Design Strategies IMPULSE - Sustainable Facades Vol 2

its production, providing strong thermal qualities,
while lime binder adds mechanical capabilities,
making it fire, rot, and insect-resistant. Although
it can possess favorable compressive strength,
hempcrete is not suitable for load-bearing
structures but is commonly used as infill in
construction [3].
Strength:
shifted upwards, leaving an overlap to prevent
spillage. Hempcrete walls are framed with 2×4s at
24-inch spacing, with potential wood use reduction
under engineer‘s guidance. Once cured, lime plaster
is applied internally and externally, with fiberglass
mesh reinforcing the exterior. Additional rain
protection may include a face brick splash guard on
a zinc shelf at the bottom, topped with flashing for a
seamless joint with plaster.
Figure 22. Rehabilitation with straw bales
• High rot, and insect resistance
• Hemp-lime buildings may collect roughly
165 kg of CO2 per m3. (manufacturers ‘Lime
Technology Ltd and Technichanvre)
• There are no solid wastes generated during
construction.
• Structural element, good thermal and
acoustic insulation, can be cast into any
shape.
5.3 Prefab hempcrete panel
Using prefabricated hemp panels for construction
offers a more efficient and faster alternative to
traditional on-site builds, reducing construction
time and eliminating the 45-day curing period
required for cast hempcrete buildings. These
panels, filled with hempcrete mixture, utilize 3-ft by
Weakness:
plaster is ideal for interior finishes, regulating indoor
moisture. Builders often include a „Truth Window“ to
showcase straw bale construction, revealing a piece
of straw within the wall.
Recycle and Reuse
Straw bale walls and panels offer environmentally
friendly building materials that can be recycled
and reused in various ways. Recycling begins
with careful deconstruction, separating
straw from extraneous components like
plaster or wood framework. The straw can be
repurposed for animal bedding, mulch, or soil
amendment, while the plaster and wood can
also be recycled. If in good condition, straw
bales may be reused for earth-building like
Adobe construction.
5. Hemp-lime products
Figure 23. Truth window
Hemp-lime, also known as „hempcrete,“ is a
bio-composite material made from lime-based
binders and hemp shiv. It offers strength, thermal
efficiency, and versatility, suitable for monolithic
walls or insulating bricks and blocks. Originating
in France, about 15% of hemp shives are used in
• The material must be well sheltered from
frost and severe rain during construction,
and the outside temperature must not drop
below 5°C.
• Protective clothing, gloves, and other gear
are necessary when handling hemp-lime due
to its skin and eye irritant properties, as well
as the potential to cause burns when damp.
• To maintain proper plaster coating and wall
finishes, maintenance is frequently required.
Hemp-lime products come in blocks, precast
elements, and in situ cast forms. In-situ
application involves molding or spraying it
around the building‘s structural frame. Blocks
are available in structural and thermal varieties,
while precast panels are filled with hemp-lime
and hung on steel, timber, or concrete frames,
providing insulation and an airtight enclosure for
buildings.
5.1 The hempcrete block
‚Isohemp‘ provides hemp blocks, a non-loadbearing
glued masonry product suitable for
various construction purposes such as residential
houses, wall doubling, industrial partitioning, and
apartments. They offer two types: solid blocks and
machined blocks. Solid hemp blocks are 60cm by
Figure 24. Hempcrete blocks
30cm, and available in thicknesses from 6 to 36cm.
Machined blocks include holed and U-shaped
blocks with thicknesses of 30 and 36cm.
Hempro System
The Hempro System by ‚Isohemp‘ utilizes two types
of 30cm thick hemp blocks: solid and machined.
Machined blocks serve as insulating lost formwork
within the building envelope for pouring reinforced
concrete structural frames. Holed blocks form
column formwork, while U-blocks facilitate beam
pouring to support floors and roofs. Additional
hemp block layers of varying thicknesses can be
added for enhanced thermal performance.
5.2 The hempcrete formwork
On-site hempcrete walls are constructed by
blending hemp hurd (the woody core of the hemp
plant), a binder (such as lime or cement), and water.
This mixture produces a durable and lightweight
material suitable for both load-bearing and nonload-bearing
walls in construction.
Construction Process
Figure 25. : Hempro system
‘Hempstone,‘ a professional hempcrete installer,
outlined the construction process for Hempcrete
Formwork. To prevent moisture absorption from the
ground, plastic membrane strips are placed directly
on the slab with spray foam insulation sealing any
cracks. Small PVC conduits on 2” x 4” studs create
an interior barrier, acting as spacers for plywood
formwork. T1-11 siding serves as the outer barrier,
secured with 5-inch
screws into studs, forming a 6.5-inch cavity for
hempcrete. After filling the mold with
hempcrete mix, the formwork is unscrewed and
Figure 26. Hempcrete formwork
Figure 27. Prefab hempcrete panel
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Design Strategies IMPULSE – Sustainable Façades 04.2024 Design Strategies IMPULSE – Sustainable Façades 04.2024
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