The lattice heat conductivity in low-doped SiC is studied in the wide temperature range 50/1200 K in order to estimate the strength coefficient a(4P) for 4-phonon scattering processes mechanism for later application in both heat conductivity and Seebeck coefficient models. Heat conductivity calculations confirm the domination of the 4-phonon mechanism and the secondary role of the 3-phonon Umklapp mechanism. The obtained a(4P)approximate to1.5(.)10(-22) s/K-2 gives very satisfactory result in Seebeck coefficient phonon drag component modeling.