Facts. In 2005, the trust applied to the board for a variance “[t]o demolish existing structures and to subdivide [the subject property] into twenty . . . buildable lots for use as sites for single-family residences.” With its application, the trust submitted a plan indicating that an existing structure, referred to in this litigation as the Global Glass Building, was to be demolished. After consideration, the board issued a variance; in its written decision the board stated that the variance included “permission to demolish the existing structures and divide property into twenty lots and construct a single family dwelling on each lot.” The written decision further provided that the “[rjights [authorized by this [d]ecision shall be exercised within one year of the grant.” Within one year of the board’s variance decision, the Fall River planning board indorsed an “approval not required” plan that showed the property divided into twenty lots, and sixteen of the lots were sold to the plaintiff. Thereafter, the plaintiff began construction of housing units on some of those lots, and the trust demolished a portion of the Global Glass Building. The trust retained for itself the four lots shown on the plan that were occupied by the remainder of the Global Glass Building.

In January, 2009, the building inspector issued a notice of violation, ordering the trust to “cease and desist” from violating a Fall River zoning ordinance that concerned execution of the variance. In essence, the building inspector sought to have the remainder of the Global Glass Building demolished in ac*1019cordance with his understanding of what was required by the terms of the variance. The trust appealed the notice of violation to the board pursuant to G. L. c. 40A, §§ 13 and 15, contending that the express terms of the variance did not impose a time deadline for completion of all matters permitted by the variance (including the demolition of the building in its entirety). The board reversed the notice of violation, citing the transfer of sixteen lots and the commencement of construction as a “substantial use of the rights” granted by the variance. See Cornell v. Board of Appeals of Dracut, 453 Mass. 888, 891-892 (2009).

Discussion. Judicial review of a zoning board’s decision pursuant to G. L. c. 40A, § 17, “involves a peculiar combination of de novo and deferential analyses.” Wendy’s Old Fashioned Hamburgers of N.Y., Inc. v. Board of Appeals of Billerica, 454 Mass. 374, 381 (2009), quoting Pendergast v. Board of Appeals of Barnstable, 331 Mass. 555, 558 (1954). The judge reviews the facts de novo without giving evidentiary weight to the board’s findings, Roberts v. Southwestern Bell Sys., Inc., 429 Mass. 478, 485 (1999), and reviews with deference the board’s “legal conclusions within the authority of the board.” Wendy’s Old Fashioned Hamburgers of N.Y., Inc. v. Board of Appeals of Billerica, supra. A board’s decision “cannot be disturbed unless it is based on a legally untenable ground,” or is “unreasonable, whimsical, capricious or arbitrary.” Id. at 381-382, quoting Roberts v. Southwestern Bell Sys., Inc., supra at 487. In this case, we agree with the Land Court judge that the board’s decision is none of those things.

The judge found that the board, when it granted the variance to the trust, “necessarily relied” on the trust’s representation that the entire Global Glass Building eventually would be demolished, but the board’s variance decision neither required demolition nor imposed a time deadline for the demolition to occur. The terms of a variance must appear on its face, see Mendoza v. Licensing Bd. of Fall River, 444 Mass. 188, 205 (2005), and nothing in the variance decision supports the imposition of a requirement that the demolition occur within a particular time.3 While the variance decision requires that “rights authorized by the decision” be exercised within one year, demolition was not a “right” authorized by the variance per se. To construe demolition as a “right” subject to lapse after one year would be nonsensical, as demolition was precisely the result sought by the building inspector in his enforcement order.

While G. L. c. 40A, § 10, permits a zoning board to impose conditions (including time conditions) on its grant of a variance, the board in this case did not expressly impose a time condition in the variance it granted to the trust. In the appeal from the building inspector’s notice of violation, the board *1020properly considered whether the city ordinance had been violated, as alleged in the notice of violation, on account of the trust’s failure to comply with the board’s variance decision within some unspecified “reasonable time.” The board’s decision that the variance does not require demolition within a particular time period is both legally tenable and reasonable. The Land Court judge likewise properly declined to impose such a condition by implication.

Judgment affirmed.