Hemp Block: How do is simulate in FR5?

Created by Vicki Marshall, Modified on Mon, 07 Nov 2022 at 12:20 PM by Vicki Marshall

Region: All States

Assessor Question:

Having been asked to complete a Thermal Performance Assessment on a Hempcrete block construction, the following specification advice was provided by the manager of Hemp Block Australia:

The blocks will be 300 mm, R 4.93 with renders on 2 sides

I am able to construct this wall using Soft board? After research, I understand Soft Board has similar thermal performance properties and 300mm has an R Value of 5.01.

Is this reasonable to assume? Would this pass an audit?

TechLink Response:

The important considerations for entering construction into wall builder are thermal heat-flow resistance and thermal mass.
Hemp block product data indicates a density of approximately 324kg/m3 for the solid load bearing blocks.
It will be necessary to identify materials that are available in the wall builder library that are the best match for both R-value and thermal mass.
Soft board will not have suitable thermal mass properties.
AAC density is 525kg/m3.
The thickness of these or other density products may then be layered and adjusted for mass and R-value to arrive at a best fit for Hemp Blocks.
Confirmation of method will need to be described in the additional comments panel to avoid confusion between NatHERS Certificate and stamped drawings.