alastairtree

$path = "C:\Sites\Website123"
$user = "domain\user"

$acl = Get-Acl $path

$arguments = $user, "ReadAndExecute", "ContainerInherit, ObjectInherit", "None", "Allow"

$accessRule = New-Object System.Security.AccessControl.FileSystemAccessRule $arguments

$acl.SetAccessRule($accessRule)