same finishing process, same fastening. Marginally higher material cost. This is the simplest high-impact substitution on this list.

Lime plaster on mineral substrate: Traditional lime plaster applied over mineral board or directly to masonry. High-pH surface naturally inhibits mold. Vapor-permeable — allows the wall to breathe. Trade-off: requires skilled application, longer cure time than joint compound, limited contractor familiarity in most U.S. markets. Best suited for masonry build options (AAC, CMU, LECA).

Sealants & Adhesives

Instead of Standard Silicone and Polyurethane Sealants

Conventional sealants release acetic acid (silicone) or isocyanates (polyurethane) during cure. Some continue to off-gas at low levels for weeks.

Ultra-low-VOC silicone sealants: Formulated for lower emissions during and after cure. Look for products with published emissions testing data (CDPH Standard Method v1.2 or equivalent), not just "low-VOC" on the label. The three-tier VOC disclosure applies: require manufacturer documentation of actual emission rates and cure timelines.

Mineral-based sealants: Silicate-based or hydraulic-lime-based sealants for masonry applications. Zero organic solvents. Trade-off: limited flexibility, not suitable for movement joints, available primarily for masonry-to-masonry connections.

Instead of Standard Construction Adhesives

Mechanical fastening where possible: The lowest-risk adhesive is no adhesive. Screws, clips, and mechanical connections eliminate off-gassing entirely. Where adhesive is structurally required, specify products with published CDPH emissions test results and allow full cure ventilation per the Clean Air Construction Protocol.

Primers & Sealers

Instead of Standard Latex or Oil-Based Primers

Dewaxed shellac: Natural resin dissolved in denatured alcohol. Rapid off-gas (alcohol evaporates within hours), effective stain and odor blocker, seals existing substrates including construction-phase mold remediation per the Mold During Construction Protocol. Trade-off: alcohol-based application requires ventilation during application, not suitable for exterior use, limited to sealing applications (not a finish coat).

Mineral silicate primers: Inorganic primers that chemically bond to mineral substrates (concrete, masonry, plaster). Zero VOC. Trade-off: require mineral substrate — do not bond to wood or painted surfaces. Best suited for masonry build options. See Paint & Finishes Protocol for full coating system guidance.

Flooring

Instead of Engineered Hardwood with Standard Adhesive

Porcelain or ceramic tile: Fully inorganic, zero VOC from the material itself. Requires thin-set morite (low-VOC) and grout. No off-gassing after cure. Trade-off: cold underfoot without radiant heat, hard surface acoustics, cracking risk if subfloor deflects.

Natural stone (sealed with low-VOC sealer): Inorganic material, durable, no off-gassing from the stone itself. Sealer selection matters — require documented low-emission sealers with defined cure times.

Solid hardwood with mechanical fastening: Nail-down or screw-down over subfloor eliminates adhesive off-gassing. Wood is organic but the surface is finished and inspectable — unlike OSB trapped inside a wall. Finish with low-VOC hardwax oil or water-based polyurethane with documented cure timeline. See Flooring Protocol for full subfloor prep and adhesive guidance.

Polished concrete: For slab-on-grade construction. Apply low-VOC densifier/sealer. Zero organic content in the floor itself. Trade-off: cold, hard, limited to slab construction, requires moisture testing before sealing.

Roofing

Instead of Asphalt Shingles

Asphalt shingles off-gas petroleum-derived compounds, particularly when heated. For most homes this is not an interior air quality concern because the roof assembly separates the shingles from living space. For highly sensitive occupants or assemblies where roof-to-interior air pathways exist (cathedral ceilings, poor attic sealing), alternatives reduce this variable.

Metal roofing (standing seam or interlocking panels): Inorganic, durable, zero off-gassing. Factory-applied coatings are fully cured before installation. Trade-off: higher material cost, requires experienced installer, acoustics in rain (addressed with underlayment and insulation).

Clay or concrete tile: Fully inorganic, extremely durable, zero off-gassing. Trade-off: heavy — requires engineered roof structure to support weight. Regional availability and aesthetic preference apply.

The Trade-Off Pattern

Every lower-risk alternative on this page shares a pattern: the material itself costs more, the installation may require more skill or different techniques, and the long-term performance justifies the upfront premium. None of these alternatives are exotic. MgO board, mineral wool, fiberglass-faced drywall, and porcelain tile are all commercially available through standard building supply channels. The barrier is not availability — it is specification. If the contractor does not receive a spec that calls for fiberglass-faced drywall instead of paper-faced, they will install what they always install.

The specification is the intervention. The Build Package provides it.