Important Considerations for Insulation



What’s Required vs. What’s Right

There’s a big difference between building to code — and building it right.

In Vermont, the most recent Residential Building Energy Standards (RBES) were updated in 2024. These reflect modern expectations for energy efficiency and comfort. Basic minimum requirements now include:

• R-30 slab edge
• R-49 roof insulation
• R-20+ wall assemblies (with additional continuous exterior insulation in many cases)
• Verified air sealing through blower door testing
• Mechanical ventilation for indoor air quality

These are the bare minimums. And yet — many builders are still cutting corners and failing to meet even these updated requirements.

You’ll still find fiberglass batts crammed into walls with minimal air sealing, houses wrapped with Tyvek over OSB, no continuous insulation, no vapor control, and no ventilation plan. These homes may technically get by on paper, but they’re uncomfortable, inefficient, and vulnerable to moisture problems over time.

Meeting code is the floor — not the goal.

Surface Numbers Don’t Tell the Whole Story

Let’s say a builder tells you they’ve used R-21 fiberglass batts in the walls. On paper, that sounds like it meets code. But what if they:

• Didn’t seal any of the gaps around the batts?
• Left thermal bridges unaddressed?
• Used no exterior insulation?
• Skipped mechanical ventilation entirely?

Then they’ve barely met code — and delivered a home with drafts, cold spots, higher energy bills, long-term durability issues and potential for health issues.

They’ve done the bare minimum — but you’re left with a subpar result.

The Hidden Value of Doing It Right

A properly designed and installed insulation and air sealing package gives you:

• A quieter, more comfortable home year-round
• Consistent temperatures (no cold feet or hot ceilings)
• Lower utility bills
• Healthier indoor air
• A longer-lasting structure without moisture issues

It also adds resale value — even though it’s behind the drywall.

Why We Don’t Cut Corners

Some builders haven’t updated their methods since the early 2000s. And while those techniques may still “pass inspection,” they don’t deliver the comfort or efficiency that today’s homes — and homeowners — demand.

At RNT Builders, we build smarter:

• We use continuous exterior insulation (Comfortboard or foam) to reduce thermal bridging and boost R-value
• We rigid insulate and seal slab edges for thermal control and moisture resistance
• We carefully choose the best insulation for each application (Rockwool, rigid foam, etc.)
• We focus on tight, detailed air sealing from sill to top plate
• We ensure a complete, continuous air barrier across the home
• We coordinate and install mechanical ventilation for a healthier home

Does It Cost More?

Slightly — but it pays off fast.

We don’t upsell insulation to inflate costs. We build packages that perform well, make your home feel better, last longer, and save money. That means:

• Lower monthly energy costs
• A more durable, mold-resistant structure
• Fewer issues over time
• A healthier, more enjoyable space to live

Want a Healthier Home, Not Just a Prettier One?

Let’s walk through what makes sense for your project. Whether you’re renovating or building new, we’ll explain the pros, cons, and what’s worth investing in.

Reach out today — no pressure, just real answers.