Do employers have to provide a place where Muslim employees can pray at work?

You should work closely with the employees to find an appropriate accommodation that meets their religious needs without causing an undue hardship for your company. Whether a reasonable accommodation would impose undue hardship and, therefore, not be required depends on the particulars of the business and the requested accommodation.

Allowing the employees to use a conference room for prayers likely would not impose an undue hardship on your company in many circumstances; when the room is needed for business purposes, your company can deny its use for personal religious purposes.

Similarly, prayer often can be performed during breaks, so that providing sufficient time during work hours for prayer would not result in an undue hardship. If going to another building for prayer takes longer than the allotted break periods, the employees still can be accommodated if the nature of the their work makes flexible scheduling feasible. You can require employees to make up any work time missed for religious observance.

In evaluating undue hardship, you should consider only whether you can accommodate the employees who make a request. If you can, you should do so. Because individual religious practices vary among members of the same religion, you should not deny the requested accommodation based on speculation that the other Muslim employees may seek the same accommodation. If other employees subsequently request the same accommodation and granting it to all of the requesters would cause undue hardship, you can make an appropriate adjustment at that time. For example, if accommodating five employees would not cause an undue hardship but accommodating six would impose such hardship, the sixth request could be denied.