Floor framing


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The floor is a structure supported by the building foundation directly. In small buildings where no deep concrete foundations along the entire perimeter are considered, the floor will have to resist fluctuating temperatures as it is in direct contact with the exterior environment. Therefore, include sufficient thermal insulation in your calculations, primarily in cool weather conditions.

The floor structure distributes the load from the walls, upper storeys and roof straight to the building foundations. In the positions of planned load-bearing walls and partitions, the floor structure should be designed to avoid too much of a deflection. This is achieved by appropriate location of load-bearing components in the floor structure which is a natural part of all good project documents.


Load-bearing floor structure; Czech Republic

From the point of view of humidity and heat transfer, this is identical to the structure of walls and roofs; therefore, the cluster of layers with vapour-impermeable film and semipermeable hydro insulation, so typical for larger buildings, is encountered here as well. The intention is preventing the inside layers from becoming wet and maintaining permeability in the outward direction.

The top floor layer is worn at places with high user exposure. One should choose materials which are easy to repair and renovate the surface of. This makes solid wood rather than sandwich-structured composites the best option.



More information can be found in this book

Individual components and functions thereof


Flooring components

1.  Foundations

2. Asphalt sheet -insulating the joists from rising moisture from the ground

3. Blocking – used as bracing for individual floor joists

4. Multiple joist – this structure distributes loads directly to the building foundations


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5. Wire lath – separating thermal insulation from the exterior environment, preventingWant to know more about floor structure? Check out my new BOOK!rodents from entering etc. Other materials can substitute for the lath – OSB/plywood or other suitable material – however, they must be permeable to facilitate vapour elimination – this may be achieved e.g. by drilling holes in the boards

6. Vapour-permeable air barrier material – preventing exterior moisture from entering the structure while letting moisture from the structure out into the exterior

7. Vapour barrier – preventing interior moisture from entering the thermal insulation while letting undesired moisture through in the opposite direction. Also prevents small parts of thermal insulation from entering the interior environment of the building

8. Wood floor joist – load-bearing function

9. Base board – bracing the entire floor structure, distributing the loads on the walls, acting as base for the finish flooring layer

10. Finish flooring – this floor layer has primarily an aesthetic function, improving the user
comfort in the environment

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