How to Plan a Historic-Home Renovation (2026)
Historic homes demand SOI (Secretary of the Interior) Standards-compliant renovation or you lose the federal 20% Investment Tax Credit, the state tax credit, and the local landmark approval. These six steps preserve eligibility and avoid the common character-defining-feature destruction pattern.
Step 1: Determine the historic-designation level: National, State, Local, or HPOZ
National Register of Historic Places = eligible for federal 20% ITC. State-level historic register = eligible for state tax credit (CA offers up to 25% under CHRC). Local landmark = subject to design review but may or may not offer tax benefits. HPOZ (LA) = design review, no tax benefits. Confirm designation level before planning.
Step 2: Map the character-defining features before ANY design work
SOI Standards require retention of character-defining features: original windows, porch railings, roof profile, siding material, door hardware, fireplace mantels, interior plaster, stair handrails. A licensed preservation architect (NCARB + NPS-certified) produces this map. Without it, every design choice is blind.
Step 3: Follow the Secretary of the Interior's Standards for Rehabilitation
SOI Standards (10 rules) govern ITC eligibility. Key rules: retain original features where possible, repair rather than replace, match new materials and profiles to original, make changes reversible. Replacement of original wood windows with vinyl = ITC denial + local landmark denial. Replacement with period-accurate wood windows = both approved.
Step 4: File Part 1 (property certification) and Part 2 (proposed work) with the NPS BEFORE construction
Federal ITC requires two-part approval: Part 1 certifies the property is a certified historic structure (NPS reviews nomination). Part 2 describes the proposed rehabilitation work (NPS reviews SOI compliance). Part 2 approval is prerequisite for ITC. State-level tax credits parallel this process. File both before construction — retroactive approval is rare.
Step 5: Require your GC to provide a preservation-experienced crew with documented case studies
General renovation GCs often lack preservation experience — they'll strip plaster, remove original trim, replace hardware. Ask for three completed historic-home renovations in the last 5 years with photographs. A true preservation GC carries insurance riders specific to historic-structure work and employs craftspeople experienced in plaster, millwork, and metal-window restoration.
Step 6: Submit Part 3 (completion certification) within 6 months of project completion
After construction, file NPS Part 3 demonstrating work matched Part 2 approvals. NPS issues a completion certification which triggers the ITC claim. State credits follow similar Part 3 processes. Missing Part 3 within the statutory window = loss of credit. The preservation architect usually handles filing.
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