When considering a pergola for your yard, you have a few options. Attached pergolas are those that are anchored to some part of a home or building. Hybrid pergolas are rare because there is generally not a need for them unless there’s no usable place on your house to fully attach the structure.
Hybrid pergolas generally have four posts, but also have some sort of architectural attachment to the house, even if it’s not providing support. The most popular pergola style is, of course, freestanding. One of the most common questions homeowners ask when considering this style is: are freestanding pergolas safe?
When anchored properly, freestanding pergolas are very safe. There are a variety of ways to anchor a freestanding pergola to any type of surface. Concrete, stone, grass, bare earth, and wooden decks are some common surfaces to which these pergolas are attached. Improper anchoring, however, can present a hazard that’s best to avoid.
Freestanding Pergolas Are Still Anchored
This term for a pergola is a bit confusing. The term freestanding only refers to the lack of a structure directly attached to the pergola. It does not mean that the pergola itself isn’t anchored to anything. All pergolas should be fastened adequately to prevent movement and to sustain structure, both of which we discuss in more detail below.
Why It’s Important To Anchor Freestanding Pergolas
At a glance, most pergolas don’t look like they can easily be moved. Most are very heavy by themselves. Plus, since they have a latticework roof, there’s not a lot of wide, flat surface that can catch the wind. However, you would be surprised at how easily a strong wind can move a pergola. Even moving the structure a few feet can result in thousands of dollars of damage to your home or yard. Not to mention the threat it can pose to your neighbor’s homes. Add to that an attached shade canopy, and you’ve got a disaster waiting to happen— even if you don’t live in an area prone to hurricanes.
But that’s not the only reason to anchor your pergola. Solid attachments can also provide the structure with the support it needs to last for many years. This is especially true for wooden pergolas that can warp over time due to moisture, exposure, and extreme temperatures.
Local Safety Guidelines
Nearly all attached pergolas require permits, but a freestanding one may not. However, it’s always a good idea to check city, county, or state code and permit requirements to be sure. If you build a pergola that is not up to local safety codes, it could cause issues if you decide to sell the house. Or, worse yet, if the structure moves or fails because of improper anchoring.
If you hire a professional contractor to build your pergola, they should be able to explain to you the local laws as well as build the structure to code.
Anchoring A Freestanding Pergola For Safety
If you wish to build a freestanding pergola yourself, there are several ways to anchor it for safety. The methods described below are a simple overview. If they are not adequate for your local laws, be sure to use a method that is.
Anchoring to A Deck
90-degree strap brackets are often used to anchor freestanding pergolas to wooden surfaces like decks. However, you want to be sure to anchor a pergola’s posts to support beams of the deck, as opposed to the boards that you walk on. The deck boards don’t provide enough resistance to properly anchor a pergola down. The support beams, on the other hand, are directly connected to the posts, which are anchored to the ground, providing a stable place to anchor pergola posts.
Anchoring to Concrete
Concrete is generally the easiest surface on which to anchor a pergola. However, most code requirements state that the concrete slab has to be of sufficient depth for anchoring. This is typically 6-inches, but that number may vary from place to place. If your concrete slab is sufficient, you can use hammer set fasteners to anchor brackets to the concrete and then attach those brackets to the pergola’s posts.
Anchoring to Grass or Earth
The easiest option for securing a freestanding pergola to grass or bare earth is helical piers. You can drill these down deep into the ground, past the frost line, to provide secure footing. You can then attach the top of the pier securely to the post. However, these items usually require special equipment to get them drilled down to a sufficient depth (usually 48-inches).
The alternative is to dig holes in the ground to a depth of one-third of the height of the posts. Four 15-foot posts would require four separate 5-foot holes. You can then situate the posts in the holes, level them, and pour 12-inches of concrete around the posts. One the concrete is dry, you can fill the rest of the holes with dirt.
Freestanding pergolas are essentially as safe as you make them. Without proper anchoring, they can move around in high winds, causing damage. Improperly fastened wooden pergolas can warp and lean over time, making them look bad and decreasing their value.
Having a professional install a pergola is what many homeowners decide to do to avoid the trouble of doing it themselves. Most areas have specific codes that should be followed when installing an outdoor structure like a pergola. However, for you DIYers out there, you can make your freestanding pergola safe with a little bit of research and some hard work.