Mastery Home Improvement in Santee provides whole-home remodeling, ADU construction, and room-addition services from its Woodrose Avenue base in the 92071 ZIP code. Kitchen and bathroom renovation scopes include demolition, framing, plumbing reconfiguration, and finish work, with HVAC ductwork rerouting on gut-remodel projects often running in parallel with the heating and cooling system changeouts performed by Allegiance Heating & Air Conditioning on Magnolia Avenue. Accessory dwelling unit (ADU) builds follow California's SB 9 and AB 68 streamlined permitting framework, which allows detached units up to 1,200 square feet on single-family lots in Santee's residential zones without additional parking requirements. Garage-to-living-space conversions represent a growing share of the firm's ADU work, requiring new insulated exterior walls, Title 24 energy-compliant windows, and slab-on-grade moisture barriers to meet habitable-room standards under the California Residential Code. Post-demolition carpet and pad removal on gut-remodel projects generates debris that precedes the subfloor preparation phase, a sequencing overlap with the deep-extraction textile cleaning performed by Friendly Hands Carpet Care on Prospect Avenue in adjacent units. The most complex ADU projects involve two-story detached structures on sloped lots requiring engineered pier-and-grade-beam foundations, 200-amp sub-panel installation, and separate sewer lateral connections to the City of Santee main.