My main floor will be on a poured slab with the perimeter foundation being a poured 8″ wall going down below frostline to a continuous footing. Centered along my gable end wall will be a fireplace, and the continuous wall footing will enlarge there to handle the fireplace foundation. My question involves the typical cantilevered fireplace base slab formed and poured atop the fireplace foundation. The cantilevered part is for the masonry hearth. Since my adjoining floor is concrete slab on grade, is it still a good idea to cantilever a monolithic fireplace base slab out, so that there is no slab joint between fireplace and hearth?
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Find online articles on A Fine Finish for Wood Exteriors; Furnace to Heat Pump Retrofit; Windows Before Housewrap?; More Building Science Mistakes to Avoid; EV Chargers and much more.
Featured Video
Builder’s Advocate: An Interview With ViewrailHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
GEne,
As long as your main floor is supported at it's edge by the block and or poured concrete wall and the rest of the slab is on compacted fill you should not have a problem placing your hearth on the slab. The purpose of a cantileved slab is to deal with the problem of wood movement in a frame building by isolating the masonry from the wood. In a properly constructed chimney/fireplace the rest of the structure could burn down around it and it would still stand. In your case you are not placing the hearth on wood so you do not need to pour the cantilevered slab.
Mark