FAQ

The Panels

  • Prefabrication offers a number of advantages compared to traditional straw bale building methods.

    • Cost: The amount of labour required is massively reduced because the hydraulic press does most of the work for us. Instead of 4-6 people installing the straw we only need 2 people.

    • Time Saving: It is much quicker to build the timber frame and compress the straw in one operation rather than separately. We can build all the panels for a typical house in a couple of weeks.

    • Uniform and Precise: Compressing the straw hydraulically inside a press is much easier to control and ensure that straw is filling all of the panel and no cold spots are present. The result is panels with uniform density and precise dimensions.

    • Reduced time on-site: We can be building panels while the foundation is being built on site which means less disruption to other trades and a build that is a lot easier to manage.

    • Dry factory environment: Panels are built and stored in a dry factory environment and so there is no potential for damage to the straw from the rain. The less time bare straw is exposed the better.

    • Pre plastered walls: Pre plastering the panels with the basecoat of plaster is a further time-saver and cost-saver. The accuracy and quality of the plaster is easier to control as well.

  • The width and height of the panels can easily be adjusted to make almost any design and size of building possible. All of our panels are 400mm thick.

    Thickness: 400mm

    Width: 400 - 1200mm

    Height: 400 - 3200mm

    Incline Angle: 5 - 45 degrees

  • Our panels are made in a custom designed hydraulic press that allows the timber frame to be built inside it and then straw is compressed into the timber frame before it is all screwed together. Once it is released from the press the straw is trimmed off the sides.

  • It depends on what the exterior cladding and interior lining is going to be.

    If a clay plaster is going to be used on the inside we supply the panels with a “slip coat” of clay to protect the straw and make the plaster application on-site easier. (A slip coat is a thin covering layer of clay that encapsulates the straw and makes future plastering easier). We can also do this with lime for the exterior face if plastering the exterior.

    We generally don’t apply base or finish coats of plaster in the factory as it makes the installation and transport of panels much more difficult at the moment.

  • One of the biggest misconceptions with straw buildings is that they are not fire resistant.

    The straw is so highly compressed that there is not enough oxygen to sustain a fire. Straw also has a high silica content, which is a natural fire retardant. When the panels burn, they smoulder and create charcoal layer on the outside that further protects the panel from flames.

    Combined with lime and clay plaster claddings, both of which do not burn, straw buildings perform extremely well in fire tests.

  • No more than typical buildings. Mice often tunnel and nest in loose straw, but our panels are too highly compressed to be attractive to them. Birds are looking for any stray seeds that may be around, but once plaster is covering the walls there is nothing for animals to look for.

  • Yes it is possible and it has been done in New Zealand and many times all around the world. StrawSIP panels are the perfect starting point for a Passive House (Passivehaus) certified home, but you will still need to take other things into account such as the design of the house, windows, ventilation etc. Talking to a Passive House designer is the easiest way to understand what you need to do to achieve the standard.

  • No, not at all. Straw is different from hay. Hay contains pollen, whereas straw is only the stalk of the plant. Additionally, the straw is fully encapsulated by the finish material and so there is no dust, pollen or other plant matter that you are in contact with.

Your Project

  • We believe our panels are reasonably priced and overall are about equal to a standard wall construction in New Zealand. We are confident that they are the most affordable way to build a straw bale house and they offer the certainty of a fixed price. Contact us with your plans (or even concept sketch/model) and we will give you a free estimate. In general you can initially estimate that our wall panels are approximately $250/m2 + GST of wall area but this depends on the panel sizes you require (i.e. 1200mm wide panels are the cheapest, with narrow panels being more expensive per m2).

  • We can build all the panels for an average sized home in 2-4 weeks.

  • Ideally you would contact us as early as possible, but in general as long as you contact us before plans have been submitted to council it is relatively easy to change the wall structure in a design to be StrawSIP panels (400mm thick).

    If you were already building a straw bale house in the traditional on site method, then it is likely to be a lot easier to use our panels even after plans have been submitted or the building process has started.

  • Yes any designer or architect can work with our panels. They are actually very simple to design with and work much like other SIP or modular systems. We can provide details and guidance and also help with the panelisation of the design to help maximise the efficiency of the panel sizing and quantity required.

  • Yes, any builder including owner-builders has the ability to assemble the panels. We provide clear, simple instructions and every panel is coded to match with the supplied layouts. It’s like assembling a giant LEGO house and uses standard construction methods, tools and materials to complete the assembly.

  • Yes, the double timber frame structure is extremely strong, probably stronger than a typical timber framed house and they can be designed and engineered for 2 storey houses.

  • We can do all the plastering in clay and lime, but depending on the project location it may make sense to use a local lime/clay plasterer or you can do it yourself. We can provide a quote for the finish plastering or can give contact details of anyone we know that is local to you.

Design Options

  • The most common and suitable interior finishes for straw houses is either clay or lime plaster. It works extremely well with the straw, is natural and healthy and looks beautiful.

    It is however possible to use almost any other type of standard interior finish such as GIB, plywood, timber panelling, Magnum board etc.

  • Our preferred exterior cladding method uses a woodfibre board as a rigid air barrier (RAB), 40/45mm structural cavity battens and a cladding material such as timber, corrugated/profiled metal, plywood, Magnum board or other approved cladding systems in New Zealand.

    Traditionally a lime plaster has been used on strawbale buildings and this is an option with our panels as well, but it does have limitations and design requirements depending on your location and climate. Often a silicate paint is used over the lime plaster for increased weather protection and to give colour to the walls.

  • StrawSIPS work with all major foundation systems including concrete slabs, concrete footings, timber piles, ground screws. We can provide details for different foundation types.

    We believe a suspended timber floor on piles or ground screws is one of the most economical, highest performing and most sustainable options and believe there are many advantages compared to concrete slabs.