Structural Raw Materials Compliance Summary
All PSI construction systems employ only two structural materials: concrete and steel. A third material – high density, modified, expanded polystyrene (EPS) foam – contributes in numerous ways to improve the structural performance of these two basic materials. It also significantly increases the buildings thermal and acoustical insulating properties as well as reducing overall field construction time. EPS foam’s use as “stay-in-place” concrete forms provides an opportunity to employ unskilled young men and women as workers in tasks previously requiring considerable skill, experience and physical strength. For these reasons, PSI considers EPS foam a third critical raw material, even though it does not contribute to the structural integrity of the building. Therefore, we have included its compliance standards.
The most common form of concrete in use throughout the US (and most other countries) employs Type II Portland Cement. In the US, this material, together with Type I Portland Cement, must comply with the standards established and defined by the ASTM C150 or C150M standards for general use. Specifications for structural concrete are defined by the ACI (American Concrete Institute) in ACI 301. PSI will insure that all concrete utilized in buildings it will construct will be in compliance with these standards as well as local and National building codes.
The geometry, reinforcements and formulations for all concrete will be specified by a registered structural engineer in compliance with these standards and will meet or exceed applicable local building codes for the intended application. Most structural applications include the use of steel reinforcing bar or other steel reinforcements as specified by the structural engineer in compliance with the standards of ACI 301. The steel bars are available in three strength levels.
PSI will use the correct steel reinforcing as determined by its structural engineers (BBM Structural Engineers, Tilteco, Inc. or MCA Engineers) and local building authorities.
In cases where structural failure will damage property or endanger occupants, concrete will be tested using retained cylinders taken at the time of pouring, stored at the site or under the same conditions as the structure, and tested for compliance at 7 and 28 days after placement.
All light gauge structural steel shapes employed in PSI construction are formed from cold rolled steel into cross sections which are designed to most effectively perform as needed when assembled into the geometry desired for walls, floors or roofs. Regardless of the application, all section properties are calculated in accordance with the AISI “North American Specification for the Design of Cold Formed Steel Structural Members”, American Iron & Steel Institute, 2001 edition.
All steel raw materials (steel coils of 14 gauge (3mm) to 28 gauge (0.48mm) shall have a bare metal thickness at least 95% of the design thickness and shall conform to ASTM A653 Grade SS or ASTM A1003 Structural Grade with a minimum yield of 50,000psi (344MPa) or 33,000 psi (227.5MPa) respectively.
Structural Steel shall be galvanized in accordance with ASTM A924, Coating class G60 or G90 or employ superior protection such as “galvalume”. Color coatings employed for architectural purposes shall not be considered as corrosion protection
EPS HIGH DENSITY (MODIFIED) FOAM:
PSI will purchase bead stock to produce the EPS molded shapes used in its various building systems from international chemical companies, such as BASF, Dow, Arco, Huntsman etc. Regardless of the source, all bead raw material will comply with surface burning characteristics (ASTM E-84 and physical property (ASTM C-578) as required by the US model building codes (fire retardant). They must also meet the UL 94 classification requirements and have obtained an HF-1 rating as described in UL listing E54675.
All EPS bead foam will meet the requirement for “modified”, which denotes material which exhibits self extinguishing characters when exposed to fire. This means that it will not support combustion and will not sustain a flame if ignited from other heat sources.