Does every Montgomery County township have the same zoning rules for home additions?

No, and this is the most important thing to understand before you start planning. Montgomery County has 62 municipalities, and each one writes and enforces its own zoning ordinance. What is allowed in Collegeville Borough is not necessarily allowed in Lower Providence Township, and what works in Worcester Township may not work in Abington. The three things that vary most from township to township are setback distances from property lines, the maximum percentage of your lot that can be covered by buildings and hard surfaces, and building height limits. There is no county-wide standard for any of these. The first call you or your contractor makes should always be to your specific township's zoning officer, not to the county.

What is a setback and why does it matter for my addition?

A setback is the minimum required distance between any structure and your property line. Every township sets its own setback distances for the front yard, rear yard, and each side yard, and these numbers vary significantly across Montgomery County. For example, in Collegeville Borough, the zoning code sets different minimum setbacks depending on which residential district your property falls in. In Lower Merion Township, setbacks also vary by district, and the township publishes a quick-reference setback chart specifically for homeowners planning additions. Why it matters: the setback lines define your "building envelope," which is the footprint area on your lot where you are actually permitted to build. If your proposed addition would cross a setback line, even by a foot or two, it cannot be permitted as designed. Either the design must change, or you must apply for a variance. Knowing your setbacks before any drawings are produced saves significant time and money.

What happens if my addition doesn't meet setback rules?

You have two paths. The first is to redesign the addition so it fits within the required setbacks. This might mean shifting the footprint, reducing the size, or in some cases going up rather than out with a second-story addition. The second path is to apply for a dimensional variance from your township's Zoning Hearing Board, which is formal permission to build closer to a property line than the ordinance normally allows.A dimensional variance for a setback encroachment is one of the more routine requests that Montgomery County Zoning Hearing Boards handle. Under Pennsylvania's Municipalities Planning Code, the board looks at whether the physical characteristics of your property, such as an irregular lot shape, shallow depth, or existing nonconforming structure, create a genuine hardship that makes strict compliance unreasonable. If the encroachment is minor, the project is well-designed, and neighbors are not negatively impacted, these requests are approved regularly.What you cannot do is simply build and hope nobody notices. Construction that violates setbacks without a variance can result in a stop-work order, a failed final inspection, and in serious cases, a requirement to remove the structure. Getting the zoning review done correctly before construction starts is always the right approach.

What is a zoning variance and how hard is it to get one in Montgomery County?

A variance is formal permission from your township's Zoning Hearing Board to deviate from a specific rule in the zoning ordinance. For home additions, the most common request is a dimensional variance covering setbacks, lot coverage, or height limits. Under the Pennsylvania Municipalities Planning Code (Section 910.2), a board can grant a variance when unique physical conditions of the property, such as an irregular lot shape, shallow lot depth, or unusual topography, create an unnecessary hardship that makes strict compliance unreasonable. Dimensional variances for home additions are granted regularly in Montgomery County townships when the request is reasonable, the hardship is tied to the property itself, and the project will not negatively affect neighboring properties. Applications must typically be filed at least three weeks before the board's scheduled hearing. Most boards in this area meet monthly, and the full process from application to decision generally takes 6 to 10 weeks. Once approved, construction must commence within 18 months or the approval expires.

Do I need a separate zoning permit and a building permit, or are they the same thing?

They are separate approvals, and you typically need both. A zoning permit confirms that what you are proposing is allowed under your township's land use rules, meaning it meets setbacks, coverage limits, height restrictions, and use requirements. A building permit confirms that the construction itself meets the Pennsylvania Uniform Construction Code, including structural, electrical, plumbing, and energy standards. Some townships process both together in a single submission. Others require zoning review first, followed by a separate building permit submission after zoning is cleared. In Lower Merion Township, you can submit preliminary drawings to the Building and Planning Department for a pre-review before committing to full architectural plans. Montgomery Township's Planning and Zoning office requires a building permit for any addition before work begins. Your contractor should know the specific process for your township before any paperwork is submitted.

Do I need a survey before I can apply for permits for my addition?

Not always, but often. Whether a survey is required depends on your township and your specific situation. Lower Merion Township notes that a survey is not always required as long as you can demonstrate through other means, such as a plot plan or deed dimensions, that your addition will comply with setback requirements. However, if your lot line locations are unclear, if you are building close to a setback line, or if a variance is involved, a current survey is almost always necessary. In many older neighborhoods across Montgomery County, homes were built before modern setback standards existed, and the actual position of the structure relative to property lines can only be confirmed with a survey. Getting one early in the process avoids delays at the permit stage and gives your contractor the accurate lot dimensions needed to design within your building envelope.

Zoning Regulations for Montgomery County Home Additions

by Steve MermanMay 28, 2024

Zoning Regulations for Montgomery County, PA Home Additions

You’ve been thinking about it for a while now. Maybe the kids are getting older and sharing a bedroom isn’t cutting it anymore. Maybe your in-laws are moving closer and you need a real space for them, not just a pullout couch. Or maybe you’ve simply outgrown your home but you love your street, your neighbors, your commute, and moving is the last thing you want to do.

A home addition is the answer. But before you start dreaming about floor plans, there’s one thing that shapes everything: what your township actually lets you build.

This is where a lot of homeowners get tripped up. At Merman Construction, we’ve worked through zoning in dozens of townships across Montgomery and Chester County for over 20 years. Here’s what you need to know before you spend a dollar on plans.

Every Township Has Its Own Rules

This surprises a lot of people. Montgomery County doesn’t have one set of rules that covers everyone. Horsham, Lower Merion, Skippack, Worcester, Abington—every township runs its own zoning code. What you can build, how close it can be to your property line, and how tall it can go all depends on exactly where your home sits.

We’ve seen homeowners fall in love with a design only to find out it can’t be built on their lot. That’s a painful and expensive lesson. Getting clarity on zoning before you hire an architect is one of the best things you can do for your project and your wallet.

When Steve starts a project, he walks the property first. He looks at the lot, checks the restrictions, and gives you a real answer about what’s possible before you spend anything on drawings.

Three Zoning Rules That Affect Almost Every Addition

You don’t need to become a zoning expert. But understanding these three concepts will help you have a much smarter conversation with your contractor and your township.

How Much of Your Lot Can Be Covered (FAR)

Townships limit how much of your lot can be taken up by your home and other structures. It’s called Floor Area Ratio, or FAR. Here’s a simple way to think about it: if your lot is 10,000 square feet and your township has a FAR of 0.30, your home and any structures can total no more than 3,000 square feet. If your house is already 2,600 square feet, you’ve got 400 square feet of room to add before you need special approval.

Smaller, older neighborhoods tend to have tighter limits. Larger lots in townships like Worcester or Upper Providence usually have more flexibility. Either way, this number tells you a lot about what’s possible on your property.

How Close You Can Build to Your Property Lines (Setbacks)

Your township sets minimum distances between any structure and your property lines. These are called setbacks, and they cover the front, back, and both sides of your lot. One township might require 25 feet from the rear line. The township next door might require 40 feet. That difference can completely change where an addition can go and whether a ground-floor bump-out or a second-story addition makes more sense for your situation.

Before any design work happens, we need to know exactly where your house sits on your lot. A survey or plot plan takes care of that.

How Tall Your Addition Can Be (Bulk Plane Rules)

This one trips people up most often. Many townships don’t just limit the height of a structure outright. They use what’s called a bulk plane rule, which limits how tall a wall can be at a certain distance from your property line. Think of it as an invisible slanted ceiling over your lot. It matters especially for second-story additions because it directly affects your roofline. A contractor who knows your township will design around this from day one, not discover it after plans are drawn.

How to Make the Zoning Process Easier

Zoning isn’t something you figure out at the permit office. You work it out before anyone puts pencil to paper. Here’s how to do it right.

Call Your Township Before You Do Anything Else

Every township has a zoning officer. Call them, give them your address, and ask what the rules are for adding onto your home. Ask about the FAR limit, the setback distances, and whether there are any special rules for your street or neighborhood. Most zoning officers are happy to help when you ask clear, specific questions.

Know What You Want Before You Call

The more specific you can be, the faster everything moves. When you contact your township or when we pull your permits, the details matter. How big is the addition? What will the space be used for? A bedroom is treated differently than a separate apartment. Having those answers ready saves time on both ends.

Talk to Your Contractor Before You Hire an Architect

This is the move that saves the most money. A contractor who works regularly in your area can tell you what’s actually buildable on your lot before you pay for drawings that might not work. At Merman Construction, we’ve pulled permits across this region for over 20 years. Give us a call before you commit to a design and we’ll give you a straight answer about what your lot will support.

What If the Addition I Want Doesn’t Fit the Rules?

You may still have options. A variance is a formal request to your township asking for permission to go slightly beyond a specific rule. For example, if your addition needs to sit 8 feet from the property line but the setback requires 10, you can apply for a variance. Hearings happen monthly in most townships, so expect the process to take 6 to 10 weeks. They’re approved regularly when the project is reasonable and the neighbors won’t be negatively affected.

In-Law Suites and Separate Apartments Need Extra Approval

If you’re planning to add a space that functions as its own dwelling unit, such as an in-law suite with its own entrance and kitchen, many townships require a conditional use permit on top of everything else. This means a public hearing before the township board. It’s not a dealbreaker, but it adds time. Ask your zoning officer about it early so it doesn’t catch you off guard later.

After Zoning Comes the Building Permit

Zoning approval gets you past the first gate. Then comes the building permit, which is a separate process. It requires architectural or engineered drawings, proof that your addition meets zoning rules, and documentation that your contractor is properly licensed and insured in Pennsylvania.

At Merman Construction, we take care of all of it. You won’t be handed a stack of paperwork and left to figure out which township office to visit. Take a look at our portfolio of completed home additions to see what’s possible, or check our FAQ page if you have more questions about how the process works.

One Thing Most Homeowners Don’t Expect: Stormwater Rules

When you add onto your home, you’re also adding more roof and more hard surface. Rain that used to soak into the ground now runs off instead. Montgomery County townships have rules about where that water goes, and depending on the size of your addition, you may need to show how you’ll manage it as part of your permit.

The good news is the solutions are practical and most of them blend right into your yard. Here are the three most common options we work with.

Rain Gardens

A rain garden is a shallow dip in the yard, usually planted with native plants, that catches runoff from your roof and lets it soak slowly into the ground. They look great when done well and they’re one of the more affordable options. They work best when you have some open yard space near the addition and your soil drains reasonably well.

French Drains

A French drain is a trench filled with gravel and a pipe that moves water away from your foundation and out to a lower point in the yard or toward a street drain. If your yard already tends to collect water near the house, a French drain often fixes that problem and satisfies the stormwater requirement at the same time. It’s a practical, no-nonsense solution that works on a wide range of lots.

Dry Wells

A dry well is buried underground and connected to your downspouts. Roof runoff flows in and slowly seeps out into the surrounding soil. You don’t see it, you don’t maintain it much, and it keeps water out of your yard and your neighbor’s yard. This is a great option for smaller lots where a rain garden isn’t practical. Most Montgomery County townships accept dry wells without any pushback.

We know this feels like a lot. Zoning rules, setbacks, FAR limits, stormwater plans—it’s enough to make anyone want to forget the whole thing and just buy a bigger house instead. But here’s the truth: most of our clients come to us overwhelmed and leave that first conversation relieved. Not because the rules disappeared, but because they finally had someone who knew how to navigate them standing in their corner. That’s exactly what we do, on every single project. And we’d love to do it for you too.

Ready to Find Out What’s Possible on Your Lot?

Most homeowners who call us expecting a complicated situation walk away from that first conversation with a clear plan and a lot less stress. Zoning feels like a wall until someone who knows the territory helps you find the door.

Whether you’re thinking about a new bedroom, a garage conversion, a sunroom, an in-law suite, or a full second story, the smartest first move is a conversation with someone who has done this work in your township before.

Schedule a consultation with Merman Construction and Steve will walk your property, look at your lot under your township’s rules, and tell you honestly what’s buildable. No pressure, no sales pitch. Just a straight answer so you can move forward with confidence.

Merman Construction Inc. | 10 Medway Circle, Collegeville, PA 19426 | PA License #066259 | 610-489-4132

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Frequently Asked Questions

Do I need both a zoning permit and a building permit?

Yes, almost always. Zoning approval says your addition is allowed under your township’s land use rules. The building permit says the construction itself is safe and up to code. Some townships process them together, others do them in sequence. Either way, we handle both for you.

How long does this whole process take?

If your addition fits within your township’s rules, zoning approval can take just a few weeks. If you need a variance, expect 6 to 10 weeks because hearings are scheduled monthly. We’ll give you a realistic timeline at the start of your project so you’re not guessing.

My lot is small and kind of oddly shaped. Can I still add on?

Often yes. Irregular lots can actually help your case when applying for a variance because they demonstrate a genuine hardship. The first thing we do is get your lot dimensions and structure position on paper so we can see exactly what you’re working with.

Will a home addition raise my property taxes?

It will likely increase your assessed value, which can lead to higher taxes. How much depends on the size of the addition and your township’s tax rate. Most homeowners find that the added comfort, space, and home value far outweigh the tax change, but it’s worth building into your budget from the beginning.