My home's unheated basement gets wet from rainwater, which soaks in from the above porch. The existing floor of the porch is made from 1x4 tongue and groove boards. How can I waterproof the floor of the porch so that water does not leak into the underlying basement?
Clancy ~ Langhorne, PA
I would recommend using an elastomeric membrane over the porch surface. There are several manufacturers of water proof elastomeric membranes all of which would work for your application. All of the membranes will eliminate the wooden porch look, so if the tongue and groove look is something you would like to preserve then you will need to waterproof the porch a different way. An invisible solution would be to pull up the existing porch and install a water proof membrane under the tongue and groove boards. You could use the same elastomeric membrane as above, a full metal cap, or even a roofing membrane over the porch framing, and then install sleepers over the membrane and attach the tongue and groove boards to the sleepers. Any time you increase the thickness of a porch you will want to be sure that you do not interfere with the operation of any doors that access the porch and you will want to make sure that you do not create a trip hazard on any stairs that may access the porch due to different riser heights. There are contractors that specialize in waterproofing porches, decks, and balconies. I think it would be a good idea to see if there are any contractors in your area that could take a look at your job and provide you with some options and pricing. Good Luck!