Basement rental conversion in Washington DC (dig-out)

18 Replies

I'm looking to convert my Brookland DC row house basement to a legal rental unit , I was wondering if anyone has done this, what was the cost?

My ceiling height is 6'2 in the front and 7'5 in the back of the house, so I know I'll need to do a dig-out.   Any input, suggestions or recommendations (Architect, Contractor, etc.) that the BP forum may have for me moving forward with my basement conversion project would be great for me and anyone else with the same question here on the forum. 

Please feel free to inbox me with contacts 



Hello Ricardo,

My name is Sean, I am a contractor in New England. Maybe there something I can help you with?

The dig out is not horrible, but you will need to dig some test pits to see how far you foundation goes. If it doesn't go down far enough, you may need to underpin the foundation which is costly. Also to make it legal, you need to make sure you have sufficient egress, fire separation between upstairs and downstairs and technically you need entirely separate mechanical/plumbing/electrical systems. You may also need sprinklers, but I'm not exactly sure when you do and when you don't anymore.

@Dan Robinson Thanks so much for your reply, I already have  one form of egress (outside door) but I may need another one.  Your right I will need a separate electrical system being that the current one is down there already (needs to be moved). I hope I don't have to underpin and, I don't know about the sprinkler system (never show one in a basement conversion) but I'll find out.

Thanks again

@Sean Babischkin Have you worked in DC before with DCRA? being that your in New England and all.

DC will require you to have 2 egresses, so you will need another door, or larger windows (with no bars).  If it's a row-house, you will need to notify your neighbors and get sign off, and I think you need at least 7 feet to make it a legal rental.  

With the underpinning, make sure you get someone whose done it before and has a lot of insurance.  And make sure they only do dig 2 feet wide at a time, even though 4 feet is allowed. These really old houses don't have cement between the bricks, it's lime and sand mortar, so it's not very secure when you dig under it. I'm sure you've seen some of these news reports with underpinning where they dug too much at one time and the wall collapsed and damaged a party wall damaging two houses. 

If you plan on living there a while, an extra living space would be great, but if you plan on selling it soon, I don't think it's a great investment of your time and money. 

@Peter Sanchez Thanks for the reply

I plan on using it as a house hack (so I'll be living upstairs) and the house is a semi attach home (share one wall).  So with this basement conversion my home will become a 2 unit dwelling (being that I'm walking distance to the Brookland metro and CUA Catholic University of America) it should rent for $1300 - $1500 easy.  

I totally agree with you on the contractor who has done this type of work before in the area and with great insurance. Great information about only digging 2 feet wide and not 4 feet because of the sand and lime mortar too.



I have.. I used to contract in dc while living in Philadelphia..

7 ft may be legal but sounds awful to live in. Im 6 ft but not  renter so moot point.

I agree with @Michael P. if you do it, you should do it right. No one likes low ceilings. I have a guy who can do it. I'll send you his contact.

@Dan Robinson , Yes, my contractor said the same thing. Have to test, dig down and see how far the foundation goes.

Ricardo, what is your budget? I am asking because construction cost right now are pretty high. Just to convert a one car garage to a two car garage my client got quotes as high as $125k.

Also be ready to spend between $10k - $20k to get a permit. That includes the architects, structural and MEP engineers fees as well as the city permit. This would just be for the basement. If you wanted work done on other parts of the house it might be higher.

Since you are going spend a good chunk of change I would go for the 8’-0” ceiling. You can use windows as your second means of egress but there are guidelines to how high the sill may be off the ground.

A few things to pay attention to:
1. waterproofing details.
2. Are these separate units? If yes they need separate electric meters. If no then they need interior access to each other and having a second kitchen may be an issue.
3. A permit will take about 4-7 months to obtain. Depends how fast your team gets the plans together and how many comments DCRA. If you get to the permitting stage I have a really good expeditor that gets plans approved quicker than normal.

PM me if you have more questions.

Good luck.

Originally posted by @Michael P. :

7 ft may be legal but sounds awful to live in. Im 6 ft but not  renter so moot point.

 I'm 6'3'' and live in an English basement in DC with 7 foot ceilings (maybe 6'11'' ceilings where there's one inch carpet) and it's fine.  I do not feel claustrophobic at all.  If you can go deeper than 7 feet then by all means go for it, but if you can only dig it out to the legal 7 foot ceilings then it's still worth it since like you said in your location someone will rent it for $1300. Also if you need another point of egress you could have the people digging out the basement also dig out another entrance for a second door.  That's what I did for a row house in Columbia Heights. The basement only had a rear entrance through a sketchy back alley so I had a front door dug out that went under the front porch. Message me if you want to see some before and after pics.

@Eric Teran Thanks for the post and to answer your question my budget is 95k- 110k and I agree with higher than 7' feet ceilings. I wanted them to be separate units, here is a quote I got so far.

1) Slab options
a. Basement slab lowering to bottom of footing + new slab     $30,000 - $50,000
b. Basement slab lowering with box footing                                $50,000 - $70,000
c. Basement slab lowering with underpinning                             $80,000 - $110,000
d. General interior remodeling work                                              $50,000 - $70,000

2) Add for kitchenette & new bath & laundry                               $80,000 – $115,000
3) Egress window well if necessary                                                 $10,000 - $18,000

which is cleanly out of my price rate (to much money) and, here's another one 

The average cost of converting a typical basement to a legal rental unit will cost $85K - $ 95K and include:

1. Conceptual design and fixed pricing for the construction.

2. Demolition of the existing basement wall, ceiling, electrical wiring and fixtures, water and sewage pipes and fixtures.

3. Installation of a separate electrical service for an apartment.

4. Build a legal rental unit with kitchen, bathroom, new windows and others, according to the design from Sokol Design-Build Group

Dig out the basement and install a new concrete slab, it's a separate addition job and will cost $ 15K - $ 20K.

much better than the first one (and yes both are insured and are experts in the field) I may have to GC this project myself to save some money.  Meaning get a Architect to draw up the plans, have a company that's insured to do the dig out and place the pluming, etc.. and I can put he flooring, kitchen and bath in myself.

Thanks again

@Ricardo James being your own GC will save lots of money. I did that when I built my modular home in Alexandria last year. Saved at least 15%. Be sure that you have lots of time and a good set of drawings so that you can make sure your sub-contractors are doing the work correctly. For the plans you will need an Architect and a Structural Engineer. It looks like you realize how expensive it is to build in DC. PM me if you need any help .

Thanks for you post! I’m about to be in a similar situation but instead of a separate apartment I’m planning on just a rentable living space instead (Petworth). My ceilings are currently at 7 but will consider the dig-out.

I’ll PM you and a few folks who provided comments. Good luck to you!

@Ricardo James Wondering How your dig-out went & what you paid in the end? I’m looking to do a similar project and I’m getting crazy quotes — closer to $200k! Thanks for any thoughts. 

$50k to $200k. We just dug and poured a basement front entrance for $20k in Capitol Hill East (RFK Stadium area). The permit was $3k, but should be $10k and above. This included enclosing the area under the existing porch, a door and egress window. Very basic finishing with cement block parging. We did not drop the basement slab, because that is the cost that could go $30k to $150k, depending if you need underpinning. Our contract said no underpinning for the entrance, but they actually did need it for our existing cement steps.

@Ricardo James Wondering how the dig out of the 2nd egress point went for you? I'm considering a dig out now and would love any recommendations and/or lessons learned. 

Create Lasting Wealth Through Real Estate

Join the millions of people achieving financial freedom through the power of real estate investing

Start here