Granite stair treads
I'm making a short set of stairs down a hillside out my back door. I'd like to use granite treads, 1' x 2' x1" and support the treads only on the wood stringer ends (no risers). Is this size slab strong enough or do I need to use a 2" thickness? Thanks for your thoughts.
-
gssfabrication
- SFA Member
- Posts:100
- Joined:Wed Apr 12, 2017 6:59 pm
- Has thanked: 34 times
- Been thanked: 21 times
Re: Granite stair treads
Hi Jengel55,
Granite (or any other stone for that matter) is strong in compression, however relatively fragile in tension (in this case deflection). Most stone masons will tell you to fully support the span for it to last many years. Can you do it? Sure.
Keep in mind decending and ascending the stairs is going to put say 250 lbs. (my current resistance to the G force on this planet) + whatever energy from your change in height in the size of about half of your foot on the stair tread. I know I can break a 3cm (1.181") piece of granite with a gap underneath it that is a little over 3 feet if I stomp good with my foot. The reason wood can get away with this is the flexibility of the wood fibers to bounce back. Stone, not so much.
Wood stringers and outdoors do not mix well with wet earth (i.e. hillside) the wood will rot away eventually. You can get in touch with a local stone mason for their advice/assistance installing the stairs you want.
Good luck,
Rick Graff.
Granite (or any other stone for that matter) is strong in compression, however relatively fragile in tension (in this case deflection). Most stone masons will tell you to fully support the span for it to last many years. Can you do it? Sure.
Keep in mind decending and ascending the stairs is going to put say 250 lbs. (my current resistance to the G force on this planet) + whatever energy from your change in height in the size of about half of your foot on the stair tread. I know I can break a 3cm (1.181") piece of granite with a gap underneath it that is a little over 3 feet if I stomp good with my foot. The reason wood can get away with this is the flexibility of the wood fibers to bounce back. Stone, not so much.
Wood stringers and outdoors do not mix well with wet earth (i.e. hillside) the wood will rot away eventually. You can get in touch with a local stone mason for their advice/assistance installing the stairs you want.
Good luck,
Rick Graff.
Re: Granite stair treads
Thanks for the info, Rick. Who woulda thunk rock was so delicate. We've decided, mostly for budget reasons, to use rough cut stone set in to a base of sand and gravel.
-
gssfabrication
- SFA Member
- Posts:100
- Joined:Wed Apr 12, 2017 6:59 pm
- Has thanked: 34 times
- Been thanked: 21 times
Re: Granite stair treads
Hi Jengel55,
That sounds like a good plan. One of the stone masons I watch always highlights the benefits of using a gravel base that allows whatever water does get through to drain through the gravel and into the soil. He works on the east coast and they get freeze/thaw that pops most stuff free in a few years time if the water doesn't have anywhere to go (snow melt).
Good luck on your project.
Rick Graff.
That sounds like a good plan. One of the stone masons I watch always highlights the benefits of using a gravel base that allows whatever water does get through to drain through the gravel and into the soil. He works on the east coast and they get freeze/thaw that pops most stuff free in a few years time if the water doesn't have anywhere to go (snow melt).
Good luck on your project.
Rick Graff.