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Groundwork & Foundations Question
Can i build another floor on top of my 1940 bungalow
i am considering building up from my bungalow. I don't know what depth the foundations are or how deep they need to be. I have limited finances and want to keep the existing ground floor building, is this possible if light weight materials are used to build the first floor?
In order to understand if your existing bungalow is strong enough to support the additional weight of an extra floor, you would first need to have the property surveyed to fully understand the construction and depth of the existing foundations. This can be done by creating strategically located boreholes that reveal the depth and construction of the existing foundation.
A qualified (and insured) structural engineer will then need to make an assessment of the maximum load the existing structure will support, and where additional structure needs to be constructed to support an additional structure. They may also request a geotechnical survey of the soil beneath your existing foundations to understand the bearing capacity of the soil. This level of analysis would definitely be required by a Building Control Officer in order to comply with Part A of the building regulations.
Light weight timber construction may be an option to construct the first floor. In a recent project, I used a timber system called 'Cross Laminated Timber' for the addition of a new floor on an existing house. This property had a ground floor constructed in brick with a reinforced concrete cellar below, the structure was calculated to be strong enough by a structural engineer to take the additional load. A new external insulation system was also specified, which was finished with a high performance render. This greatly improved the thermal performance of the existing and new building fabric.
To fully understand the cost of this project, you would need a comprehensive set of construction drawings that a few timber frame contractors could price against. There are lots of different timber systems available on the market, which vary in terms of price and quality. There plenty of advantages of using these systems, because they create certified enclosures which often reduce the amount of structure required (especially around window openings). There is also the added advantage of very fast construction time of the superstructure ( potentially within 2-5 days) which enables work to simultaneously proceed on the inside and outside of the building.
Answered 21st Oct 2013
It is viable, the footings need to be of a reasonable depth and the only way to find out is to excavate a trial hole next to the house, it would then be inspected by the Building Inspector of your local council to confirm if the depth is sufficient or if underpinning would be needed.
If under pinning is needed, then it is for an engineer to design to what extent they are installed, it maybe the entire dwelling or just localised under heavily loaded areas.
It may prove to be more economical to flatten the bungalow and start again?
Light weight materials don't help!
Oh yes you WILL need planning permission first.
Answered 21st Oct 2013