Unlock Hidden Square Footage. Finish Your Basement or Build a Legal ADU.
Your unfinished basement is the most underused asset in your home. We turn raw concrete into legal living space, rental-ready ADUs, and high-performance rooms — waterproofed for Connecticut's climate, permitted through your town, and built by one crew from start to finish.
Why Connecticut Homeowners Trust Lagace
Licensed & Insured
NHC License #0016939. HIC #0615939. Every basement project is fully permitted, inspected, and documented — protecting your insurance and resale value.
Design-Build Process
One team handles design, permits, structural work, and finishes. No subcontractor juggling. No finger-pointing. One point of accountability from demo to final walkthrough.
Local CT Expertise
24+ years building in Andover, Hebron, Coventry, Southington, and surrounding towns. We know your soil, your codes, and your building department by name.
Hundreds of Square Feet. Doing Nothing.
Most Connecticut homes sit on top of 600 to 1,200 square feet of unfinished basement. That is space you are already paying to heat, insure, and maintain — but getting zero return from.
Meanwhile, your family is outgrowing the main floor. You need a home office. Your aging parent needs a private living space. Or you are watching rental income opportunities pass you by because you think an addition is the only option.
It is not. A basement finish or ADU conversion delivers new living space at a fraction of the cost of building up or building out — without touching your yard, your roofline, or your foundation footprint.
How Lagace Finishes Basements in Connecticut
We do not cosmetically cover concrete and call it done. Every Lagace basement project follows a construction sequence engineered for below-grade New England conditions:
Step 1 — Moisture Assessment & Waterproofing. Before any framing, we evaluate exterior grading, inspect foundation walls for active water intrusion, and install interior perimeter drainage with battery-backup sump systems and continuous vapor barriers.
Step 2 — Structural Framing & Egress. We frame walls using moisture-resistant materials, install code-compliant egress windows with foundation cutting and exterior well work, and rough-in all electrical, plumbing, and HVAC.
Step 3 — Insulation & Thermal Envelope. Closed-cell spray foam on rim joists. Continuous rigid insulation on foundation walls. Comfortable temperatures year-round without condensation or mold risk.
Step 4 — Finish Work & Final Inspection. Drywall, 100% waterproof LVP flooring, trim, lighting, and paint. Every project passes municipal inspection and receives a Certificate of Occupancy where required.
Basement Services We Deliver
Comprehensive solutions to expand your living space — fully permitted and built to code.
Legal ADU & In-Law Suites
Full apartment conversions with kitchenettes, legal bedrooms, separate entrances, and complete CT code compliance. The most cost-effective path to rental income or multi-generational living.
Basement Bathrooms
Half-bath or full bath installations. We handle below-slab plumbing, waterproof tile systems, proper ventilation, and all permit requirements for below-grade wet rooms.
Family & Entertainment Rooms
Open-concept spaces with 100% waterproof LVP flooring, recessed lighting, acoustic design, and zoned HVAC for year-round comfort.
Home Offices
Dedicated workspaces with isolated electrical circuits, sound-attenuating wall assemblies, and climate control that keeps the space productive in every season.
2026 Basement Cost Guide for Connecticut
Pricing varies based on scope, waterproofing requirements, and finish level. Here is a transparent framework for 2026:
| Finish Level | Estimated Cost Range | Typical Features Included |
|---|---|---|
| Tier 1: Basic Finish | $32 – $45 / sq ft | Drywall, paint, laminate flooring, standard lighting, basic trim |
| Tier 2: Mid-Range Space | $50 – $80 / sq ft | 100% waterproof LVP flooring, half-bath addition, zoned HVAC, recessed lighting, egress window |
| Tier 3: Luxury / Legal ADU | $85 – $130+ / sq ft | Full kitchenette, legal bedroom with egress, full bathroom, separate entrance, full permit package, C.O. |
*Where the money goes: 30–40% of basement finishing cost is labor for framing, electrical, and plumbing.
Want to compare this against a full structural addition? See our Home Addition Cost Guide for a side-by-side breakdown.
Need More Than a Basement Can Offer?
A finished basement is the most cost-effective way to add living space. But if you need a full second story, a standalone backyard cottage, or a structurally independent in-law apartment, we build those too.
Basement Finishing & ADU FAQs for Connecticut Homeowners
Yes. Basement finishing in Connecticut requires building permits for electrical, plumbing, framing, and any structural modifications. If you are converting to an ADU, you will also need zoning approval. Requirements vary by town — Andover, Hebron, and Coventry each have their own building department and zoning regulations. Lagace Construction handles the entire permit process from application through final inspection.
Public Act 21-29 legalized Accessory Dwelling Units as-of-right in most Connecticut residential zones. A basement ADU conversion is one of the most affordable ways to create a legal rental unit or in-law apartment because the foundation, shell, and roof already exist. Specific setback, parking, and size requirements vary by municipality — we verify compliance before design begins.
Three factors determine readiness: ceiling height (minimum 7 feet in most CT jurisdictions), moisture history, and structural condition. Any history of water infiltration must be resolved with proper drainage and waterproofing systems before finish work begins. We provide a free on-site assessment to evaluate all three.
Costs range from approximately $32 per square foot for basic finishing to $130+ per square foot for a full legal ADU with kitchenette, bathroom, and separate entrance. The biggest cost variables are waterproofing scope, plumbing complexity, and whether egress window installation is required. We provide detailed line-item estimates — no vague allowances.
Luxury Vinyl Plank is 100% waterproof. Unlike laminate or engineered hardwood, LVP handles the humidity fluctuations and occasional moisture events that are normal in below-grade New England environments. It is also dimensionally stable across temperature swings, which matters in a space that can shift 20+ degrees between seasons.
Significantly. A basement finish typically costs 40–60% less per square foot than a ground-level addition because the foundation, walls, and roof structure already exist. For homeowners who need space but want to avoid the cost and disruption of a structural addition, a basement finish is the fastest path to usable square footage. If you are considering a larger project, our Home Addition Cost Guide provides a full comparison.
Ready to Put Your Basement to Work?
Get a free on-site assessment and a detailed, line-item estimate. We will walk your space, evaluate moisture conditions, and give you an honest picture of what your basement can become — and what it will cost.
Book Your Free AssessmentOr call (860) 933-2700