A Simple Guide to Building a Deck Around an Underground Irrigation System


Many of our deck projects involve working around an existing in-ground irrigation system or one that the homeowners will install after we finish the deck.

There’s a common concern among homeowners about the currently installed systems getting damaged during the deck build. Or questions come up regarding the best way to reroute the lines during the building process. 

It can all become a little overwhelming, especially for homeowners handling the project on their own. That’s why we’ve created a simple guide to answer these common questions, ease your concerns and give you our best advice along the way. 

Installing a Deck Before Irrigation

The process is simple if you install your deck before your irrigation system, which is sometimes the case for new construction homes. You don’t need to worry about rerouting lines or the possibility of damage.

But even if you only have the deck planning done first, your deck builder will likely be happy to stake out or paint on the ground where your new deck is going. Then your irrigation specialist will know exactly where to put (and equally important, where not to put) irrigation lines and sprinkler heads.

PRO TIP: Drip Lines

Are you going to add gardening beds around your deck with perennials, shrubs, etc.? Ask your irrigation specialist to install drip lines for this type of landscaping; it’ll save you hours of manual watering.

Installing a Deck After Irrigation

If you already have an irrigation system installed, there are a few more things to consider. 

Deck footings are dug between 12-42 inches deep or more depending on your region (here in SE Michigan, we dig 42 inches deep). In comparison, irrigation lines will typically be about 3-9 inches deep, regardless of your frost depth (which is why you must have them blown out come Fall/Winter). That means any irrigation lines running under where you’ll build your deck will be susceptible to damage. 

Beyond that, irrigation specialists carefully plan where to put the sprinkler heads, how many to install, how many per zone, and what type should be used (distance coverage, degree coverage, etc.). So when you install a new deck or patio, you want to make sure your grass and landscaping still have enough coverage from the sprinklers.

Are You Replacing an Old Deck?
If you’re replacing your existing deck with a new one of the same footprint, good news, you hit the “easy” button! Nothing extra needs to happen; your new deck should fit in like a puzzle piece.

Are You Building a New Deck or Using a New Design?
Now, if you’re building a new deck or one with a different design than your existing deck, then your irrigation will most likely need rerouting. In this case, you’ll want to rely on your irrigation specialist. You have two options:

  • Proactively have the specialist come out before you build the deck.
  • Reactively have the specialist come out after you build the deck.

Let’s take a closer look at both, and we’ll give you our two cents on the better choice.


Before you start digging your foundation, have your irrigation company come out and reroute any sprinkler heads that would be under your new deck. 

Note: You don’t want to simply “cap” off any unwanted sprinkler heads, particularly the last one in line for that zone. Because when it comes time to get your irrigation lines blown out for the winter, there will be no place for the water to go. If there are any heads under your deck, they’re best capped off at the preceding head in that run of that zone. And it’s best to let your irrigation specialist handle that.

The challenge with the proactive method is your deck builder may not know precisely the position of the deck or for example exactly where the bottom of the stairs will land. Also, if any lines get damaged during the build, the irrigation company may need to send someone back to make the repairs (and many of them charge a trip fee).

However, in some situations, your irrigation specialist may be able to determine where the lines run, especially if you’re dealing with the company that installed the original system. In that case, it may be possible to dig post holes around the lines without causing any damage. 

It’s worth giving them a call to see. But more often than not, your deck builder is limited by code on where they can dig and place the deck’s structural posts. That brings us to the second approach.


We’ve gotten input from many irrigation companies we’ve worked with or spoken to over the years. And the overarching recommendation is that it’s best for them to come out after your deck is complete.

That way, they can accurately reroute sprinkler heads to match your actual deck instead of guessing where they should go. Plus, the specialist can fix any damaged heads or lines at the same time, resulting in only one visit from your irrigation specialist (if any at all).

What Happens if an Irrigation Line is Damaged?

Considering irrigation lines don’t follow a regular pattern from one home to the next, it’s anyone’s guess where they are underground.

The good news is if a line is hit, the repair is usually easy to fix. If we nick or cut a line during our builds, we’ll repair it at no cost. Under the circumstances where the line wraps around the auger during digging and gets pulled out by many feet, you’ll want to work with an irrigation specialist to ensure that it’s fixed properly.

What Else Do I Need to Consider?

On top of dealing with systems like irrigation, your deck builder should also call the state “call before you dig” hotline (here in Michigan, it’s Miss Dig). Utility companies can come out and mark the location of public lines such as:

  • Water
  • Electrical
  • Gas
  • Sewage
  • Communication (such as Comcast and AT&T)

Keep in mind that these companies won’t know where any private utility lines are, so they won’t be able to mark them. Besides irrigation, these can include:

  • Landscape lighting
  • Electrical to detached garage
  • Sump pump lines


We hope you found this post helpful! Remember to consider any irrigation system you have while you’re planning out your new deck. Will your deck cover any sprinkler heads? What other lines might you want to put in? Etc.

Your irrigation company can help you determine where your lines are and the best course of action when it comes to reroute. But 95% of our clients opt for the “reactive” approach, which is our recommendation more often than not. Why pay for an irrigation specialist to come out once or even twice if you may not need to pay for one to come out at all?

What Next?

Are you ready for a new deck but don’t want to take on the project yourself? Let’s chat!

At Custom Deck Creations, we build composite decks for customers across Southeast Michigan. We’ll work with you to design a functional deck you love that also meets your budget. And if you already have an irrigation system, that’s no problem for us! Feel free to check out some of our recent builds or get in touch for a free, over-the-phone quote. 

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