How to Build a Pole Barn — Getting Started Guide for Eastern Washington Homeowners & Contractors

Getting Started: What to Think Through Before You Ever Pick Up a Shovel

Every year we talk to homeowners, ranchers, and contractors all over Eastern Washington who are ready to build a pole barn — whether it’s for hay storage near Colville, a truck and RV shop out past Airway Heights, or an equipment barn up around Kettle Falls. The pole barn (post-frame) design has stayed popular for decades because it’s fast to build, flexible in size, and generally more affordable per square foot than stick-framed construction. But building one right in our region means designing around real snow loads, frost depth, and soil conditions — not just copying a plan you found online for a milder climate.

This guide walks through the questions we hear most at our Airway Heights, Colville, and Kettle Falls stores, and what you need to nail down before you start digging post holes.

Start With Intended Use, Then Size Up

Before you think about lumber or steel, answer this: what is this building actually for? A hobby shop for one truck and a workbench is a very different structure than a pole barn meant to store a 34-foot RV, run a tractor through, or eventually finish out as a heated shop. We consistently hear from customers who wish they’d added another 10-12 feet of length or bumped their wall height from 12 feet to 14 feet before they built. Trusses and posts cost a lot less to size correctly on paper than to retrofit later. If there’s any chance you’ll want a mezzanine, hay loft, or vehicle lift down the road, plan your wall height and truss design around that now.

Permits and Local Code Requirements Come First

Almost every jurisdiction in our service area — Spokane County, Stevens County, and the cities and towns within them — requires a permit for a permanent pole barn, and most require engineered, stamped plans, especially once you’re dealing with our region’s snow loads. Here’s the general order of operations we recommend:

• Call or visit your local zoning office first, before you finalize a design, to confirm setbacks, allowed uses, and whether a zoning permit is needed.
• Once zoning clears, take your site plan and engineered building plans to your building department for a permit review.
• Ask specifically about your required ground snow load, frost depth, and wind exposure category — these numbers change depending on elevation and location, and Colville and Kettle Falls often carry heavier design snow loads than lower-elevation parts of the Spokane area.
• Check any covenants, and if you’re near a rural fire district, it doesn’t hurt to loop in the fire marshal, especially if you’re building close to other structures.

Skipping this step is the single most common — and most expensive — mistake we see. An unpermitted pole barn can turn into a real headache at resale time, or worse, get flagged and require retrofitting mid-project.

Choosing the Right Foundation for Eastern Washington Soil and Frost

Our soils vary a lot across the region — glacial till and rocky ground in the higher country around Colville and Kettle Falls, sandy loess soils through much of the Spokane area, and clay pockets that hold water almost everywhere. That variability makes foundation choice one of the most important decisions in the whole project.

Direct-Buried Posts vs. Concrete Piers

The classic pole barn approach is direct-buried, pressure-treated posts (commonly 6×6 or 6×8, rated for ground contact) set into holes with a concrete footing at the bottom. General guidance for our climate calls for:

• Hole depth of 3-5 feet, below the local frost line — always confirm the exact frost depth requirement with your building department, since it varies by elevation.
• Hole diameter roughly three times the width of the post, to allow for a proper concrete footing and backfill.
• A gravel base at the bottom of each hole for drainage before pouring the footing.
• Posts set plumb on the footing, braced securely, then backfilled with concrete or a concrete-and-gravel combination as the design specifies.

In wetter, rot-prone ground — low spots, areas with a high water table, or heavier clay — some builders dig 6 inches deeper than required and backfill with crushed rock instead of soil around the post to improve drainage and reduce long-term rot risk. If you’re building on a site that holds water into spring, this small extra step is worth the material cost.

An alternative, especially popular where owners want to avoid any wood-to-soil contact, is setting posts on concrete piers with metal brackets above a slab. This costs more upfront but removes a major source of long-term post failure.

Slab, Gravel Floor, or Both?

For cold storage or equipment barns, many of our customers skip the slab entirely and go with a compacted gravel floor — 4-6 inches of compacted base is typical. If you’re planning a shop, workspace, or anything with a vehicle lift, a proper concrete slab over a compacted gravel base is worth the investment, both for durability and for keeping moisture out of the structure.

Framing, Roofing, and Materials That Hold Up to Our Weather

Eastern Washington throws a lot at a building over the course of a year — sustained sub-freezing stretches, heavy wet snow loads, then bone-dry, intensely sunny summers with big daily temperature swings. Material choice matters more here than in milder climates.

Trusses and Framing

Roof trusses need to be engineered specifically for your local ground snow load — this isn’t a place to eyeball it. Design snow loads across our service area often run in the 30-60 psf range depending on exact location and elevation, with higher elevations around Colville and Kettle Falls typically requiring heavier truss designs than lower-elevation sites near Airway Heights. Purlins (roof) and girts (walls) are usually 2×4 or 2×6 SPF or Doug-fir, spaced per the engineered plan — don’t stretch spacing to save material, since that’s exactly where roof failures start under heavy wet snow.

Metal Roofing and Siding

Painted steel panels — typically 26- or 29-gauge — are the standard for both roofing and siding in our region, and for good reason: low maintenance, long service life, and good snow-shedding performance with the right panel profile. A few practical tips we give customers at the counter:

• Overlap roofing panels by one full corrugation, and follow the panel manufacturer’s fastening pattern exactly.
• Use color-matched, corrosion-resistant screws with neoprene washers — and don’t over-tighten them. Crushed washers are one of the most common causes of roof leaks we see on pole barns a few years in.
• Choose a panel and coating rated for UV resistance; our summer sun is intense enough that cheaper coatings will chalk and fade faster than you’d expect.
• If there’s any chance you’ll insulate and condition the space later, ask about a condensation-control (drip-stop) underside membrane on your roof panels now — retrofitting this later is far more work.

Planning for Future Insulation

Even if you’re not conditioning the space right away, it’s smart to frame with future insulation in mind. Fiberglass batts between wall girts and blown-in insulation over a ceiling liner are common upgrade paths. Think through vapor barrier placement now — our winters are cold enough, and summers hot and dry enough, that getting vapor barriers backwards can cause real condensation problems inside wall and roof cavities down the line.

Site Prep, Layout, and Avoiding the Most Common Mistakes

A huge share of pole barn problems trace back to site prep and layout, not the framing itself. Here’s what experienced builders in our area do differently.

Grade for Drainage First

Clear vegetation and topsoil several feet beyond your actual building footprint to give yourself room to work and stage materials. Then grade the pad so water sheds away from the structure — a minimum 2% slope away from the building is a good baseline. If you’re on a hillside site (common around Kettle Falls and parts of Stevens County), plan for a swale or French drain uphill of the building to intercept seasonal runoff before it ever reaches your foundation.

Get Your Layout Square Before You Dig

Use batter boards and string lines to mark your building perimeter, and check squareness with diagonal measurements (or the 3-4-5 triangle method) before you dig a single post hole. An out-of-square layout might not seem like a big deal at first, but it compounds fast once you’re trying to hang doors, run siding, or install trusses — and it’s a much cheaper fix on paper than in the ground.

Common Mistakes We See Most Often

• Shallow post holes. Digging above the frost line seems like a shortcut, but it invites frost heave that can crack concrete and shift posts within a couple of winters.
• Skipping engineered plans. Non-engineered, generic plans often don’t account for our snow loads and won’t pass permitting anyway.
• Building too small. This is the single biggest regret we hear after the fact — go bigger than your current need if you have the room and budget.
• No contingency budget. Site surprises (rock, unexpected water, extra gravel needed) are common. Build in 15-20% above your material estimate.
• Poor bracing during construction. Posts need to stay plumb and well-braced while concrete cures — a windy Eastern Washington afternoon can undo a poorly braced wall in a hurry.

DIY, Hire a Pro, or Split the Difference?

We get this question constantly, and the honest answer depends on the size and complexity of your project.

When DIY Makes Sense

If you’re building something in the range of a 24×24 to 30×40 single-use shop or storage building, with a simple rectangular footprint and standard roof pitch, DIY is very doable for someone with basic carpentry skills, a good set of engineered plans, and access to the right equipment (auger or rented mini excavator for post holes, a level and string lines, and help lifting trusses safely). Many of our customers buy a pre-engineered kit package — posts, trusses, hardware, and metal specified together — which takes a lot of the guesswork out of matching materials correctly.

When to Bring in a Contractor

Larger buildings (40×60 and up), tall RV or equipment bays, anything with a planned mezzanine or living space, or sites with tricky soil or slope conditions are where we recommend hiring a post-frame contractor. Look for a contractor who specifically does post-frame construction (not just general framing), knows local snow and wind load requirements, and works with a licensed engineer on plans. A cohesive, experienced crew of three or four is typically enough to frame a standard pole barn shell efficiently.

The Hybrid Approach

A lot of our customers split the project: hire a contractor for the shell, posts, and slab, then handle insulation, interior finishing, and non-electrical work themselves. It’s a good way to control cost while making sure the structural work — the part that really matters in our climate — is done to code.

What It Actually Costs, and What Drives the Number Up or Down

Costs shift with material prices and site conditions, but the drivers stay consistent. A bare-bones cold-storage pole barn — direct-buried posts, gravel floor, simple metal roof and siding, minimal doors — sits at the low end of cost per square foot. Add a concrete slab, electrical rough-in, and quality overhead doors, and the price climbs meaningfully. A fully insulated, conditioned shop or barn-dominium-style space with windows, HVAC, and interior finishes sits at the top end.

Beyond size, the biggest cost drivers are your local snow/wind load requirements (heavier engineering means more material), foundation type, site work difficulty (a sloped or rocky Kettle Falls lot costs more to prep than a flat Spokane-area pad), and how many doors, windows, and electrical runs you’re adding. Whatever your estimate comes to, build in a 15-20% contingency — site surprises are the norm, not the exception, out here.

Whether you’re just starting to sketch out your pole barn or you’re ready to start ordering posts, trusses, metal roofing, and fasteners, our team at Builders Supply & Home Center has been helping Eastern Washington customers plan and build these structures since 1979. Stop by our Airway Heights, Colville, or Kettle Falls locations to talk through your project with someone who knows our local codes, snow loads, and soil conditions firsthand — we stock the post-frame materials, metal roofing, concrete supplies, and hardware you’ll need to get it done right. Browse what we carry online at https://bldrsupply.epicor-inet.com/departments.

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