Wis. Stat. § 779.05

(1) Any document signed by a lien claimant or potential claimant and purporting to be a waiver of construction lien rights under this subchapter, is valid and binding as a waiver whether or not consideration was paid therefor and whether the document was signed before or after the labor, services, materials, plans, or specifications were performed, furnished, or procured, or contracted for. Any ambiguity in such document shall be construed against the person signing it. Any waiver document shall be deemed to waive all lien rights of the signer for all labor, services, materials, plans, or specifications performed, furnished, or procured, or to be performed, furnished, or procured, by the claimant at any time for the improvement to which the waiver relates, except to the extent that the document specifically and expressly limits the waiver to apply to a particular portion of such labor, services, materials, plans, or specifications. A lien claimant or potential lien claimant of whom a waiver is requested is entitled to refuse to furnish a waiver unless paid in full for the labor, services, materials, plans, or specifications to which the waiver relates. A waiver furnished is a waiver of lien rights only, and not of any contract rights of the claimant otherwise existing.