Flashing A Covered Concrete Porch?
Here’s the setup:
Wife and I are in the early stages of building a house. Gonna be a 2-story, covered porch type of place. ICF foundation, stick-built walls.
My father-in-law is GC, my own Pops is the architect. Both been in their respective businesses about 40 years. (Can you guess where this is headed already?)
So, them and me and the Missus and kids are all over on our building lot today, discussing site plan, elevations, top-of-foundation stuff. Then it comes to the porch.
I wanted an actual porch, with wood floors, but I gave it up, since I was apparently the only one who did. So we’ll get a poured perimeter foundation on the porch instead, with a poured slab floor – a glorified stoop, essentially.
Now that I’ve set y’all up, there was a discussion about flashing at the point where the porch floor meets the foundation wall of the house itself. My FIL’s position is that it doesn’t need to be flashed at that juncture, since it’ll be covered by a roof and “it would look stupid,” which doesn’t strike me as a reason rooted in best practices, but what do I know?
But…we live in Eastern Nebraska, where it can and frequently does rain/snow sideways – certainly sideways enough to get under the 6-foot overhang. My FIL does very good concrete flatwork as his main trade, so I presume he knows what he’s talking about. My own dad (the archy, remember) didn’t dispute him, even though he brought up the flashing in the first place, so it wasn’t apparently that important in his mind, either.
However – I, the homeowner, was/am a bit perturbed by this whole thing. I verge on paranoia when it comes to matters of uninvited water in my house. (For my wife’s part, I had to explain what flashing was, so she’s of no help here).
I'd flash it.
Moisture will find it's way in somehow.
Consider WR Grace Perma barrier flashing (similar to
Ice & water shield) behind siding and then flash it.
Also, if there is a possibility of snow laying against any
of the sides use the PAB behind siding. It seals around the nails.
Gee, are you in for a memorable experience!
As for flashing, I agree that flashing would not look good. I would suggest something nearly like what the other poster suggested. You have to waterproof the basement over the ICFs and the gooey rubber membrane (like Grace Ice & Water Shield) is one of the best methods. I would run the membrane up the basement wall all the way above the level of the porch floor. Then at the level of the porch floor, I'd flash with PVC roll flashing placed horizontally to be several inches above and below the level of the floor surface. Then place the concrete against it (or with an expansion joint). The housewrap would overlap the flashing from above. Then the siding for the house would start at the level of the porch surface (actually about 1/4 inch above so it doesn't make contact with the concrete) and go up from there.
The membrane provides the waterproofing and capillary break. The PVC roll flashing protects the exposed 1/4" of membrane from UV damage (which it is quite prone to). Layering the housewrap over the PVC flashing over the waterproofing membrane will provide a very effective system to prevent water penetration.
I agree, by the way, with a concrete porch. It will last centuries, whereas a wooden porch will be trouble after only a decade.
Thanks for the info.
Incidentally, got a preferred brand / product name for the PVC roll flashing? Makes it easier for an idiot like me. : )
I'm sorry I don't. I haven't bought any since I moved a few years ago.
you would flash it like any house that has an eave and patio. but around here we dont flash that area.
I had responded to your post a couple days ago.
The reason I had mentioned Grace's Perma barrier Flashing
is because it's an Ice& water shield with a bonded pvc type
wear surface attached. go to grace's website and check it out.