It is imperative the installers who attach a safe room to an existing slab use the best possible anchor for the given situation, and they are trained and certified to correctly install them.
ICC-500 has set forth requirements for anchoring safe rooms to existing concrete slabs. Generally any slab on a residential or commercial project that was done to code standards will be at least 4” thick on average. This is more than adequate to safely anchor to. Different types of concrete (or even cracked concrete) can be anchored to by utilizing different types of anchors; one anchor does not meet every requirement. For instance, if there is a crack in the concrete is does not render the slab deficient, most cracks are only superficial and do not degrade the slab integrity. However, in the extremely rare circumstance that we have to anchor to or near a crack in the concrete we will utilize an epoxy type (chemical) anchor. This will serve to provide a chemical bond for the anchor to the concrete. In fact, our above ground shelters we usually utilize this type of anchor.
Outdoor Safe Room Installations
We can also install a safe room outdoors in situations where the home or facility does not have a garage or carport. In this situation we can dig a footing that is 24” deep and 24” wider than the safe room. We then insert rebar, pour the concrete footing and slab in one continuous poor, wait for it to harden, then install the safe room on top of it. Additional costs do apply in this situation due to the multiple site visits, excavation, and concrete.
We use only Hilti brand anchors, fasters, drill bits, adhesives, and epoxies. They are the industry standard for reliability, product development, and research and engineering. Each anchor Hilti epoxy anchor bolt is rated at 8,100 lbs. of up force capacity and 5,300 lbs. of shear capacity per anchor, there are 26 anchors in a safe room on average (depending on size).
We choose to use this anchor because it is the best choice available for such crucial anchoring. In fact it is above and beyond what is required, but we cannot be too safe when peoples’ lives are in our hands. Some companies choose to use a wedge lock or expansion type anchor, which does save installation time. Basically an expansion anchor is drilled into a pre drilled pilot hole, then is tightened until the expansion wings separate and dig into the concrete providing a wedge with holds the shelter to the slab. We choose not to use this type of anchor because they can begin to crack the concrete over time.
Depend on Us for Safe Rooms & Shelters
Our methods do take a little extra time but we believe we have the correct process. Taking an extra 30 minutes to wait for the epoxy to harden is not too difficult when such important things are riding on our work. Our type of rods are used when failure is not an option.