waterproofing boiler room walls

I need advice on what materials I can use to waterproof the walls enclosing my boiler and a recommendation for someone to do the work.

My brownstone, like many in Park Slope, has issues with occasional water in the cellar. Until my budget allows a full waterproofing job, the biggest issue is the boiler room walls. The walls are gypsum-board — which means that from floor level to about 8″ up, I have moldy board that has to be removed. I only want to do this job once.

Can I replace the bottom 12″ of the walls with an apron of waterproof material, such as cement-board (e.g. durock, or permabase)?

If I do that, does there need to be any other barrier material placed between the cement board and the studs? If so what?

And if this is the wrong idea, what other materials should I used that gives me a 12″ high water barrier on walls that need to remain in place under the building code?

And as I said, I am looking for a recommendation for someone to do this job, which should be fairly simple if it only involves putting up the apron and sealing the seams between it and the remaining gypsum board.

Thanks in advance