Ask the architect: Should I go for a polished concrete floor?
Q: We are building a new extension and I like the look of polished concrete floors, but am worried that they will make the house feel cold - will they? Susan, Co Meath
A: There are essentially two elements to your question - whether it actually will feel cold, or colder - than other floor options, and whether it might give the impression of being cold, or colder, than other floor options.
A polished concrete floor is essentially no different in its make-up than the floor construction beneath most new homes and extensions, and many older homes.
In these instances, it has the added benefit of sitting on a heavy-duty damp-proof membrane and a significant thickness of insulation (generally between 100mm and 150mm), which combine to prevent moisture and cold travelling from the ground up into the floor of the house.
Accordingly, as you are considering a polished concrete floor for a new extension, the floor will be constructed to current regulations and will be damp-proof and insulated. The surface temperature of the floor should therefore be no different than if it were tiled, for example. Timber and laminate floors may feel slightly warmer, and likewise carpet, but the actual temperature of the floor itself will be no different by virtue of a polished concrete finish.
Many new floors in extensions and new houses now incorporate underfloor heating systems as opposed to traditional radiator systems. This results in a more even, ambient temperature throughout, rather than hot-spots and temperature differences created by radiators. With underfloor heating, the concrete itself essentially acts as a giant storage-heater, releasing the heat from the embedded pipework.
Polished concrete works extremely well where underfloor heating is used, as there is no barrier between the source of the heat (the concrete itself) and the space you want to heat. Depending on the specification, some carpets and timber floors can significantly reduce the impact of the underfloor heating system, acting almost as a damper, preventing the heat from passing efficiently from the slab up into the room.
Therefore a concrete floor has no real negative thermal impact, and in reality, is more thermally efficient than many other flooring options.
As to whether it has the capacity to make the house 'feel' cold, this can be significantly influenced by the finished appearance of the concrete. There are numerous factors to consider - the supplier of the concrete, the quarry the stone comes from, and the sand used can all contribute to the perceived 'warmth' of the floor. After that, the depth to which the floor is polished will also have a significant impact. A light grind will expose only some of the stone, creating almost a 'speckled', somewhat even, appearance, whereas a deeper grind will expose more of the stone, creating a more varied 'busy' aesthetic.
One of the real visual benefits to a concrete floor, however, is the lack of joints. Aside from expansion joints, there is nothing like the amount of 'lines' you'll have with a tiled or timber floor. This generally helps to allow the floor recede into the background and not overly draw attention to itself, allowing the real focus of the space to centre on the furniture, fittings, views through and out, or the people within!
If you are considering changes to your home, work with a registered architect. You can find a registered architect on riai.ie. The RIAI is the Registration Body for Architects in Ireland.
Gareth Brennan is a partner in Brennan Furlong Architects & Urban Planners; brennanfurlong.ie