Steel Building Base Conditions

Every metal building has some sort of lateral member or girt that runs the entire perimeter of the building at or near its base. This "base condition" is important for several reasons.

For one thing, it provides the lower anchor for the wall panels. Perhaps more importantly, it determines exactly how the panels relate to the foundation. To keep water and pests from entering the building at its base, the panels must extend below the outside of the slab. This can be accomplished in several ways, and different approaches work better in different situations, STEELBUILDING.COM's online design and pricing system offers a number of different base options which are illustrated and described in detail below. We recommend that the first three options -- base angle, base trim, and deluxe base trim -- be used with concrete slab foundations (option 3 is our favorite). The remaining three options -- base girt, base channel, and base channel with trim -- are designed for special circumstances.

Our online design and pricing system offers standard base angle as the default base condition. It is included in the base cost of any building you design, and unless you select another of the cost-added options, this is what you will get. It consists of a single angle member which is attached with exposed fasteners to both the wall sheets and the slab. Note that it requires that the slab be formed with a 1½" sheet notch to allow the sheets to extend below the top of the slab. This approach has several disadvantages over other options. For one, the wall sheets frequently end up in direct contact with the concrete, which may chemically react with the sheets and cause them to discolor. More importantly, the money spent to extend the slab the additional 1½" for the notch often totals more than the cost of one of the more desirable base options described below.

Base trim adds a trim piece to the standard base angle. This extra trim provides a better barrier against pests and puts a piece of steel between the wall sheets and the slab, reducing the possibility that the sheets will directly contact the concrete, which in rare cases can react with the sheets and discolor them. It is available in all standard trim colors.

Deluxe base trim is our favorite option for steel buildings with concrete slab foundations. We think it looks the best and provides the most cost-effective protection for your building. The deluxe base trim combines the base angle and trim into one piece to provide all the benefits of base trim while concealing the wall fastener. Deluxe base trim is only available in the neutral color burnished slate.

The base girt option is designed for buildings that sit on piers rather than a full slab. Unlike most other base options, a base girt system does not rest on or attach directly to the foundation. Instead, it typically attaches to clips on the columns about 6" above the foundation. The base girt provides a connection for liner panel.

Base channel consists of a "cee" section that covers the perimeter of the building flush with the floor. It is most commonly used when a liner panel, or interior wall, is going to be installed. The "cee" section provides a pre-positioned connection point for inside panels. This approach requires a sheet notch in the slab (for an alternative, see the combination of base channel and base trim below).

This combined approach solves two problems. The base channel provides a connection point for the liner panels, and the base trim removes the need for a sheet notch in the slab. As explained above, this means that the slab does not have to be extended an extra 1½" beyond the frame line.