HempWool Installation Guide: Sustainable and Efficient

As more homeowners and builders turn to sustainable building materials, HempWool insulation emerges as an eco-friendly and efficient choice for insulating homes and buildings. This guide provides detailed instructions on the storage, safety, cutting, and installation of HempWool insulation, ensuring maximum thermal performance and safety throughout the process.

Storage and Preparation

Before installing HempWool, proper storage is crucial to maintain its quality and effectiveness. HempWool should be kept in its original packaging, away from rain and sunlight. The ideal storage location is indoors, in a cool, dry place. If outdoor storage is unavoidable, ensure the pallets are covered with a waterproof tarp to prevent water accumulation.

Safety Measures

Handling HempWool is safe; it does not irritate the skin like some other insulation materials. However, it is essential to wear protective clothing, gloves, and eye protection when cutting and installing HempWool to avoid any potential injury from tools. Always adhere to OSHA guidelines to ensure a safe installation process.

Cutting HempWool Insulation

HempWool comes factory cut for a friction fit between framing dimensions of 16” to 24” OC. For non-standard dimensions, cut the batts with an additional 1/2 - 3/4” width than the studs to ensure a snug fit. Use tools such as a table saw, grinder with a metal cutting disc, or a Bahco Profcut insulation saw for efficient cutting. Mark the insulation with a Sharpie or by imprinting with your finger for accurate cuts.

 Interior Walls

Preparation: Before installing HempWool in interior walls, ensure that all architectural designs and specifications are closely followed, especially those specific to your climate zone and local codes. The surfaces to be insulated should be clean, dry, in good condition, and free from leaks.

Installation Process:

  • Measuring and Cutting: Measure the distance between studs and cut the HempWool batts slightly larger (about 1/2" to 3/4" extra) than the measured gap to ensure a snug fit. This added width helps create a friction fit between the studs, ensuring perfect contact and eliminating gaps.
  • Fitting the Insulation: Place the HempWool batts between the studs. Compress the batts slightly on both sides to leverage the "spring effect," allowing the insulation to expand and friction-fit securely within the cavity.
  • Ensuring Continuity: Adjust the panels to ensure they are perfectly joined without any gaps. It's crucial to maintain the continuity of insulation at junctions between walls, floors, ceilings, and crawl spaces. Use cut-offs from the site to fill in any small gaps or junctions.

Conditioned Attics

Preparation: Conditioned attics require careful preparation to ensure that they are insulated properly. Start by following all relevant design details and installing a water-resistive barrier (WRB) on the exterior side and a vapor control barrier, such as an Intello Membrane, on the inside as recommended.

Installation Process:

  • Layering: Begin by placing a layer of HempWool between the rafters using the friction fit technique. The dimensional stability of HempWool will keep it in place.
  • Adding a Second Layer: Depending on the roof R-value requirements, a second layer of HempWool installed perpendicularly to the first layer can enhance insulation performance. This cross-jointing method helps in minimizing thermal bridges and maximizes energy efficiency.
  • Securing Insulation: Ensure that the insulation fills the cavity completely without any gaps and that continuity is maintained at all junctions.

Unconditioned Attics

Preparation: For unconditioned, ventilated attics, it's essential to ensure proper ventilation to avoid moisture condensation. The use of an interior membrane tailored to the specific climate zone, local codes, and architectural design is recommended.

Installation Process:

  • Base Layer Installation: Install HempWool between the attic floor joists. Ensure that the insulation is cut to fit snugly, with an extra width of about 1/2" to 3/4" for a friction fit.
  • Adding Layers for Higher R-values: To achieve higher R-values and minimize thermal bridges, add a second layer of HempWool on top of the first layer, laying it perpendicular to the joists. This technique significantly reduces heat transfer.
  • Ventilation and Safety: Make sure the insulation does not obstruct attic vents and is kept at least 6 inches away from heat sources like chimneys or spot lighting. Use protective covers or non-combustible material to create a safe distance around heat sources.

Suggested Tools

Grinder with a Metal Cutting Disc

  • Purpose: The grinder is the primary tool for cutting HempWool efficiently, especially for quick and rough cuts. The metal cutting wheel can handle the coarse nature of HempWool better than standard blades designed for softer materials.
  • Recommended Size: For thicker layers of insulation, a 7” cutting disc is advised to accommodate the depth and provide a clean cut through the material.

Serrated Insulation Knives

  • Purpose: For those who prefer a non-mechanical option or need to make more precise cuts without setting up a grinder, serrated knives designed for cutting mineral wool can be effective. These knives allow for manual control over the cut, making them suitable for detailed work.
  • Example: Bahco Profcut Insulation Saw or similar tools designed for mineral wool.


Table Saw with a Specialized Blade

  • Purpose: When precision is key, especially for cutting HempWool to widths that deviate from standard framing dimensions, a table saw is recommended. It ensures straight, uniform cuts across larger volumes of material.
  • Blade Types: A metal cutting blade or a Hardie Board blade is suitable for this purpose, designed to slice through the tough fibers of HempWool without dulling quickly.

Utility Knife

  • Purpose: A utility knife with a 1” blade is essential for opening HempWool pallets and bundles. Its sharpness and precision are perfect for cutting through packaging materials without damaging the insulation.
  • Usage: It's also useful for making minor adjustments or cuts to the insulation after the primary cutting has been done.

Measuring Tape

  • Purpose: Accurate measurements are crucial for cutting insulation to fit specific spaces. A measuring tape is indispensable for marking the dimensions needed before cutting.
  • Usage: Combined with a Sharpie or a simple finger imprint on the HempWool, it ensures that each piece is cut precisely to the required size.

Marking Tools

  • Purpose: For marking cuts on HempWool, a Sharpie is recommended due to its visibility on the coarse material. Alternatively, users can imprint the insulation with their finger to leave a temporary reference mark.
  • Usage: These marking tools are essential for guiding the cutting process, ensuring that each piece of insulation fits perfectly into its intended space.