RTM & Modular Home Foundations in Calgary

The real work behind rtm, modular & mobile home foundations

On a typical build the foundation comes first and the framing that follows quietly soaks up its small mistakes. Ready-to-move and modular homes flip that order. The house shows up complete — on a flatdeck or as factory modules, with drywall hung and the roof already on — so the foundation has to be right before any part of the building is on site. Whatever state the piles are in on delivery morning is what the home has to live with.

Right has two meanings here. First, every pile head must land on the same plane within a tight tolerance, since a finished, already-square house exposes any low support immediately — doors that drift open by themselves, a floor with a slope you can feel underfoot. Second, the heads must sit beneath the lines where the factory built in the load path: the main beams, the steel chassis, the marriage line between halves. A pile a few centimetres off a bearing line supports nothing. And once the mover has the unit suspended, every fix happens with a house hanging in the air and the clock running.

Wind is the third issue. These homes are wide and relatively light, frequently set on open acreage with nothing to break the wind, and uplift can control more of the design than the home’s weight. A helical screw pile resists pull-out directly, through the soil sitting above its helix, without needing a large mass of concrete. Older mobile homes on timber cribbing usually have neither the level nor the tie-down they were supposed to have.

On site, from start to finish

The controlling document is the manufacturer’s foundation drawing: where the bearing lines are, where point loads fall, and what kind of support the home expects. If you do not have it, we will ask for it before we quote, because bearing lines guessed from a floor plan produce a pile layout nobody can land a house on. From there, layout is run off a survey benchmark, since the reference is finished floor elevation, not the lawn.

Installation then follows normal screw pile practice: turn each pile to the torque the design needs, which can mean a different depth at every location, then trim heads to a laser elevation and cap them. Trimming is what achieves the tolerance, and it is how the whole array lands on one plane across uneven ground. Our aim is to be done and gone before the mover arrives, leaving as-built head elevations so the set crew is working from measurements. Re-levelling an existing mobile home runs the same process backwards: it is jacked toward level gradually, never all at once, with the old cribbing swapped for screw piles and adjustable caps as it comes up.

What shapes the design

The manufacturer drawing effectively is the spec: bearing line spacing, concentrated loads where the sections join and where beams terminate, and the support style the unit was built for — piers under the chassis, a continuous perimeter beam, or a crawl space. If you want skirting or a closed-in crawl space, expect a grade beam to join the scope. Where re-levelling down the road is a real possibility, adjustable screw-jack caps get specified on purpose.

Exposure takes care of the remainder. On an open acreage, the tie-down demand may size the screw piles before gravity load does. The last limit is delivery day: the mover needs a way in and the crane needs a place to set up, and neither can sit on top of the finished piles. A perfect array that no truck can reach is not really a foundation.