...did you close in your stairs/railing areas? If not, how do you baby proof them so DC doesn't climb on/over the sides of the stairs?

DC is 16 mos old and is a climber - our house is a converted bungalow with the main living area upstairs and lofted to the downstairs section. Our LR furniture is up against a 4' wall, and we could easily see him trying to climb over if we're not paying close attention. FIL wants to build the wall all the way up, but I think it's temporary and don't want a permanent new structure. DH wants to take his father's advice and of course we want to do what's best for the DC, but I'm wondering if other families have had similar questions??

TIA for your input!