Home Additions & dormers in St. Louis
Sometimes the best version of your home isn’t about changing what’s already there. It’s about adding what’s missing. When you love your neighborhood but not your square footage, an addition lets you keep both.
Growing your home without leaving it
The decision to build an addition usually comes down to a simple calculation. The cost of adding space to a home you already love is often less than the cost of selling, buying something bigger, and moving. And you get exactly what you want instead of compromising on someone else’s floor plan.
But additions are the most complex type of residential construction. New space has to tie into existing structure, match the home’s architecture, connect to current systems, and meet local codes. Getting it wrong means an addition that looks bolted on rather than built in.
Our design-build approach is especially valuable here because every decision, from foundation to roofline, needs to be coordinated between design and construction. The architects planning your addition work alongside the builders who will construct it.
Types of additions we build
The right type depends on your home, your lot, your goals, and your budget:
Dormer additions
One of the most efficient ways to add usable space without expanding the footprint. Raises a roof section to create a full-height living space on an upper floor. Especially popular in St. Louis bungalows and 1.5-story homes.
Second-story additions
When your lot doesn’t allow building outward, going up can double your living area. Requires careful engineering to ensure the existing foundation can support the new load. We make it look like it was always two stories.
Room additions
Extend your home’s footprint outward. New primary suites, expanded kitchens, family rooms, or home offices. Foundation, framing, roofing, and exterior finishing that must match the existing home.
Bump-outs
A smaller-scale extension of an existing room by a few feet. Push a kitchen wall out for an island, widen a bathroom for a double vanity, or extend a bedroom for a walk-in closet. Less disruptive and less expensive than full additions.
In-law suites & ADUs
Self-contained living spaces with a bedroom, bathroom, kitchenette, and separate entrance. For aging parents, adult children, or rental income. Zoning varies with each St. Louis County municipality.
What a Home addition project can include
Home Addition projects touch nearly every building trade:
Foundation work
New footings, crawlspace, or slab. Frost depth and St. Louis soil conditions factored in.
Structural framing
Floor joists, wall framing, roof framing, and modifications to tie into the existing structure.
Roofing & exterior
Matching existing roof style, pitch, and materials. Siding, trim, and windows that blend seamlessly.
Plumbing, electrical & HVAC
Extending or adding new systems. New circuits, plumbing runs, ductwork, or mini-split.
Interior finishing
Drywall, flooring, trim, paint, and custom features coordinated with the existing interior style.
Windows & natural light
Strategic window placement, especially in dormers, to transform dark spaces into bright rooms.
Permits & engineering
Required in every municipality. Structural engineering for dormers, second stories, and load changes.
Site work
Grading, drainage, and landscape restoration. Protecting existing landscaping during construction.
Home Additions across St. Louis
The type of addition that makes sense depends heavily on your home’s age, architecture, and location.
South City, Webster Groves & Maplewood
Bungalows and 1.5-story homes are the most common dormer candidates. Sloped ceilings and limited headroom can be opened up dramatically with a shed or gable dormer. Our Webster Groves third-floor project added a full primary suite where only cramped attic bedrooms existed before. Back additions and bump-outs are popular for expanding small kitchens.
Kirkwood, Ladue & Clayton
Mid-century homes needing room additions for primary suites, expanded family rooms, or home offices. Built with smaller bedrooms and limited closets by today’s standards. An addition solves these issues while maintaining architectural character.
Town and Country, Frontenac & Chesterfield
Larger lots with flexibility for significant additions. Full wings, attached guest houses, and major second-story expansions. Projects often involve substantial architectural design to ensure the addition is proportional to the home and surrounding properties.
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
Do I need an architect for a home addition?
For anything beyond a simple bump-out, architectural plans are typically required. As a design-build firm, our team handles this as part of the project, so you don’t need to hire separately.
What permits are required for a home addition in St. Louis County?
All additions require building permits. You may also need electrical, plumbing, and mechanical permits. Zoning approval may be needed for lot coverage, setbacks, or height restrictions. Our team manages all of it.
Can I add a second story to a ranch?
In most cases, yes, but it’s a significant structural undertaking. The existing foundation and first-floor framing need evaluation and often reinforcement. Staircase placement, roof integration, and proportional aesthetics all need careful design. We assess feasibility during the design phase.
Related home renovation services
Planning an addition alongside other renovations? Explore our other services:
Kitchen renovation
We rethink how your kitchen flows, functions, and feels from layout to custom storage and premium appliances.
Learn more →
Bathroom renovation
Convert dated bathrooms into spa-like retreats with custom tile, modern fixtures, and intelligent layouts.
Learn more →
Whole home renovation
Transform your entire living space — updating layouts, finishes, and systems so everything works together.
Learn more →
Ready to add the space you need?
Whether it’s a dormer that unlocks your upper floor, a room addition that gives your family breathing room, or a full second story that transforms your home, every project starts with understanding what you need. Let’s talk about what’s possible.