Philippe was born in Sceaux, Hauts-de-Seine, south of Paris, the son of Lucien de La Guêpière, clerk of the works at the château de Sceaux, where the architect employed by Louis XIV's natural son, the duc du Maine, had been his uncle, Jacques de La Guêpière (1670-1734).
Apparently having followed the architectural courses of the theoretician Jacques-François Blondel, from the 1730s La Guêpière took courses in architecture in Paris.