House Extension query - help!

    hi all,

    im planning to increase my home living quarters by adding two rooms downstairs. a single story side extension to my lovely semi detached house.

    the single storey side extension will be 4m wide and the total span length wise will be 12.5m. the roof space / atitic space will (im assuming) be quite massive?

    the info im after and the help i need is calculating how much space i will get under this new roof to play with (perhaps enough to accomodate a spare bedroom?)

    anyone know of any websites or information for calculating potential roof space on such projects

    thanks in advance


    i'm not an expert but wouldn't you just look at is as a big prism and just work out the volume of that?
    so it'd be the length x the width x the height then divide that by 2, to give you the volume in cubic metres that you'll create. i think.

    This all depends on the roof pitch, which would usually be the same as your house so it looks ok. You would certainly have enough space in the roof for another room, using the correct roof trusses will also open this up for you, but they do cost more.


    Your architect will tell you that,, unless you are doing the plans yourself but you will have to provide load calculations for all roof and floor joists.:w00t::oops::santa:

    Original Poster

    thanks for all the replies thus far. bit more background which i was unable to give earlier

    i contactd my local authority for some pre-planning advice on a double storey side extension, who immediately dismissed the idea. so my hopes of having a nice master bedroom with ensuite were somewhat dashed.

    what they did say and have granted is a good size single storey extension, and me being me to maximise space was thinking i could possibly get a somewhat 'squeezed' master bedroom in the roof space abve the single storey extension.

    my semi has a very shallow roof, the max height in attic being just 1.2m!
    (if i have to match/reflect this which i know some/most councils insist with the new single storey extension then its a project id think twice about before attempting!)

    i know that most of the attic would be unusable (corner of triangle etc) but was hoping the huge expanse almost 12.5m in length would create a good roof picth within which i could possibly get a bedroom in!

    anymore ideas as to what the minimum and maximum roof pitch (attic hieght) would be on a 12.5m extension?

    once again thanks
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