It is becoming increasingly popular to incorporate elements of steel framework into timber frame and kit houses in order to achieve larger spans than are normally available with timber. This is often down to the preferences of the engineer doing the calculations rather than being an inherent necessity. Very often laminated timber would do the job better in several ways
- lower embodied energythe total amount of energy it takes to make a material (or a building). See more on embodied energy
- less thermal conductivity. As the insulation standards for housing become more stringent, cold bridgingthis is a pathway where heat can easily escape (or get in) through some part of the structure. It is usually caused by some element of structure such as a steel lintel or wooden studwork. Also known as a thermal bridge. see more on cold bridging becomes more of a problem and steel is a particularly poor insulator. This may be important in outside walls or at the bottom and top of columns. With PassivhausSee more on the Passivhaus standard. The PassivHaus Institute has pioneered a standard for low energy buildings. It includes very low energy usage and ways of achieving this. The word is derived from the idea of buildings which are fundamentally low energy and passive solar heated rather than using extra gadgets to heat them. See Passivhaus for the UK branch of the organisation. or code 6 standards it may be necessary to position the steel elements on the inside of the main envelope to avoid thermal bridgingthis is a pathway where heat can easily escape (or get in) through some part of the structure. It is usually caused by some element of structure such as a steel lintel or wooden studwork. Also known as a cold bridge. see more on thermal bridging.
- better fire performance (steel usually needs cladding to protect it from fire whereas timber is usually simply increased in width by 25mm per exposed face to give fire protection.)
- steel erector not required (though for small jobs a general contractor can usually handle the erection work)
- timber columns can usually go straight onto the foundation slab whereas steel requires fixing plates set in the concrete. The point here is that timber columns can be made slightly over length and trimmed on site whereas steel columns usually need nuts and studs or bolts with shims to make final adjustments.
The Building RegulationsThese are the mass of regulations that cover safety, health, welfare, convenience, energy efficiency etc. in the way buildings are constructed. Not to be confused with Planning consent (which is more to do with whether you can put up the building in the first place) part A covers the structure of a building. This Approved Document goes into a lot of detail for traditional masonry buildings but almost none for timber frame, steel frame, earth building SIPsStructural Insulated Panels - prefabricated (usually in a factory) timber panels often forming part of an integrated building system and aimed at fast site erection. see more on SIPs etc. For these you will need to consult a structural engineer (while SIPs structures are usually handled by the manufacturer)
With most forms of construction there will be implications concerning fire safety. These are covered in the Building Regulations and you can see examples of how to conform with these in Part B (Fire Safety)
Site preparation and resistance to contaminants
This section, Part C, covers site remediationthe term applied to the method of dealing with pollutants and contaminants in the ground. The Building Regulations cover this in detail. See info about Approved Document C – Site preparation and resistance to contaminants and moisture along with protection from nasties which might affect the construction and occupants such as damp, rain, radon etc. There is an abridged version of the Approved Document specially for houses.