Thinking about a new shed, above-ground pool, or patio this summer? Good. However, the part most homeowners skip is the part that lasts longest: the ground underneath. Proper shed and pool site preparation is what keeps your project level, dry, and standing straight for years. Skip it here in Frontenac County, and frost and soft soil will do their work.

We have prepped a lot of backyards around Kingston over the past 20 years. So in this post, we will walk you through what good shed and pool site preparation actually involves, from excavating and levelling, to the right gravel base, to drainage that moves water away from your structure.

Why shed and pool site preparation matters so much

A shed or pool is only as stable as what sits below it. For example, set a shed on bare grass, and the soil holds moisture, settles unevenly, and the floor racks within a season or two. Set a pool on a soft, sloped spot, and the liner wrinkles or the wall bows.

Around here, two things cause most of the trouble: frost and soft, poorly drained soil. Our winters push ground frost well down, and the freeze-thaw cycle lifts and drops anything sitting on unprepared dirt. That movement is called heaving, and it is the main reason good shed and pool site preparation pays off.

The fix is not complicated. However, it does take the right steps in the right order. Because once the shed is built or the pool is filled, fixing the base means tearing it all out.

Step one: excavate and level the pad

Every solid base starts below grade. First, we strip off the sod and topsoil. Topsoil is organic, so it holds water and compresses over time. You never want it under a structure. If you want to know what you are looking at, our guide on how to spot good soil is a helpful read.

The next step for shed and pool site preparation is the levelling. A pool pad in particular needs to be flat, often within an inch across the whole footprint. That is hard to eyeball, so we bring in laser levels and the right machines. Proper excavation and grading gets the base flat and the subsoil compacted before any gravel goes down.

How deep you dig depends on the project:

• Garden shed: strip topsoil, then 100 to 150 mm of compacted gravel.
• Large shed or garage: deeper excavation, often 200 mm or more of base.
• Above-ground pool: level the subgrade, then a sand or fine gravel bedding layer.
• Patio or walkway: 150 mm of compacted granular under the pavers.

These are typical ranges, not rules. Soft spots or slopes change the plan. That said, the principle holds: dig out the weak stuff, then build back up with material that compacts and drains.

Choosing the right gravel base

Not all gravel is equal. The wrong product stays loose, holds water, or washes out. For a shed or pool pad, you want an angular, well-graded crushed aggregate that locks together when compacted. We cover the differences in our post on gravel types explained, and the same logic applies to pads.

Here is the short version:

• Granular A (3/4 inch crushed with fines): the workhorse base. It compacts tight and sheds water.
• Clear stone (3/4 inch, no fines): drains fast, great for the bottom of a wet pad or under pavers.
• Screenings or stone dust: a fine levelling course on top, often under pool liners or patio stones.

For many backyard pads, we build a clear-stone drainage layer first, then a Granular A layer on top for a tight, level surface. We handle both the material and the placement through our topsoil and gravel delivery service, so you are not stuck sourcing and hauling it yourself.

How much base material do you need for shed and pool site preparation?

Volume trips a lot of people up when it comes to shed and pool site preparation. Gravel is sold by the tonne or cubic yard, and a thin layer eats more than you expect. As a rough guide, one cubic yard covers about:

• 108 square feet at 3 inches deep.
• 81 square feet at 4 inches deep.
• 54 square feet at 6 inches deep.

So a 12 by 12 foot shed pad at 4 inches needs roughly 1.8 cubic yards before compaction. Always order a little extra, because compaction and uneven subgrade both use material. When in doubt, call us with your dimensions and we will size it for you.

Compaction: the step everyone underrates

Dumping gravel is not the same as building a base. Loose stone settles under load, and that settling shows up as a sunken corner or a cracked patio. Compaction is what turns loose aggregate into a solid, load-bearing pad.

We compact in lifts, which means layers. Each layer, usually 75 to 100 mm, gets packed with a plate compactor or roller before the next goes down. Compact too thick a layer at once, and the bottom stays loose. In short, thin lifts and patient passes beat one big dump every time.

Good compaction also fights frost heave. A tight, well-drained base holds less water, and water is what freezes and lifts. You can see the payoff in projects like our gravel pad and topsoil grading project, where the finished pad stays flat and firm.

Drainage and grading away from the structure

Water is the enemy of any backyard build. Therefore, the base must shed water, not trap it. We grade the surrounding ground so it slopes away from the pad, usually a drop of about 2 percent, which is roughly 2 cm per metre.

Why does this matter so much in Frontenac County when it comes to shed and pool site preparation? Because our soils vary a lot from lot to lot. Some drain freely, others sit wet for weeks after a thaw. If you want to understand your own property, the Canadian Soil Information Service publishes soil survey data for the region. On a wet lot, we often add a clear-stone layer or a simple perimeter drain to carry water off.

Grading is a craft. Done right, water runs where you want it. Done wrong, it pools under your shed or pushes toward your foundation. Our site grading and lot preparation work is all about getting those slopes exactly right.

A worked example: a backyard pool pad near Kingston

Say you want a 24-foot round above-ground pool. First, we strip the topsoil and check the subgrade for soft spots. Next, we cut the area dead level, because an above-ground pool wall will not tolerate a tilt.

Then we lay and compact a clear-stone drainage layer, top it with a fine levelling course, and slope the surrounding ground away. The same levelling discipline shows up in driveway work too, like a driveway grading job on Picton Road, where a flat, well-drained surface was the whole point. Finally, we check the fall around the pool so rain and splash-out run off, not back toward the wall.

Permits, locates, and property lines

Before any machine touches your yard, call for utility locates. It is free, it is the law, and it keeps everyone safe. Mark out your project first, then book the locate and wait for the all-clear.

Permits depend on where you live and what you are building. Inside Kingston city limits, the City handles building permits. In South Frontenac, Central Frontenac, or Loyalist Township, your own township building department is the one to call. A detached shed under a certain size often needs no permit, but a pool almost always needs a fence and may need a permit, so check first.

If your lot borders a creek, wetland, or shoreline, you may also need approval from your conservation authority. Conservation Ontario explains how those permits work and when they apply. We are happy to point you to the right office for your address.

When to bring in a contractor

Plenty of folks lay a small shed base themselves. However, bigger jobs, wet lots, and pool pads reward a pro with the right machines. A plate compactor and a shovel will not level a 24-foot circle, and renting the gear often costs more than you think.

We also handle bigger site work when a backyard project turns into a full regrade. Our crew does everything from pads to road work, so no matter the scale, the base gets built right the first time.

In short, the cost of doing the base properly is small next to the cost of ripping out a settled pool or a racked shed later.

Get a free quote on your site prep and gravel

Ready to start your project on solid footing? We will visit your property, assess the soil and slope, size the base, and deliver the right gravel. One crew, one call, from excavation to the finished pad.

Call M. Riddle Excavating at 613-545-7955 or request a free quote through our excavation and grading page. Serving Kingston and all of Frontenac County.

Frequently asked questions

How thick should the gravel base be under a shed?

For a small garden shed, 100 to 150 mm of compacted granular is usually enough. Larger sheds and garages often need 200 mm or more. The soft soil gets stripped first, then the gravel is placed in thin, compacted lifts.

Do I need a permit for a backyard shed or pool near Kingston?

It depends on size and location. Inside city limits, contact City of Kingston Building Services. In South Frontenac, Central Frontenac, or Loyalist Township, contact that township. Most pools need fencing, and some need a permit, so always confirm before you dig.

How much gravel do I need for a 12 by 12 pad?

At 4 inches deep, a 12 by 12 foot pad needs roughly 1.8 cubic yards before compaction. Order a little extra, because compaction and uneven ground both use material. We can size the order exactly from your measurements.

Why does a poorly prepared base cause settling?

Loose or organic soil holds water and compresses under load. When that water freezes, it lifts the structure, and the thaw drops it unevenly. Proper compaction and drainage remove the water and the weak material, so the pad stays put.

Can you deliver gravel and do the site prep together?

Yes. We handle both the excavation and the material supply, so you get one crew from start to finish. Call 613-545-7955 to arrange your site prep and gravel delivery.