Block, ponywall or screw pile: choosing a foundation for a fabric building

The foundation decides more about a fabric building than most owners expect. It sets the building’s usable height, how it handles loaders and stockpiles, whether it can move later, and a good share of the budget. Here are the options we install most often and where each one makes sense.

The questions that decide it

Before choosing a system, answer these:

1. Is the site permanent? A lease site, a mine plan or a construction project favours foundations that lift away cleanly.
2. What goes against the walls? Stockpiles and loader traffic need a rigid wall at the base. Racking and parked equipment don’t.
3. What are the soils and frost conditions? A geotechnical review may be needed on poor or variable ground.
4. How much headroom do you need at the sidewall? Raising the arch on a wall gains usable height.
5. What will the building department accept? Most permitted buildings need a foundation design that matches the building’s anchor layout.

Concrete block and lock-block

Interlocking concrete blocks set on compacted gravel are a common choice for storage and industrial sites. They raise the building, resist impact and can be removed and reused.

Good for: bulk and salt storage, laydown, sites that may change. Watch for: a level, well-compacted base is essential, and blocks must be engineered for the building’s anchor loads.

Cast concrete ponywalls

A cast-in-place wall, typically a few feet to several feet high, with the building anchored on top. Ponywalls take loader bucket impact and let you pile material full-height against the wall without loading the fabric.

Good for: salt and sand sheds, bulk storage, permanent facilities with heavy equipment. Watch for: it’s the most permanent option, needs frost-appropriate design and adds concrete cost and curing time to the schedule.

Screw piles

Steel piles driven into the ground with a helical plate, cut and capped to support the building’s base. They install quickly with little excavation and can work in winter.

Good for: remote sites, uneven ground, projects where concrete is impractical, buildings that may relocate. Watch for: soils must suit the pile design, and they don’t provide an impact-resistant wall on their own.

Sea cans and ballast

Shipping containers or ballast blocks set the building on a base that needs no groundwork at all. Containers add secure storage along the sidewalls and raise the building.

Good for: lease sites, oilfield and mine sites, temporary and project-term buildings. Watch for: containers must be positioned, connected and ballasted to the engineered design, and the base must be level and compacted.

Grade beam and slab

A full concrete slab with integrated grade beams gives a finished floor for shops, warehouses and buildings people work in every day.

Good for: truck shops, maintenance buildings, warehouses with racking and forklifts. Watch for: highest cost and least flexibility, and it needs to be coordinated early with the building’s anchor layout.

Mixing systems

Many buildings combine approaches: a ponywall along the loading side and blocks elsewhere, or containers along the sidewalls with a gravel floor that can be paved later. The right answer is usually the least foundation that safely does the job.

Getting it right

Most foundation problems we see come from a mismatch between the foundation and the building above it, which is a common reason permits get held up. Designing the two together, under one contractor, avoids that. Tell us how the building will be used and where it’s going, and we’ll recommend a foundation and price it with the building.

Foundation design depends on site conditions, soils, the applicable building code and project-specific engineering. This article is general information only.