Your builder has answered thousands of questions about square footage, finishes, and timelines. They have almost certainly never been asked about the formaldehyde content of their sheathing. That asymmetry is not an accident — and it is not in your interest.
Why These Questions Matter
The standard homebuyer conversation covers price, layout, neighborhood, and maybe energy efficiency. It almost never covers the chemistry of the materials being permanently sealed inside the structure. This is not because the chemistry is unimportant — indoor air quality in a new home built to standard US specifications is typically 2 to 5 times worse than outdoor air, according to EPA research. It is because neither buyers nor builders have been trained to think about it.
These five questions are designed to change that dynamic. They are not trick questions. A builder who is specifying thoughtfully will welcome them. A builder who defaults to standard-grade materials will be uncomfortable — and their discomfort is information.
Ask every question before signing the contract. Ask them in writing if possible, so the answers become part of the record. A builder who refuses to answer in writing is telling you something important.
How to use this guide: Each question is followed by what a Standard-grade answer sounds like, what a Domus-grade answer sounds like, and why the difference matters. You do not need to be a building scientist to use this guide — you need to be able to recognize evasion when you hear it.
Question 1
Oriented strand board (OSB) — used in approximately 90% of new American residential construction — is bonded with urea-formaldehyde resins. It off-gases continuously into the living space for the life of the structure. In energy-efficient, tightly sealed homes, these emissions accumulate. A study in Environmental Science & Technology measured formaldehyde levels in homes with standard engineered wood products at 40–80 μg/m³ — four to eight times the WHO's guideline for long-term exposure of 10 μg/m³.
This question forces the builder to either produce documentation or admit they don't know. Most have never been asked.
"It's all up to code" is the most common evasion. Code minimum is the floor of legality, not a ceiling of health. If they can't produce an emission test document, they haven't sourced to a health standard.
CARB Phase 2 compliance documentation, a Declare label, or a Health Product Declaration (HPD). Even better: a switch to inorganic sheathing products that have no formaldehyde to measure.
Question 2
This is the most technically revealing question on the list. Moisture management is the single most predictive variable in whether a home develops mold within its first decade. The materials matter — organic materials (OSB, wood framing, paper-faced drywall) provide substrate for mold growth; inorganic materials do not. But the assembly design matters equally: how vapor moves through the wall, where it condenses, and how it drains.
A standard-grade builder will describe a wall assembly designed to prevent moisture entry, typically by sealing it out with vapor barriers. This is the wrong strategy — water always finds entry through imperfect details, and a wall with no drainage plane traps moisture when it does. The correct strategy is to design for moisture management: a drainage plane that allows incidental water to escape, a sheathing material that doesn't degrade when wet, and a vapor-variable approach that lets the assembly dry in both directions.
"We seal everything tight" is a mold recipe. Water intrusion happens in all climates. The question is whether your wall can recover when it does. A sealed assembly traps moisture; a managed assembly drains it.
The words "rainscreen," "drainage plane," "vapor-open," or "drying potential" in the answer. These indicate a builder who understands building science rather than just building code.
Question 3
Modern energy-efficient homes are built tight by design — low air infiltration is the mechanism by which they achieve low heating and cooling costs. The problem is that tight buildings need mechanical ventilation to maintain indoor air quality. Without it, every off-gassing material in the home accumulates in a sealed environment. The EPA estimates that indoor air in American homes is 2 to 5 times more polluted than outdoor air; in a tight home without adequate ventilation, the upper end of that range becomes the floor.
ASHRAE 62.2 is the ventilation standard for residential buildings. It specifies minimum fresh air rates based on floor area and occupancy. Many builders meet code without meeting ASHRAE 62.2. Fewer still install Energy Recovery Ventilators (ERVs) or Heat Recovery Ventilators (HRVs) — the correct solution for tight high-performance homes, which supply fresh air while recovering the energy in the exhaust stream.
Bathroom exhaust fans and range hoods are spot ventilation — they exhaust stale air but supply no fresh air. In a tight home, every cubic foot exhausted must be replaced through infiltration, typically via the path of least resistance through gaps and building envelope defects. This is not a ventilation strategy.
An ERV or HRV specified by manufacturer and model, sized to ASHRAE 62.2, with a continuous low-speed fresh air rate and documented CFM design. This is the standard in Passive House construction and should be standard everywhere.
Question 4
Spray polyurethane foam (SPF) — particularly closed-cell SPF — has been marketed as a premium healthy-home upgrade because it improves energy efficiency by creating an air-tight thermal envelope. Its Salus Evaluation is Fails — it fails on IAQ, fire resistance, and durability. The reason: SPF is manufactured from isocyanates, one of the most potent respiratory sensitizers known, which off-gas for 24 to 72 hours post-installation at minimum, and often longer. Inadequately cured SPF can continue releasing isocyanates for weeks. Closed-cell SPF also contains hydrofluorocarbon blowing agents — potent greenhouse gases — and often halogenated flame retardants linked to endocrine disruption.
Fiberglass batts — the most common alternative — use formaldehyde binders that also off-gas. Mineral wool (rock wool or slag wool) is the Domus-grade alternative: no formaldehyde binders, inherently non-combustible without chemical treatment, and a Salus Evaluation of Salus-approved — it passes all five Domus Principles.
"It's the best insulation available" conflates energy performance with health performance. SPF achieves excellent R-values and air-sealing. It also introduces a chemical class that the EPA identifies as an occupational sensitizer. The premium product in energy terms is a significant concern in health terms.
Mineral wool (Rockwool, Thermafiber, or equivalent), cellulose, or cork. Any insulation specified without a formaldehyde binder, isocyanate precursor, or halogenated flame retardant. The product data sheet should be available on request.
Question 5
This is the economic question — and it may be the most uncomfortable one for a standard-grade builder to answer honestly. Standard asphalt shingle roofing has a real-world service life of 20–25 years. Vinyl siding has a service life of roughly 20–30 years before replacement. A homeowner who occupies a standard-grade home for 40 years will replace both — typically twice in the case of a longer ownership. These replacement costs are predictable, significant, and absent from every builder's estimate.
Asking this question out loud forces the builder to either provide the honest lifecycle math — which validates the Domus premium — or avoid answering, which tells you they've never considered it. Either answer is useful.
Manufacturer warranties on asphalt shingles are almost universally prorated — they cover diminishing percentages of replacement cost over time, and the coverage at year 20 (when you're most likely to need it) is typically a fraction of the replacement cost. Ask to see the warranty document, not the marketing summary.
A builder who can produce a 40-year lifecycle cost comparison unprompted, or who responds to this question with actual replacement cycle data rather than warranty marketing. This is the builder who has already done this math and is confident it supports their specification choices.
What to Do With the Answers
The purpose of these questions is not to catch a builder in a lie. Most standard-grade builders are not making dishonest choices — they are making default choices, and no one has ever pushed back. The purpose of these questions is to create a data set that lets you make an informed decision.
If a builder answers all five questions fluently — with documentation, specific product references, and lifecycle cost awareness — you have found someone who has already solved these problems before you needed to ask. Contract with them.
If a builder becomes defensive, dismissive, or repeatedly redirects to code compliance and warranty marketing, you have learned that health and durability are not considerations they have built into their process. That does not make their work illegal. It does tell you exactly what you are buying.
The builder's estimate shows you the cost of construction. These five questions show you the cost of occupying what they build.
A third common outcome: the builder is genuinely curious and open, but has never been asked before. This is the most promising scenario. Share this guide with them. Many builders who understand the Salus Standard and the material alternatives will adopt them willingly — they simply haven't been given the market signal to do so. You asking is that signal.
Quick Reference: Salus Evaluations for Common Specification Materials
| Material | Standard-Grade Standard | Salus Evaluation | Domus Alternative | Score |
|---|---|---|---|---|
| Wall Sheathing | OSB | Fails | MgO Board | Approved |
| Insulation | Closed-Cell Spray Foam | Fails | Mineral Wool | Approved |
| Structural Lumber (treated) | Pressure-Treated Pine | Fails | Naturally rot-resistant species | Approved |
| Exterior Cladding | Vinyl Siding | Fails | Fiber Cement (James Hardie) | Conditional |
| Roofing | Architectural Asphalt | Fails | Standing Seam Metal | Approved |
| Interior Finish | Standard Latex Paint | Fails | Lime Wash / Mineral Paint | Approved |
The conversations that shape a home's material specification happen in the six weeks before contract signing. After that, the walls go up, and what's inside them stays inside them — for forty years, for a generation, for longer if the structure holds.
These five questions are the conversation. Ten minutes of informed inquiry before signing determines the chemistry of the air your household breathes for the next four decades.
No good builder will be threatened by them. Only a builder who hasn't thought about these things — or who has thought about them and chosen not to — will struggle to answer.
Build Domus. Live Salus.