No, in Canada there is no limit to the tax exemption for primary residence.
> the US where mortgate payments are sheltered
Not sure what you mean by this. In the US, the interest on your mortgage is tax deductible up to a certain amount. But the amount of this tax advantage is fixed at your purchase price. You don't get increasing tax savings as the value of your home increases. As for capital gains tax deduction, this is limited to $250k for a single filer, or $500k for married.
> the US where mortgate payments are sheltered
Not sure what you mean by this. In the US, the interest on your mortgage is tax deductible up to a certain amount. But the amount of this tax advantage is fixed at your purchase price. You don't get increasing tax savings as the value of your home increases. As for capital gains tax deduction, this is limited to $250k for a single filer, or $500k for married.