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8+ years building in West Michigan · Fixed-price contracts (the quote is the price) · 3D design sketch on the first visit · 2-year workmanship warranty · 4.7★ on Google (19 reviews)
Built for Forest Hills the way Forest Hills is actually built: large lots with the footprint room for ground-floor multi-room additions, and boom-era ranches and colonials with the structure to carry a full second story. Primary suite additions, second-story builds, in-law suites, ADUs, bump-outs, sunrooms, and full-wing expansions for Forest Hills Northern, Central, and Eastern — designed for families staying in the district for the long haul, not flipping. One team from permit to final walkthrough.
Book Your Free Discovery Call619 36th St SW, Wyoming, MI 49509 · About 20 minutes from most Forest Hills homes. By appointment only — we come to you for in-home consultations. · Open in Google Maps →
Forest Hills homeowners ask different questions than the rest of the metro. The school district keeps families in place for twenty and thirty years — so an addition isn't a flip, it's a long-term investment in the home you're staying in. The lots are larger, the finish expectations are higher, the permitting depends on which township controls your address, and the projects routinely sit in the six-figure range. Four real things separate a Thornapple addition from the typical Forest Hills-area remodeler.
An estimate is a guess. A fixed-price contract is binding. On a $200K, $400K, or $600K addition, that distinction is the single most important protection you have. The number we put in writing after design is the number you pay — no allowance games, no surprise change orders, no end-of-project reconciliation. The only way it moves is if you choose to change scope. See how the process works.
Our in-home Forest Hills consultation is a working session, not a sales pitch. We measure your lot and existing structure, model the addition in real-time 3D in your living room, and hand back an honest budget range tied to actual scope choices — footprint, finish level, structural complexity — before you commit to anything. You walk away knowing what's buildable on your specific Forest Hills lot and what it would cost.
Forest Hills is unincorporated, so your addition routes through whichever township controls your address — usually Grand Rapids Township, Ada Township, or Cascade Township — each with its own building department, setbacks, and site plan review thresholds. We verify jurisdiction up front, handle the submittal and any site plan review, file with Kent County Health where septic is involved, and coordinate every inspection. You never call a building department.
Every Thornapple client gets a private project portal with the full schedule, photo updates after each day on-site, change-order history, and a single point of contact. On a multi-month Forest Hills addition that's the difference between living through chaos and living through a managed project. We expect to manage it so you don't have to.
Forest Hills has a specific kind of housing stock and a specific kind of homeowner, and a smart addition strategy starts with both. The lots — particularly in Forest Hills Northern and Eastern and on the wooded ridges — are large by West Michigan standards. That footprint flexibility is the single biggest advantage you have: ground-floor primary suites, in-law and ADU wings, garage conversions paired with a new detached garage, and full multi-room additions are all on the table on a Forest Hills lot in ways they simply are not on a tight city lot.
The homes themselves are mostly 1980s and 1990s boom-era builds — colonials, ranches, and one-and-a-half-story houses with genuinely good bones and floor plans that haven't kept up with how families actually live. The original primary bedroom is too small. There's no main-floor primary. There's no real mudroom. The kitchen wants to push out into the yard. Those are exactly the problems an addition solves — and on these well-framed boom-era homes, a full or partial second story is frequently a real option when you want to add the most usable square footage without giving up the backyard.
And the people: families come to Forest Hills for the schools and stay for decades. So the right addition isn't designed for a quick resale — it's designed for the next thirty years in the home you already love. That's the lens we bring to every Forest Hills addition: maximize the lot, respect the bones, and build for the long haul.
A bump-out, a full second story, and a multi-room in-law wing are very different jobs. The Thornapple process — discovery, design, fixed price, build, walkthrough — is the same for all of them. Forest Hills lots are generally large enough that most of these options are genuinely on the table for your home.
Small footprint expansion — extending a kitchen, adding a breakfast nook, expanding a primary bath, or pushing a family room out a few feet. Often the most cost-effective way to fix the one thing that's been driving you crazy without rebuilding the whole house. Forest Hills lots usually give us the setback room for this without a variance.
Full second floor or partial second-story addition to a ranch or one-and-a-half-story home. Adds the most usable square footage without consuming yard space — the right play when you want to keep the backyard intact. Requires structural reinforcement of the existing first floor, careful coordination around an occupied house, and weather windowing on the exterior. Forest Hills's well-built boom-era homes are frequently strong candidates. We design that complexity in from day one.
Ground-floor primary suite — bedroom, walk-in closet, spa bath, often a private sitting area or coffee bar. Built on grade for aging in place or to free up second-floor bedrooms for kids. The single most common addition type we build for Forest Hills homeowners planning to stay in the home for the next 20 to 30 years.
Multi-generational in-law suites and accessory dwelling units — full kitchen, private entrance, accessibility-ready design. Because Forest Hills spans three townships, we coordinate with the right building department on what's permitted on your specific lot before design. Detail on our in-law suite additions and ADU builder pages.
Insulated, full-mechanical sunroom built to be used every month of the year — not a glorified screened porch. Tied into the main HVAC, with the windows and roof system engineered for West Michigan winters. A common request on Forest Hills wooded-lot and ravine properties where the view earns the investment.
Converting an attached garage into living space — office, gym, guest suite, mudroom — usually paired with a new garage build on a different part of the lot. Common on larger Forest Hills lots where the property supports a detached garage and the original attached structure is the easiest place to add real living square footage.
Often paired with a kitchen remodel or garage conversion — adding a real mudroom, pet station, drop-zone, and side entry to a boom-era Forest Hills home that was originally designed without one. Small footprint, outsized impact on day-to-day livability for a busy family.
Major expansion — a new wing with multiple rooms, an in-law suite plus great room, a dedicated home office and guest quarters, or a full primary suite plus mudroom plus mechanical reroute. The "when you want the house to feel like a different house" scope. Custom architecture, full site plan review, highest level of finish — and exactly the kind of project a large Forest Hills lot can absorb.
Forest Hills is an unincorporated community, not an incorporated city — so there's no single "Forest Hills" building department. Your addition routes through whichever township controls your specific address. Forest Hills Northern mostly falls under Grand Rapids Township, with a small slice near Cannonsburg in Cannon Township. Forest Hills Central is primarily Grand Rapids Township or Cascade Township, depending on where the property sits relative to the East Beltline corridor. Forest Hills Eastern often falls inside Ada Township as you move east toward Ada Village — and Ada contracts its building-permit issuance and inspections out to Cascade Township, so even there your plans pass through two desks.
Additions raise issues an interior remodel never does. Anything that changes the building footprint, impacts drainage, or comes close to setback or lot-coverage limits typically triggers site plan review before permits issue — figure roughly 4 to 8 weeks added to the pre-construction timeline. Larger Forest Hills lots on private well or septic — more common on the wooded Ada-Township-side estates and along the Thornapple River corridor — trigger a Change of Use review and require permits from the Kent County Health Department when an addition increases bedroom count beyond the system's rated capacity. PUD-zoned lots carry their own special setback rules.
Thornapple handles every step of that pathway as part of the fixed-price contract — verifying the correct jurisdiction, the township submittal, any site plan review conditions, the Kent County Health filing where it applies, the HOA architectural review packet, and every inspection. You don't step into a township office. Read more on our Grand Rapids remodeling permits page.
Below are honest 2026 ranges for Forest Hills Northern, Central, and Eastern. Pricing depends on scope, square footage, finish level, and structural complexity. Forest Hills numbers index toward the upper end of the West Michigan range because the lots support larger projects and the finish expectations are higher. Final pricing is locked into a fixed-price contract after the design phase. For the broader Grand Rapids-area breakdown, read our full home addition cost in Grand Rapids guide or run a quick range in the cost estimator.
Small footprint expansion — kitchen extension, breakfast nook, primary bath bump, or family-room push. Usually the highest return per dollar spent on a Forest Hills home where the layout almost works but one room is constraining everything.
Insulated year-round sunroom with full mechanical integration. Built for the wooded view, the ravine lot, the morning light — without the seasonal limits of a screened porch.
Ground-floor primary suite — bedroom, walk-in closet, spa bath, often a private sitting area. Built on grade for aging in place or to redistribute family bedrooms. The most common Forest Hills addition for homeowners planning the next 20 to 30 years.
Converting an attached garage into living space, usually paired with a new garage build elsewhere on the lot. Adds finished square footage without disturbing the rest of the floor plan — a natural fit on a larger Forest Hills lot.
Full second floor or partial second-story addition on a ranch or one-and-a-half-story home. Maximum usable square footage, no yard impact, longest timeline. Structural reinforcement and weather windowing are designed in from day one.
Multi-generational in-law suites and accessory dwelling units — full kitchen, private entrance, accessibility-ready. The township that controls your lot dictates what's permitted — we confirm that in the discovery phase.
Major expansion with multiple rooms, in-law suite plus great room, full primary suite plus mudroom, or new wing with dedicated office and guest quarters. Custom architecture, site plan review, highest level of finish.
The Forest Hills per-square-foot range depending on finish level, structural complexity, and addition type. Bump-outs at the lower end. Second-story and ADU at the upper end because of structural and mechanical complexity.
Forest Hills properties on private wells or septic systems carry a meaningful adder when the addition increases bedroom count beyond the system's rated capacity or alters drain field setbacks. We plan for those realities in discovery and price them into the fixed contract — they don't become surprise change orders mid-build.
Five phases, no surprises. Every one is documented in your project portal so you always know where you are.
Want more detail on any phase? Read the full design-build remodeling process — or jump straight to booking a discovery call.
Real Thornapple addition projects from Forest Hills and surrounding West Michigan homes. Descriptive names — no client names, no street addresses. See the design intent, the integration with the existing structure, and the protection process at work.
A multi-room rear addition expanding the kitchen footprint and adding a full great room, with the exterior trim, roofline, and siding matched precisely to the original house so the addition reads as if it had always been there. Scope: structural tie-in, full mechanical extension, kitchen rebuild, great room, exterior integration, and landscape restoration. Built for a family staying in the district long-term.
An insulated four-season sunroom addition built to be used every month of the year, not just summer. Scope: full HVAC tie-in to the main house, engineered window package for West Michigan winters, properly sized header and structural support, finished interior with trim level matching the rest of the home, and exterior siding and roofline carried over so the room reads as original.
A rear footprint addition adding meaningful kitchen and family-room square footage, with exterior trim, siding profile, and roof pitch matched to the original house so the addition disappears into the architecture. Scope: foundation, framing, structural tie-in, kitchen extension, full exterior integration, new windows matching the existing pattern, and landscape restoration along the rear elevation.
“Nate and Austin are great to work with, can pivot throughout the project and address obstacles that sometimes arise. Communication was constant and the result was exactly what we asked for.”
“More than accommodating, professional, personable, and kept me updated every step of the way. Communication and work completed was high quality.”
“Incredible! Reliable, friendly, hardworking, passionate about their work. Highly recommended.”
A meaningful share of Forest Hills home additions are not for the next five years — they're for the next thirty. The Forest Hills Public Schools district brought the family in, and the relationships, the neighbors, the wooded lot, the proximity to family — none of that needs to change. The floor plan does. And the goal isn't to outgrow the home, it's to make it work for the rest of your life.
We design for that future intentionally. Ground-floor primary suites that disappear into the architecture but solve the upstairs-bedroom problem before it becomes a problem. In-law suites with separate entries for an aging parent who needs proximity and privacy. ADU additions for an adult child returning home or a remote-working family member. Wider doorways, comfort-height fixtures, reinforced wall blocking for grab bars where they'll eventually go — designed in, never bolted on later. Slip-resistant surfaces that still read as luxury, and layered lighting that protects against falls without ever feeling clinical.
Done right, you won't see the planning. You'll see a Forest Hills home that simply feels good — at fifty, at seventy, at every stage in between. The aging-in-place framework is detailed on our accessibility remodeling in Grand Rapids page. Multi-generational and in-law suite specifics live on our in-law suite additions page.
Forest Hills sits at the intersection of several established West Michigan communities — and shares its three townships with most of them. From our Wyoming office about 20 minutes from most Forest Hills homes, we cover the full surrounding service area. This page is part of our broader Grand Rapids remodeling practice and our parent home additions service line.
The real questions Forest Hills homeowners ask before committing to a six-figure addition — not the generic ones the other guys recycle.
Forest Hills home additions typically run from $100,000 for a small bump-out up to $650,000+ for a full-wing or large second-story addition. The bands we see most often: bump-out and small footprint additions $100K–$175K; sunroom and four-season rooms $125K–$200K; ground-floor primary suite additions $175K–$325K; garage conversions $125K–$200K; second-story additions $275K–$475K; in-law suites and ADUs $200K–$400K+; full-wing multi-room additions $375K–$650K+. The Forest Hills per-square-foot benchmark lands in the $450–$650 range depending on finish level. Every Thornapple project locks at a fixed-price contract once scope is finalized — the price we quote is the price you pay. Full breakdown in our home addition cost guide.
Forest Hills is an unincorporated community, so the building department that controls your addition depends on your specific address. Most Forest Hills Northern properties fall under Grand Rapids Township, with a small slice near Cannonsburg in Cannon Township. Forest Hills Central is mostly Grand Rapids Township or Cascade Township. Forest Hills Eastern often falls inside Ada Township as you move east toward Ada Village — and Ada contracts its building-permit issuance and inspections out to Cascade Township. Each jurisdiction has its own building department, inspection schedule, setback rules, and site plan review thresholds. We verify the correct jurisdiction for your address, pull every permit, and coordinate every inspection as part of the fixed-price contract. Full breakdown on our Grand Rapids remodeling permits page.
Most Forest Hills home additions run 5 to 10 months from permit issuance to final walkthrough. Bump-outs and sunrooms typically land at 3 to 4 months. Primary suite additions usually run 5 to 6 months. Second-story and full-wing additions run 7 to 10 months depending on scope, structural reinforcement, finish level, and weather windows on exterior trades. Design and permitting add roughly 8 to 14 weeks before construction begins — longer if site plan review is required by Grand Rapids Township, Ada Township, or Cascade Township. Every milestone is mapped in your fixed-price contract and tracked in your project portal before the first piece of demolition.
It comes down to your lot. Forest Hills lots are generally large — especially in Forest Hills Northern and Eastern and on the wooded ridges — so ground-floor primary suite additions are more feasible here than inside the city. You usually have the yard space and the setback room. Ground-floor primary suites are faster, friendlier to aging in place, and let you stay on one level. Second-story additions preserve your yard and add the most usable square footage, which matters on tighter lots or when you want to keep the backyard intact — but they require structural reinforcement of the existing first floor and a longer build timeline. We model both options in 3D during the design phase so you can see the trade-offs — yard impact, light, traffic flow, and cost — before committing to either.
Yes. In-law suite and ADU additions are an increasingly common request in Forest Hills — usually multi-generational families wanting an aging parent close but with privacy, or a separate suite for an adult child, guest quarters, or a live-in caregiver. Because Forest Hills spans Grand Rapids Township, Ada Township, and Cascade Township, the accessory-dwelling-unit rules that apply to your lot depend on which township controls your address — size, setback, separate-entrance, and occupancy standards vary. We confirm what's permitted on your specific lot with the controlling township before we design the addition. Full structural, mechanical, and accessibility detail lives on our ADU builder and in-law suite additions pages.
Often, yes — and that's a key difference between an addition and an interior remodel. Any addition that changes the building footprint, impacts drainage, or comes close to setback or lot-coverage limits can trigger site plan review by the controlling township before permits issue, which adds roughly 4 to 8 weeks to the pre-construction timeline. Separately, many Forest Hills neighborhoods — Boulder Creek, Bailey's Grove, the Thornapple River Drive corridor, and others — have HOA architectural review for exterior changes, which an addition almost always involves. Thornapple handles the township submittal and the HOA architectural review packet as part of the fixed-price contract, so you never coordinate either yourself.
The Forest Hills benchmark lands in the $450 to $650 per square foot range, depending on finish level and structural complexity. Bump-outs at the lower end of that range. Second-story additions toward the upper end because of structural reinforcement, weather exposure during construction, and the need to coordinate around an occupied first floor. ADU and in-law suites with full kitchens, separate entries, and accessibility features can push past $650 per square foot. For comparison, a basic addition in lower-cost West Michigan markets can land in the $300–$400 range — Forest Hills's higher number reflects finish expectations, larger and more complex projects, and the township site plan review pathway. Read our full home addition cost in Grand Rapids guide for the detailed breakdown, or run a quick range in our cost estimator.
For most Forest Hills homeowners, yes. The Forest Hills Public Schools district is the reason most families are here in the first place — and the reason they stay for twenty and thirty years instead of trading up. Between tight Forest Hills inventory, real-estate commissions on a sell-plus-buy, transfer taxes, moving costs, and the premium you'd pay for someone else's compromised floor plan, a well-designed addition almost always pencils out better than a move. You keep the lot, the wooded or river view, the neighbors, the school district, and the address — and you finally get the floor plan you actually want in the home you already love. We run the real numbers honestly during the discovery call so you can make the call with full data, not a guess.
Our full home addition page — scope, process, what's included, and FAQs.
Real Grand Rapids-area addition costs broken down by scope, size, and finish level.
Accessory dwelling unit additions — design, build, zoning coordination across all three Forest Hills townships.
Additions for Ada Township — the same jurisdiction many Forest Hills Eastern addresses share.
Luxury primary baths and aging-in-place builds — a frequent pair with a primary suite addition.
Run a quick range for your specific addition scope before booking the discovery call.
Home additions are one piece of our design-build remodeling in Grand Rapids practice — design, build, and budget under one roof. Addition work often pairs with a broader Grand Rapids remodeling project.
A kitchen that finally works for you — from 3D design to expert installation, protected from start to finish.
Fixed-price bathroom remodels in Grand Rapids — primary baths, guest baths, accessibility, basement bath builds.
When every room needs attention, you need a partner who coordinates every trade, timeline, and detail.
It starts with a free discovery call — a quick conversation to talk through your project, get honest answers, and see if we're the right fit. No commitment. No pressure. Just clarity.
Book Your Free Discovery CallOr call us at (616) 404-3400
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