Terry W is correct.
Even renting out a 'portion' of your house (even if that is one bedroom of say, a 6 bedroom mansion!), your property becomes an investment property and CGT will be payable upon sale; apportioned to the years of it being rented out.
That said, during the years that it is rented out, you are actually positioned quite well, tax-wise (Depending on your income level). I say this because the way house/apartment sharing works when the owner also occupies it is this: the usage of the property as an investment property is claimable only in proportion of common areas used. This means, for example, a 2-bedroom unit where you live in one and someone lives in the other, means that both people use the non-bedroom 'spaces' of the unit 50/50, so you can claim up to only 50% of the entitlement of expenses such as strata, water rates, interest on mortgages etc.
Where this arrangement gets better, though, is in larger properties. I'd need to double-check this (so peers - please don't pull me apart on this if I've presented this incorrectly) and would preface this by strongly suggesting you contact the ATO to uncover the full detail here... but;
Say you have a 6-bedroom house which you own and live in one bedroom, and you rent the other 5 bedrooms out, you would be entitled to claim up to 80% of the claimable amounts for things mentioned above.