Before you can upgrade your house, you must make room for it. This means expanding your yard to get more land, and remove any obstructions around your house. Once this is done, head to the A&G Construction Building that is located next to the Commerce Guild. Look at the catalogue there and see the options for upgrading your house.
It is possible to upgrade your house a total of 3 times in My Time At Portia, and by the third upgrade your house will look like a mansion! Each new level of house upgrade also gives you increased max health, stamina, attack, and defense stats, as well as the option to invite pets to live with you. You will also need to upgrade your house if you want to marry an NPC.
Upgrading your home from the A&G Construction Building will cost you both Gold and materials, and see below for what is required for each upgrade.
Level 2 House Upgrade materials required- 20 Hardwood Planks
- 20 Bronze Bars
- 10,000 Gols
Level 3 House Upgrade materials required- 20 Iron Wooden Planks
- 20 Aluminum Plates
- 10 Strengthened Glass
- 50,000 Gols
Level 4 House Upgrade materials required- 20 Aluminum Plates
- 20 Concrete
- 10 Wooden Pillars
- 100,000 Gols