Work on Tisbury’s new $7.4 million emergency services building is expected to be delayed at least a month so a botched job of laying the concrete floor can be fixed.

The floor in the apparatus bay was designed to have a slight fall, allowing it to drain. But the concrete workers failed to follow the specifications, so water drains the wrong way and forms pools, a potential danger to emergency services workers.

The Tisbury selectmen convened a special meeting on Wednesday morning with the project’s architect, the project manager, representatives of the fire department and building committee to discuss potential fixes.

The selectmen formally pronounced the job inadequate, and eventually agreed to “option six” proposed by the project managers, which involves employing a new contractor to grind the concrete floor down to something approaching its planned slope, and then apply a nonslip epoxy surface to it.

Selectman and board chairman Jeff Kristal said the town had been aware of the problem since the day the slab was poured in late October by a subcontractor to Seaver Construction, the general contractor for the building.

“They poured the floor and they didn’t pitch it correctly and they were caught a little less than halfway through. So half pitches the way it’s supposed to, and the other part does not. There’s an area where it pitches almost backwards, and another area where it’s flat. The puddles wouldn’t be really huge, but the point is, it wasn’t done to specifications,” Mr. Kristal said.

Wednesday’s meeting considered options as radical as ripping up the whole floor and starting over. But that would have disturbed the structural integrity of the building. Another option would have cut the floor down three inches, then poured more concrete over the top. That was rejected because it risked damaging radiant heating in the floor.

The option chosen by the selectmen came from Netco, the project managers, in part because it seemed the least likely to interfere with other work on the building.

Mr. Kristal said the town will not pay for the repairs.

“We’re not paying. We’re looking for a credit and the recovery of any legal fees we’ve incurred. Seaver is the general contractor and they brought in concrete contractors,” he said.

Said the chairman of the emergency services building committee Joe Tierney: “We realized on the day of the pour there was a problem, but could not immediately assess the scope of it because they [the subcontractors] put moisture retention pads on top of it.”

Mr. Tierney said the repairs would involve grinding down parts of the floor by less than an inch.

And there would be the indirect benefit that the town would get a nonskid surface on the floor.

The delay would be about a month, Mr. Tierney estimated. But he had no idea of the cost of the fix, pending further discussions with the architects, project managers and others.

The building is scheduled to be completed in the summer of 2011.