Before we spend much time designing a home addition, I want to know whether the property can actually accommodate it.
That means looking at setbacks, zoning, easements, septic, wells, utilities and the physical conditions of the lot.
It isn’t the exciting part of building an addition. But it’s a whole lot better to find a problem now than after you’ve paid someone to design the thing.
First, we need to know what you actually own.
A fence isn’t necessarily a property line.
Neither is the edge of the lawn.
Neither is the row of trees your neighbor planted 20 years ago.
If we’re designing an addition close to a boundary, guessing isn’t good enough.
Existing surveys, subdivision plans and recorded property information can help establish what we’re working with. Depending on the property and how close the project gets to a restriction, an updated survey may make sense.
Then we can start figuring out where you’re actually allowed to build.
A setback is basically a required distance between a structure and a property boundary or other defined line. Your municipality’s zoning ordinance may establish front, rear and side-yard requirements.
So if you have 20 feet between your house and the side property line, that does not automatically mean you have 20 feet available for an addition. Part of that space may need to remain open.
And there isn’t one setback number I can give every homeowner in Central PA. These requirements can change from one municipality or zoning district to another.
That’s why one of the first questions isn’t just “How big do you want the addition?” It’s “How big of an addition can we put here?”
These get lumped together all the time. They shouldn’t.
Zoning deals largely with what and where you’re allowed to build on the property.
Building code deals with how the structure has to be built.
An addition can be perfectly buildable from a structural standpoint and still not work under the property’s zoning requirements.
Pennsylvania has a statewide Uniform Construction Code, or UCC. But more than 90% of Pennsylvania’s municipalities administer and enforce the UCC themselves or through certified third-party agencies. Local land-use and zoning requirements are another part of the picture.
That’s why I’d rather check the actual municipality than give you a generic answer based on what was allowed on another project ten miles away.
For an addition, we’re not only dealing with drawings of the new rooms. Where those rooms sit on the property matters too.
Pennsylvania’s UCC requirements for additions include site-plan information showing things such as the location and size of new construction, property boundaries and distances from lot lines.
That’s important because it forces us to answer some pretty basic questions early:
A good floor plan that doesn’t fit the property isn’t a good floor plan.
Property lines aren’t the only lines that matter. You can also have easements running through a property.
An easement can give another party certain rights to use a portion of your land. Utility easements are a common example. You might technically own the ground while still having restrictions on what can be built over or within that area.
This is another reason I don’t like designing an addition solely from what we can see standing in the backyard. There can be restrictions on paper that aren’t obvious from the lawn.
This is especially important on rural properties around Central PA.
If you’re on public sewer, this part is usually simpler. If you’re on septic, we need to know where everything is. The tank. The absorption area. Any replacement area required for the property. And potentially whether adding bedrooms changes anything about the existing system or approvals.
You don’t want to design your new primary suite directly over something the septic system needs. And you definitely don’t want to discover that after you’ve paid for completed construction drawings.
Same idea. If the property has a private well, its location can affect what makes sense.
We’re not designing on an empty sheet of paper. We’re designing around a functioning property that already has infrastructure. The more of that we identify at the beginning, the fewer surprises we have later.
Where does the electric service enter the house? Where is the meter? Is there an underground service? Where does the sewer leave? Where does the water enter? Where are the HVAC equipment and vents? Where is the propane tank, if there is one?
None of these necessarily kill an addition. But they can affect where it goes and what it costs.
Moving a utility because we designed straight through it is a lot different from knowing it’s there and designing around it. We go further into that in what happens to your HVAC, electrical and plumbing when you add onto a house.
Something can work beautifully on a site plan and still be a pain to build.
Maybe the proposed addition sits on a steep slope. Maybe access for equipment is terrible. Maybe there’s rock. Maybe water naturally runs toward that side of the house. Maybe the addition would eliminate the only reasonable access to the backyard.
Those are construction problems rather than lines on a zoning map, but they matter just as much when we’re deciding where an addition should go.
Sometimes moving the addition a few feet or changing its shape can make the entire project simpler. That’s why I like looking at the property before getting too attached to a design.
This doesn’t necessarily mean the conversation is over. Depending on the specific zoning ordinance and circumstances, there may be a process for requesting zoning relief or a variance.
But I wouldn’t design a project assuming you’ll get one. That’s putting the cart way out in front of the horse.
First, find out what the ordinance allows.
Then determine whether the addition can be designed within those requirements.
If it can’t, then you can look at what other options may exist with the appropriate municipality.
Sometimes the best answer is changing the design.
If you can’t go out, sometimes you can go up.
A second-story addition has an entirely different set of structural and construction considerations, but it doesn’t consume the yard the way a first-floor addition does. That can make it worth exploring on a tight property.
It doesn’t automatically make it cheaper. In fact, going up can require significant work to the existing structure and roof. We’ve got a separate article on building up vs. building out because there are enough tradeoffs there to deserve its own conversation.
Setbacks aren’t always the only zoning limitation. Some properties can also be restricted by how much of the lot may be occupied or covered by buildings and other improvements.
That becomes especially relevant when a property already has a house, garage, shed, driveway, patio or other improvements taking up space.
Again, this is municipality-specific. The takeaway isn’t that every Central PA homeowner has a particular lot-coverage limit. It’s that open space and buildable space aren’t necessarily the same thing.
Here’s the order I’d rather see:
What I don’t like is spending thousands of dollars designing the perfect 700-square-foot addition and then asking the township whether you’re allowed to build it.
That’s backwards. And it’s avoidable.
People sometimes think the construction project begins when an excavator shows up. For us, it starts well before that.
A lot of the expensive mistakes in construction are decisions that should have been made before construction started. Where the addition goes is one of them.
We want to understand the house, property, zoning issues, utilities, site conditions and rough budget before we start pushing a design too far. Then we can spend our time figuring out how to make the addition great instead of figuring out whether it can exist.
If you’re considering an addition in Selinsgrove, Lewisburg, Sunbury, Northumberland, Danville, Shamokin Dam, Milton, Watsontown or the surrounding Susquehanna Valley, don’t feel like you need completed plans before talking to a builder. I’d actually rather have the conversation earlier.
If you’re still deciding whether adding on is the right move at all, read should you build an addition or move. And if the biggest question right now is budget, start with our addition pricing guide.
How close to my property line can I build an addition in Pennsylvania?
There isn’t one statewide setback that applies to every residential addition. Setbacks depend on the local zoning ordinance, zoning district and property, so the specific municipality needs to be checked before designing around a number.
Do I need a permit to build an addition in Pennsylvania?
Yes, residential additions are permit work under Pennsylvania’s Uniform Construction Code. The exact application and review process depends on who administers the UCC where the property is located.
Do I need a survey before building a home addition?
Not every project automatically requires a brand-new boundary survey, but you do need reliable information about the property and proposed construction. If boundaries are uncertain or the addition is close to a setback or other restriction, getting accurate boundary information becomes particularly important.
Can I build an addition over a septic system?
Don’t assume you can. The locations of the septic tank, absorption area and other required areas should be identified during planning, and the applicable local or county requirements need to be checked before designing the addition around them.
Can I get a variance if my addition is inside the setback?
There may be a local process for requesting zoning relief, but approval shouldn’t be assumed. I’d first see whether the addition can be designed to comply with the property’s existing requirements before building the entire project around a hoped-for approval.
Can I build a second story if I don’t have enough room beside my house?
Potentially. Building up can preserve yard space and sometimes solves a tight-lot problem, but the existing foundation, framing and overall structure need to be evaluated to determine what’s practical.
Fifteen minutes on the phone. You’ll have a realistic range before we hang up — and if we’re not the right people for it, I’ll tell you.