• An owner, contractor or subcontractor cannot by any term of the prime or sub contract, waive or impair the lien rights of others.

• An owner of a building, land, or improvement upon which a Mechanic’s Lien of a subcontractor may be filed, is not required to pay the principal contractor compensation for work done or material furnished until 90 days following the completion of the building or improvement unless the principal contractor furnishes the owner with receipts and Waiver of Mechanic's Lien signed by all parties who furnished material or performed labor, or a bond, approved by the owner, holding the owner harmless from any loss the owner might sustain in the event liens are filed by subcontractors.
• "Paid if Paid" is enforced if explicit.
• Iowa courts will most likely enforce "pay-when-paid" provisions.  "Pay when Paid" suggests time for payment.
• Pay-when-paid clause in the subcontract or purchase order does create a condition precedent to payment.

Retainage Provisions

Public

• 573.12  PAYMENTS AND RETENTION FROM PAYMENTS ON CONTRACTS.  The contractor may retain from each payment to a subcontractor not more than the lesser of 5% or the amount specified in the contract between the contractor and the subcontractor.