The Pre-Purchase Checklist for an Autolift Garage: Sequencing a 30×40 Farm Shop Build

Every spring we get the same email from someone putting up a shop outside the Des Moines metro, and it usually arrives in the wrong order. A farm shop owner tells us the 30×40 pole building is already framed, the concrete went in last fall, the walls are twelve feet, and now he would like to know which lift fits. We can almost always make something work — but the best autolift garage projects we have ever done started with a phone call before the concrete truck showed up. This is the checklist we wish everyone had in hand at that stage: what to measure, what to pour, what to rough in, and in what order, so the equipment decision is the easy part instead of the compromise.

Step One: Decide What the Building Is Actually For

The first question on the checklist has nothing to do with lifts. It is whether the building is primarily for working on vehicles, primarily for storing them, or genuinely both. Those three answers point at three different pieces of equipment. A shop where you do oil changes, brakes, exhaust, and general daily maintenance wants a two-post — full undercarriage access, arms out of the way, wheels hanging free. A building where you want to park a car up top and another underneath wants a four-post. A guy who wants both usually ends up with a four-post and a rolling jack, or a two-post plus separate storage racking.

One customer we worked with a few years back — a farm owner northwest of the metro with a new 30×40 pole building, concrete floors, twelve-foot sidewalls — described exactly this. He wanted to do his own maintenance on passenger vehicles under 7,000 pounds and store one car on the lift with another potentially underneath. That combination points straight at a four-post in the 8,000 to 9,000 lb range with a caster kit and a set of sliding jack trays. He could still pull wheels, just with an extra step. Had storage not mattered, we would have put him on a 10,000 lb two-post and he would have liked it better for wrenching. Naming the primary use first saves you from buying equipment that does two things adequately instead of one thing well. Every autolift garage decision downstream flows from this one.

Step Two: The Ceiling Measurement People Get Wrong

Twelve-foot sidewalls does not mean twelve feet of usable height, and this is the single most common measurement error we see. In a pole building the sidewall height is measured to the top of the wall girt, not to the underside of whatever is hanging below the truss. Purlins, a truss bottom chord, a garage door track and opener, conduit, lighting, radiant tube heat, a ceiling fan — all of it eats headroom. We have shown up at builds with a stated twelve-foot wall and measured 10 feet 4 inches of true clear height at the lowest obstruction over the intended lift location.

Measure to the lowest thing above the lift footprint, and measure it before you buy. For a standard overhead two-post you want 12 feet clear; there are baseplate models that run in a shorter building by moving the crossbar down to the floor, which trades a little drive-over convenience for a lot of ceiling. Four-post storage lifts are more forgiving — you are stacking two vehicles, so the math is roughly the height of the bottom car plus the runway thickness plus the height of the top car plus a few inches of margin. In a 10-foot building you can often stack two low sedans but not a car under a pickup. Also check where the garage door opener rail lands, because relocating an opener after the fact is annoying and relocating a lift is worse. Do this measurement in person with a tape, not from the builder’s plan set.

Step Three: Concrete Specs Before the Pour

If you are reading this and the slab is not down yet, you are in the best possible position. Tell your concrete contractor you are installing a lift and where. For a two-post we want a minimum 4-1/4 inches of 3,000 PSI in the column footprints, and we would rather see 6 inches at 4,000 PSI with proper rebar. Thickened pads in the two column locations are cheap insurance and cost almost nothing while the forms are already set. Keep control joints and expansion joints away from where anchors will land — an anchor set too close to a joint edge loses a lot of its holding value, and that is a hard problem to fix later.

Four-post lifts spread the load across eight or more feet of runway support, so they are far less demanding on the slab. Many freestanding four-posts do not require anchoring at all in a residential setting, which is exactly why they suit a pole barn with an unknown pour. Twenty-eight days of cure before anchoring, no exceptions we are willing to make. If your slab is already in and you have no documentation, we can core-sample or at least sound it out during a site visit before we commit to a two-post. Getting the concrete right is the one item in an autolift garage build with essentially no cheap retrofit, which is why it sits this high on the checklist rather than at the end.

Step Four: Power, Air, and Rough-In Sequencing

While the walls are still open is the moment to run everything. Most single-phase two-post and four-post power units want 230V on a dedicated circuit — typically 20 to 30 amps depending on the motor. Decide which end of the lift the power unit sits on now, because that is a fixed location and you will want an outlet within a few feet of it, not across the shop. Run the circuit in conduit while the girts are exposed and you save yourself a surface-mount conduit run you will look at for twenty years.

Air is the other rough-in. Two-post lifts almost universally use an air-actuated lock release, and four-posts often use air for the lock system as well. A small compressor is plenty for lift function alone, but if you are also running impacts, plan capacity accordingly. Drop an air line to the lift location while the walls are open. The same goes for lighting — put fixtures where they will not be blocked by a raised vehicle, which usually means running rows along the sides rather than straight down the center. Floor drains, if you are adding them, need to be positioned so they do not land inside a column footprint. That is the sequencing point of this whole checklist: the utilities decision and the lift location decision happen at the same time, before drywall or steel liner panel goes up. Every autolift garage we have installed into a finished building involved at least one workaround that a five-minute conversation would have prevented.

Step Five: Capacity, Vehicle Fit, and Honest Margin

Seven thousand pounds sounds like plenty for passenger vehicles, and for a sedan or a small SUV it is. But capacity math should include the thing you might buy in eight years, not just what is in the driveway today. A half-ton crew cab pickup runs 5,000 to 5,800 pounds. A three-quarter-ton diesel gets into the 7,500 to 8,500 range. A dually or a loaded work truck goes past that quickly. For general daily maintenance on a mixed rural fleet — a couple of pickups, a car, maybe a side-by-side or a small trailer — we usually recommend 9,000 to 10,000 pounds even when the customer’s stated need is 7,000.

The upcharge from a 7,000 lb unit to a 9,000 or 10,000 lb unit is modest relative to the total project, and it buys you margin on both capacity and component life. Also check length, not just weight: four-post runway length determines whether a long-bed pickup fits without hanging the tailgate off the back, and a standard-length four-post will not comfortably hold a crew cab long bed. Extended-length runways exist and are worth asking about. Width matters for the two-post case — measure your drive-through opening and confirm the column spacing works with your door. We have had customers get a lift installed only to discover their overhead door track sits inside the column line. Fifteen minutes with a tape measure on this step of the checklist prevents the most expensive category of mistake in the whole autolift garage project. See our related article on four-post versus two-post for a home garage.

Step Six: Delivery, Unload, and Install Realities

Lift equipment ships heavy and it ships on a semi. A two-post arrives as two columns, an overhead assembly, four arms, and a power unit — call it 1,800 to 2,400 pounds depending on capacity. A four-post is similar or heavier. If you are on a gravel lane off a county road outside the Des Moines metro, the driver needs somewhere to turn around, and you need a way to get the crate off the truck. A skid loader with forks handles it. A tractor with a loader and a set of pallet forks handles it. Two guys and good intentions do not.

Ask about liftgate service when you order if you have no equipment on site, and be honest about access. We do a lot of our own delivery and installation across central Iowa specifically because this step goes sideways so often when it is handled by a freight broker who has never seen a farm lane in March. Frost heave season is real — we have rescheduled installs because a driveway would not hold a truck. On install day, plan for four to six hours for a straightforward two-post with power already in place, longer if there is drilling into thick concrete or if the layout needs adjusting. Have the bay clear and the floor swept. Have the power live. Those two things alone cut an hour off most jobs. Our piece on what to expect on lift installation day covers the rest.

The Short Version of the Autolift Garage Checklist

Print this and stick it in the truck. One: name the primary use — service, storage, or both — and let that pick the lift type. Two: measure true clear ceiling height at the lowest obstruction over the lift footprint, not the sidewall height on the plan. Three: spec the concrete before the pour at 4-1/4 inches minimum and 3,000 PSI minimum, thicker and stronger if you can, with joints kept away from anchor locations, and give it 28 days. Four: rough in 230V power and an air drop at the exact power-unit location while the walls are open. Five: size capacity for the heaviest vehicle you might own in a decade, and check length and width fit, not just weight.

Six: plan the delivery and unload honestly, including lane access and whether you have a machine to move a two-thousand-pound crate. Seven, and this one is free: call us before you finalize any of the above. We have walked hundreds of these builds across central Iowa and we can usually spot the constraint you missed in a ten-minute conversation. There is no charge for that call and no obligation to buy anything from us. We would genuinely rather see a well-planned autolift garage in a pole barn near Des Moines than sell someone a lift that fits badly. Call 800-674-9302, send us your dimensions, and we will tell you straight what fits and what does not.