Cross-laminated timber and insulated concrete forms give us stronger, greener, buildings. But is one better than the other?
As the demand for new homes continues to increase, builders and homeowners are looking at alternatives to traditional construction methods. Two of these methods, cross-laminated timber (CLT) and insulated concrete forms (ICF), are incredibly successful.
CLT and ICF both save time and money in construction, have environmental benefits, and improve building safety. Here, we take a closer look at these alternatives to traditional building.
What is ICF?
Insulated concrete forms are created with an insulating material such as polystyrene foam or polyurethane foam. The insulating material makes up the sides of the form, which is then reinforced with metal. The forms lock easily into place like giant LEGO bricks, so there’s no need for mortar. Once in place, the empty space in the forms is filled with concrete to create a solid wall.
What is CLT?
Cross-laminated timber is created by laminating multiple layers of wood together in alternating directions. This creates a strong wood panel that can be cut to size at the factory. Windows and doors can also be cut before the panels arrive at the jobsite. The panels fit together easily, and construction is very quiet compared to other methods.
Faster, cheaper construction
Traditional construction can be slow. ICF and CLT both greatly reduce the amount of work required to build a home’s exterior walls.
New Avenue is seeing the cost and time savings of ICF firsthand. On one ICF project, we are achieving a 7% decrease in direct labor and materials compared to traditional construction. There’s also been a two-month reduction in construction time on that project, which means even more savings.
The savings can be passed on to the homeowner, even though ICF is a higher-value product. For one new home, New Avenue saved our clients $100,000 by using ICF, even with the addition of a radiant heating system.
CLT is also more efficient than traditional construction. Because the components arrive at the job site prefabricated and ready to piece together, there’s enormous time savings. The fact that the panels are lightweight reduces construction costs further. And in construction, time is money.
Quieter job site
On a typical construction site, the noise of jackhammers and saws fills the area, disturbing neighbors. The noise is significantly reduced with ICF and CLT construction because the panels and forms lock smoothly into place. CLT has been chosen for construction of university buildings and hotels in part because of its quiet construction processes.
Both ICF and CLT walls are well insulated and sealed, reducing the energy needed for climate control. An ICF home uses around half the energy a traditionally framed home uses for climate control. CLT’s energy efficiency depends on the thickness of the walls and the climate. Regardless of thickness, CLT walls lock together well to create an efficient building envelope. With both options, there’s very little heat transfer.
Outside of energy savings, the major difference lies in the materials used.
CLT construction uses timber. Unlike most construction materials, timber is a renewable resource. CLT can be sourced from managed forests and can be made from trees killed by pine beetles. Home construction is an ideal use for this type of wood. While some glue used by CLT manufacturers is not considered environmentally friendly, there are greener alternatives. Another environmental benefit of CLT is carbon storage; timber buildings lock up CO2, keeping it out of the atmosphere.
ICF uses insulating foam, metal, and concrete. While these aren’t renewable materials, building homes with insulated concrete forms is a green solution in several ways. ICF walls will last more than 100 years with minimal maintenance. There’s no threat of damage from moisture or wood-boring insects.
Both CLT and ICF are resistant to fire, high winds, and earthquakes. Walls built from concrete or laminated wood panels are extraordinarily strong.
The fire resistance is particularly impressive for both types of construction. In the US, CLT panels meet ASTM E119; they have a two-hour fire resistance rating. ICF walls have a four-hour rating, meaning they’re nearly fireproof. Compare these ratings to 15 minutes for a traditional wood-framed wall.
Code-friendly materials and processes
ICF has been around for decades. City officials are generally familiar with it. While CLT is newer, it’s an internationally recognized material. Although CLT and ICF buildings are different from traditionally built structures, there won’t be any problem getting approvals from city officials.
“Every person that has come to our ICF job in Alameda and looked at it is thoroughly impressed,” noted Amer, who is running the current ICF project. “The structural engineers did their work very thoroughly. This technology is tried and true and tested and approved. Everybody likes it. There’s absolutely no problem.”
According to Amer, the only downside to ICF construction is in remodeling. Changing the layout of concrete walls can be difficult.
While CLT is more easily remodeled, changes during construction can be difficult. This is because CLT panels are manufactured and cut before they arrive at the job site. Design revisions after this point can be costly and add time to the project.
With any form of construction, the building site must be considered. For example, CLT might not be possible if cranes can’t get proper overhead clearance. ICF may not be a good option for buildings that will one day be expanded. With both ICF and CLT, the site’s location may affect the cost of shipping the necessary materials.
CLT or ICF may be the best choice for your new home or accessory dwelling
If you like the idea of efficient, long-lasting construction for your new home, consider CLT or ICF as an alternative to traditional building methods. New Avenue’s designers and contractors are ready to help you choose the design and materials that are right for you.
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