Remodelling your Home
Posted May 22, 2018
In the first instalment of our 2017 design guide, I discussed the main considerations for a kitchen project, which we undertake on most if not all of our refurbishment projects. Closely linked to the dream of a beautiful family kitchen is the desire to create a general sense of open plan living. This article explores some of the common structural considerations to take into account when planning your project
One of the major costs of an extension and refurbishment project is that of structure – the bit that physically holds everything together. We’re often asked by Clients, ‘is what we want to do possible?’ and with modern technology and structural engineering there is little which is impossible, so it is more the question of value for money, and this can only be decided by the Client, on a project by project basis.
There are two main structural strategies that we employ and the choice comes down to the overall the aesthetic that is to be achieved, an assessment of the existing structural strategy of the house and the complexity of the new structural installation. The first solution is to create ‘downstand’ beams, whilst the second is to utilise ‘concealed’ structure. As you can imagine, these factors have a bearing on the cost of the works (pun intended!).
The most straightforward way to create an open plan living space within an existing dwelling is to use the downstand beam method. A downstand beam is a steel beam that sits beneath the ceiling level and spans across the new opening. The beam bears onto either existing, or rebuilt wall ‘nibs’ or ‘piers’. Depending on the aesthetic, the beam can be left exposed or re-plastered, both strategies normally require fire protection. Where there’s an existing period feature such as a plaster cornice, this can be carefully taken down before the works begin and reapplied over the beam once finished. The downstand strategy is usually the more cost effective solution as the structural design redistributes the load from the existing elements above, be it a load bearing wall or the first floor joists, whilst minimising the amount of invasive works to the existing elements.
The second strategy is more complex but ultimately gives a more aesthetically pleasing solution. New structure is inserted within the existing structural elements, such that no structure, downstands or boxings are visible once the works are complete. Typically, there is twice the amount of steelwork required and more often than not different types of steel beam are used to isolate the different wall and floor loads. Secondly the works require different installation sequencing and temporary propping methods to that of a simple downstand beam design. Furthermore steel posts may be required in order to remove the nibs to leave a flat wall surface. The results are fantastic, and speak for themselves, offering a seamless transition between spaces without the tell-tale signs of where the new meets the old.
Other more technical factors that will also affect the price is the extent of fire protection that could be required, both to the new structure and upgrading the emergency egress strategy (protected fire escape route). The possible scenarios or numerous, and there is no rule of thumb here. However by way of an example, an open plan ground floor with the kitchen and only stair case for the property collocated within the same space may contravene building regulations, as it does not offer a protected route out of the building. Where poor ground conditions exist or where the existing structure is too lightweight to bear further load; underpinning, local pad foundations additional stiffening of steelwork and strapping may be required to create the desired open plan affect. These are elements which will be concealed but do add extra cost.
Structural works to existing buildings are complex and each situation needs to be assessed on its own merits. It goes without saying that work should only be undertaken by qualified professionals. At Make we don’t believe in charging for extras – our method is to fully resolve the structural strategy and communicate this to you before the project begins on site, giving you peace of mind as to both the total cost and the nature of the works is in line with your overall vision.