I'm considering building on top of my kitchen extension (single story) to add a new bathroom.
Before I go for planning etc, how do I determine if the existing extension can support the weight of another floor?
Someone said it's about the depth of the foundations and another said it's about the strength of the structure being able to support the new weight. I guess it's a combination of factors so I need to know what the steps are in making this decision.
Any suggestions on the "process"?
On Sat, 18 Aug 2007 11:37:31 +0100, a particular chimpanzee, "kd" randomly hit the keyboard and produced:
The depth of foundations are largely irrelevant to whether they can take a single storey or two storey building. It's what they are bearing onto, and how wide they are that are more important.
If the original extension is recent (say, the last ten years or so), there should be records at Building Control. The surveyor may not have recorded the ground conditions, but it is possible. He may also have endorsed the notes with a stipulation that the ground conditions were suitable for a single storey extension only if the original ground was poor.
Irrespective of whether records are available, you'll almost certainly need to dig a trial hole (or two). Dig down alongside the foundation, make it wide enough so that a person can get down into it (at least
600mm x 600mm), to a depth _below_ the foundation so that one can see what's below the foundation. [A number of times I've seen a trial hole about a spade's width only as deep as the top of the concrete.] Where to dig the trial holes will depend on your circumstances, but a good place to start will be at the junction of the original building and on an external corner.
Quite a few years ago, perhaps 20, an uncle of mine was upset because, at the insistance of the planners, the single storey part of his kitchen extension had had to be built with foundations that would take another level in case he ever wanted to extend upwards i the future. He bemoaned the extra cost. Is it not universal to require single storey extensions to have two-storey-capable foundations?
The house was built in 1868 and the extension has to be at least 50 years old
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