Updated September 10, 2026
How much housing does Gaithersburg have?
The Census counts 27,386 housing units in Gaithersburg for a population of about 69,225 — roughly 2.5 people for every housing unit.
That makes Gaithersburg the third largest of the four Maryland cities with a page here; Baltimore counts 293,631.
Who arranges chimney work on a Gaithersburg home?
About 51.3% of occupied Gaithersburg homes are owner-occupied, which leaves about 48.7% rented.
Even at 51.3% owner-occupied, the remaining 48.7% of Gaithersburg homes are rented, where the person who notices a problem and the person who authorizes the repair are not the same. Say which you are when you send a request.
Tenure also decides who keeps the paperwork. A Gaithersburg chimney's earlier reports follow the property, not the occupant, so ask for them whichever side of that 51.3% you are on.
Which cities near Gaithersburg have their own page here?
Frederick, about 23 miles away, Baltimore, about 33 miles away, and Hagerstown, about 44 miles away — measured from Gaithersburg.
Those are great-circle distances between the Census 2023 Gazetteer interior points of each place, so the drive is longer than the figure.
Frederick's median build year is 1990 against Gaithersburg's 1989, a 1-year difference in the housing the two chimneys belong to.
What you can observe safely
- Note whether stains return after rain.
- Photograph the pattern without scraping or applying chemicals.
What to avoid
- Do not climb onto the roof or enter the chimney.
- Do not alter gas components, venting, or safety controls.
- Do not use a test fire to diagnose the problem.
Possible causes to assess
- Moisture movement
- Soluble deposits
- Other surface staining requiring identification
A symptom cannot establish the cause remotely. An assessment of the complete system helps determine the appropriate repair.
Chimney repair in GaithersburgA few common questions
Can this be diagnosed from a photo?
A photo can document a symptom and help prepare a visit. It cannot confirm concealed conditions or establish that a chimney or fuel-burning appliance is safe.