Knowing which permits and inspections you will need when renovating a bathroom in the Washington DC area can be confusing.  Each state and county has a different process.  This post will focus on the rules and regulations in Montgomery County.


The first question many people ask us, is “Do I even need a permit”?  The answer is yes in almost all cases.  Whether re-configuring a master bath, or performing a simple pull and replace bathroom remodel, the county wants you to have a permit.  They want to make sure that the work is done in a safe and proper manner, and that applicable building codes are followed.


Now that you know you need a permit, how do you go about obtaining one?  First, you will need to put together a set of plans.  These can be relatively simple, but should show the existing layout, proposed layout, and focus on code related items rather than aesthetics.  Make sure you show the proper fixture clearances and insulation details for exterior walls – even if it is not changing.


Once you have completed the plan set for your bathroom, fill out a permit application for interior alterations, and bring it to the Department of Permitting Services at 255 Rockville Pike, 2nd Floor Rockville, MD 20850.  The permit application, fee structure, and additional information can be found at:  In general, you will find the staff there to be helpful, and with any luck, you will walk out in a couple of hours with your building permit for the bathroom.   If you are working with an architect or design-build remodeling company, they should be able to take care of the entire process for a fee.


In addition to the building permit, you will most likely need a plumbing and electrical permit.  These should be acquired by plumbers and electricians who are licensed in Montgomery County.  They will need the building permit number to reference before they go.  The electrical permit should be easy, but plumbing permits can be more complicated.


Unlike Washington DC, plumbing permits in Montgomery County are given out by WSSC – not the county.  They have very strict rules as to the ratio of the incoming water pipe to the number of plumbing fixtures in the house.  Furthermore, they use an arcane system to calculate this ratio which most lay-people will have a hard time understanding.  If they deem the incoming pipe to be insufficient, they can force you to upgrade to a larger one, which can cost ten to twenty thousand dollars.  Although one would think that this would only be relevant if you are adding fixtures to a bathroom, that is not the case.  If the previous homeowner added fixtures without upgrading the incoming pipe, you could end up picking up the tab.


During and after the project, you will need to have your bathroom inspected.  You will most likely need a close-in and final inspection from both WSSC and the county.  Remember to call WSSC first – Montgomery County won’t come out until the plumbing inspection has been completed.  Whereas the permitting system in Montgomery County is efficient, the inspections are not.  You will find some of the inspectors to be picky about irrelevant details.  In addition, having multiple inspectors for one small bathroom can add days (and thus cost) to your bathroom renovation.

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