Repair old windows, add storm windows, or replace them?
Updated · KeystoneProGuide editorial team
Which is better for an old house: repair, storms or replacement?
For sound older windows, the federal preservation guidance favors repair plus storm windows, and keeps replacement for windows too far gone to fix. The National Park Service says historic windows and doors can often be repaired or upgraded to improve energy efficiency and comfort, that a good storm window can then be added, and that replacement is a reasonable step when windows are beyond repair. The decision is made window by window, not for the house as a whole.
How do you decide for each window?
By inspecting it and sorting what it needs. The Park Service recommends photographing each window, then keeping a window schedule: a list of every part of every window, with space for its condition and the repair it needs. That turns a vague "the windows are shot" into a concrete list.
It then sorts the work into three categories:
- Routine maintenance
- Structural stabilization
- Parts replacement
Its rule of thumb is simple. If most of the work falls into the first two categories, the window should be repaired. If a large number of new parts are required, it may be appropriate to invest in a good, matching replacement window. The test is applied to each window, so the answer can differ from one opening to the next.
What does repair involve?
Less than people expect for the first category. The Park Service says some repairs, such as reglazing, are relatively simple and suit a do-it-yourselfer, while more extensive repairs may need a professional. Caulking, weatherstripping and replacing deteriorated glazing compound come first in its list, because energy is lost through air leaking around the sash and frame as well as through the glass.
There is also a long view. The Park Service says windows that have worked for more than 100 years will, with regular maintenance, usually outlast and outperform a replacement, and that new window assemblies cannot be repaired, only replaced again. It publishes a full brief on repairing historic wooden windows, dating from 1981, among its Preservation Briefs.
What can storm windows do?
Improve the window's thermal performance without removing it. The Park Service says adding storm windows can improve the thermal efficiency of any window, historic or new. The Park Service cites a 2002 study in which a storm window over a historic window performed thermally about as well as a new low-E vinyl replacement, and notes that the remaining draftiness around such an assembly is mainly a comfort issue rather than an energy one.
Its practical advice on storms:
- If you already have storms, make sure they are tight-fitting and in good working order.
- Install new ones without damaging the historic frames.
- Line up the storm's meeting rails and divisions with those of the window behind, and paint the storm to match the frame.
- For decorative or multi-light windows, consider interior storms, which hide less of the detail.
The Department of Energy notes that ENERGY STAR now certifies residential storm windows, which must carry NFRC ratings, and that storms with a low-e coating reflect heat back inside in winter. Fixr, a commercial cost site, lists storm windows at $200 to $700 each.
And doors?
Keep sound historic doors, says the Park Service: solid and paneled wood doors have good thermal properties, and with maintenance, paint, caulking and weatherstripping they should be retained. It adds that storm doors are generally not cost effective on houses, because the cost is high against the likely savings, and work best in cold climates on doors with glass.
When is replacement the right call?
When a window needs more new parts than old ones, or is past saving. In that case the Park Service's phrase is a "good, matching replacement". ENERGY STAR notes that wood frames are generally favored in historical neighborhoods and that many wood windows are clad outside in aluminum or vinyl to cut maintenance.
On price, the published surveys give a sense of scale. This Old House's 2026 survey of 1,000 window customers found an average of $544 per wood window installed and $517 across all frame types. Fixr gives $600 to $2,000 per wood window.
Does the lead rule apply either way?
Yes, on a pre-1978 house. The EPA's rule covers window replacement regardless of size, and it also covers paid repair work that disturbs paint, such as carpentry and paint preparation, unless the job disturbs no more than 6 square feet per room inside or 20 square feet outside, or the paint has been certified free of lead. A paid repairer, like a replacement crew, must be certified. If you reglaze your own windows, the EPA's lead-safe practices for do-it-yourselfers apply in spirit even where the rule does not: contain the area, keep others out, mist before scraping and clean up daily.
What if the house is historic?
Check before you choose. In Philadelphia, a property on the historic register needs Historical Commission review to install, repair, replace or cover windows and storm windows, though replacing clear window glass needs none. Suburban municipalities can run their own review under state law. The details are in the guide on historic houses, in the next wave of this series. Businesses that repair and replace windows are on the exterior remodeling directory page, and the savings side is in will replacement windows lower your bills.
Sources
- Weatherization of Historic Buildings: Repair and Upgrade Windows and Doors, National Park Service
- Preservation Briefs, National Park Service
- Purchasing Energy-Efficient Residential Storm Windows, U.S. Department of Energy (Federal Energy Management Program)
- How Much Does Window Replacement Cost? [2026 Data], Fixr
- Window Replacement Cost (2026), This Old House
- What makes it ENERGY STAR? (Residential windows, doors and skylights), ENERGY STAR (U.S. Environmental Protection Agency)
- Renovation, Repair and Painting Program: Contractors, U.S. Environmental Protection Agency
- Get approval for work to a historic property, City of Philadelphia
- Lead-Safe Renovations for DIYers, U.S. Environmental Protection Agency