The International Information Center for Structural Engineers

Tuesday, 08 August 2017 00:00cat

This new construction system allows affordable and easy to build concrete walls of any shape, thickness and size

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The company claims that about half the time or less is needed to erect a residential structure compared to the time it takes to build using the traditional methods

The Spider Tie concrete wall system is the new way to form a concrete wall easily and quickly. Developed by the residential home construction manager Greg McDonagh, it provides a temporary frame work that is attached to the plywood panels using special plastic ties. These ties hold the frame work in place until the concrete (of any type) has cured, and afterwards you simply unscrew it so that it can be used again for future projects. The special ties on the other hand, made of recycled plastic, are used just once as they stay in the concrete once it has been poured. "It gives you a really easy way to hold your forms together while you're pouring concrete," McDonagh says. "It doesn't require whalers or extra bracing, it's simply a screw every six inches." The system can be used for walls as high as 9 ft. and it is available in two types: Spider Tie Dry and Spider Tie Wet (for swimming pools).


According to the company’s site, the system was designed as a much easier way to form concrete walls, requiring less labor. A residential structure can be built in about half the time or less, in comparison to traditional methods. Also, they claim that it is affordable, costing about the 1/6 of a typical I.C.F. system and may offer up to a 30% savings compared to using a typical panel forming system. Its thermal qualities are enhanced greatly, thus temperature is stabilized (heat or cool air do not transfer from within the structure) and its fire rating is about 2 hours/inch thickness. 

The system consists of 4 main components:

  1. The Spider Tie forming system which uses Plastic interlocking form ties to create a frame work for the form plywood to attach to with special screws.
  2. The special concrete mix called Light Weight Cellular Concrete (LWCC) that is used.  This concrete has undergone an air entrainment process which provides it with considerable insulation properties.  The mix design can achieve strengths of up to 4500 PSI and the weight of the finished product is reduced by as much as 45%.
  3. Special fibers, also referred to as ‘micro rebar’, are introduced into the concrete mix design, as their use considerably reduces the need for large rebar. They are made of zinc coated steel stands 1 ½” long and are thoroughly mixed into the wet concrete before placement, creating a stronger matrix than traditional concrete and rebar methods. Rebar is still needed though in load bearing locations.
  4. The Speedfloor forming system is used to quickly form suspended concrete floors. It consists of rolled steel joists spanning the width of the room and spaced 4” apart. Cross bars are then inserted into the floor joists providing support for the forming plywood that is laid on top. 


spider tie 1

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