What is the practical size to allocate for a doma (earthen floor space)?

The appropriate size varies depending on its intended use, but an area of approximately 4 to 6 tatami mats allows for versatile functionality. For storage of bicycles or strollers, 2 to 3 tatami mats may suffice. Considering the family composition and lifestyle, it is advisable to design with some margin to accommodate potential future changes in use.

What materials are suitable for flooring in earthen-floored spaces (doma)?

Common materials include tamped earth (sanwado), mortar, and tiles. Mortar is relatively inexpensive and provides a clean finish but requires measures to prevent cracking. Tiles offer excellent ease of cleaning and a wide range of design options. Natural tamped earth has moisture-regulating properties but requires regular maintenance. Selection should be made according to the intended use.

How should the boundary between the earthen floor area and the living space be planned?

It is common practice to establish a clear distinction by incorporating a step or level difference. A height difference of approximately 15 to 20 centimeters helps prevent the intrusion of dust and dirt. Using sliding doors or shoji screens as partitions allows for flexible control between openness and privacy. Additionally, to maintain thermal performance, proper insulation and airtightness treatment at the boundary are crucial considerations.

What are the appropriate methods for implementing thermal insulation measures in earthen floors?

The standard practice is to install insulation materials beneath the earthen floor slab, known as slab insulation. It is essential to use airtight gaskets between the foundation and the sill plate to prevent cold air infiltration into the interior. Additionally, an appropriate ventilation strategy is necessary to address condensation issues. Designing with consideration for the overall thermal performance balance of the entire residence is crucial.

Is ventilation equipment necessary for work conducted on earthen floors?

Depending on the nature of the work, we recommend installing exhaust fans to manage odors, humidity, and dust emissions. It is effective to combine mechanical ventilation with natural ventilation. Please also consider integrating the system with a 24-hour ventilation system.

Is it possible to design with an emphasis on the connection between the earthen floor space and the garden?

By incorporating sliding doors that provide direct access from the doma to the garden and creating large openings without level differences, a seamless integration between indoor and outdoor spaces can be achieved. Techniques such as extending the eaves to form a semi-outdoor area or continuing the doma flooring material onto the outdoor terrace are also effective. This approach results in a highly attractive residence that allows for gardening activities even during rainy weather.

House with a Doma｜Q&A

Q&A