How can I tell the difference between a metal building system and a conventional building?
In many cases this is not possible from the exterior. A large percentage of conventional structures are supplied as metal building systems.
Does using a pre-engineered steel building limit me to a basic, rectangular-shaped structure?
No, Not at all. Latest design and drafting software gives the flexibility to engineer a very complex structure, including hip/valley roofs, skewed walls and even hexagonal or octagonal shapes.
Why are metal building columns so deep compared to conventional steel framing?
The main reason is in the approach to the design and type member used. Metal buildings utilize a rigid frame in lieu of a conventional column and rafter design. The rigid frame is a continuous design from base plate to base plate utilizing built up sections rather than prismatic hot rolled shapes and place steel only where steel is needed to satisfy the design requirements. The member is shaped to follow the areas that need deeper sections due to the forces. Automated manufacturing plants allow the additional labor to be offset by the savings in steel thus producing a more economical frame.
What if the consultants are asking for a “Green” building. Can MBS supply a 'Green Metal Building'?
Yes, we can. Metal construction offers recyclability and durability in and of itself. Our buildings can contain 30-50% of recycled material, depending on the project. Many of our “cool color” panel finish options meet the reflectivity and emissivity performance levels required by LEED and Energy Star. In addition, we offer insulated panel systems that allow the designer to obtain superior R-values for greater thermal efficiency.
How do I store the material at site?
MBS products are dispatched from our factory with good packing and condition. To maintain this, we recommend that the bundles of sheets, purlins or channels are stored 150 mm clear of the ground, with a slope of 1:25, to allow for water drainage. Cover the stack with a waterproof cover, leaving the ends open to allow for free circulation of air.
Upon receipt of materials, it is recommended that bundles of panels be checked. If any water is entrapped between sheets, the sheets should be carefully dried, and then re-stacked allowing for free air circulation.
It is recommended that panels be installed as soon as possible after delivery. Extended site storage is not recommended. MBS will accepts no responsibility for staining of Galvanized, Aluzinc or Aluminum products, or deterioration of Painted products due to incorrect site storage.
Why is the foundation design not included with a Metal Building package?
MBS does not perform foundation design as outlined in the Metal Building Manufacturers Associations Common Industry Practices section 3.2.2. However, MBS does provide the location, diameter and reactions required for each individual column to allow a professional foundation Engineer to design a foundation that meets the specific soil and site conditions.
It is difficult to allow an x-bracing in the side walls of my building. What can I do?
X-bracing is the most economical method of moving the eave force due to longitudinal wind from the eave to the foundation. If x-bracing cannot be used, there are other methods. Many times the x can be separated and put one of the diagonals in adjacent bays or separated by one bay. If this option is not acceptable, alternative methods may be used, such as portal frames, minor axis bending or diagonal pipe struts, which act as both a tension and compression member. Sometimes the walls are open for other materials that can be used for bracing. Masonry walls or concrete tilt walls are good examples. The eave force must be transferred to the wall and the wall capable of resisting this longitudinal force. The designer of the wall must verify the adequacy of the wall to accept this force.
I am designing a warehouse building that has full height concrete tilt walls. Can I eliminate the steel sidewall columns and utilize the tilt wall as support?
Yes, this can happen, but the connection at the rafter to tilt wall will have to be designed and analyzed by the designer of the tilt wall. In addition the horizontal force at the top of the tilt wall will have to be transferred to the roof bracing by some method.
My customer relocated a walk door, now it interferes with the “X” bracing in the wall. Can I remove the bracing in that location?
No; X-bracing provides a critical function in the longitudinal stability of the building. If the bracing cannot be relocated to another bay, there are a number of alternative bracing methods available (e.g., portal frame, portal rafter, minor axis column bending, shear wall). Each unique situation needs to be addressed on a per job basis. Our engineering support team in the office will gladly assist you in choosing the best alternative method.
What is the difference between “turn-of-the-nut” and “snug-tight” for method of tightening bolts?
Turn-of-the-nut is a method that provides a specific tension in the bolt. It requires an additional amount of nut rotation beyond snug tight. Snug-tight is the full effort of a man on a standard spud wrench. Snug-tight is allowed as long as the building has no cranes and the building is not located in a high seismic area. For these two conditions, turn-of-the-nut is required (see the AISC for further specifics on the turn-of-the-nut procedure).
What is the minimum thread penetration required for high-strength bolts?
None. As defined in RCSC Commentary Section C2, full thread engagement is achieved when “…the end of the bolt is at least flush with the face of the nut.”
How should suspended equipment be attached to the purlins?
Suspended equipment should be attached to the web of the purlin. This will allow the load to be properly transferred to the purlin without causing the purlin to roll, as is the case when large loads are suspended from the purlin leg or lip.
Why do the girts sag, is this normal?
Yes, Girts in a metal building system are designed to resist the wind loads from wall sheeting in the direction parallel to their web. In order to arrest this sagging it is recommended to use wooden spacers at every 1.5 to 2.0 meters to keep them straight until wall sheeting is installed.
What is the difference between, Galvalume, Aluzinc, Zincalume?
These are all same type of steel sheet material, conforming ASTM A792M steel sheet, with 55% Aluminium and 45% Zinc Alloy coated by Hot dipped process.
How does the corrosion resistance of Aluzinc sheet compare with that of galvanized sheet, and how long can a Aluzinc sheet roof be expected to last?
Aluzinc sheet has been successfully used in roofing applications for more than 25 years; it has been evaluated in outdoor R&D tests for well over 30 years. Based on these tests, in which corrosion weight losses were measured and compared with galvanized, Aluzinc sheet is projected to outlast galvanized sheet (with an equivalent coating thickness) in various atmospheres by up to nine times. These roofs are in excellent condition and are projected to last 30 to 40 years before requiring major maintenance.
What is the life of a prepainted Aluzinc roof or wall?
From a practical standpoint, the life of a prepainted Aluzinc panel is dictated by the performance of the paint film, i.e., appearance as affected by conditions of fade, chalk and peel, and the life of the paint film is determined by the type of paint system and the weathering conditions to which it is exposed. Almost all building owners will repaint a prepainted roof or sidewall when the appearance of the paint film is determined to be aesthetically unattractive from weathering.
Paint systems applied on modern coil coating lines can be expected to provide good to excellent performance in nearly every environment. The most commonly used topcoats are acrylics, polyesters, siliconized polyesters, fluoropolymers and plastisols. When combined with chemical pretreatments and high-performance primers, these topcoats enhance adhesion of the paint film to the metal coating and increase overall corrosion resistance, particularly at cut edges, scratches and bends.
What types of insulation are recommended for Aluzinc roofs? Are there any to be avoided?
By far, fiberglass roll insulation is the most commonly used insulation for Aluzinc steel roofs on nonresidential buildings. It can be used in any of the available thicknesses to give the required insulation value. One of the main benefits of retrofitted Aluzinc roofs installed over leaking nonmetallic flat roofs is the ability to add insulation under the new Aluzinc roof and realize significant energy savings from reduced heating and cooling requirements. In such instances, fiberglass roll insulation can either be placed on top of the old nonmetallic roof or under the new retrofit roof.
Wet insulation, which may be rain soaked at the site or wet from condensation or a leak in the roof, should not be in contact with Aluzinc roof panels. Insulation should be dry when installed and kept dry after installation. Fiberglass insulation retains water and can cause rapid inside-out corrosion on Aluzinc sheet panels. Also, spray-on insulation is sometimes used inside buildings under roofs and on siding. This insulation may contain fire retardant chemicals that can be corrosive to Aluzinc sheet. Manufacturers should be consulted about such fire retardant additives if spray-on insulation is used.
What is k-Value?
k- value is ‘Thermal conductivity’, it is the property of a material reflecting its ability to conduct heat.
The thermal conductivity (k) expressed in units of W/(mK) (Watt per meter Kelvin), is defined as the amount of heat that is transmitted per second per one square meter of area through a depth of one meter of the material for a temperature difference of one Kelvin between the outside and inside face of a material, measured at an outdoor temperature of 20 deg Celsius.
What is U-Value?
For the calculation of the insulation efficiency of a compound of different building materials, the thermal transmission U, expressed in units of W/(m2K) (Watt per square meter Kelvin), is used. It is the amount of heat transmitted per second per one square meter of area through the insulating material for a temperature difference of one Kelvin between the outside and inside face of the material, measured when the outside temperature is 20 deg Celsius.
To obtain the thermal transmission (U-value), the value for the thermal conductivity (k) has to be divided by the thickness of the insulating material in meter.
Lower the U-Value, better the insulation material.
What is R-Value?
The R-value is a measure of thermal resistance. The bigger the number, the better the building insulation's effectiveness. R-value is the reciprocal of U-value.
Around most of the world, R-values are given in SI units, typically square-metre Kelvin’s per watt or (m²·K/W) or (m²·°C/W). In imperial units, R-values are given in units of (ft²·°F·h/Btu).
It is particularly easy to confuse SI and imperial R-values, because R-values both in the US and elsewhere are often cited without their units. The correct units can be inferred from the context and from the magnitudes of the values. United States R-values are approximately six times SI R-values. Example, R30 is easily understood as in imperial units, and R3 or R5 is SI units.
What is the difference between PUR and PIR panels?
PUR stands for Polyurethane foam, these are produced as a result of a chemical reaction between Polyol and Isocyanate in a controlled environment. Special catalyst, blowing agent and surfactants are added as per the required quality.
PIR stands for Polyisocyanurates and can be produced with no polyol using only Isocyanate and catalysts – blowing agents and surfactants. Instead of reacting with polyol the Isocyanate reacts with itself to form a highly cross-linked thermosetting polymer with a ring like structure.
PIR foams have superior fire resistance and toughness, with superior R-value per mm. Excellent performance in code required fire test and compatibility with most roofing and sheeting systems.