You may, but I probably wouldn't. First you will have to create your own spacers behind the board to cover the gap underneath the endu boards. The baseboard from the factory has stem in this area which takes care of it. But even then, I dont know what kind of material your baseboard is, most likely its not 100% waterproof, and you would experience warping, swelling etc in the future. You can use the Astec molding that is made for outdoors. I would think they make 1x5 boards but you will have this aggressive wood pattern on them that is nice for outdoor sheds etc, but probably not good for indoors. Not sure if there is a price advantage. All depends on the size of your project of course and how much you have left. Cutting corners now may make your life harder in the future (like its true in so many areas of life I suppose!) If you upload photos of what you have and I can take a look to be sure.
Dont use them. They will bend and worp and delaninate
You may, but I probably wouldn't. First you will have to create your own spacers behind the board to cover the gap underneath the endu boards. The baseboard from the factory has stem in this area which takes care of it. But even then, I dont know what kind of material your baseboard is, most likely its not 100% waterproof, and you would experience warping, swelling etc in the future. You can use the Astec molding that is made for outdoors. I would think they make 1x5 boards but you will have this aggressive wood pattern on them that is nice for outdoor sheds etc, but probably not good for indoors. Not sure if there is a price advantage. All depends on the size of your project of course and how much you have left. Cutting corners now may make your life harder in the future (like its true in so many areas of life I suppose!) If you upload photos of what you have and I can take a look to be sure.