A site plan for a building permit is a scaled, top-down drawing of your whole lot. It shows the property lines with their lengths, every building already there, the new work, and the measured distance from that new work to each lot line. Draw it to scale, add a north arrow, label the streets and any easements, and you have what most residential reviewers need to check setbacks and lot coverage before they look at anything else.
For many small projects you can draw it yourself on top of an existing survey or plat. Some cases need a licensed surveyor, though, mainly new homes and work close to a lot line. This guide covers both. You'll see what the model code requires, how four official checklists compare, a step-by-step drawing method, and a fully worked example with the setback and coverage arithmetic laid out so you can follow the same steps for your own lot.
Site plan basics in one minute
- It's a code requirement, not a courtesy. Section R106.2 of the 2024 International Residential Code says the construction documents must come with a site plan showing the size and location of new construction and existing structures, and their distances from lot lines. Local adoptions repeat that wording, for example the Columbia County, Georgia deck permit packet (PDF).
- Demolition counts too. If you're tearing something down, the same section asks the plan to show what comes out and what stays.
- Small interior jobs may be exempt. The building official can waive or modify the site plan requirement for alterations and repairs. Seattle, for instance, accepts a simpler "key location" plan for interior-only work (SDCI Tip 103, PDF).
- Hand-drawn is often fine. Montgomery County, Maryland says it will accept a hand-drawn site plan as long as it is drawn to scale and shows accurate distances from the buildings to the property lines (MC311: Hand Drawn Site Plans).
Site plan, plot plan, survey or plat: what the counter means
Permit pages use these words loosely, and that confuses a lot of first-time applicants. The model code treats "site plan" and "plot plan" as the same thing. A survey or plat is a different document that you can often draw your site plan on.
| Term you may see | What it is | Who usually prepares it | Where it shows up |
|---|---|---|---|
| Site plan / plot plan | Your scaled drawing of the lot with existing and proposed work and the distances to lot lines | You, your designer or your contractor | IRC R106.2 and nearly every residential checklist |
| House location survey / house location plat | A survey drawing that shows where the house sits on the lot | A surveyor, often from when the house was built or sold | Montgomery County, MD accepts it in place of a site plan for Fast Track permits and asks you to sketch a new deck onto it |
| Record plat / subdivision plat | The recorded map of the subdivision with lot lines and dimensions | Recorded when the land was divided | Montgomery County accepts a record plat for some older homes, with all structures and distances drawn on. Denver uses recorded plat dimensions when no survey is provided |
| Improvement survey plat / boundary survey | A new survey that locates lot lines and, for an improvement survey, existing structures | A licensed land surveyor | Denver requires one in specific cases (see the survey section below) |
| Key location plan | A simplified plan that just shows where the work is | You or your designer | Seattle, for interior-only alterations and some minor projects |
Sources: Montgomery County DPS Fast Track, Montgomery County deck guidelines (PDF), Denver Residential Permitting Guide (PDF), Seattle SDCI Tip 103 (PDF).
What to show: four official checklists side by side
The model code sets the minimum. Local checklists add to it, and how much they add depends on the project. The table compares the model code with three published local lists for an ordinary single-family project. "Not listed" means that page doesn't mention the item. It doesn't mean the reviewer won't ask for it.
| Item | IRC R106.2 (model code) | Montgomery County, MD | Denver, CO | Seattle, WA (basic site plan) |
|---|---|---|---|---|
| Drawn to scale | Not stated in R106.2 | Yes, even when hand-drawn | Yes, with a graphic or engineering/architectural scale shown | Yes, final drawing to scale |
| North arrow | Not stated | Not listed on the pages used here | Yes | Yes, pointing to the top of the sheet |
| Property lines and their lengths | Implied by "distances from lot lines" | Lot lines on the plat or survey | Yes, each zone lot line labeled (primary street, side, rear) and dimensioned | Yes |
| Existing structures | Yes, size and location | Yes, all existing buildings | Yes, including decks, patios, sheds, window wells and AC units | Yes, including retaining walls, patios, decks, porches and rockeries |
| Proposed work | Yes, size and location | Yes | Yes (for a garage, include its height) | Yes, clearly shown |
| Distances to lot lines | Yes | Yes, accurate distances | Yes, to the nearest exterior face of each structure | Yes, front, side and rear, plus distances between structures |
| Streets and alleys | Not stated | Address, street and alley location (deck guidelines) | Yes, labeled, with alley width and public or private status | Yes, street names and alleys |
| Driveways and paving | Not stated | Not listed on the pages used here | Yes, new and existing, dimensioned | Yes, driveways, parking and other paved areas |
| Easements | Not stated | Construction can't encroach into County easements | Show and label easements | Enhanced plans only, with the recording number |
| Setback lines | Not stated | Setback distances for sheds | Show and dimension all minimum required setbacks | Setbacks appear on the sample basic plan |
| Coverage calculation | Not stated | Not listed on the pages used here | Building coverage as a percentage of zone lot area | Land use calculations on enhanced plans; the sample basic plan shows lot coverage |
Sources: IRC 2024 Chapter 1, MC311, Montgomery County sheds, Denver Residential Permitting Guide (PDF), Denver Residential Garages, Seattle Tip 103 (PDF).
The pattern is clear. The more complex the project, the longer the list gets. Denver's guide for new homes and additions also asks for spot grades at the lot corners, fences with their height and material, trees in the street setbacks and the reference lots used to set the front setback. Seattle's enhanced plan, which it requires for a new house, adds 2-foot contours on sloping sites, utilities and stormwater systems. A shed or fence needs far less, so always start from your city's checklist for your specific project type.
Do you need a surveyor, or can you draw it yourself?
Most homeowners can draw their own plan for a deck, shed, fence or small addition. That holds as long as they have a reliable record of where the lot lines are. The cases below are the ones where the published rules point to a surveyor. Work through them in order:
- Are you building a new house on vacant land? Denver requires a boundary survey, land survey plat or improvement survey plat. Seattle requires an enhanced site plan for a new house, and its Tip 103 lists a topographic survey by a licensed surveyor as one way to get the base information. Plan on a surveyor.
- Will the new wall be within about 3 feet of a lot line? Denver requires an improvement survey plat for additions whose exterior wall is less than 3 feet from the lot line, and a survey for a new garage within 3 feet of a property line. It does not accept an Improvement Location Certificate in place of a required survey.
- Is the new work close to the minimum setback itself? Under Denver's policy ADMIN 133.3, if the proposed exterior wall is less than 3 feet from the minimum setback, the drawings must show verification dimensions to the foundation, the wall and the roof fascia. If it is less than 1 foot from the setback, a licensed surveyor must check the formwork before the foundation is poured.
- Is the site on a steep slope, in a floodplain or near a wetland or shoreline? Seattle's environmentally critical area site plan must be prepared and stamped by a Washington-licensed surveyor.
- None of the above? Find your existing survey, house location plat or record plat and draw on it. Montgomery County's deck guidelines say you can get a copy of the house location plat from its Zoning Section if one is on file, and a record plat will do for some older homes. Seattle points applicants to the surveyor's map that often comes with the deed, the county assessor's records and the city's microfilm of earlier site plans. Our permit search by address can help you find old permit records that sometimes include a site plan.
One caution applies everywhere. A permit doesn't settle where your property line is. Montgomery County says plainly that disputes over whether a fence crosses into a neighbor's lot are a legal matter between the owners. If you aren't sure where the pins are, a survey costs less than moving a foundation.
How to draw a site plan, step by step
This method works on paper or in any drawing program. It follows the order Seattle recommends in Tip 103: lot lines first, then existing features, then the new work, with dimensions and notes last so they don't collide with the drawing.
- Get the lot's shape and size from a record, not from memory. Copy each lot line length from your survey or plat. Denver asks for surveyed and recorded dimensions when you have a survey, and the recorded plat dimensions when you don't.
- Measure what's on the ground. Measure the house, garage, shed, deck, patio, driveway and anything else permanent. Seattle suggests measuring with two people and a 25- or 50-foot tape, holding the tape level and square to the line you're measuring from. Write everything on a rough sketch first.
- Pick a scale that fits the sheet. Choose one ratio and use it for the whole drawing, then write it on the sheet. Seattle's own sample basic site plan uses 1/8 inch = 1 foot. Montgomery County's deck guidelines call for sheets at least 11 by 17 inches and a minimum scale of 1/4 inch = 1 foot for the deck drawings. Denver wants a graphic or standard scale shown.
- Draw the lot lines in heavy line weight and label each one by its role: front (street), side and rear. On a corner lot, label both street sides.
- Add the north arrow and the streets. Name every street and alley that touches the lot. Show the sidewalk and driveway apron if your city asks for them.
- Draw every existing structure, including the ones you think don't matter: AC units, window wells, patios, retaining walls and sheds. Denver lists all of these. Show roof overhangs as dashed lines. Seattle's sample notes that the overhang is the eave plus the gutter.
- Draw the proposed work and make it stand out. Use hatching or shading and a note such as "PROPOSED ADDITION." Add the height for a garage or accessory building, and the height above grade for a deck.
- Dimension from each lot line to the closest point of each structure. Denver measures to the nearest exterior face. Seattle asks for front, side and rear distances and the gaps between structures.
- Check your strings. The chain of dimensions across the lot should add up to the overall lot dimension. If they don't, something is mismeasured.
- Add easements, the setback lines and a small data box. The data box holds the address, owner, parcel or legal description, lot area, footprint areas and the coverage percentage if your city asks for it.
- Make it legible. Seattle asks for lettering at least 1/8 inch high. If you scan a hand drawing, make it a clean, high-quality scan.
A worked example: rear addition on a 60 by 120 lot
This is a made-up example. The lot, the buildings and especially the zoning numbers below are invented to show the arithmetic. They are not a rule anywhere. Look up the real setbacks and coverage limit for your zoning district before you draw.
The owner wants to add a one-story, 20-by-14-foot room to the back of the house. Here is what the existing survey and a tape measure show:
| Item (example only) | Size | Position on the lot |
|---|---|---|
| Lot | 60 ft wide x 120 ft deep = 7,200 sq ft | Interior lot, street to the south, alley to the north |
| House | 32 ft wide x 40 ft deep = 1,280 sq ft | 25 ft from the front lot line, 12 ft from the west side line |
| Detached garage (existing) | 20 ft x 22 ft = 440 sq ft | Northeast corner, 5 ft from the east side line and 5 ft from the rear line |
| Proposed addition | 20 ft wide x 14 ft deep = 280 sq ft | On the rear wall of the house, flush with its west wall |
| Proposed roof overhang | 18 in (eave plus gutter) | On all sides of the addition |
Now assume, purely for the example, that the zoning page for this district lists a 25-foot rear setback, a 5-foot side setback and a 35% maximum building coverage. Here is the check, line by line:
| Check | Arithmetic | Result vs. example limit |
|---|---|---|
| Depth string | 25 (front yard) + 40 (house) + 14 (addition) + 41 (rear yard) = 120 ft | Matches the lot depth, so the dimensions close |
| Width string at the house | 12 (west yard) + 32 (house) + 16 (east yard) = 60 ft | Matches the lot width |
| Rear setback to the wall | 120 - 25 - 40 - 14 = 41 ft | 41 ft vs. 25 ft required: passes with 16 ft to spare |
| Rear setback to the overhang | 41 - 1.5 = 39.5 ft | Still passes. Show both numbers if your city measures to the fascia |
| West side setback | Addition is flush with the house wall: 12 ft (10.5 ft to the overhang) | Passes the 5 ft example minimum |
| Gap from addition to garage | The garage's south wall sits 120 - 5 - 22 = 93 ft from the front line; 93 - 79 = 14 ft | Note it on the plan. Some codes regulate separation between buildings |
| Building coverage | (1,280 + 440 + 280) / 7,200 = 2,000 / 7,200 = 27.8% | 27.8% vs. 35% example limit: passes |
| Room left under the cap | 7,200 x 0.35 = 2,520; 2,520 - 2,000 = 520 sq ft | Useful to know before adding a shed later |
Two lessons from the example carry over to real projects. First, measure to the overhang as well as the wall. Denver's setback verification policy explicitly measures to the roof fascia, and an 18-inch eave can turn a pass into a fail on a tight lot. Second, use your city's own definition of coverage. Denver divides the area of building footprints by the zone lot area. Some places count other surfaces too, such as patios or driveways. Our concrete and paver patio guide shows how a few published cities draw that line.
If the numbers had failed, say the addition pushed the rear yard under the minimum, the choices are to redesign or to seek relief. Our guide to a zoning variance for a setback explains that path. A dimensioned site plan is the core of that application too.
Details the official checklists single out
These are the items that published checklists name specifically. That's usually a sign reviewers see them left off:
- Roof overhangs and gutters. Seattle wants overhangs drawn and dimensioned, gutters included. Denver dimensions setbacks to the fascia when you're near the line.
- Small fixed items. AC units, window wells, site stairs and fire pits are all on Denver's site plan list.
- Easements. Montgomery County's deck guidelines say no construction can encroach into the ground or air space of a County easement, and a fence inside a drainage or utility easement needs approval from the agency that holds it.
- Deck height. Montgomery County asks for the height from grade to the top of the deck on the site plan itself.
- Driveway details for garages. For a new driveway, Denver asks for its width, its material and its distance to the property line and to neighboring driveways.
- Fences on the line. In Montgomery County, a fence or retaining wall on the property line needs a letter of approval from the neighbor with the application.
If a reviewer still sends the plan back, the fix is usually quick. Our guide to plan review comments shows how to answer each comment and resubmit cleanly.
Before you upload: a final check
- ☐ Address, owner and parcel number or legal description on the sheet
- ☐ Scale written on the sheet, plus a north arrow
- ☐ Every lot line labeled and dimensioned, with the strings adding up
- ☐ All existing structures shown, including the small ones
- ☐ Proposed work hatched or shaded and clearly labeled
- ☐ Distances from the new work to every nearby lot line and building, measured to the wall and, where it matters, to the overhang
- ☐ Easements and required setback lines drawn
- ☐ Coverage math in a data box if your city asks for it
- ☐ Legible text and a clean PDF in the sheet size your portal accepts
For the rest of the application, such as forms, fees and who signs, see how to apply for a building permit. If you aren't sure your project needs a permit at all, try our Do I Need a Permit checker first.
Frequently asked questions
Can I draw my site plan by hand?
Often, yes. Montgomery County accepts hand-drawn site plans that are to scale and show accurate distances, and Seattle accepts high-quality scans of hand drawings. What gets plans rejected is drawing without a scale or guessing at distances, not the pencil.
What scale should a residential site plan use?
Use whatever your city's checklist names. If it names none, pick a standard scale that fits the whole lot on the sheet and write it down. The official examples above range from 1/8 inch = 1 foot (Seattle's sample site plan) to a 1/4 inch = 1 foot minimum for Montgomery County's deck drawings.
Do I need a site plan for a deck or shed?
Usually. Montgomery County requires a site plan showing the shed's location and setback distances even when the shed is small enough to skip structural review, and its deck guidelines ask you to sketch the deck on the house location plat. Our guides to shed permits and deck permits cover the other requirements.
Is a site plan the same as a survey?
No. A survey is a licensed surveyor's record of the lot lines and, for some types, the existing structures. A site plan is your drawing of the project, and you often draw it on a copy of the survey. Some cities accept a house location survey in place of a separate site plan. Denver requires a new survey only in specific cases.
Bottom line
A good site plan answers one question at a glance: does the new work fit on this lot? Start from a real survey or plat, draw to scale with a north arrow, show everything that's there, dimension the new work to every nearby line, and check your strings and coverage math before you upload. For bigger projects, such as a room addition or a detached garage, check early whether your city wants a surveyor's plan. That's the one piece you can't redraw overnight.
Last checked: November 4, 2026.
Official sources
- International Code Council: 2024 International Residential Code, Chapter 1 Scope and Administration (R106.2 Site Plan or Plot Plan)
- Columbia County, GA Development Services: Residential Deck Permit Packet, quoting 2024 IRC R106.2 (PDF)
- Montgomery County, MD MC311: Hand Drawn Site Plans
- Montgomery County Department of Permitting Services: Residential Fast Track Permit Process
- Montgomery County DPS: Residential Sheds Permit Process
- Montgomery County DPS: Residential Fence Permit Process
- Montgomery County DPS: Guidelines for Residential Decks (PDF)
- Denver Community Planning and Development: Permitting Checklist for New Homes and Additions (PDF)
- Denver Community Planning and Development: Residential Garages
- Denver Building Permit Policy ADMIN 133.3: Setback/Separation Verification for One- and Two-Family Dwellings (PDF)
- Seattle Department of Construction and Inspections: Tip 103, Site Plan Guidelines and Requirements (PDF)
PermitCove is an independent guide, not a government agency. Rules and checklists change, so confirm the current requirements with your local building and zoning departments.
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