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Frequently Asked Questions
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The best way is to rip a plywood strip 2 to 2 1/2" wide and screw it in place to the webs along all the walls. Fasten these strips at every fourth web. Now the drywall contractors can set their drywall on top of it, and will cut their top sheets accordingly to suit this height. The result is you have full wood fastening for nails along the complete wall surface and the plywood is guaranteed to be covered by the baseboard.
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Our form panel thickness is 2 5/8”. This is deep enough to accommodate almost every standard depth electrical box. Deeper boxes are easily accommodated by simply gluing a square of foam on the inside of the form at the location being planned for the box during the pre-pour phase of the installation process.
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The NUDURA form unit has a fastening strip located every 8” (200mm) on centre. These fastening strips are continuous up the full height of the form unit, and have a patented mechanism that interlocks one fastening strip to the one below it or above it. These fastening strips are indicated on the surface of the form by a diamond pattern. They are 1 ½” wide and have a higher pull out strength than a dimensional stud. Different types of cladding will have different installation procedures.
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A standard #6 x 1 ½” to 1 ¾” coarse thread “bugle” style or “flute” head (1/4” dia. head) zinc coated or otherwise non-corrosive screw will do nicely (NOTE: as inexpensive as they are - drywall screws with the black sulphur coating will eventually corrode).
Equally as useful are standard bright (chrome like) finish #6 or # dia. x 1 12” pan head coarse thread self-tapping screws. These have the added bonus of being able to be used for a multitude of anchorage purposes besides siding fastening and do not corrode as easily as drywall screws.
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To achieve your desired length of wall, you will have to use standard form units, corner form units, and then remove certain lengths off each of these to get the desired length of wall. The form is designed to make measuring as easy as possible for the installer. Each interlock along the top and bottom of the form is 1”, and the score line on the outside of the form panel denote 2”. By knowing that the webs are 8” apart, you can use these three units on the form to find where you need to make your cut.
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The aggregate R Value of a NUDURA ICF Wall, with concrete and gypsum board interior finish in place, is 22.4. We state this as a standard value across all thickness of form unit as the thermal resistance of concrete is nearly negligible. The actual R Value would have to be determined from the overall performance of the wall as a system. A performance R Value which is based on energy savings and studies of thermal resistance of an ICF wall shows that a wall of R50 is not at all uncommon.
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To convert R Value to RSI, use the following equation: R1 = .176 RSI . Therefore- to convert R Value to RSI, simply divide the R Value by the inverse (5.685) Ex) R14= ???RSI RSI= 14/ (1 /.176) RSI= 14/5.685 RSI= 2.46
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USE SCREWS- NOT NAILS. Pull testing of fasteners into polypropylene has determined that the most assured fastening for resisting required loading as noted in local building codes are screws – a #6 self tapping screw into NUDURA fastening strips can provide an ultimate pullout holding capability of approx. 222 lbs of force. In addition, use a power driver with the torque set to the lowest possible setting. Your objective is to stop driving the siding BEFORE it begins to dimple into the foam. You want the siding to slide loose so that it can expand and contract in the sun. Remember, it hangs from the screws rather than being anchored firmly by them to the surface of the
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NUDURA has found the peel and stick waterproofing membrane/ termite barriers to be the most cost effective. The “XT” Membrane System by Polyguard is among the most well known termite barriers and can be obtained through their distribution by contacting: Polyguard Products, Inc. Polyguard website.
Additionally, NUDURA can provide detailing to your NUDURA Trained Installer to enable treatment of the grade level of the form system with a feature called an “inspection strip”. This is a specially cut horizontal band that reveals the concrete in the cavity directly to the outside, preventing any termite from being able to access the foam at grade or get to it without first being ejected to grade at the outside. The presence of termites will then be visible as they create a mud ‘shelter tube’ to get back below grade.
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In our NUDURA Insulated Concrete Forms, the webs are composed of high-density polypropylene, made from 100% post-consumer recycled plastic. This plastic is totally inert and emits nothing. Copies of the MSDS sheets for the virgin version of this material are available from either NUDURA’s Technical Service Department, or your local distributor.
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If the average temperature in a three day period is below 40̊ F or 4.5̊ C then this would be considered to be a cold weather pour. Concrete can be heated and the mixture can be altered as well for this scenario. Provisions can be made so that the full compressive strength of the concrete can be achieved in these lower temperatures. If you have further questions please contact your local distributor.
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The solution to this problem is to cut a hole in the bottom of the wall the diameter of your forced air tube. By connecting a piece of duct to this hole, you can force warm air through the cavity and cause the ice to melt. To achieve this as quick as possible, it is best to cover the top of the wall with an air barrier to hold in the heat.
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When using the NUDURA ICF for a foundation wall, and you have stepped footing, the best possible increment to use is 18” (450mm). As the height of the form unit is 18”, you can rip a standard form unit in half for a 9” (225mm) increment. This is also a favourable increment to step footings at.
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A lift height is how high you pour your concrete in one pass around the perimeter of your wall. By ACI 318 standard practice, your lift heights should be 4’ (1200mm) per hour.
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Concrete is typically poured in 10-12’ (3050-3658mm) levels. Therefore according to the last question and answer, a typical pour consists of 2-3 lifts.
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When consolidating concrete after it has been poured, one must do it in a consistent manner, dipping the ‘stinger’ the total height of the ‘lift’. This type of vibrator should be dipped into the concrete every second web.
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The simple answer to this question is NO. There is enough material in the wall with the webs and reinforcing steel to stop the mixture of the concrete being poured to separate.
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The concrete as NUDURA specifies, has a 28 day cure time. Concrete mixtures can vary with different amounts of Portland cement, aggregate size, slump and additives like plasticizers, fibres, and flyash.
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Without going into the specifics of the engineering, here are the differences in a standard 8’ (2438mm) high foundation wall. With a backfill soil type of sand and gravel, applying a 30 pcf (480kg/m³), and a backfill height of 7’ (2134mm), an 11 ½” or 290mm concrete block is required if it isn’t reinforced. If reinforced, then a block 7 ½” or 190mm is required with a No. 6 (25M) vertical bar at 4’ (1200mm) on centre . For this same wall in NUDURA ICF, you can use a 6” (152mm) concrete core, with a No. 4 (10M) bar at 16” (450mm) on centre. Significantly less labour, and a far quicker installation, makes the NUDURA choice, a far better one.
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Because of the nature of foam plastic insulation in contact with fire, it is required by code to meet a thermal barrier requirement. This requirement is that there be a barrier that will stay in place for a minimum of 15 minutes in the USA, and 10 minutes in Canada. There are provinces in Canada that require a 15 minute barrier as well, however, the same ½” (12.7mm) gypsum board will satisfy both 10 and 15 minute time spans. Drywall of larger thicknesses, cement board, ¾” (19mm) plywood will also serve this purpose, but may not always be as cheap or efficient.
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Although NUDURA is committed to making the permit and design process as easy as possible for you, we do not keep engineers on staff. We do carry prescriptive data for many of your building situations however, so before you think you need an engineer; check the installation manual at the following website link for data that could possibly be pre engineered. Available prescriptive data includes typical details and sections, backfill tables (reinforcing schedules) and lintel tables.
Download our Installation Manual or contact us for a local Authorized Distributor for a hard copy.
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When the forms are unloaded on a site, it is always best to leave them in their wrapping until they are stacked on to the wall. When the EPS is exposed to UV, like many other materials it starts to break down at a molecular level. When you have your forms up for a little while, you will notice a chalky dust on the surface of them. This is the EPS breaking down, however the chalky residue left over will slow this down. We, of course recommend cladding your walls as soon as possible, however, if you cannot for some reason, this shrinkage is so low it is practically negligible.
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EPS foam is an inert material, meaning it is very slow in any reaction, and there are no active properties to it. This does not mean however that mold will never propagate on an ICF wall just because it uses EPS as insulation. The truth is, if you do not have sufficient air flow, you can accumulate an excess of moisture through condensation at your openings. This build up of water, if not evaporated, will eventually cause mold to grow on the paper of the drywall. This is why, when dealing with your HVAC system, you must adjust it accordingly for a tighter building envelope, therefore requiring more air exchanges
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Typically in the past people have thought that ICF is only good for foundations, however this is a myth. The truth is if the structure is engineered, you can use NUDURA to build up as high as you please. Of course as the building gets taller, the thickness of the wall will increase. The reinforcing steel within the wall may get thicker or spaced closer, or you may simply have to use NUDURA as an infill or curtain wall with a post and beam structure. Our prescriptive data will take a residential project up 2 storeys before requiring engineering, but there are many projects on a commercial level that have gone up multiple storeys using the NUDURA ICF to form structural walls.
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NUDURA is Green in a number of ways. The material of the webs is 100% recycled. The material for the foam is 100% recyclable. The EPS foam emits no CFC or HCFC’s or VOC’s. Using NUDURA as opposed to traditional building methods cuts down the amount of wood used, which has become a precious commodity. By minimizing mold growth and giving a more sound proof home, your indoor comfort is increased dramatically. By reducing waste and shipping space required, NUDURA also impacts the environment in a very positive manner. These are just a few of the reasons why NUDURA ICF is an environmentally innovative material to use in your buildings.
For more information on NUDURA Concrete Forms green attributes visit our building green section for more information.
For homeowners visit our green homes section.
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NUDURA Insulated Concrete Forms come in 5 different core sizes. Standard thickness are 4” (100mm), 6” (150mm), 8” (200mm), 10” (250mm) and 12” (300mm). NUDURA also sells the form units in unassembled forms as well for flexibility. With the new 4 Way Web Connector, you can now take any of the thicknesses mentioned above and combine them for different combinations of larger sizes. Ask your local distributor about the 4 Way Web Connector and what you can do with it.
Download our Product Guide.
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Your plans do not HAVE to be designed for NUDURA Forms. It helps the construction process go faster if the modular dimensions of the form unit are considered, however NUDURA’s forms are flexible in that you can adapt it to an existing design. Should you want to design using NUDURA’s most optimal dimensions, ask your local distributor for the Dimension Layout Guidelines.
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Although the joints between the NUDURA form units are tight, below grade a waterproofing is still necessary. NUDURA sells a peel and stick waterproofing, that is easy to apply and carries a warranty of two years. This membrane must cover the foundation walls. In situations where you have an attached garage, the below grade wall shared with the basement must be covered, and a 4’ (1200mm) overlap to the adjacent walls.
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According the standard ASTM E 96, to qualify as a vapour barrier, a material must not exceed 45 ng/Paּsּm².This unit denotes the ‘permeance’ of the material, meaning how much moisture per force applied (air pressure), in a second over a square area. Our EPS foam has a permeance value of 36 ng/Paּsּm²,therefore the NUDURA Type II EPS qualifies as a vapour barrier. Better recognize.
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Curved walls are created using a combination of unassembled NUDURA form panels, and factory cut inner segments. When building curved walls, one must completely set up the wall, and any openings must be frame in place before the pour is done. When the concrete has cured, the openings and bracing can be removed. Contact your local Authorized NUDURA Distributor for the detailed installation procedure.
If we haven't answered your question please Contact Us and we will have one of our Technical Representatives contact you.
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