Peparing base for granite steps so they’ll stay put
Looking to replace my decaying brick steps with granite. Seems like standard practice for the base is 12-18″ of compacted process gravel though some seem to like a concrete pad. Either way I don’t see a lot of provision for things to stay put. Between tunneling critters and time, it seems like a 3500 lb slab sitting on a couple of 11″ fillers has a pretty good chance of settling and pitching back toward the house. What are the pros and cons of tying in to the foundation, either with angle iron or tying a pad in? It’s not clear to me to compact base under an angle iron anyway, just askin’.
Also I was planning to flash down from the door sill to the foundation with Vycor so there’s a continuous moisture barrier the width of the slab. Make sense?
Replies
Pete
Not knowing your location,it would be difficult to advise using a footing placed below the dictated frost depth,
but.
Any masonry stoop, slab or steps will move with settling and frost heave. To limit that from happening in a northern climate I've only seen one thing work-foundation on a footing below frost depth and on undisturbed ground. A couple of yrs ago I built a porch with only a couple of limestone steps out from it. We placed a footing along with the one for the structure, laid block up to just below grade and bricked up from there with the stone slabs placed upon the brick. No movement whatsoever.
If you build up off a brick ledge or angle fastened to the foundation, that might take care of the stone against the house, but what is to keep it from moving away from your foundation?
In the NE there's alot more granite steps used and I'm sure they could advise you better than a dumb carpenter from Ohio.
Here in cold Maine, angle brackets are often attached to the foundation, not a continuous angle iron, just a couple 2" brackets on each end. These prevent the steps from sinking next to the house. The steps are kept away from the house about 2-3" so water, snow and ice can fall through to the ground and not be trapped against the house. Typically, the steps are pitched slightly away from the house for water run off. Often, an 8" bed of compacted gravel is placed under the steps, this allows water to drain through and helps prevent frost lift. Over time, the front steps may sink into the ground an inch or two, they are heavy. It can depend on ground conditions and water management. Larger sets of steps may require a concrete pad on top of the gravel bed. Here are some PDF instructions from a local granite supplier.
http://www.swensongranite.com/resources/instructions.php
A proper sill pan flashing along with a correctly installed bituminous membrane behind the kick board is a good idea. We are using synthetics for the kick boards and door casings.