Frequently Asked Questions on AMVIC ICF
Q. How wide is the concrete core inside the Amvic system?
A. There are two thicknesses available, 150mm (the 280 system) and 200mm (the 330 system).
Q. How high can you concrete the Amvic ICF system in a single pour?
A. Up to 3 metres high of concrete can be placed in any single concreting day, so building and concreting a full storey height at a time is quite convenient.
Q. Does the concrete core require steel reinforcement?
A. In the UK, as a rule of thumb steel reinforcement is only required over the top of window and door openings for low rise structures. However, retaining walls (basement shells and swimming pools) and structures taller than 3 storeys high are always reinforced throughout.
Q. Does the concrete need to be vibrated once poured?
A. Whilst not strictly necessary for above ground construction, for basement and swimming pool shells, we routinely vibrate the concrete in the Amvic system to ensure full compaction around any steel reinforcement.
Q. Can you render onto the Amvic system?
A. Yes. Acrylic or polymer modified render systems are available that have been designed to be applied onto polystyrene (EPS). With this type of render system no supporting eml (expanded metal lathing) is required. These systems are also ‘through-coloured’ and so do not require painting.
Q. How is a brick or stone finish achieved?
A. There are two ways of achieving a masonry finish – either by building a full brick or stone skin around the Amvic shell, or by applying brick/stone slips directly to the surface of the Amvic blocks. The brick /stone Wall ties are cast into the Amvic concrete core to support the full masonry skin option, whereas slips are bonded to the face of the Amvic system using a high adhesive bonding mortar over a supporting eml which is pinned back to the Amvic concrete core.
Q. How is the internal finish applied?
A. The plastic webs within the Amvic system have been specifically designed to provide a fixing strip which runs the full height of the block to which plasterboard can be fixed using coarse threaded dry-lining screws.
Q. Can curtain rails / shelves / heavy items be hung on an Amvic wall?
A. The plastic webs to which we fix the plasterboard (see above) can also be used to support light to medium weight loadings. Alternatively, for heavier items such as kitchen cabinets, fixings can either be drilled or precast into the concrete core.
Q. How are internal services accommodated?
A. Electrical conduits and water pipes can be recessed into chases cut into the polystyrene at the time of installation. SPECIAL NOTE: PVC cables should be kept from direct contact with polystyrene by placing it inside plastic conduit. This is to stop the cable sheathing reacting with the EPS and becoming brittle over time. However, low-smoke cable and plastic plumbing can remain in direct contact with EPS without issue.
Q. How do Amvic ICF build costs compare to traditional building?
A. Amvic build costs, including materials and labour, are on average about the same as traditional construction. However, the Amvic ICF system provides far better levels of thermal and acoustic insulation for that same cost. Indeed, to match the performance of an Amvic home, a cavity wall construction would cost around 40% more to build, and take significantly longer to erect.
Q. How does fire affect the Amvic system?
A. The polystyrene bead used in the production of the Amvic system is a flame retardant grade. If the Amvic forms are exposed directly to a naked flame the polystyrene will burn, but once the flame is withdrawn or the Amvic burns clear of it, the polystyrene will self-extinguish, i.e. the Amvic system will not contribute to the spread of the fire. Add to that the fact the solid structural concrete core cannot burn and you can appreciate just how safe and robust Amvic homes really are.
Q. Is condensation ever an issue with Amvic?
A. The internal surface temperature of the Amvic wall will be within one or two degrees of the room air temperature, preventing condensation from forming on the internal wall face. Amvic is a vapour permeable method of construction, so in theory the occurrence of interstitial condensation is possible during the winter months. However, this will then quickly disappear during the rest of the year. In fact, to date interstitial condensation has never been detected in an Amvic ICF wall.
Q. Can Amvic be built to dimensions based on traditional construction?
A. Amvic is a fully metric system based on a 50mm modular size. However, it’s relatively easy to build to any dimension required simply by cutting ‘off-module’ through one block in the same wall position on each course. To support the vertical co-incidence of the cut joints we then simply screw plywood across the joint into the plastic webs of the Amvic system either side until the concrete has been placed.