AHMC Hemp Roofing & Subfloor Insulation
AHMC – HEMP LIME ROOFING INSULATION
Using a very light Hemp lime mixture as roofing insulation creates a very effective thermal envelope, maximising airtightness, operational energy efficiency and significantly reducing energy costs.
Hemp lime roofing insulation is raked into place with minimal compaction to form an insulation wafer. It is important to take care that all gaps are filled.
Where the roofing insulation is installed from outside, temporary planks or battens should be attached to give the installer additional security. All safety precautions associated with working at heights must be observed. The material should be protected from rain and should be covered as soon as possible.
AHMC – HEMP LIME SUBFLOOR INSULATION
The same lighter hemp lime formulation that is using in roofing insulation can also be used as subfloor insulation and as insulation for suspended floors. The material has high vapour permeability, high elasticity and flexibility and it is an excellent insulator.
As with walls, all electrical conduits and plumbing need to be fixed before the hemp lime insulation is installed from above.
The formwork or cladding which is usually either 12mm magnesium oxide board or a composite wood sheet is attached under the floor joists and this must be supported appropriately when the insulation has been freshly installed.
- Depending on the climate zone 150mm – R3 to 250mm – R5 of hemp lime insulation is recommended for roofing in Australia.
- In extremely cold climates up to 300mm of roofing insulation is used.
- For floors a minimum of 100mm – 150mm of hemp insulation is recommended.
- For R values
WEIGHTS OF WET AND DRY MATERIALS
- The roofing (or flooring) engineering must be designed to support the damp weight (35% heavier than when dry) of the insulation material.
- Weight of freshly mixed insulation material is 218Kg per cubic metre
- Dry weight is 143kgs per cubic metre.
Notes: Synthetic insulation materials such as polystyrene or polyurethane should be avoided in hemp lime construction because they compromise the breathability of the hemp lime walls.
It is also normally not advisable to place an insulation quilt or batt directly in contact with hemp masonry, as moisture when the material is initially cast, can migrate to the insulation material.