DISCLAIMER: This question is for educational purposes only. I know I need a structural engineer to determine safe loads so please don't answer if that is all you have to say. I would like clarification so i understand how this calculation works.
I have a 1993 home with 2x10 floor joists 16" on center. The span is 13ft from foundation to the center supporting I-beam. From span tables (correct me if i'm wrong) it appears this correlates to 30psf live + 20psf dead load or 40psf live 10psf dead load. https://www.mycarpentry.com/joist-span-table.html
How would a roughly 4ft x 4ft hearth with a wood stove impact this? I made a sketch (not to scale). I estimate the total weight over this 16sqf area would 1200lbs, located essentially mid span. I have not found anything written on how to understand floor load and span with respect to relatively concentrated permanent loads. I find this surprising since it seems relevant to common things like kitchen islands, pianos, stoves, and fish tanks. Back of the napkin estimates can really help you know when you're about to have issues...
I can think of three ways to calculate a concentrated dead load:
- Weight/footprint:
1200lb/16sqf = 75psf
That seems excessive.
- The hearth would touch 3-4 joists. Average the concentrated load over the entire area of these joists:
3 joists x 16" spacing = 4ft
4ft x 13ft span = 52sqf
1200lb/52sqf = 23psf extra dead load?
- Average the concentrated loads over the whole room, essentially worrying about total weight. 1200lb/230sqf = 5psf extra dead load
Is any of these methods correct? What would be the approach?
Thanks!
