Licensed General Contractor · Licensed New Home Builder in MD · 20+ Years DC, Maryland & Virginia Construction Experience
Understanding building permits in Montgomery County, Maryland is the difference between a project that starts on time and one that's delayed by months. And there are two kinds of people in MoCo: those who have navigated the Department of Permitting Services, and those who still have hope in their eyes.
I'm exaggerating. Slightly. DPS is staffed by competent people doing important work. But the permitting process for new residential construction in MoCo was clearly designed by someone who believes that if a thing is worth doing, it's worth doing through seven different agencies with overlapping jurisdictions and no shared calendar.
Most homeowners never learn how this process works because their builder handles it. Which is fine — until you realize that permitting delays are the #1 cause of construction timeline overruns, and you have zero visibility into why your project hasn't started yet.
This is the permit guide that builders keep as institutional knowledge. I'm writing it down because Iron Gate's entire philosophy is that homeowners deserve to know what's happening with their own project.
Quick answer: Montgomery County generally requires permits for new construction, home additions, structural alterations, and many projects involving electrical, mechanical, plumbing, or changes to exterior openings. Requirements depend on the scope of work. Separate trade permits, WSSC approvals, fire-protection permits, or inspections may also be required. Homeowners should confirm the applicable requirements before construction begins.
The Six Permits (and Reviews) You'll Probably Need
1. Building Permit (DPS)
The big one. Issued by Montgomery County's Department of Permitting Services. Covers structural, mechanical, electrical, and plumbing work. Your architectural plans must be stamped by a licensed architect or engineer. DPS reviews plans for code compliance, and they're thorough. First-pass approval is rare. Plan for at least one round of revisions.
Timeline: 6–16 weeks from submission to approval, depending on complexity and current backlog.
2. Stormwater Management (DPS)
If you're increasing impervious surface (which you almost certainly are on a teardown-to-new-build), you need a stormwater management plan. This involves engineering calculations, site grading plans, and one or more stormwater management facilities — anything from an infiltration trench to a bioretention area.
This permit can run concurrently with the building permit if your civil engineer coordinates early. If not, it becomes a sequential delay that adds weeks.
3. Sediment Control (DPS / MDE)
Required before any land-disturbing activity. This includes demolition, grading, and excavation. You cannot move dirt without an approved sediment control plan. The Maryland Department of the Environment (MDE) may also be involved depending on the size of the disturbance.
This is the permit that gets people fined. Start grading without it and you'll meet the enforcement team faster than you'd like.
4. WSSC (Water & Sewer)
Washington Suburban Sanitary Commission handles water and sewer connections. If you're upsizing the home significantly, you may need to upgrade your water meter, replace the sewer lateral, or install a new connection. WSSC has its own plan review process, its own fee schedule, and its own timeline that exists in a parallel dimension from the rest of the permitting world.
Timeline: 4–12 weeks for plan review and approval. Inspections scheduled on WSSC's terms, not yours.
5. Tree/Forest Conservation (MNCPPC / DPS)
Montgomery County's forest conservation law is among the strictest in the region. If your lot has significant tree canopy, you may need a forest conservation plan, tree-save plans, and posted bonds for trees that will be impacted. The Maryland-National Capital Park and Planning Commission (MNCPPC) reviews certain aspects, while DPS handles others.
The intersection of tree preservation and building envelope is where some of the most expensive surprises in MoCo construction live.
6. HOA / Architectural Review / Municipal Review
If your property is in an HOA, a municipality like the Town of Chevy Chase, or a special district, there may be additional design review requirements. These can range from minor (material and color approval) to significant (full architectural review with design guidelines). These reviews typically need to happen before you submit to DPS, because DPS may require evidence of local approval.
The Critical Path: What to File First
Not all permits are sequential. Here's how to run them efficiently:
Phase 1 (concurrent): Sediment control, stormwater management, WSSC plan review, and HOA/architectural review can all begin simultaneously while your building permit is under DPS review.
Phase 2 (sequential): Building permit must be issued before construction begins. Sediment control must be approved before demolition or grading. WSSC inspections happen during construction at specific milestones.
The families who lose months are the ones who file permits sequentially — waiting for one approval before starting the next application. The families who stay on schedule are the ones whose team files everything in parallel on Day 1.
This is, frankly, one of the highest-value things a construction consultant does. Permit sequencing isn't glamorous, but getting it wrong costs more time than almost any construction delay.
Common Rejection Reasons (And How to Avoid Them)
Incomplete submissions: DPS will bounce your application if anything is missing. Architectural stamp, structural calculations, energy compliance documentation, site plan — every piece must be there on first submission or you go to the back of the line.
Zoning non-compliance: Your design exceeds FAR, violates setbacks, or triggers a use restriction. These are the errors that should have been caught when you evaluate the lot's buildability — before design even started. Make sure you understand setback requirements before submitting for permits , and review building coverage and setback calculations to avoid costly redesigns.
This applies to accessory structures too. If you're considering a detached ADU or backyard cottage in Montgomery County , the permitting requirements are similar — and the zoning constraints around setbacks, lot coverage, and size limits are even more restrictive.
Stormwater conflicts: Your stormwater management plan doesn't adequately address runoff for the proposed impervious area. This often requires civil engineering revisions, which take time.
Tree conflicts: Your proposed building footprint, grading plan, or construction access impacts protected trees in ways that weren't addressed in your forest conservation plan.
The theme: nearly every rejection is preventable with proper upfront analysis. The lot feasibility work we do at Iron Gate isn't just about understanding costs — it's about identifying permitting landmines before you step on them. For homeowners who want to navigate this process directly while keeping builder-level oversight on the permit set, our owner-builder consulting program walks you through every county filing in sequence.
Which Projects Generally Require a Permit
In Montgomery County, permits are generally required for new construction, additions, structural alterations, decks, garages and accessory structures, finished basements, and most electrical, mechanical, and plumbing work. Changes to exterior openings — enlarging a window or door, or cutting a new one — typically require a permit as well. Cosmetic work such as painting, flooring, or replacing cabinets generally does not. Because the answer depends on scope, confirm with Montgomery County DPS before work begins.
Home Addition Permits
A residential addition permit is required before any construction that increases the area, height, or footprint of an existing one- or two-family home or its accessory structure. Additions also trigger zoning review, so your design has to respect setback requirements and the lot coverage limits covered in our guide on how big of a house you can build on your lot . Depending on the project, separate electrical, mechanical, right-of-way, well, septic, fire-protection, or utility approvals may also apply.
Replacement Windows: When a Permit Is Required
A building permit is generally not required when windows are replaced in kind — same opening size, same net clear opening dimensions. A permit or additional approval may be required when the opening is enlarged or reduced, structural framing is altered, emergency-egress dimensions are affected, or the home sits inside a historic district. When in doubt, confirm with DPS before ordering units.
Basic Application Requirements
The general path is consistent across most residential permits: select the correct permit type, submit the online application, pay the applicable fees, upload drawings through the County's electronic plan-review (ePlans) system, complete zoning and code reviews, respond to correction comments, and receive the issued permit before construction begins. Reviews from other agencies — WSSC, MNCPPC, a municipality, or fire protection — may run in parallel.
Required Plans and Documents
What you submit depends on the project. A typical residential application may include a zoning or site plan, architectural floor plans, elevations, sections, construction details, structural drawings, energy-compliance documentation, and supporting agency approvals. Follow the DPS checklist and ePlans requirements for your specific permit type — incomplete packages are the most common reason a submission stalls.
Who May Apply for a Permit
A property owner may apply for many residential permits in their own name, though some permit types carry restrictions. When a contractor will perform the work, DPS recommends listing that contractor as the party responsible for the work, and contractors must hold the appropriate licenses. If you plan to hold the permits and contracts yourself, our owner-builder guide explains what that responsibility actually involves.
What Happens After You Submit
Your application enters review, where zoning and code reviewers examine the drawings and issue correction comments. You revise and resubmit through ePlans until each discipline signs off. Once all reviews are approved and fees are paid, the permit is issued — and only then can construction begin. Expect at least one round of comments; planning for it is far cheaper than being surprised by it.
Required Inspections
Required inspections depend on the permit type and scope of work. The approved permit documents identify which inspections apply to your project. Inspections must be completed in the correct sequence, and the permit and approved plans must remain available at the job site. Final inspections must be completed before the permitted work is considered complete or ready for use.
Frequently Asked Questions
Yes. A residential addition permit is required before construction that increases the area, height, or overall footprint of an existing one- or two-family home or its accessory structure. Depending on the project, separate electrical, mechanical, right-of-way, well, septic, fire-protection, or utility approvals may also be required.
A building permit is generally not required when windows are replaced in kind without changing the opening size or the net clear opening dimensions. A permit or additional approval may be required when the opening is enlarged or reduced, structural framing is changed, emergency-egress dimensions are affected, or the property is located within a historic district. Homeowners should confirm the requirements with Montgomery County DPS before beginning work.
Requirements vary by project. The general process may include selecting the correct permit type, submitting an online application, paying the required fees, uploading drawings and documents through the County's electronic plan-review system, completing applicable zoning and code reviews, responding to correction comments, and receiving the permit before construction begins. Reviews or approvals from other agencies may also be required.
The required documents depend on the project. A residential application may require a zoning or site plan, architectural floor plans, elevations, sections, construction details, structural drawings, energy-compliance information, and other supporting documents. Applicants should follow the Montgomery County DPS checklist and ePlans requirements for their specific permit type.
Required inspections depend on the permit type and scope of work. When a permit is issued, the approved permit documents identify the inspections required for that project. Inspections must be completed in the proper sequence, and the permit and approved plans must remain available at the job site. Final inspections must be completed before the permitted work is considered complete or ready for use.
A property owner may apply for many residential permits in their own name, although some permit types may have restrictions. When a contractor will perform the work, Montgomery County DPS recommends listing the contractor as the party responsible for the work. Contractors must hold the appropriate licenses for the work being performed.
Permit requirements vary by project. Properties located within municipalities, historic districts, or homeowners associations may also be subject to additional requirements. Homeowners should confirm current requirements with Montgomery County DPS and any other applicable authority before beginning work.
📋 DOWNLOAD Montgomery County New Construction Permit Checklist & Timeline Template Want the exact permit checklist and timeline template we use for new construction projects in MoCo? It covers every agency, every permit, filing sequence, and typical timelines. → Request the free checklist at irongateusa.com/contact
Vipin Motwani
Founder, Iron Gate Development