Sonoma Multifamily Exterior Siding & Windows Renovation

When an apartment owner or an HOA board in Sonoma starts planning an exterior renovation, the questions are different from a single-family re-side. Who approves the scope? How do you keep residents housed and informed for weeks of work? Does the City's updated fire map change what material the building needs? How do you phase the spending across budget years without ending up with mismatched elevations?

Bay Area Siding Company is a Larkspur-based (Marin) siding and window contractor that works across the North Bay wine country. We take on re-siding, window replacement, and full exterior renovation for apartment buildings, condominium and townhome associations, and small commercial and mixed-use properties. We scope each job building by building and plan it around the people who live there.

Planning a capital project? Request a bid or call (415) 619-5167 to schedule a site consultation.

Start with the fire map, because it may shape the whole scope

Sonoma's fire exposure is real. The 2017 Nuns Fire burned through the surrounding valley and hills. In early 2025, Cal Fire's statewide remapping, reflected in the City of Sonoma's revised Fire Hazard Severity Zone map, expanded the High and Very High fire-hazard areas within and around the city. A property manager who last reviewed a building's exterior several years ago may find the parcel is now designated differently.

That matters for a multifamily project for two reasons:

• Material selection across many units. Where a parcel carries a High or Very High designation, California Building Code Chapter 7A can govern the exterior wall covering, glazing, and certain other assemblies involved in the work. In practice that generally steers projects toward noncombustible or ignition-resistant cladding and multi-pane, tempered glazing at the regulated openings.
• Budget and phasing. A fire-driven requirement applied to one building in a complex affects cost and appearance across the whole community. Boards need to know that before they vote on a spec.

Chapter 7A applies to specific assemblies and openings. It does not automatically apply to "the whole property," and whether it applies depends on the parcel, the scope, and whether the work is classed as a repair or an alteration. We confirm that with the City of Sonoma Building Division during scoping rather than assume it. That gives your board or ownership group an answer it can plan around, not a guess.

Keeping residents housed, informed, and safe while work runs

Most multifamily exterior work in Sonoma happens with the building occupied. The job has to be planned so tenants and owners can keep living their lives. How we typically structure it:

• Phasing by building, stack, or elevation. Instead of opening up an entire complex at once, we work in defined sections, closing one up before moving to the next. This limits how many units are affected at any time and keeps the site manageable.
• Advance notice windows. We give management a schedule early enough to issue notices before crews reach each unit, especially for window replacement, which requires interior access.
• Access, parking, and staging. Scaffolding, material drops, and dumpsters get planned around resident parking, walkways, and any shared amenities. The sequence is agreed with management, not improvised day to day.
• Weather-tight at the end of each day. Open walls don't stay open. Sections are dried in before crews leave, and the valley's hot, dry summers are useful for keeping long exterior phases moving.
• One point of contact. Management gets a single line of communication for schedule changes, resident concerns, and anything found behind the siding.

What opening the walls tells you about the building

A re-side on an older building is also an inspection. Removing the cladding exposes the sheathing and substrate, the water-resistive barrier (WRB), and the flashing at windows, doors, penetrations, and transitions. Those layers decide how the building performs over the next decades, and on older buildings they're frequently where problems hide. Soft sheathing at window corners and along the base of walls, missing or torn building paper, and absent or reversed flashing are the kinds of conditions a tear-off brings to light.

For a board or owner, the practical point is budgeting. We document conditions as walls come open and flag anything outside the base scope before we act on it. That includes sheathing that needs replacement, or rare cases where framing behind it has to be opened. Change decisions then go through your approval process, not ours.

If your building has balconies, decks, or walkways, those components may fall under California's exterior elevated element inspection laws: SB 721 for many apartment buildings and SB 326 for condominium associations. We're a siding and window contractor, not the required inspector. Still, a re-side is a sensible time to coordinate with whoever handles those inspections, since flashing and weather barrier at those connections overlap with our work.

Consistency for HOAs and character near the Plaza

Associations usually care about one thing above almost everything else: every building should look like it belongs to the same community when the project is done, even if the work is spread across more than one budget year. That comes down to locking in a profile, exposure, trim detail, and color system at the start and holding it. Factory-finished products help here. James Hardie's ColorPlus finish carries a 15-year finish warranty when installed to spec, and it keeps color more uniform from phase to phase than field paint.

Near downtown, character is a second consideration. The blocks around the Sonoma Plaza National Historic Landmark district set the tone for the town. If a mixed-use or residential property sits in a historic overlay or has preservation status, approved materials and finishes may need to be part of the conversation with the City before anything is specified. Raise it early and we'll build it into the scope.

Materials that make sense at building scale

We install and compare systems in person, matched to the building's exposure, style, and long-term maintenance plan:

• James Hardie and fiber cement generally. These are noncombustible and low-maintenance, a frequent fit for fire-designated parcels. James Hardie's HZ10 line is made for California conditions and carries a transferable 30-year non-prorated substrate limited warranty when installed to spec. That is useful when a property may change hands.
• LP SmartSide. This engineered wood gives a warm wood look with less upkeep than solid wood. It's lighter and easier to handle, and it needs periodic paint.
• Vinyl and CertainTeed. These lines are for budget-sensitive projects where fire designation doesn't rule them out and no repainting is a priority.

For the broader re-side decision, see our Sonoma siding replacement page and the Sonoma James Hardie page.

Windows in the same mobilization

Replacing windows during a re-side is often the most efficient path for a multifamily building. With the cladding off, openings can be done as new-construction (full-frame) installs so the flashing and WRB tie in correctly. Where siding is staying and frames are sound, retrofit (insert) installs replace units with less disruption to each apartment. Replacement windows are regulated fenestration under Title 24, so energy compliance is part of the permit. Performance targets vary by climate zone and code cycle, and we confirm current numbers at permit time. We install Anlin, Milgard, Andersen, Marvin, Pella, and aluminum windows. Details are on our Sonoma window replacement page.

What drives a multifamily bid

We don't publish pricing because two Sonoma properties rarely scope alike. The main drivers are:

• Building count, wall area, and stories, including scaffolding and lift access
• Material and finish selection, and whether Chapter 7A requirements apply to the parcel
• Sheathing, WRB, and flashing conditions found once walls are open
• Window count and install method (retrofit vs. full-frame)
• Phasing, occupied-building logistics, and schedule constraints
• Historic-overlay or HOA design requirements

A site walk lets us give ownership or the board a scope and bid they can actually compare.

FAQ

Our Sonoma complex was just placed in a higher fire-hazard zone. Do we have to re-side? A designation doesn't by itself require you to re-side. It affects what's required when you do regulated work on certain exterior assemblies. We check your parcel against the City of Sonoma's current map and confirm the specifics with the Building Division before your board commits to a spec.

Can residents stay in their units during the project? In most cases, yes. We phase work by building or elevation, close walls up daily, and coordinate advance notice for any interior access that window work requires.

Can an HOA spread the project over multiple budget years? Yes. The key is fixing the product, profile, and color system up front so later phases match earlier ones. Factory-finished products help keep that consistency.

Who handles permits? We handle permitting through the City of Sonoma Building Division, including Title 24 documentation for replacement windows.

Get a bid for your Sonoma property

Whether you manage one apartment building or a multi-building association, we'll walk the site, identify fire-map and permit considerations, and lay out a phased plan. Request a bid, browse past projects, see our wine country service area, or call (415) 619-5167.