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In-Law Suites and Accessory Dwelling Units

The build is the straightforward half. Whether your parcel allows a second dwelling, and on what conditions, is the half that decides the project.

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Sunlit dining addition lined with floor-to-ceiling windows and glass doors onto the patio, furnished with a trestle table and woven chairs

Licensed CLG.127339

Quick answer: An in-law suite or ADU in the Charleston area typically runs $85,000 to $260,000. Zoning, not construction, is usually the binding constraint. Southeastern Renovation is a licensed South Carolina general contractor (CLG.127339) serving Daniel Island, Mount Pleasant, Isle of Palms, Sullivan’s Island, James Island, West Ashley, Summerville and downtown Charleston. Every project is fixed-price in writing and backed by a 1-year workmanship warranty. Call (843) 718-8177 for an estimate.

200+ Renovations

In-Law Suite and ADU Construction

In-Law Suites and Accessory Dwelling Units

Demand for these has climbed steadily — ageing parents, adult children, and in some jurisdictions rental income. What has not kept pace is a straight answer about whether you can build one. The rules differ between the City of Charleston, the Town of Mount Pleasant, unincorporated Charleston County and Daniel Island, and they differ again on whether the unit may have its own kitchen, its own entrance, or be rented at all.

An attached suite sharing the main structure is a different permit, a different cost and often a different zoning outcome from a detached unit in the rear yard. We work out which one your parcel supports before drawing anything, because the most expensive version of this project is the one designed twice.

Serving Charleston, Mount Pleasant, Daniel Island, Isle of Palms, Sullivan’s Island, West Ashley, James Island and Summerville — and the York County and Charlotte SC-metro side from Clover. Part of our Home Additions work.

Your Estimate in 3 Simple Steps

Check the parcel first

Zoning, lot coverage, setbacks, and whether a second kitchen or separate entrance is permitted. Before design, not after.

Fixed price, in writing

Foundation through finish, with the permit path priced in rather than discovered later.

Ten to twenty weeks

Detached units take longer than attached suites. Utilities and inspections drive the schedule.

Recent In-Law Suite and ADU Construction Projects

Mount Pleasant

Attached in-law suite with a private entrance, fourteen weeks

West Ashley

Detached ADU over a garage, full kitchen and bath

James Island

Garage conversion to a one-bedroom suite, nine weeks

Why Charleston Homeowners Choose Us

Zoning answered before design

We establish what your parcel actually allows first. It is the cheapest hour of the whole project.

Attached vs detached, honestly

They are different projects with different costs and different approvals. We will tell you which one fits.

Accessibility built in

If the suite is for a parent, step-free entry and a bathroom that works long-term are cheaper now than retrofitted later.

One licence, one contract

Full structural, electrical, plumbing and HVAC scope under SC licence CLG.127339.

Common Questions

Can I build an ADU or in-law suite on my property in Charleston?

It depends on the jurisdiction and the specific parcel, and the answer genuinely varies street to street. The City of Charleston, the Town of Mount Pleasant, Charleston County and the Daniel Island covenants each treat accessory dwellings differently — particularly on whether a second full kitchen is allowed, whether a separate entrance is permitted, and whether the unit may be rented. This is the first thing we check, before any design work, because it determines whether the project exists.

What does an in-law suite cost in the Charleston area?

Typically $85,000 to $260,000. An attached suite that extends the existing structure and shares utilities sits at the lower end. A detached unit needs its own foundation, its own utility runs and sometimes its own service connections, which puts it near the top. Converting existing space such as a garage or a bonus room is the least expensive route where the zoning allows it.

Is a garage conversion cheaper than building an addition?

Almost always, because the foundation, walls and roof already exist. The costs people do not anticipate are insulating and conditioning a space never built to be lived in, raising the slab or addressing drainage, adding egress windows, and replacing the parking the zoning may still require. It is usually the cheapest path, but not as cheap as the square footage suggests.

Can I rent out an ADU in Charleston?

That is a separate question from whether you may build one, and the answer is often different. Several Lowcountry jurisdictions permit an accessory dwelling for family use while restricting or prohibiting short-term rental, and some restrict long-term rental as well. HOA covenants frequently add another layer on top of the zoning. If rental income is part of your reasoning, confirm it before you build, not after.

Ready to talk about your in-law suite and adu construction?

Fixed price in writing · SC licensed CLG.127339 · Workers’ comp and liability on every jobsite

Get Your Fixed Price ☎ (843) 718-8177

Plan the cost around your scope and location

Separate an existing-space conversion from an addition. Discuss kitchen and bathroom facilities, access, utilities, structural work and address-specific approval requirements before comparing budgets.

Browse cost guides by project and location

Published ranges are planning references for the scope and location named in each guide. Confirm your address, selections, allowances and exclusions in a written estimate. Fixed-price and cost-plus contracts are both available depending on scope.