D. Types of Gravel

Types of gravel is the fourth section in our homeowner education series on "Landscaping Yards". When we talk about gravel for this particular article, we are referring to products used as a sub-base underneath a patio, wall or other project.

If you are just joining us on this page, our goal with this series is to help you to understand the landscaping process from start to finish.

We visited a landscape supply yard and looked at the products available, and how to estimate your requirements.

Then we put it all together with pictures so you could essentially start with window shopping and estimating at the same time.

Links to other parts of this series can be found at the bottom of this page.

Besides talking about gravel and crushed rocks, this section will also include sand, and drain rock used for back fill behind walls. The next section will be types of rocks which will include decorative rocks.

There are many different gravel types landscapers use under their patios and walls for sub base materials. Road crush, crushed limestone, drain tile, and crushed washed ¾ inch rock are some of the more popular choices.

For anyone looking for more specific how-to landscaping information, please visit The Yard: Landscaping How-to Modules. These are very educational and full of great landscaping tips for homeowners.

Special thanks once again to Ornamental Stone Calgary for providing us with a great facility to put this article together. If you are looking for Landscape supplies or rock in Calgary, they are the place to visit.

Common base materials.

Along with the information on our website, you can always check with your local gravel yards on what professional landscapers use for their projects. Remember that material availability can change in different parts of the world.

Tips for Better Compaction

Stay away from rounded materials like pea gravel, they don't hold together or compact very well.

“Mechanical bond” is the ability of jagged and broken edges of rock to hold, or lock together. They pack in much tighter when compacting a sub-base.

Round rocks can will shift, and displace very easily.

Always pack in layers using power tampers (plate vibration tampers). This will ensure better compaction. Packing your base in 2 inch layers is the most effective method.

You have probably seen road builders using water with their packing equipment to pack sub-base materials. This is something that will help you achieve better compaction.

Using water must be done in moderation so you don't drown the area. Too much water could lead to problems down the road.

Estimating for Gravel

Estimating gravel at your local gravel yards is much easier when you know the formulas. Estimates are never perfect, but they are designed to get you pretty close. If you are unsure of the variables that can effect your estimates, please go back to our "Estimating Materials" introduction page. Here we discuss some of the important factors that can effect your estimates.

Take the length times the width of your excavation area and multiply it by the depth (LxWxD). This will give you the cubic feet of sub base material you will need.

For example:

12 ft. times 12 ft. = 144 sq. ft. times 6 inches. (.5 of a ft.) = 72 cubic ft.

Most landscape yards sell in cubic yards, so you will need to convert cubic feet to cubic yards by dividing by 27.

72 divided by 27 = 2.6 cubic yards of gravel required.

Accounting for Compaction

To account for compaction of gravel, you will need to increase your amount by at least 5% to 10%. Rounding up with most orders will usually cover your needs as a homeowner. This means 2.6 yards becomes 3 yards after rounding up.

It really depends on what you are compacting, and what your are compacting with. The heavier the compaction equipment, the more compaction you will get using a hand tamper will have much less compaction than a power tamper.

Most landscape supply yards sell in one yard, or sometimes half yard buckets. Some suppliers will have a scale for more accurate measuring of materials bought and sold. You will have to scale in before loading, and scale out when you are done.

If you have a patio project of 12x12 You will need to have an excavation site of 12.5x12.5. Always excavate a larger area than what is required by at least four to six inches. The base needs to extend further than the edge by this amount for proper support of your edges. (We just used those numbers for easy math.)

Pretty simple, right?

Now you have the magical formula for estimating gravel, soil, decorative rock, sand and anything else sold by the square foot, cubic foot or cubic yard.

Need help? Use our volume conversion calculator to convert from cubic feet to cubic yards.

For more information on estimating go to our Quick Landscaping Estimating Reference for formulas and examples.

UnitConversion.org - online unit converter of length, weight, volume, area, and more.

Estimating for a Paver sand base

Let's order some sand for that same patio. Let's say you are going to need a one inch layer of sand for your bedding material. (Convert the 1 inch to feet by dividing by 12 = .08)

12 ft. times 12 ft. = 144 sq. ft. times 1 inch (.08 of a foot.) =11.52 cubic ft. divided by 27 = .42 cubic yards. I would make this ½ a yard of sand required for the one inch base.

Glad you have that mastered.

Now let's take a look at the types of rocks you may be using in and around your projects.

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Introduction Estimating Materials

Table of Contents: Landscaping Yards

A. Landscaping Yards Introduction

B. Landscape Blocks

C. Patio Bricks and Paver Stones

D. Types of Gravel

E. Types of Rocks

F. Buying Rock

G. Buying Flagstone