I don't know how you have linked your tables. I am assuming you have the following relationship:
Properties:: PropID = Certificates:: PropID
In your Properties table, define the following calculation field, cPropIDCert:
For manual finds, place this field on a layout based on your Properties table.
Enter find mode
Enter an = in cPropCert
Perform the find
The resulting group of records will be all property records that do not have related records in Certificates.
Thank you, that certainly answers my query, but taking it a a step further...
The Safety Certs table is actually a Join Table (containing the certificate expiry dates) between the Property Table and Certificate Types table ie Gas, Electric, Fire Safety, etc...
How do I create a new layout that shows the properties that do not have a certain type of certificate?
By the way, I am new to Filemaker, currently running version 10.
Instead of creating a new layout, you can perform a find to show just those properties lacking a given certificate.
Enter find mode on a property layout that also displays the "Certificate type" field in a portal.
Enter the type of certificate in question.
Click the omit button
perform the find
This finds all Property records that don't have related record with the specified certificate type.