It is very cold, and I am warm.
Fire has been an obvious winter pallitive since long before the Clan of the Cave Bear. Houses are another matter.
Ayla the Intelligent left the rocky lands and crossed the frozen Eurasian plains, no cave in sight. She gathered dry grass and branches and set them alight with sparking rocks. Extra branches were stacked high and the sleeping skins spread near the fire, in the lee of the fuel.
The wind shifted, Ayla awoke cold, drew the caribou robe closer around her shoulders, and thought.
On some subsequent night she perfected the idea. Her fuel reserve encircled the fire. Let the wind blow as it will. It remained only to lay some poles and skins across the woodpile. The roof was born, and the concept of a house as a human contrivance was complete. All else is detail.
Thank you, Ma'am.