For general information regarding Accessory Dwelling Units in Montgomery County Maryland, check out Part I of this post, in the link.
Here in Part II I'm going to try to cover some more technical information to help you get an idea of the actual drawings required to go along with your Accessory Dwelling Unit permit. Of course I'd love it if you wanted to hire me to design and get your ADU permitted, but doing it on your own is ok too. If that's your plan (get it?) you might be interested in my plan review service.
When you're done here head over to Up Craftsmen, a boutique Silver Spring ADU builder I've begun working with.
FREE ZONING ANALYSIS:
Email me your property survey and I'll get back to you with a one-page report outlining the important Zoning features of your property, including what size ADU you might be able to build!
What drawings do I need to build an ADU?
The obvious caveat here is that every site and project is different. I can’t promise exactly what you’ll need. BUT…just for permitting, here’s a mostly complete list of the drawings and information required. This should get you 80% of the way there, and either fill you with confidence or dread.
What’s required to actually build the thing is open to interpretation and personal preference between owner, architect and builder. How this information is conveyed and where in a drawing set is usually up to the architect, so I'm not telling you what information has to go where. I'm just presenting a list of the minimum requirements that have to be in the plans somewhere.
Architectural Site Plan.
This needs to show the property boundaries, the existing house footprint and parking (if required). You need to show the footprint, dimensions and location of the proposed ADU, and the required property setbacks.
Zoning Information.
You need to show allowable lot coverage, current lot coverage and proposed lot coverage. You need to show calculations for the size of the ADU. You need to show the height of the ADU. You’ll need to provide the property address, zone, subdivision, lot, block and tax id.
Drainage Information.
You may need a drainage plan that shows how you intend to keep rainwater on site. This can be done a variety of ways, most commonly with a dry well. You need to show the grade contours of the site, spot elevations at each gutter downspout discharge, spot elevations at the corners of the property, and at the dry well location. You need a technical drawing of the dry well construction and dimensions as well.
Sediment Control.
You may need a sediment control permit. These drawings need to show the area of construction, the limit of disturbance and a path to access the construction area from the public right of way.
Floor Plans.
Architectural Floor Plans for an ADU need to show the size of the building and the rooms. You need to show the location of doors and windows. Note tempered windows where required. Bedrooms should meet minimum code dimensions and have an egress window. Kitchens need to have cooking appliances, a sink, a fridge and cabinet and counter space. You will also need to show compliance with energy efficiency code somewhere.
Sections and Elevations
You need to show a section of the building from foundation to roof ridge that shows the structure, wall and roof assemblies. Show all major structural elements. Show window and door location and materials.
Energy Efficiency.
You need to show compliance with current energy efficiency code. This includes proper insulation levels in the roof, walls and below the slab or crawl space among other things.
Structural Drawings.
You need to show a foundation plan, a floor framing plan (if you have designed a framed floor) and a roof framing plan. You need to show a wind bracing plan as well.
What drawings are NOT required?
All of the above will get you the building permit. Mechanical, electrical and plumbing all require trade permits, and don't need specific architectural drawings in Montgomery County.
Fire sprinklers are required for a new detached Accessory Dwelling Unit, but you don't need to provide a sprinkler plan for the permit.
In terms of construction, mechanical is pretty easy, electrical can be easy-ish and plumbing can be a major challenge.
Does this cover the DHCA permit also?
More or less. See Part I for the different permits needed for an ADU. The DHCA drawings will be an abbreviated version of the site plan and floor plans. DHCA cares about the size, location and living amenities. DPS cares about that stuff too, but also about life safety, hence the more complete drawings required.
How do I get started on my own ADU?
Ask me! Send me an email with your property survey and I'll get back to you with a free analysis of the key zoning aspects of your property. Or book a free project startup consult if you're looking for an architect.
Already have your own plans or building designer? Consider a plan review to help make the permitting process as easy and surprise-less as possible.