FAQ

FREQUENTLY ASKED QUESTIONS:

Q. What is the span to depth ratios of walls over door openings and typical rules of thumb for floor openings?

A. The depth ratio is 30cm to 850+cm. Please note added reinforcing to be sprayed in to form a lintel.

Q. How is tying laterally, vertically and around floor plates perimeters achieved?

A. This is achieved by using 3mm hot galvanised steel wire and 50mm x 50mm BRC mesh set into brackets tying ceiling, wall floor, vertically horizontally and laterally as shown. On the top of the wall the junction with the floor plates polyinsulator is removed and we form a concrete ring beam as shown in diagram 6.

Q. What is the overall self weight?

A. Using 3mm wire with 100mm x 50mm polyinsulator strips adding a 25mm render on either side of the panel the system weighs 140 kg per m2.

Q. What tolerances on plan location and verticality are achieved?

A. Normally work to 5mm or 10mm – the walls are tied together and as they are predetermined dimensions the tolerances remain low.

Q. What are the typical deflections/stiffness of floor plates?

A. With a domestic load 1.50 KNm2or a 4m x 4m simply supported floor structure the deflection will be2.2mm. This compares with a 5m x 5m floor span, again simply supported, where the deflection will be 5.4mm.

Q. Is there any danger of pop through deflection of floor plates if they initially arch and then buckle under increased loads?

A. There is no danger of pop through deflection because you would calculate the maximum load you intend and would add extra reinforcing as necessary, either by thickening the floor screeding or adding some BRC fabric. Obviously industrial or extra heavy loads would need to be reviewed specifically.

Q. What are the failure modes of floor plates, and supporting walls?

A. On floor plates approximately 17 tonne. The only way you can make the wall or floor plates fail is by loading either directly or in compression. With the Sirum tests that were undertaken in Malaysia and witnessed by a representative of Warrington, there was no sign of failure at 43.5 tonne at which time the test was concluded for fear of breaking the testing equipment. The floor plates failed at 17.2 tonnes, this was tested using a central load.

Q. What are the specific maintenance criteria of the system, what elements are life long, maintainable or replaceable?

A. The system uses polypropylene in the render and then uses 2 coats of sealant which has a guaranteed life of 25 years by the manufacturer. The sealant is used in the building of reservoirs. The usage of hot galvanised wire means the wire is self healing. If the wall’s surface is punctured it should be repaired using an epoxy material to ensure no shrinkage. Adding pigment to the exterior render negates the long-term need to repaint the outer surface. Sections of panel can be removed and replaced as required using a skill saw or by refixing new panels to the existing structure and rerendering the outer surfaces.

Q. What building controls to date have approved the design and what under codes of practise or testing regime?

A. Sirim Malaysia – where the tests that were undertaken were witnessed by a representative fromWarrington. This included structural tests as well as 2 hr fire test. Asian Institute has certified the system for usage in Thailand based on the Sirim testing programme. European Agrement was achieved when the system was comprehensively tested in Romania. They verified the Sirim tests complementing this with a 3 week long testing programme that was undertaken in Alba this included both structural and fire tests.

Q. Can the system support a balcony?

A. Yes. Cold bridging would be avoided by using a soft board such as a sofit to surround the panel. There may also be additional insulation under the screed to further enhance the insulating properties.

Q. How could collapse be limit in the event of a panel being removed?

A. You would take the same precautions as you would with conventional construction materials such as propping until you have put in a lentil or beam to ensure structural integrity and stability.

Q. Can panels be thinner or thicker than 156mm?

A. Yes the thickness of the panels can be changed but individual building standards must still be met.The composition of the panel affects both the thermal and acoustic properties of the panel.

Q. What U-values can be achieved?

A. A U-value of 0.34 w/m2/k is achieved on 100mm polyinsulator panel. This test was carried out on panels using polyinsulator we believe a better U-value would be achieved if phenolic foam were to be used. Greater U values can also be achieved if required through the incorporation of additional cladding.

Q. Can new openings be made to an existing structure?

A. New openings can be simply achieved by cutting out the required opening using a skill saw.

Similarly openings can be filled by tying in new panels cut to fit the edifice. In making new openings greater than 850mm further support would be required above the opening such as a lentil or supporting beam.

Q. What is the overall size of the panels?

A. See diagram 220cm x 122cm for standard panels dimensions, lengths can be varied to suit application.

Q. How are they lifted into positions?

A. The lightweight nature of the panels allows for them to be lifted by hand.

Q. Do they arrive on site as cages and are spray with concrete insitu or are they delivered asmanufactured precast concrete panels?

A. The panels are manufactured and sprayed on site.

Q. What fire rating has been achieved?

A. Following the Sirim fire test Speedwall received a 2 hr fire test. The test was undertaken on a 156mm panel which was fixed in a jog and then torched until the concrete cracked under the heat.

Q. Is there the possibility of fire spreading through polyinsulator core to other areas of the structure?

A. Whilst the tests showed that polyinsulator blocks will melt in direct contact with flames, when covered in render they will not combust. For fire to spread as a result of the polyinsulator combusting, a total collapse of the panel would need to happen, this would not occur in 2hrs or less.

Q. Can the Speedwall panels be designed to support fixings for façade brickwork / curtain wall?

A. Yes it can, it should be looked at like any other comparative building materials such as breeze block.

Q. Can higher strength bars (e.g. 460 N / mm2) be used?

A. Yes it can although the higher strength wire is less flexible and more costly, more difficult to weld and does not really achieve any real advantage.

Q. How does the render bond to the Polyinsulator?

A. The render doesn’t bond to the polyinsulator; 2 coats of polypropylene are used in the mix which is a fibre. Hence after it is sprayed on the surface it acts like a grout or unibond. Once it has dried the polypropylene binds behind the wire which makes it virtually impossible to break.

It is actually a positive feature that the render doesn’t bond with the polyinsulator, because this allows the polyinsulator a degree of movement hence if there was any significant movement such as an earthquake the render would not sheer off. The bonding agent that is used is also used to bond cement to cement, which is notoriously difficult to achieve.

Q. Can the Polyinsulator rot from being damp?

A. No the Polyinsulator that is used experiences no degradation in quality as it is not water absorbing. 

A special quality pellet is used in the manufacture of the polyinsulator that provides a high fire rating.

Once inside the wall, the polyinsulator will not be exposed to any moisture. To start with, when the block of polyinsulator is cast it passes through a heat tunnel ensuring there is absolutely no moisture left in polyinsulator block. This is done to make cutting the block cleaner. If moisture is left in the block it squeezes and makes the block difficult to cut cleanly. Furthermore 2 coats of Sica 1 sealant are used as part of the process of rendering the finish. The sealant used comes with a 25 year guarantee from the manufacturer. It is used in the building of reservoirs.

Q. How deep should the foundations be when building a single or double storey structure?

A. The depth of the foundations will be determined depending on the soil and the loads that are to be exerted on the structure. However, in most cases when constructing a single or double storey residential structure, a 6 or 8 inch slab would be used together with a 6mm or 8mm BRC fabric reinforcing mesh. There would be 2 layers of mesh; one 2 inches from the bottom of the slab and one 2 inches from the top of the slab.

The concrete used would have a high rating such as C30 or C35. This is used because of its high crushing strength.

For larger multi-storey structures, column bases would be incorporated every 7m. To further reinforce the structure a reinforcing ring beam of 18 inches x 18 inches would be used– this also has a BRC reinforcing mesh inside. The structure would be designed so that it transfers loads into the column bases this is done by using diaphragm walls.

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