Preconstruction library items are only available to Preconstruction Bundle subscribers.
In the Library tool in Account Administration, you can set up pre-defined standards for costs and line items that can be used as default data for Preconstruction projects in your account.
Click the Preconstruction card in Library to open the Preconstruction library page.
From this page, you can access the Line Items and Costs tabs where you can set up these library items for use in Estimate and Takeoff.
Configure general settings for base currency and time frame conversation, and assign classifications to Preconstruction library in Preconstruction library Settings. Account Administrators can access these settings by clicking the Settings link on the Preconstruction library page.
To configure general settings for Preconstruction Library:

Classifications must be added to the account Library in Account Administration before they can be assigned to Preconstruction Library. Learn more about managing account classifications in Library.
Account administrators can configure settings to assign library classifications to their account’s Preconstruction Library. Once assigned, classification structures from your account library can be used by Preconstruction Library line items.
Assignment of library classifications to Preconstruction Library is required for library line items to be tagged with classifications.

Click +Assign structure.
In the Select classification structure modal, select up to 5 classification structures from Library to make them available in the Preconstruction Library.
Click Add.
The assigned library classifications will now be available to items in your Preconstruction Library.