One of the first questions you have to answer when designing a large shop or storage building is, “should I use wood or steel for framing?” At Farrow Built we only supply and build wood frame buildings but we will do our best in this article to lay out the pros and cons of both wood frame and steel frame.
Four main factors come into play.
Cost
Insulation
Interior Finish
Fire
Let’s examine each one of these areas.
1. Cost - Time, Labor & Materials
Contrary to popular belief, steel buildings are more expensive than a wood frame building of the same size. Since most steel frames are sold as kits, it’s tempting to compare the cost of the kit with the full installation cost of wood framing. This would be a mistake.
Steel frame kit suppliers often don’t come with engineered foundation drawings. Since steel buildings have in-depth foundation requirements, this can add time and money.
Labor is still needed to put up the framing. And footings still need to be poured. Exteriors still need to be clad. When the final tally is done, wood framing still comes in just under or close to the same as the price of steel.
2. Insulation
Steel frame builders often use roll-out insulation between the purlins and the exterior sheeting. When the exterior sheeting is screwed on it compresses the insulation. Insulation that has been compressed loses a huge amount of its R-value. As a result, every purlin becomes a cold spot.
Another issue with this method of installation is leaks. Over time, as the insulation compresses, the screws can loosen and begin to leak. If you have an insulated steel building, we recommend re-tightening all screws every 3-5 years. This helps prevent permanent damage. To avoid this problem we recommend spray foam insulation for all steel frame buildings.
Wood frame buildings are much simpler to insulate. Batt insulation is installed between the studs. The increased depth keeps the insulation working at its full capability.
The exterior cladding is then attached directly to wood framing. This results in a much better seal with no leaks.
Spray foam insulation is also an option for either the wood or steel frame buildings.
3. Interior Finish
Finishing the interior of a steel building is time consuming and not cost effective. Having interior supports made solely out of steel means there are fewer points for attaching interior cladding.
After you insulate, your interior walls are essentially the backside of the insulation. If you want to cover it up, wood or steel studs need to be installed between the purlins. While this can give you an amazing finish, it will drive prices up.
The interior of wood frame buildings are very simple to finish. Metal cladding, plywood, or drywall can be installed directly to the framing. We recommend bright white metal cladding for an easy to clean and maintain finish. Shelving, cabinets, and workbenches are also easy to attach.
4. Fire
One reason many people go with a steel building is because they believe it to be more fire-resistant. Actually, steel loses 80% of its structural integrity at 1,000 degrees Fahrenheit. When a steel building reaches this temperature during a fire it will instantly collapse.
Wood will retain full structural integrity over 2,000 degrees Fahrenheit. This is because the charcoal that builds up as it burns insulates the inside of the wood from burning too quickly. During a fire, a wood building will slowly collapse.
Ask most firefighters which building they would rather go into during a fire. You will find the common answer to be a wood building.
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