Construction: housing; frost protection requirements for accessory dwelling units; provide. Amends 1972 PA 230 (MCL 125.1501 - 125.1531) by adding sec. 13h.

2025-2026 Regular Session Introduced by Sharon MacDonell and 1 co-sponsor

ADU conversions must meet frost protection foundations unless a 10-year-old structure plus an engineer’s no-heave certification allows an exception.

bill electronically reproduced 06/16/2026

#construction:housing

Summary of HB 6082 (Session 2025-2026, Michigan)

Purpose and intent

The bill amends the Stille-DeRossett-Hale single state construction code act to address frost protection requirements for converting an existing building or structure into an accessory dwelling unit (ADU).

It aims to ensure that new ADU conversions meet frost protection standards unless specific conditions allow an exception.

Key provisions and changes

Sec. 13h(1): When an owner of an existing building/structure seeks to convert it into an ADU, the converted structure must have a foundation that complies with the frost protection requirements in the construction code.

Sec. 13h(2) Exceptions to the frost protection requirement:

An owner can apply for an exception if the owner accompanies the building permit application with:
(a) An attestation that the building/structure was constructed not less than 10 years before the permit application date.
(b) A statement from a structural engineer indicating there is no evidence of significant frost heaving that would raise concerns about the structural integrity of the building/structure.

Who is affected

Owners of existing buildings or structures in Michigan that want to convert those buildings into accessory dwelling units.

Building permit applicants seeking to convert to an ADU, who may qualify for an exemption if they meet the age and engineer-certification criteria.

Local building authorities and code enforcement officials who administer the frost protection requirements and review the exemption attestations and engineer statements.

Procedural and timeline aspects

The bill establishes a two-part conditional approach:

General rule: ADU conversions must comply with frost protection foundation requirements.
Conditional exemption: If the applicant provides the 10-year construction attestation and an engineer’s assessment ruling out significant frost heaving, the frost protection requirement may not apply.

There is no retroactive applicability stated beyond the eligibility criteria for exemptions, but the text specifies the conditions under which the frost protection requirement can be waived for permit applications.

Notable details

The bill specifies “Sec. 13h” within the construction code act (198 of 1972, PA 230).

The exemption requires both a timing criterion (building constructed at least 10 years prior) and a professional assessment from a structural engineer.

Effective date

The text provided does not state a specific effective date; as introduced, it would become law upon enactment and publication, subject to any future legislative or regulatory actions.

If you’d like, I can provide a comparison with current frost protection requirements or outline potential practical implications for ADU projects in Michigan communities.