Table of Contents
- Do You Need a Permit for a Backyard Greenhouse in Colorado?
- What Happens If Your Greenhouse Needs a Permit?
- A Real Example: When the Permit Changed the Plan
- Denver's Greenhouse Rules Are More Complicated Than Most Cities
- How to Find Out if Your Backyard Greenhouse Needs a Permit
- Our Honest Take
- Let's Help You Plan Your Backyard Greenhouse
- FAQs
If you're planning a backyard greenhouse in Colorado, the permit question is usually the first thing to sort out, and the honest answer is: it depends on the greenhouse's size and your specific city or county. Here's what we tell customers, including a real situation where the permit question changed someone's entire order.
Do You Need a Permit for a Backyard Greenhouse in Colorado?
In most Colorado jurisdictions, a backyard greenhouse under 200 square feet typically doesn't need a building permit. That's the number we lead with when a customer asks.
But that threshold isn't universal, and it's shifting in some places. A growing number of cities are tightening their rules, some now cap exempt structures at 120 square feet instead of 200, and a few require a permit for any greenhouse regardless of size. Our honest advice: before you assume your greenhouse qualifies for an exemption, check directly with your city or county. Don't rely on the 200 square foot rule of thumb without confirming it's still what your jurisdiction uses.
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What Happens If Your Greenhouse Needs a Permit?
This is the part that catches people off guard. If your greenhouse does require a building permit, many Colorado jurisdictions also require engineered, stamped drawings certifying that the structure can handle local wind and snow load requirements. Whether that's automatic or decided case by case depends on the county, but it's common enough that you should plan for it as a real possibility, not an edge case.
Getting those stamped drawings isn't free or instant. A structural engineer typically charges somewhere in the $500 to $3,000 range for a design package proving load compliance, with simpler calculations sometimes running closer to $250 to $1,000. Turnaround is usually 1 to 10 days once the engineer has your greenhouse's specs. Exact cost and timeline vary by engineer and by how complex your specific structure is, so treat this as a general planning range rather than a quote.
We have contacts for engineers who do this kind of work, but the permit application and the engineering process itself is on the homeowner to sort out and pay for directly.
A Real Example: When the Permit Changed the Plan
We had a customer order a greenhouse over 200 square feet. After placing the order, they found out they'd need a permit, and that permit required a certified engineer stamp. Rather than go through that process, we canceled the order, and we're now helping them pick out a smaller greenhouse that stays under the threshold and avoids the permit entirely.
That's not always the right call, though. Some customers go through with the permit and the engineering stamp on purpose, because they'd rather have the exact size they want than compromise to avoid paperwork. There's no universally right answer here. It depends on how much the extra square footage matters to you versus how much you want to avoid the cost and time of permitting.
Denver's Greenhouse Rules Are More Complicated Than Most Cities
Denver deserves its own mention because its rules aren't a simple size cutoff. Denver's building permit exemption is written for "tool and storage sheds, playhouses, and similar uses" that are non-conditioned, meaning no heat or air conditioning. A greenhouse isn't explicitly named in that exemption language, which leaves real ambiguity about whether it qualifies, especially since many greenhouses use supplemental heat or venting to protect plants, which likely makes them "conditioned" and removes the exemption regardless of size.
On top of that, Denver has a separate zoning permit requirement that depends on your specific zone district. We cover the full Denver breakdown, along with the rest of the Front Range jurisdictions, in our Colorado Building Permits for Sheds, Greenhouses & Saunas guide. If you're in Denver, that's worth reading before you buy.
How to Find Out if Your Backyard Greenhouse Needs a Permit
Before you order a greenhouse, take these steps:
- Call your city or county building department directly. Don't assume the 200 square foot rule applies where you live. Ask specifically about the current threshold for accessory structures.
- Ask about heating, venting, or electrical. If you plan to add any of these, ask whether that changes the permit requirement, even if the structure is small.
- Ask whether an engineer-stamped drawing would be required if you do need a permit. This affects your budget and timeline, so it's worth knowing upfront, not after you've already ordered.
- Confirm your zone district if you're in Denver. The city's own permit rules depend on it.
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Our Honest Take
If avoiding a permit matters to you, check your city's current size threshold and plan your greenhouse around it rather than guessing. If the size you actually want is more important than avoiding paperwork, going through the permit and engineering process is a completely reasonable choice, plenty of our customers make it. What we'd caution against is ordering a greenhouse first and finding out the permit requirement after the fact. That's exactly what happened with the customer above, and it's a more expensive and frustrating way to find out.
Let's Help You Plan Your Backyard Greenhouse
Whether you're trying to stay under your city's permit-exempt size or you've decided to go through the permitting process for a bigger greenhouse, we can help you think through the right size for your space and point you toward engineering contacts if you need them. Get in touch with South Table Sheds to talk through your project, or check out what a greenhouse installation actually costs while you're budgeting.
FAQs
Do you need a permit for a backyard greenhouse in Colorado?
It depends on your greenhouse's size and your city or county's specific rules. Many Colorado jurisdictions exempt structures under 200 square feet from a building permit, but that threshold varies, some cities use 120 square feet, and a few require a permit for any greenhouse regardless of size. Always confirm with your local building department before you buy.
What size greenhouse can I build without a permit in Colorado?
In many jurisdictions, a greenhouse under 200 square feet doesn't need a building permit, but this is changing in some cities, which have lowered the exempt threshold to 120 square feet or require a permit regardless of size. Check with your specific city or county rather than relying on the 200 square foot figure alone.
Does a backyard greenhouse need an engineer-stamped drawing?
If your greenhouse requires a building permit, many Colorado jurisdictions also require engineered, stamped drawings proving the structure meets local wind and snow load requirements. Whether this is automatic or decided case by case depends on the county.
How much does it cost to get engineer-stamped drawings for a greenhouse?
Costs typically range from $500 to $3,000 for a full design package, with simpler load calculations sometimes running $250 to $1,000. Turnaround is usually 1 to 10 days once the engineer has your greenhouse's specifications. Get a quote from a local structural engineer for an exact number.
Do I need a permit for a greenhouse in Denver specifically?
Denver's rules are more complicated than a simple size cutoff. The city's building permit exemption is written for non-conditioned sheds and similar structures, and it's unclear whether greenhouses qualify, especially if yours has supplemental heat or venting. A separate zoning permit requirement also applies depending on your zone district. Call Denver Community Planning and Development directly to confirm before you build.
Should I downsize my greenhouse to avoid a permit, or go through the permitting process?
There's no universally right answer. If avoiding the cost and time of permitting matters more to you, downsizing under your city's threshold is the simpler path. If having the exact size you want matters more, going through the permit and engineering process is a reasonable choice that many homeowners make.
