average height of fireplace hearth
The International Residential Code requires that a wood burning fireplace have a minimum horizontal hearth extension of 16 inches for a firebox opening of less than 6 s.f. and 20 inches for an opening greater than 6 s.f.he International Residential Code requires that a wood burning fireplace have a minimum horizontal hearth extension of 16 inches for a firebox opening of less than 6 s.f. and 20 inches for an opening greater than 6 s.f.