We recently hosted Lindsey Love on our Regen Building on our Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or share it with a friend or colleague, you can now do so, as the recording is available below. In addition, Lindsey answered some of the remaining Q&A below, and your question may have additional follow-up below.  

The webinar survey responses reveal a high level of engagement and learning about natural insulation materials, particularly straw, hemp, wool, cellulose, reed, and cork. Many participants were surprised by the fire resistance, mold resistance, and growing affordability of these materials. Several learned about specific products like straw structural insulated panels (S-SIPs), cellulose batts, bound reed boards, and hemp fiber boards. Concepts like vapor permeability, moisture management, and cavity vs. exterior insulation were clarified for many. There was also increased awareness of the geographic variability in product availability and the evolving supply chain. Questions still remain around moisture modeling for specific climates, fire resistance standards, code enforcement, best practices for installation (like running electrical through straw), and the long-term durability of natural materials. Some attendees expressed interest in reviewing more on vapor permeable systems and wished for better regional access and training on these alternatives.

Q&A Response

### Q2: How do some of the “in cavity” applications perform with self-drying due to vapor drive?  

**A2:** Natural insulations can work well in cavity if they are surrounded by or encapsulated with vapor-open materials. Moisture will migrate towards an equal state, so if you allow it to escape to a dryer environment, it will. Plastic vapor barriers and foam insulations are not vapor open, which increases the risk of moisture problems. Using “smart membranes,” vapor-open weather resistant barriers, vapor-open finishes, shear panels (plywood or OSB), and/or exterior insulations are safer and lead to more durable assemblies.

### Q3: Can you elaborate more on the rainscreen cavity acting as a chimney, specifically regarding fire mitigation rather than ‘what is a rainscreen’?  

**A3:** While we don’t often see rainscreens with very wide gaps, it’s good to be aware that if they are over 1/2″ wide and open at both the top and bottom, they may have the potential to act as a chimney under the right conditions.

### Q4: How do you handle moisture management in a strawbale wall? Is it less critical if you’re not trying to keep the interior face of sheathing warm?  

**A4:** It’s important to keep materials inside a wall dry, regardless of whether it’s straw, fiberglass, or foam insulation. The strategies for straw bale walls are not different from any other. Straw bales make a great plaster substrate, and using natural, vapor-open plasters (lime or clay) is effective. If sheathing is necessary, use plywood instead of oriented strand board, along with a vapor-open weather resistant barrier and rainscreen with your finish of choice. Good drainage and flashing design on the exterior are especially crucial when using plasters.

### Q5: It’s great to see foam products reducing their GWP, but they’re still flammable, right?  

**A5:** Yes, foam products always require chemical fire retardants and remain quite flammable, even with these additives.

### Q6: Are there recyclable options for tapes/membranes?  

**A6:** In my community, plastic recycling options are limited to bottles only. While some areas have recycling opportunities for flexible plastics like bags, building membranes are not yet recyclable. Tapes are typically a single-use material due to their very sticky adhesives, but membranes can be salvaged and reused.

### Q7: What is the best thermal performance (R-value) of some of these natural materials?  

**A7:** Fiberboard insulations have a slightly higher R-value per inch, while batts and boards range from 3.3 to 4 per inch. Straw bales and chopped straw have slightly lower R-values, and when combined with a binder, such as “light straw clay” or “hemp+lime,” the R-value decreases, creating a different application.

### Q8: What do you think about using Aerobarrier for air sealing?  

**A8:** Although it’s not available in my market yet, my colleagues in Colorado have used it and liked it. It seems to be a great option, using a relatively small amount of petrochemicals to effectively target air sealing. Air sealing is easiest and most effective early during construction, but Aerobarrier can be utilized at multiple phases because it is fairly invisible and can serve as a backup plan if needed.

### Q9: We are building in coastal Florida with AAC block, so we do not have additional exterior wall insulation. How can we achieve a sealed attic without spray foam?  

**A9:** I need more information about what you mean by a “sealed attic.”

### Q10: Can Structural Insulated Straw Panels be used horizontally or angled as part of a roof assembly?  

**A10:** Yes, companies like Savick in Canada offer roof and floor panels made with chopped straw. New Frameworks and their SEED partners provide similar options but use cellulose instead of packed or chopped straw. Some European companies also produce horizontal panels, and “Strawtegi” panels with chopped straw can be used in this manner. A roof would be treated like an unvented “hot roof” and should be moisture protected, meaning you need to air seal at the interior, avoid penetrating the air seal with systems, and use vapor-open sheathing and roofing membranes.

### Q11: How do electricians and plumbers deal with the panels?  

**A11:** It depends on the panel. Some panels are best served by having an interior cavity for services, while others may have different requirements.