article2-10-04

ICF Construction Techniques

It was great to get the second floor finished. From the beginning, when we were designing the house, we knew we wanted to do something different and innovative with the second floor. On other construction we'd seen I was always disappointed with wood joist type of construction. Wood floors make too much noise, creaking when walked upon. Steel construction that utilizes I-Beams while strong, is something we thought we couldn't do ourselves.

While visiting a building show in Orlando two years ago, we were introduced to the ICF market. ICFs are Insulated Concrete Forms, and though not new to the construction industry, they are just now being accepted as a viable construction alternative. One of our neighbors has an entire 3000 square foot luxury waterfront home constructed out of these unique building materials (he was the first one in the county to use ICFs).

Over the past year, while discussing our plans with other builders, we came across much resistance to our plan of using ICFs from people who had never used them. Now that we're done we can tell these people who had misgivings that they were wrong. ICF construction, done properly, is one of the most efficient and time saving methods of pouring concrete. Considering that the two of us did all the installation work of the forms and bracing ourselves, and had no formal training or previous experience with ICFs, they were extremely easy to install. It is not a physically demanding or heavy product to use. They are surprisingly robust even though people think they are like coffee cups made from styrofoam. Once you use them, you will appreciate all the engineering that has gone into their design. The finished walls and second floor have superior strength and insulating qualities.

Deborah laid out all the RewardWall blocks for the theatre in about 20 minutes for a dry fit and to check the amount of product we had on hand. This product is unique in that there is a toothed keyway that is reversible and it firmly locks the blocks together and holds them securely. Then we disassembled them to start the real assembly process with the foam glue and foam gun from Wind-Lock and the rebar for engineered strength. We are sold on the foam to foam glue product and we use it for everything now! When dry it is stronger than the surrounding block material, but it expands to fill large gaps and it still easy to trim with a hot knife.

When we poured the theatre wall, it was the most anxious moment for the unbelievers. But we followed the instructions from the manufacturer and they performed flawlessly. Instructions were to pour in 3 foot or less lifts and to make sure that there was time for stabilization of that layer before the next lift. Just don't pour ten feet of vertical concrete all at once. We used about 10 yards of fibered 3000 psi concrete in the form and it was exactly what we had estimated.

As per our engineer, we waited at least a week before pouring the second floor to give it time to cure for the load it would bear. The second floor ICF is Insul-Deck, an engineered panel that creates it's own beam when connected to each other by tongue and groove. There are two galvanized I-Beams embedded in the foam to increase strength and also allow attachment of drywall, lighting fixtures or ceiling fans. The center part of the channel creates two large (6") tubes for air passage or plumbing. There are also 4 smaller tubes the size of electric conduit or water lines. This has been very useful for reducing ductwork and chasing utilities efficiently around the building.

People who have never seen these products are very skeptical about them, so we sought out a concrete finisher that had worked with them before. Each product is different and has different requirements for engineering and installation. You need to assess the product for the job and make the best choice for the application.

The two of us installed all the decking for the second floor. It was slower going making the unique compound curve cuts for the dome wall curve, but we did it all with a hand held power saw (metal blade) and a sawzall with an extra long blade. There were 42 pieces in all, some as long as 18 feet. The other hindrance to speed was the raising of the support jacks and 2 x 10 planks for two people. It would go much faster with a crew of strong young men according to Debbie. We brought in a crew of three day-labor guys to help Billy place the steel in the troughs and tie them with chairs. That took about one day (6 hours). There was #5 rebar in the dome wall that was placed in the shotcrete process. The beams were designed to meet up with these pairs of rebar to form the lateral beams.

Billy went around and around the edge of the dome under the decking where there were some really rough saw cuts. Some of the gaps were over three inches, and if left open, concrete would pour through. Billy used pieces of left over foam to fill some larger gaps and sealed it in place with the Wind-Lock foam glue. This stuff is really great. We didn't have even one leak around the edges or the beams of the entire second floor. On the front edges of the balcony and on each side, we used plywood to face them out and hold the concrete at the correct depth.

On the day of the pour we rented a pump and hose man to help Larry Regier with the task of getting the concrete up to 11 feet. Steve Koehler (concrete finishing) and his wife Pam finished the stairs and worked with Larry as he was pouring. He used a unique way to set the grade for the 3 inch depth of concrete, since you can't drive a stake into the forms for screeing. His trick was a small piece of angle iron and a c clamp to adjust for height, by using a laser level and adjusting the c clamp to accommodate the beam level.

Our floor turned out fabulous. Over the next seven days we kept the concrete sprayed with water to keep it curing slowly. The theory is that this will reduce cracking. We had poured our stairs at the same time for strength and continuity. We used wood forming techniques and some leftover ICFs for the stem wall under the landing.

These new products give people more options in their design and construction. If novices like us can do it, anyone should be able to accomplish their construction goal using new technology to their advantage.

Billy Elkins