Tips on How to Install a Concrete Slab for Supporting Granite Steps
By Mark J. Donovan
||Question: Hi Mark, I enjoy your newsletters very much. Your eBook helped us thru the process of a kitchen remodel in 2011 on a seasonal cottage in Maine.
We need to redo the entry steps there….old fieldstone treads with risers varying 6 1/2″ to 9″ have got to go. We have picked out granite treads and landing at Swenson Stoneworks and making a plan for the new stairs–watching side yard setbacks closely, have about 1″ to spare.
However, we can’t find any info on the concrete footer underneath as far as Maine codes.
We are trying to find out the required depth of the footer, and whether or not it needs to be concrete block, poured concrete, and/or tamped earth and stone. The granite steps will consist of three treads and a granite landing with the granite sides (haunches essentially).
Do you know a good source of info in regards to concrete footer requirements for granite step installation? I know the excavation contractor will know what to do, however I am wondering about how much digging must be done just to get a sense of the work involved.
|Again I appreciate all your info. Next year we tackle the crawlspace under the cottage. We must insulate and install a vapor barrier. In the spring and fall you can feel the cold coming up through the floor. Thanks! Paula
Answer: Glad to hear I’ve been some help Paula.
In regards to your question on putting in a concrete footer for some granite steps/landing; the simple answer is you don’t need concrete footings. You have a couple of options. I installed granite steps on the front of my house a few years ago.
I dug down about two feet and then poured crushed stone and gravel into it and compacted it. I then drilled several holes (approximately two inches deep) into the side of my home’s foundation wall. Next I installed rebar rods into the holes in the foundation wall. I then installed additional rebar perpendicular to those rods and tied them together with wire. Then I built up a frame and poured my concrete slab. I then placed my granite steps on this concrete slab and have never had any issues with heaving or settling (and this is in New Hampshire).
Lastly install rebar into the Sono-tubes. Then pour your concrete into the Sono-tubes and slab area. The slab/pad should be 6 to 8 inches thick, with the finished pad surface at the desired level of your bottom step. When cured, the Sono-tubes will effectively create piers for help supporting the far-end of the pad. The rebar that attached into the foundation walls will also act to help support the near-end section of the slab/pad. They will also prevent any heaving. Also note that near the foundation wall the heat from the basement area will prevent deep frost from forming, thus why you don’t need to install Sono-tube piers near the foundation.
For more help on building a home addition, see HomeAdditionPlus.com’s Home Addition Bid Sheets. Our Home Addition Bid Sheets provide you with the knowledge and information on how to plan a home building project, and what to look for when hiring contractors. They also include detailed cost breakdown tables and spreadsheets for estimating your own new home construction building costs.
- Installing a Proper Foundation for a Home Addition
- Insulating Exterior Foundation Walls
- Concrete Block versus Poured Concrete Foundation Walls
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