Md. Code, Tax-Prop. § 8-235

(a) In this section, “normal repairs and maintenance”: (1) means an expenditure to replace original components of a building to maintain the physical character of the building in its current condition; and (2) includes: (i) interior or exterior painting; (ii) landscaping; (iii) fencing; (iv) replacing gutters or downspouts; (v) adding storm windows, storm doors, or weatherstripping; (vi) adding insulation; (vii) electric rewiring; (viii) replacing plumbing and light fixtures; (ix) replacing a furnace with more efficient oil or gas burners; (x) redecorating; (xi) installing new ceilings or wall surfaces; (xii) removing room partitions to change the shape of a room; (xiii) replacing a roof with a roof of a similar type and material; (xiv) replacing an existing driveway and lead walk; (xv) repairing a foundation because of structural defect or age if there is no enlargement of the improvement or building; and (xvi) replacing an existing air conditioner or other built–in appliance. (b) Normal repairs and maintenance may not be separately assessed for inclusion in the assessment of real property used for residential purposes.