Johan Tijssen

About the Guest

Johan Tijssen is the CEO of Hempblock International and a long-time builder and entrepreneur with more than 25 years’ experience working with hemp-lime (hempcrete) construction systems. Originally from the Netherlands, Johan moved to Australia and became deeply interested in why modern housing had become so complex, fragile, and uncomfortable. Through years of hands-on building, experimentation, and R&D, he developed an interlocking hemp block system designed to simplify construction while dramatically improving thermal comfort, fire resistance, and durability. Today, Johan works with owner-builders, architects, and developers globally to rethink how walls—and homes—are built.

Episode Summary

In this episode of Shape the System, host Vincent Turner speaks with Johan Tijssen about what’s fundamentally broken in the way we build houses—and why walls are at the centre of the problem. Johan contrasts today’s lightweight, multi-trade wall systems with thicker, simpler, and more durable approaches used historically, arguing that modern construction has traded long-term performance for short-term speed and perceived cost savings.

Johan shares his personal journey from traditional building into hemp-based construction, after discovering hempcrete’s unique properties: insulation, fire resistance, breathability, and longevity. From there, he explains how Hempblock International evolved the material into a modular, interlocking block system that removes on-site mixing, reduces trade complexity, and enables faster, more accessible builds—even for owner-builders.

The conversation explores the practical realities of construction economics, labour shortages, bushfire risk, and health issues like mould and humidity. Johan also outlines a bigger vision: scaling hemp construction into social housing, large developments, and even Olympic-scale projects, while regenerating soil and sequestering carbon through industrial hemp farming.

Key Takeaways

Modern wall systems rely on multiple materials and trades, increasing cost, coordination risk, and long-term failure points.

Hemp block walls deliver R-values up to 4.8, over 3 hours fire resistance, and natural humidity regulation in a single system.

The interlocking hemp block approach allows walls to be built at roughly 10 minutes per square metre, with minimal specialised skills.

Hemp-lime walls petrify over time, improving durability rather than degrading like many petrochemical-based materials.

Scaling hemp construction could support carbon-negative housing, healthier indoor environments, and regeneration of polluted soils.

Notable Quotes

“Walls are really like a complex system… and they require lots of different trades and moving parts.” — Johan Tijssen

“I was totally fascinated by the fact that this one wall thickness would do everything—insulate, fireproof, and perform over time.” — Johan Tijssen

“You’d be with a sledgehammer for half an hour before you get a hole in a hempcrete wall.” — Johan Tijssen

“Hemp and lime petrify over time. There are no petrochemicals that break down.” — Johan Tijssen

“The success is when people love where they live and feel safe, healthy, and comfortable in their own homes.” — Johan Tijssen

Resources

Hempblock International — https://hempblockinternational.com/?u...