Home additions and dormers in Webster Groves, MO
Webster Groves homes were built with the assumption that the second floor was the top of the house. The pre-war bungalows, four-squares, and Tudors that line Lockwood, Plant, Selma, and the streets around them have unfinished attic space waiting above the second floor. A dormer addition turns that volume into livable space. A third-floor build-out turns it into a primary suite. We’ve done both, repeatedly, including the project that earned a Home Builders Association Remodeling Project of the Year award.
Why Webster Groves homeowners trust Aleto with additions and dormers
Webster Groves housing stock is unusually consistent for an inner-ring suburb. Bungalows from the 1910s and 1920s. Four-squares from the same era. Tudor and Colonial Revivals from the 1930s and 1940s. What runs through all of it is a building era that didn’t finish attic space and didn’t conceive of a primary suite. Most original Webster Groves homes have three bedrooms on the second floor, one full bath at the top of the stairs, and an attic accessed through a pull-down stair or a small door at the end of the hall. The square footage above the second floor is real, often 700 to 1,200 square feet, and almost always underused.
A dormer addition or third-floor build-out is the single most effective way to add usable space to a Webster Groves home without changing the footprint or the front elevation in a way that disrupts the streetscape. The structural work involves reinforcing the existing second-floor system for new live loads. The dormer adds the code-required headroom in the right places. The plumbing routes down through closets to existing waste lines. The new staircase fits within the existing house volume. Done well, the addition reads as if it were always part of the home.
Aleto Construction Group has been completing additions in Webster Groves for decades, including the third-floor primary suite addition that won HBA Remodeling Project of the Year. As a design-build firm rooted in St. Louis since 1955, we know how these homes were framed, where the structure can take new loads, and how to design dormers that look native to a 1920s four-square rather than transplanted onto it.
What an addition or dormer in Webster Groves, MO can include
Every project is scoped to the home and the homeowner. Here are the addition types we complete most often in Webster Groves:
Third-floor primary suite addition
Building a full primary suite (bedroom, walk-in closet, primary bathroom) in the attic and third-floor space, with dormers for headroom and proper egress
Shed dormers
Wide flat-roofed dormers that maximize usable floor area and headroom on one side of the roof, often the back of the home where they’re less visible from the street
Gable and eyebrow dormers
Smaller architectural dormers that add light and a pocket of headroom while preserving the home’s original front elevation and roofline
Rear additions
Single or two-story additions off the back of the home, often opening into the kitchen and family room, with sympathetic exterior detailing to match the original home
Side additions
Lateral additions on lots with the side yard to support them, including expanded kitchens, family rooms, primary suites at the first floor, or attached garages with finished space above
Detached and accessory structures
Detached garages with finished bonus space, in-law suites, home offices, or accessory dwellings on lots that allow them under the City of Webster Groves zoning
Sunroom and screened porch additions
Three- and four-season sunrooms, screened porches, and covered outdoor living spaces that extend the home into the rear yard
Historic-sensitive design
Roof pitch, dormer proportions, window selection, exterior trim, and siding language designed to read as period-correct rather than as additions
What additions and dormers look like in Webster Groves, MO
Webster Groves additions are shaped by the architectural vocabulary of pre-war housing on tight inner-ring suburban lots. Here are the scenarios we see most often.
Building a primary suite in the attic
The most common addition project in Webster Groves is a third-floor build-out that creates a primary suite where one didn’t exist. A typical 1920s Webster Groves four-square has unfinished or under-finished attic space that, with proper structural and headroom work, can support a full primary suite: bedroom, walk-in closet, and a primary bath with a real shower, double vanity, and water closet. The structural work involves engineering the existing second-floor framing to carry new live loads, often with sistered joists and new structural beams in load paths that didn’t exist in the original framing. Plumbing routes down through closets to existing waste lines. A new code-compliant staircase fits within the home’s existing volume, often by reclaiming closet or hallway space on the second floor. The result is a home that finally has the primary suite it should have had to begin with, without changing what makes it a Webster Groves home.
Choosing the right dormer for the home
Dormers come in several flavors and not all of them fit every home. A shed dormer (wide, flat-roofed, often spanning most of one side of the roof) maximizes usable floor area and headroom but reads as more contemporary and is best on the rear of the home where it’s less visible. A gable dormer (smaller, peaked roof) reads as period-correct on a four-square or bungalow and is appropriate for the front elevation. An eyebrow dormer (curved, low-profile) is architecturally specific and works on certain Tudor and Cape Cod homes. Picking the right dormer type for the home, and detailing it correctly (proportions, roof pitch matching, trim, window selection), is the difference between an addition that looks intentional and one that looks added.
Working within the Webster Groves municipal review
Webster Groves has its own building department, zoning code, and permit review process. The City of Webster Groves Planning and Zoning Commission reviews exterior additions for compliance with setback requirements, lot coverage limits, height restrictions, and (in some areas of the city) historic preservation guidelines. Additions that change the home’s exterior in significant ways may also require Architectural Review Board input. We handle the full permit and review process, design additions to meet the city’s requirements from the start, and keep the project moving while approvals work through the city.
Sympathetic detailing for a 100-year-old home
The fastest way to ruin a Webster Groves home is to add an obviously contemporary addition without sympathetic detailing. Roof pitch should match. Window proportions should match (typical 1920s windows are taller than wide; double-hung six-over-one or one-over-one is era-appropriate). Trim profiles should match the home’s existing millwork. Siding language and material should pick up what’s already there. None of this means the addition has to be a literal reproduction. It means the addition has to be of the same family. Done well, a visitor walking past couldn’t tell which part is original and which was added in 2026. That’s the bar.
What our clients are saying…
“I used Aleto for an attic addition, and they were great! They were always so kind and helpful. The planning process takes a bit of time, but it is definitely worth it because it allows for a very detailed budget and makes the project go faster when they are actually in the construction phase. They are always very communicative and on schedule for the most part. I recently had a piece of siding come loose from the addition. I texted Mike and he had it taken care of right away. They stand behind their work, and I will only use Aleto for any future projects.”
Aja Martin
Featured home addition project
Lindenwood Park Upgrade
A home in the Lindenwood Park neighborhood just got an elevated upgrade—literally. This second-story addition features a spacious owner’s retreat with a light-filled bedroom, a walk-in closet, and a beautifully tiled full bathroom.
Custom details include 5×5 ceramic wall tile, a 1″ hex mosaic floor with 2′ square rug insets, and warm wood-look LVP throughout. A custom staircase ties it all together with elegance and craftsmanship.
Frequently asked questions
How much does a third-floor addition cost in Webster Groves?
Third-floor additions in Webster Groves typically run from the high six figures into the seven figures, depending on size, finish level, and the structural and exterior work involved. A typical primary suite addition in attic space (bedroom, walk-in closet, full primary bath, dormer additions for headroom, code-compliant staircase) is usually in the high six-figure range. Smaller dormer additions that don’t involve full primary suite build-outs run lower. We provide a detailed estimate with a clear scope before construction begins.
How long does an addition take in Webster Groves?
Most third-floor additions take 14 to 22 weeks of construction. Rear and side additions run similar timelines depending on size and finish. The schedule includes structural reinforcement, exterior framing and roofing, mechanical and plumbing rough-in, finishing, and the new staircase. Permit and review processes through the City of Webster Groves typically add 4 to 8 weeks before construction can begin.
Will our Webster Groves home support a third-floor addition structurally?
In most cases, yes, with proper engineering. The original second-floor framing in 1910s through 1940s Webster Groves homes was sized for the loads typical at the time, which usually means it needs reinforcement to carry new live loads from a finished third floor. The reinforcement typically involves sistering joists, adding structural beams in load paths, and verifying that the foundation and bearing walls below can carry the cumulative loads. A structural engineer evaluates the home during the design phase before any commitment is made.
Does Webster Groves require historic preservation review?
It depends on where the home is located. Portions of Webster Groves are within designated historic districts where exterior changes require review. Other areas don’t. The City of Webster Groves’ Architectural Review Board may also weigh in on additions that significantly change the home’s exterior, regardless of historic district designation. We confirm the home’s status during design and handle the full review process where it applies.
Can we live in the home during a Webster Groves addition?
In most cases, yes. Third-floor and dormer additions are typically built from the outside (framing, roofing, exterior weatherproofing) before the existing ceiling is opened to connect the new space. That means the household lives normally for the first several weeks of construction. The connection phase, when the new staircase is cut in and the new space is integrated, is the most disruptive period and typically lasts 2 to 4 weeks. Rear and side additions are usually less disruptive throughout because they don’t involve opening the existing roof.
More home renovation services in Webster Groves, MO
Looking at a different scope? Explore our other services available in Webster Groves, MO:
Kitchen renovation
We rethink how your kitchen flows, functions, and feels from layout to custom storage and premium appliances.
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Bathroom renovation
Convert dated bathrooms into spa-like retreats with custom tile, modern fixtures, and intelligent layouts.
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Whole-home renovation
Full reimagining of your home from top to bottom, designed and built as one cohesive project.
Learn more →
Ready to add space to your Webster Groves home?
A home addition starts with a conversation about how your home isn’t working today and what it could become. Tell us what you’re thinking, and we’ll take it from there.