Can a builder increase the price after I sign a new home contract in Alberta?

This answer covers the law of Alberta.

Whether a builder can raise the price after you sign depends mainly on what your purchase contract says. If it has a price escalation clause, the builder may be able to adjust the price in the ways that clause describes; if it does not, what happens depends on your situation and the rest of the contract. A lawyer can read the wording and tell you which applies.

Look closely at what triggers any increase, whether there is a cap, and whether you can cancel instead of paying. If you bought a new condominium unit from a developer, you may rescind by written notice within 10 days of the later of receiving the required documents or signing the agreement, and the developer must return all money paid within 15 days of the notice. A developer must also give written notice of material changes to the disclosed information before you take possession. Any waiver of your rights under the Condominium Property Act is void.

Outside those condominium rules, your options usually come from the contract itself, so keep every written notice and get advice before you sign an amendment or pay more.