New Build Basements

Building below ground dropped out of fashion just after the First World War when land was abundant and basements were dark and damp. But in these days of high-density, planning guidelines developers are being forced to consider basements once again. “Over the last couple of years we have noticed an increasing interest”, says Alan Tovey, Director of The Basement Information Centre (TBIC). There are several reasons for this explains Tovey; “Increased densities related to higher land costs will influence the cost of basements and with a poorer quality of land, foundations are more expensive so builders want to get something for extra cost”.
 
Basements have also evolved to become more than just storage areas. Developers and home owners are looking to transform them into high quality living spaces. GeMech state “Basements are now becoming sitting rooms, gyms, pools and games rooms. Whereas a room in the roof doesn’t increase the footprint much, a basement is a blank canvas that rarely has planning issues. If a developer has a reasonable amount of land he can batter back on one side and put windows in so that it becomes another level to the house”.
 
Despite the fact that “virtually everyone wants a basement”, according to Tovey, they continue to struggle when it comes to wooing the volume builder. Michael Edwards, Marketing Director of Thermonex says “Most of our business is with small self builders. The cost of land is going up so housebuilders will want to maximum what they have”. A spokesman for GeMech states “we have noticed smaller developers doing bespoke jobs have started to build new basements”.
 
One housebuilder that took the plunge was Martin Grant. Thermonex carried out the design and installation of 35 basements on Martin Grant’s 89 unit site on the banks of the river Cam on the outskirts of Cambridge. Four pre-casters were chosen for the different pre-cast concrete works. Edwards says “Some people are frightened of basements because they haven’t seen them before. Martin Grant thought they had made a mistake but came back and said they wish they had done them all that way”.
 
A basement is undoubtedly an attractive feature for the potential buyer but larger housebuilders are still put off by the price and work involved. Ian Randall, Managing Director of Linden Homes South East says “The additional space is always popular with homebuyers, but they are not usually prepared to swallow this cost”.
 
He adds “Basements are a great way of getting around land shortages. But the additional cost per square foot in a basement compared to a regular storey is considerable due to insulation and ventilation challenges. Consequently, we have not found basements cost effective in mid-market”.
 
Basement enthusiasts would say much of the cost is cancelled out because expensive foundations are not needed. The TBIC says that basements can, in fact, increase margins by reducing the amount of land used. On a 129 sq.m house, TBIC calculates a fully below ground basement will add 6.7% to the construction cost, but will save 21% on land and increase margins by 9.3%. Margins on houses with a partially below ground basement