What Multifamily Window Replacement Costs Per Unit

Ask five contractors what it costs to replace the windows in a 96-unit community and you will get five numbers built five different ways. The spread is rarely about margin. It is about what each bid assumed — how many openings, which installation method, whose crews carry the residents through it, and who repairs the drywall afterwards.

This page is about that build-up. It will not give you a per-unit figure, because a per-unit figure is the thing you should be most suspicious of.

Why per-unit is the wrong starting point

Window count per unit is the single largest driver of cost, and it varies more within a community than most people expect. A studio with three openings and a three-bedroom corner unit with eleven differ by a factor of three or four, and a community with a mixed unit stack will have both. Averaging them produces a number that is wrong for every actual unit and only right for the building as a whole — which is fine for a total, and useless for a phase.

Count openings. Everything else follows from that.

How the number is actually built

1. The opening count and the size mix

Windows are priced by size as well as by count. Pull the unit mix, count openings by unit type, and note anything oversized, arched, or made up of multiple joined units — those cost disproportionately more and tend to sit in the most visible elevations.

2. The installation method

Retrofit and full-frame are materially different prices, because full-frame includes cladding removal, flashing and repair at every opening. On a mixed-condition building the bid should assume a split and price both. If you have not decided this yet, retrofit versus full-frame for apartment buildings covers what determines it.

3. The window itself

Frame material and glass package. For a rough order of magnitude before bids, the installed per-window ranges Heritage Exteriors publishes for Northern California — current as of May 2026, per window, installed — run roughly $400 to $800 for vinyl, $500 to $1,000 for aluminum, $700 to $1,200 for fiberglass and $800 to $1,500 for wood. Those figures come from our Northern California window replacement cost page and are residential. Multifamily moves off them in both directions and you should expect a real bid to differ; use them to size a reserve, not to challenge a quote.

4. Access

Ground-floor units from a ladder and fourth-floor units from a lift are different labour. So is a community with interior corridors versus exterior walkways, and a site where the crew can park next to the building versus one where everything is carried. Access is where two bids on the same building diverge most and explain themselves least.

5. Phasing and resident management

Notification, scheduling, access coordination, re-visits for units nobody was home for. On an occupied property this is a real line item and a real risk — a phase that stalls because thirty units could not be accessed costs money whoever is at fault. It belongs in the bid, priced, with the responsibilities named. Our guide to phasing a window replacement across an occupied building covers how that plan should look.

6. Interior finish restoration

Full-frame work disturbs interior casing, stool and apron, and sometimes drywall. Retrofit disturbs less but is not always clean. Whether the bid includes putting it back — and to what standard — is one of the most common differences between a low bid and a complete one.

7. Compliance

Replacement windows must meet the California energy standards in force when the permit is applied for, and those tightened on 1 January 2026. This is a specification floor rather than a separate cost, but it does mean a bid built on an older specification is not comparable to one built on the current requirement. See Title 24 compliance for multifamily window replacement.

A worked structure, not a worked price

For a first pass at a building total, the arithmetic every bidder does is:

• openings per unit type × number of that unit type = building opening count
• opening count × installed per-window range for the frame material you want = window and labour
• plus full-frame premium × the number of openings expected to need it
• plus access, phasing and resident management
• plus interior finish restoration
• plus permit and disposal

Doing that yourself before bids arrive is the single most useful hour a property manager can spend, because it tells you which bids have quietly left a line out.

What to require so bids are comparable

• Opening count stated, by unit type, so you can check it against your own.
• Both installation methods priced, with the assumed split.
• A unit price for a method change discovered during work.
• Interior finish restoration scope, explicitly in or out.
• Resident notification and access — who does it, and what happens on a no-access unit.
• The window specification, including the performance figures, so you can confirm compliance rather than assume it.
• Disposal and permit, in or out.

The same discipline applied to cladding is in our multifamily siding scope-of-work guide.

Working with Heritage Exteriors

We price multifamily window work from a real opening count, with the assumptions written down, so you can compare it line by line against anyone else. If you want a number you can take to a board, we will walk the property, count the openings, and give you the build-up rather than a total. Call (916) 546-2991 — CSLB #1055919.