Hi Joe! Take a look at the wood restoration products from Abatron. If it is just rot at the bottom and the integrity of the columns is otherwise alright the products should work out great for you. If something has eaten, not rotted the base of the columns you should probably think about replacing them. Abatron has amazing customer support by the way. I found the company when I was restoring sailboats and used their products all the time in restoring antique homes. Be warned the prices are not for the faint of heart but the products are well worth it and certainly cheaper than column replacement if it fits your situation.