Sound sense about solid floors

// the building envelope

HA Magazine hears from George Pickard, FCIOB, Sales Director for Litecast about the growing evidence backing the use of precast concrete floors for domestic properties, at upper as well as ground floor level.

If we look back to when HA Magazine was first published in the late nineties, housebuilders generally viewed precast concrete floor systems as a solution they turned to on sites where they were faced with difficult topography or poor soil conditions. Otherwise their groundwork sub-contractors would continue to build ground-bearing slabs across an infill of hard-core.

Fast forward two decades and not only has their use become routine to improve speed and guarantee certainty over cost, but the systems such as that offered by Litecast have been greatly developed to incorporate very high standards of insulation. And the use of precast solutions is also now far more commonplace at upper floor levels where their inherent fire resistance and excellent acoustic characteristics are deemed desirable.

More recently also, it is with regards to their thermal mass where specifiers are starting to value the solidity and substance of concrete as a means to improve both energy performance and occupant comfort: when designing the structure and to residential buildings.  

A study carried out by the world renowned Arup Research and Development, is regarded as the most comprehensive examination to date of embodied and operational carbon dioxide emissions covering dwellings.

Crucially it compared not just the energy involved in sourcing, manufacturing and transporting timber and masonry building components to site, but also the different ways in which their physical characteristics impacted on the operation of a building throughout its life.

It is already well documented that the lifetime running costs and energy consumption of most properties is many times greater than that involved in their construction. However the Arup study showed that thermal mass plays a very important part in the equation. 

George Pickard of Litecast commented: “The carbon emissions of a house in use have far more impact than the embodied energy of the materials and labour utilized to build it. Some 50 per cent of the UK’s emissions are produced by the consumption of largely fossil fuels to heat, cool and light buildings: meaning that specifiers have to give very careful consideration to the specification of materials and their cumulative impact over the lifetime of a property.

“Arup’s analysis of energy consumption and CO2 emissions of timber dwellings compared to masonry homes concluded that the denser the structure, the lower the total energy consumption and carbon dioxide emissions. The thermal mass ensures that those dwellings constructed using masonry were warmer in the winter and cooler in the summer than lighter, timber frame houses.
“Therefore in this context, with its inherent thermal efficiency, fire resistance, high levels of sound insulation, robust nature, ease of availability and low maintenance costs, precast concrete flooring has to be the number one choice on every homeowner’s wish list.”         

George also cited the comments of Elaine Toogood architect from The Concrete Centre who previously confirmed: “It has become more apparent to specifiers in recent years that concrete is an appropriate form of construction at upper floors in houses, the fire, acoustic and thermal benefits are significant benefits.  In addition, NHBC report that 48% of all complaints in detached houses relate to creaking floors.

“If we were building cars, with this level of complaints, they may well have been recalled, but because they are houses, we somehow tolerate the situation. The use of concrete is often the preferred construction between dwellings, while not enjoy the same quality within a house?  Concrete floors provide a robust, fire proof structural platform, saving time and money during construction and their inherent acoustic and thermal performance so important for the housing if our new homes are to meet the needs of todays and future occupants.”

There are a worrying number of cases where highly insulated buildings are suffering from overheating in summer, but specifiers can prevent the problem through the straightforward use of solar shading, ventilation and thermal mass.    

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