Icelandic/ North Atlantic turf house, made of turf both for wall and roof, is probably the best example to answer OP's question. Turf is good at keeping the warmth inside the house during the winter, and this kind of house is now nominated to UNESCO's World Cultural Heritage in 2011: https://whc.unesco.org/en/tentativelists/5589

Norse settlers brought the building tradition originally from their Scandinavian homeland to the new settlements, but the inner structure of the building in the North Atlantic Isles developed in course of the Middle Ages from the single large room to multiple room structure, sometimes also with the animal room (as they did in Norse Greenlandic settlements), so the current tradition is not exactly the same as that of the Viking Ages.

As for an example of the early turf house in medieval Iceland, you can see some photos in the official site of the reconstructed farmstead museum (Þjóðveldisbærinn Stöng), administered by the Natiional Museum of Iceland: http://www.thjodveldisbaer.is/en

This reconstructed Viking Age farmstead is located nearby the original farmstead of Stöng that was buried under the volcanic ash from Mt. Hekla's eruption in the beginning of the 12th century.

Another traditional Icelandic turf house settlement, now administered also by the National Museum, is Keldur in Southern Iceland: https://www.south.is/en/what-to-see-do/places/history-and-culture/keldur-at-rangarvellir

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Scandinavians (especially Icelanders where geothermal has provided them with abundant hot-water springs) has been known to take a bath (with bathtub!) since the Middle Ages (more specifically, since the Middle Ages in Iceland as well as Greenland and latest also since the end of the Middle Ages in mainland Scandinavia), as I briefly summarized before in How Did They Warm Baths Before Electricity? and How did people keep warm in Iceland before central heating in the winter?

The following is a citation from my previous answer in How did the people (especially the noblity) in kalmar union sweden live?

Olaus Magnus writes in his Description of the Northern Peoples (Chap. 35) as following: ‘In a great many parts of the world we generally find that baths are taken for pleasure, especially in Italy, as the ruins of the luxurious bathes at Rome and in the country round about Pozzuoli testify. Yet nowhere on earth is the practice as indispensable as in the northern kingdoms, where both private and public baths are found in various places, well distributed and with all necessary utensils. The private baths of notable personages are built near running water and pleasant gardens, while there are many public baths as are needed in the cities and villages, according to the number and standing of the inhabitants (Quoted from: Foote et al. trans. 1996, i: 760)’.

The Norsemen (Scandinavians) has been famous for their practice of bathing since the Viking Age. Especially in Iceland, where the volcanic activity provides natural hot springs, the sagas sometimes mention the scene in the bathing pool. The account of Olaus Magnus, cited above, suggests that the Black Death and the Reformation did not apparently change their practice of bathing to greater extent as it did in Continental Europe, where most of the public bathhouse was to be closed in the end of the Middle Ages.

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Major winter activities of pre-modern Scandinavians are also covered by my answers in the following thread at least to some extent, I hope:

• How did pre-modern Scandinavians maintain their sanity throughout the long winters?
• What did pre-modern societies, such as the inuits, who lived in the far north think about the incredibly long days in the summer and incredibly long nights in the winter?