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How to Measure Your Space & Order the Right Pergola Kit

Before you order a pergola kit from us, it's important to first measure the space you plan to install the pergola. This article explains how to correctly measure your space and what factors to consider so there aren't any unpleasant surprises when the kit arrives and you go to install your pergola.

Important Things to Know

Overhead schematic of a traditional free-standing pergola illustrating that the shade purlins run the width of the pergola1. Width & Depth Are NOT Interchangeable - It's very important to know that the width and depth of a pergola are NOT interchangeable.

On a free-standing pergola, the shade purlins run the width of the pergola (as illustrated in the diagram to the right). Therefore, your shade will be maximized when the pergola is oriented such that the evening sunlight comes from the width side.

Attached pergolas attach to your house (or other building/structure) on the width side, as shown in this diagram. So make sure that the pergola's width matches the length of where the pergola will attach to your home. For a house-attached pergola, the depth refers to how far out from the home the pergola will go.

2. Width & Depth Refer to the Dimensions of the ROOF - When we say a pergola is 12' wide by 18' deep, we're saying that the pergola's ROOF is 12' wide by 18' deep (not including end caps, which extend beyond the ends of the beams and rafters as discussed in #3 below). In other words, the beams and shade purlins will be 12' long (as they run the width of the pergola) and the rafters will be 18' long (as they run the depth of the pergola). The dimensions of the pergola (i.e. 12' x 18') do NOT necessarily refer to the distance between the posts (columns) holding up the pergola, as the posts are oftentimes not placed right in the corners (as explained in #4 below).

3. End Caps on Traditional Pergolas Extend Beyond the Ends of the Beams & Rafters - When you order a traditional pergola, you'll decide what style of end caps you want for the beams and rafters: a) scrolled, b) beveled or c) flat. Scrolled and beveled end caps add an additional 9" of length (assuming 2x6" beams/rafters) or 12" of length (for 2x8" beams/rafters, typically only on larger 20'+ length pergolas) to each end of the beam/rafter. (So, for example, a 12-foot long beam will actually end up being 13.5 feet long once you insert the 9" end cap on each end.) Flat end caps don't add any length and are typically selected only if you want the "hybrid" (semi-modern) look. You'll want to consider the additional 18-24" of length that scrolled/beveled end caps add to the width and length of the pergola when ordering your kit. (Note: Modern pergolas don't have end caps.)

Picture of a white traditional pergola with overhangs with all 4 posts sitting atop brick pillars near a swimming pool4. There Are Important Differences Between Traditional and Modern Pergolas - Traditional pergolas usually have (but don't necessarily need to have) overhangs, meaning that the beams/rafters extend beyond the posts (columns) holding up the pergola. As you can see in this diagram for traditional pergolas, the posts can be installed right underneath the ends of the beams (so the outside edge of the post and the end of the beam are perfectly flush, resulting in no overhang at all) or up to 36" in from the ends of the beams... or anywhere in between 0" and 36". Modern pergolas, on the other hand, never have an overhang; the posts (columns) are always right in the four corners of the pergola.

5. Posts Must Be Secured to a Solid Base at Least 2" from the Edge - The bottom of the posts (columns) must be secured to solid base, such as a cement slab, deck footings or concrete footings. And it's important to note that the outside edges of the posts must be at least 2 inches away from the edge of the base. For example, the outside edges of the posts cannot be flush with the edges of a cement slab.

6. Even Though Our Pergolas Are Custom, Trimming May Be Required - In order to make our pergolas as affordable as possible, we only manufacture the beams, rafters, purlin holders and shade purlins in 2-foot increments (and in 4-foot increments above 20 feet), as follows: 8 feet, 10 feet, 12 feet, 14 feet, 16 feet, 18 feet, 20 feet, 24 feet, 28 feet, 32 feet and so on. Thus, if you wanted a pergola that has roof dimensions of exactly 12.75' width by 17.33' depth (not including end caps), you would need to a) order our 14' x 18' pergola kit, b) trim down the 14' beams and shade purlins to 12.75' and c) trim down the 18' rafters and purlin holders to 17.33'.

Now that we've laid the ground work, let's talk about how to actually measure your space and decide which pergola kit to order.

How to Measure Your Space

As you may have already recognized on your own, you really need two sets of measurements:

  1. How far apart the posts will be (from outside edge to outside edge); and
  2. The dimensions of the pergola's roof ~10 feet up from the ground (remembering to take end caps into consideration).

Picture of a sandstone tan modern-style pergola sitting on a wooden deck behind a tan houseIf you're planning to get a modern pergola kit, these are one and the same (since modern pergolas never have overhangs or end caps). But if you're planning to purchase a traditional pergola, these two sets of measurements will be different if you're planning on the beams and/or rafters having overhangs.

So before you take the measurements, you'll need to decide two things if you're planning to buy a traditional pergola: 1) what style of end caps you want (scrolled, beveled or flat), and 2) how long of overhangs you want.

Picture of a white pergola with no overhangs and flat end caps covering part of a deck, with overlaid text Traditional Configured to Look ModernMost customers ordering a traditional pergola choose to either a) use the standard 12" overhangs shown in our CAD drawings for each pergola kit (along with either scrolled or beveled end caps) OR b) go with the "hybrid" semi-modern look (no overhangs and flat end caps). Once you've made this decision, you'll know whether the posts will be installed 12" (or 21" if you count the end caps) in from the ends of the beams/rafters or if they'll be installed right in the corners.

Typically, the size/dimensions of the base (i.e. cement pad, deck, etc.) will be your constraining factor. (Remember that there needs to be at least 2" of space between the edge of the base and the outside edge of the posts.) But you'll of course want to also make sure that the roof of the pergola (which may extend past the posts in one/both directions, depending on whether you want overhangs) won't run into your house, trees or any other obstructions.

How to Order the Right Pergola Kit

Now that you have your measurements, it's time to order your pergola kit. Click here to see all of our available pergola kit configurations by size (width x depth). Remember that width and depth are not interchangeable, and be careful to select the correct width (attached to the house in the case of attached pergolas) and depth (distance out from the house in the case of attached pergolas).

Remember that since our pergola components come in increments of 2 feet (or 4 feet once you get above 20 feet), you'll need to order a kit that is at least as wide and deep as you want the pergola's roof to be (not including end caps)... and you may need to trim some of the components down to the right size when you receive the kit (which is very easy to do).

If you have any questions, please don't hesitate to contact us.