You can borrow 95% of the cost of the renovation or addition to an existing house.
The amount you can borrow will depend on when you’re renovating:
You already own the house: If you intend to knock down and rebuild or carry out major renovations, you can borrow up to 95% of the current house and renovations.
You're buying a house: If you're buying a home and have a building contract to start renovations, then this is favourable by lenders. You could borrow up to 100% of the house with a guarantor plus the building contract price.
Having a licenced builder to help with your renovations is more favourable to lenders than owner-builder.