ADU Construction in Big Lake, MN

Adding a Second Dwelling Without Buying a Second Lot

Minnesota has no statewide accessory dwelling unit law, so zoning is decided city by city and parcel by parcel, and Sherburne County has no standalone ADU ordinance of its own. Curtis C Contracting LLC approaches ADU construction in Big Lake, MN, Elk River and Monticello by confirming first with the city or county what your lot allows, then designing to it: detached backyard units, above-garage suites, basement and interior conversions, 42-inch footings, radon systems and code-height ceilings.


Zoning confirmation comes before drawings on every project, so we sit down with the City of Big Lake or Sherburne County, read the district rules covering your parcel, and tell you plainly what is permitted before you pay for a design. We carry Minnesota residential building contractor license BC808587 and BBB A+ accreditation, and put 30 years of hands-on framing and finish work into compact structures. Design questions and free quotes both start on our contact page.

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Accessory Dwelling Units We Build

  • Zoning and Ordinance Review Before Design

    Every parcel gets checked against the zoning district that governs it before anything is drawn: whether a second dwelling is permitted, lot area and setback rules, height limits, parking requirements and any occupancy conditions attached to a written approval.

  • Detached Backyard Units

    Freestanding units sit on footings at 42 inches, with a slab or crawl space, framed walls, roof structure and exterior finish matched to the house. Water, sewer and power run underground from the main dwelling or the street, where the utility permits.

  • Above-Garage and Attached Suites

    Building over a garage or off the back of the house shortens utility runs. Floor framing has to carry a living load the garage was never designed for, so we verify the walls and footings below and add fire separation.

  • Basement and Interior Conversions

    Converting existing space is usually the least disruptive route where zoning permits it, though egress windows, ceiling height and a separate entrance drive the work. Non-habitable basement areas need 6 feet 8 inches; habitable rooms need 7 feet under Minnesota Rules 1309.0305.

  • Utility, Well and Septic Capacity Planning

    Adding a household changes demand on water, sewer, power and, on rural parcels, the well and septic system. Drainfield sizing is based on bedroom count, so an extra bedroom can require a septic upgrade before the county will sign off on the build.

  • Egress, Ceiling Height and Radon Systems

    Sleeping rooms require an egress window sized for escape and rescue, ceilings hold to the 7-foot minimum, and new construction since June 1, 2009 carries a passive radon vent stack. Radon above the EPA action level is common across the county.

Why Choose Us for ADUs

Zoning Answers Before You Pay for Plans

You find out early whether a second dwelling is allowed on your parcel, what size it can be and where it can sit, because we ask the city or county first. If the answer is no, you learn that before design fees.

Straight Answers When a Lot Will Not Work

Not every parcel supports another dwelling. Setbacks, lot coverage, septic capacity or an outright prohibition can end the idea, and we say so rather than selling a design that will never clear review. Sometimes an addition is the workable path instead.

Setbacks and Sight Lines Handled With Neighbors in Mind

Placement decides how the build lands with the people next door: window alignment, where the entrance faces, where cars park and how far the structure sits from the property line. We site the unit to respect both the ordinance and the neighborhood.

Utilities Sized for a Second Household

Panel capacity, water service diameter, sewer or septic load and heating equipment all get calculated for two households instead of one, and separate metering gets decided early. Licensed electricians and plumbers on our projects pull the permits that scope requires.

Compact Layouts That Live Larger Than the Square Footage

Under 1,000 square feet, every inch counts, so storage goes into knee walls and stair landings, doors swing where furniture will not, and sight lines run the long way through the unit. Ceiling height and window placement do the rest.

Rental-Ready Finishes That Survive Turnover

Renting the unit changes the finish list: scrubbable paint, solid-core doors, hard-surface flooring, moisture-resistant bath assemblies and fixtures that a plumber can service without opening a wall. Choices like that cost slightly more once and save repeated repairs later on.

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Ask What the Lot Allows Before You Draw the Plan

Zoning is the gate every ADU has to pass through, and it swings differently on each parcel, which is why the first conversation is worth more than the first drawing. Curtis C Contracting LLC builds accessory units in Big Lake, MN only after the city or Sherburne County has confirmed what your property permits, and we tell you honestly when the answer closes the door. If it opens, you get a unit built to the same footings, ceiling heights, egress and radon standards as a new house. Bring us the address and the idea, and request a free quote through our contact page.

Frequently Asked Questions

  • What is the difference between an ADU and a guest house?

    An ADU is a complete, independent dwelling with its own kitchen, bathroom, sleeping area and entrance, while a guest house typically lacks a full kitchen and cannot be occupied as a separate household. Zoning treats the two categories very differently.

  • Do I need a permit to build an ADU?

    Yes, and zoning approval comes before the building permit, because Minnesota has no statewide ADU law and each city or county sets rules. Curtis C. Contracting confirms what your parcel allows in Big Lake, MN before any plan is drawn.

  • Can I rent out an ADU on my property?

    That depends entirely on local rules, since some cities allow long-term rental, restrict short-term rental, or require the property to be occupied by the person on the deed. Check the ordinance and any rental licensing before counting on income.

  • Is it better to build an ADU or a home addition?

    Additions expand the house you live in and usually cost less per square foot; an ADU creates a separate dwelling that can house family or produce rent. Where zoning blocks a second unit, an addition is often the only route.

  • Can I build an ADU on a lot with a septic system?

    Often, though the septic system has to handle the added load. County environmental services review drainfield capacity against bedroom count, and an undersized or aging system usually needs upgrading or replacing before a second dwelling can be approved on the parcel.

  • Does an ADU need its own utility hookups?

    Not always, since many units share the water, sewer and electrical service with the main house, while others get separate meters for billing. Curtis C. Contracting sizes the panel and water service for both dwellings on ADU projects in Big Lake, MN.

  • How big can an ADU be?

    Size caps come from the local ordinance, and Minnesota cities that allow these units commonly land somewhere between 200 and 1,000 square feet, sometimes expressed as a percentage of the main house. Lot coverage and setbacks can shrink that further.

  • Does an ADU add to my property taxes?

    Almost certainly, because the assessor values improvements, and a second dwelling adds assessed value the way a finished basement or an addition does. The increase depends on the assessment, not on whether the unit is rented out to a tenant.