After you address air leaks in your home by air sealing, then … and only then … you can add insulation.
- Start here to read the beginning of the “Ready your envelope” series.
Why it matters: Adding insulation without air sealing is like putting on a sweater over bare skin and walking outside when it’s 20 degrees and windy.
- As great as that sounds when it’s 100 outside, if you’ve done that in the winter you know that air moves through insulation.
⚙️ How it works: Loose fill and batt insulation is a THERMAL barrier only —> which resists the transfer of heat.
- It’s not an air barrier or a moisture barrier.
- Wind blowing through soffit vents in the attic or pressure differences between your attic and house can draw air and vapor through the insulation.
🙋 What about spray foam?
- Spray foam comes in two main varieties —> open cell and closed cell.
- Open cell is most commonly used for spraying the underside of the roof deck —> closed cell used the same way is even better, which is why it’s much more expensive.
- Closed cell is what you buy in the individual cans and should be used to cover seams and crack before open cell is sprayed.
- Closed cell is also great for air sealing penetrations in walls and ceilings.
🥊 Reality check: Done correctly, spray foam can be very effective.
- But, but, but … depending on your attic shape, it can be very difficult to do it well —> which is why it’s more effective in new construction.
- And spray foam carries a few other risks like creating potential moisture issues at the ridge line of the attic and making it difficult to diagnose a roof leak.
✅ For your Smart Homeowner list
- Before you invest in more insulation, make sure your attic is properly sealed.
- Which can be tested and verified using the right equipment.
- If you need help navigating your next step, let’s chat.