Why should there be a knee-high step at the patio door? Not every house is built that high above ground level.
Calculate it: slab + floor structure + threshold. You easily get knee-high.
And yes, you can also have gravel laid right away and then have a lower step. But then you already have done the bigger part of the costs for paving by yourself.
By the way, there are doormats against dirt in the house.
I just had my experience with that. I vacuum the doormat every day, yet the dirt spreads in the hallway. And when the stroller is rolled in when it’s wet, it drags the trail of dirt through the hallway. Totally awesome and worth imitating.
but by then you might have saved up something that you don’t have to pay 4% interest on.
Where do you get the money from? In an honest calculation, the money in the other case must go into an extra repayment and then doing it right away becomes almost as expensive as doing it in 5 years. Only with the difference that you have something for 5 years.
Or you do it slowly yourself and only have to buy the material.
“Only the material” also hits the pocket quite hard. If you don’t build on perfectly level ground or still have excavated soil from construction to dispose of, then substantial earthmoving is also necessary. Bringing gravel under the paved areas and compacting it as well. That quickly exceeds what you can manage as an amateur with a rented 1-ton mini excavator. The step to the finished terrace is then mostly done.