@Baco 

You will need minimum three Deco nodes, one on each floor. Maybe more, depending on where Ethernet cables terminate and what walls are made of in your house. Before I can give more detailed recommendations for Deco hardware, please clarify the following: is modem/router located in the middle of the floor or at one of the corners? Also, where Ethernet cables terminate on other floors: in the middle of the floor or at the corner?

One more thing: according to what I googled, your Tim Hub router is 2.4GHz/5GHz. Does it provide good 5GHz coverage all over the house, does it provide good 2.4GHz coverage? That may help to guesstimate number of Deco nodes you'll need per each floor.