Should I use InsulBuck™ or wood?
Written by guest writer Greg Doren, Advantage ICF Brand Manager
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Rough opening bucks in ICF construction have typically been constructed using a lumber frame to form an opening in which a window or door will be placed. The bottom portion of the buck is designed to allow concrete to be poured through it into the blocks that sit below it. In the final construction the buck also creates an attachment point for windows and door frames. “Bucks” have typically been made from Pressure Treated Wood (PTW) dimensional lumber. Commonly used in construction for many years PTW has been the product of choice for ICF construction since it is readily available and easy to use.
It comes in a variety of dimensions and can be ripped down or furred out to accommodate different widths of ICF products. The attachment of the window or door to the buck is done with a common fastening screw. The drawbacks to PTW bucks are that they are heavy, have minimal R-Value (critical for LEED points), are subject to warping, rot and are a food source in termite infested areas.
InsulBuck™ is a vinyl/EPS alternative to PTW bucks for building window and door bucks in ICF construction. InsulBuck consists of two exterior extrusions of vinyl, which are also used for the fastening of the windows and doors, bridged by 2 inches of high density Type 3 expanded polystyrene (EPS) insulation planking. InsulBuck is cost effective, easy to use and the continuous EPS layer around the opening eliminates the thermal break typically created by PTW bucks.
The most impressive benefit with InsulBuck is that it is a ZERO waste product. With PTW the cut off pieces associated with accommodating window and door size are thrown into landfills, increasing costs as well as waste. InsulBuck extrusions and planking come in 8 foot lengths; when they are cut to length to accommodate window and door sizes the leftover pieces can be used in another buck by simply splicing them in. Short pieces of extrusion can be used with longer pieces of EPS insulation planking and vice versa. This cuts down on waste critical for the bottom line.
Other key components to assemble InsulBucks are “F” Clips and “InsulPlates”. The “F” clips hold the corners together where the EPS planks meet. The InsulPlates are metal inserts used on doors and larger windows. These inserts go through the EPS planks near the exterior or interior and are anchored into the concrete before it is placed. The doors are fastened to the plates to allow for the pressures and movement associated with opening and closing the door.
Ripped down plywood is used to help brace PTW bucks around the perimeter to keep them square and prevent concrete from leaking out. InsulBuck extrusions are designed so they are attached to the ICF Block so which this does not allow the buck to move. An extruded lip on the InsulBuck allows bonding between the concrete and buck, whereas PTW bucks need to be “porcupined” with nails around the outside middle of the buck.
Both PTW and InsulBuck require cross and angle bracing to keep them square and to keep them from bulging when concrete is placed, especially larger openings.
InsulBuck is an vinyl/EPS buck for an ICF project, it maintains the energy efficiency that an ICF wall is intended to provide, which is simply something that PTW cannot accomplish. InsulBuck is economical and an effective approach to creating block-outs in ICF walls and will enhance any ICF project.
Stay tuned for our newest video: “How-to build a window or door opening using Plasti-Fab InsulBuck” …..coming Wednesday!