What Roof Systems Do You Have for Homes Built with ICF Construction?
I want to talk about some roof systems for Insulated Concrete Forms (ICF) homes. ICF is essentially a form block made of foam. It’s held together with plastic ties and then filled with concrete after stacking them up where the walls go. The concrete contractor installs rebar inside the foam, just like setting up concrete retaining walls. A lot of people are doing these because they’re in a wildfire zone and they want to make sure their house is safe. Many people lost homes in the fires and they want to avoid another experience. These homes are also being used for energy efficiency and are very durable as well.
ICF Roof Systems
I want to discuss roof systems for an ICF home. When you start to design a home, you must take into account that ICF walls are thicker than normal stud walls. We draw the home layout and calculate if we have enough room throughout the home. The home loses about 11 to 12 inches on the thickness of the walls. Each wall consists of 2.25”foam, six inches of concrete, another 2.25” on top of that, plus another inch of drywall by the end. Ensuring enough space exists inside the house is imperative.
Additionally, the footings must be enlarged and reinforced stronger in consideration of the added wall weight. Oftentimes we build the interior walls out of wood or steel studs to help save on the added engineering. Interior steel studs are another way to get away from wood members.
Ties and Drywall Anchor Points
The plastic ties, or tees, help keep the foam together when pouring concrete. After the blocks are filled, those plastic ties can function as anchor points for screwing in drywall. You can also screw in siding, or you can do an EIFS type stucco system on the exterior of these homes as well. Whatever the need, you can utilize those plastic tabs as anchor points for any fastening required on the interior or exterior walls. Since most of the heat/cold transfer comes from the outside world, the anchor point tie-ins give you more value for fastening the exterior finish.
Concrete Roof System
Once you have established your walls, you can determine the roof system that you want. A complete ICF structure essentially includes decking as the roof system. The roof can be pitched, raked, or even flat. This method requires pouring concrete beams with lots of rebar. The roof is poured with shoring underneath to hold the concrete in place, and the shoring must remain in place for 28 days. Once the roof is fully cured, it will span the entire house.
Foam Roof Systems
Foam is used late to build up the slope on a concrete flat roof to get the flow needed to drain. This is an expensive option because of all the required labor. The other alternatives are a wood or steel truss system that stacks on top of the concrete walls.
if you use trusses, there are a couple of concerns from a fire perspective. Wildfires can destroy a house regardless of whether we use wood or steel. Roof ventilation is the biggest threat for home burndowns. We use the spray foam insulation that adheres to the underside of the roof in the attic. The spray foam insulation allows us to prevent any openings in the attic space. These attics include some air exchange from within the home and they are considered a semi-conditioned space. Standard, unconditioned attics must meet one square foot of attic ventilation for every 50 square feet of roof sheeting. Eliminating all of these roof penetrations prevents loose embers from entering the attic space.
Wood vs Steel Trusses
If you decide to go with steel, you’re going to spend a little bit more money on the trusses, but you don’t have to worry about wood. There are no termites, no combustible issues with fire, nothing like that. That’s a good positive. If you use wood trusses, there’s an option to treat them with a fire-resistant compound that will keep the wood trusses from catching on fire. You can put a torch on the thing and it will not light that thing on fire. If you choose to treat it properly, the treatment must occur during the framing stage.
You can also upgrade to fire-resistant roof sheeting too. That adds an extra barrier underneath a Class A roof. So you’re going to have a Class A fire-rated roof that’ll go on top of that, or it’ll go on top of your fire resistance sheeting. So if anything was ever gone through, if you had the wind blow off any shingles, whatnot, and it got onto that sheeting, that’s going to protect it as well underneath the Class A fire-rated roof.
Recap on ICF Roof Systems
Those are three different options for roofing an ICF house. You can go with a true ICF roof, you can install steel trusses, or you can use wood trusses. The wood truss system can upgrade to a fire-rated product as well. I hope this helps you understand what goes into planning an ICF home. If you want more information about building an ICF home, look around the website. Our resources page and FAQ page has a ton of information.
Take a look at our comprehensive collection of similar videos on our YouTube channel, The Real Property Show. Thank you for your time and have a great rest of your day.
We Build CUSTOM HOMES, ADUS, & Do HOME REMODELING
Top Notch Quality Homes, on time, on budget, and without hassles.
Freeman’s Construction, Inc. has been building new custom homes and completing whole house remodeling projects in San Diego County for over 37 years. To schedule a project consultation, please call us today at 760-788-6846 or fill out a request form.
Areas We Serve:
Ramona, CA | Poway, CA | Escondido, CA | Julian, CA | San Marcos, CA, | San Diego, CA | Rancho Santa Fe, CA | Lakeside, CA | Rancho Bernardo, CA | Scripps Ranch | Carmel Mountain Ranch | 4 S Ranch
