Expand A Basement Outisde The Perimeter Of Your House? Any Contractor Friends?

Discussion in 'General Discussion' started by cm11599ps, Mar 22, 2010.

  1. cm11599psWell Known MemberMember

    Ever since I saw that 55,000 gallon fish tank built nrxt to that guys house I've been doing some thinking.

    When you walk into our house you are faced with a landing. There 6 steps to go up to the top level of the house and six steps to go down to the lower level of the house.

    The lower level is actually about 1/2 way in the ground. When you look out the windows down there you are basically at eye level with the ground.

    The upstairs level has a sliding door with a nice covered wooden deck attached. Since the deck is attached to the second level it is in the air. I'd say the planks are about 4.5 - 5" in the air. As a result, there is a 10'x20' section under the deck which is basically wasted space. There's probably only about 4' of room there between the ground and the bottom of the deck.

    If at all possible, one day I'd like to cut through the poured concrete walls there and dig out under the deck to add some extra living space, which would be about 10x20 , the size of the deck above.

    Does this seem like a feasible project? I can do the framing work myself, I would just need to have someone dig out that area and pour the walls and foundation. If it's possible, how big of an opening can we make in that concrete wall?


    Here's a picture of the backyard and deck. I'd like to add this room under that deck.

    Oh, this room would be a fishy room with a big tank. lol
  2. navyscubaWell Known MemberMember

    Sounds like is not a weird idea at all but depends on how is the deck supported right now. If they are some post down the middle of the deck you would need to re-think and move those before start digging. Those are holding a big part of the deck weight.
  3. cm11599psWell Known MemberMember

    Yes, they are a number of 4x4's connecting the deck to the ground. I don't see why we couldn't temporarily support the deck by other means, get the new room built, and then use new supports for the deck down to the new foundation.
  4. navyscubaWell Known MemberMember

    I'm not saying is not possible. The issue is that you can to put the supports as close to the original position as possible or put a beam across and support it on the ends.
  5. w_boughnerValued MemberMember

    im a contractor and ive done this before..

    the easiest and best way is to take down your deck then dig and pour footing and foundation before you even think about cutting in to the wall. you could have it as living space in under two weeks with a organised contractor who knows what there doing.
    and remember concrete is stronger and quicker than block and you wont have water isues you will with block. block is cheaper for the contractor but will probably cost you the same i see it all the time.. anything to make a buck

    then you should pour a suspended slabfor your celing. you can build your deck on the slab or if you want more head room have them do a stamped patern on the concrete
    and you can keep it higher.

    hope this helps if you have any more questions let me know
  6. cm11599psWell Known MemberMember

    Hmm, sounds good and glad to know it's possible.

    The area we would be digging out at a maximum is 13'x16' The 16' section is the length of the foundation wall line but we may not have to go that long.

    Any idea on a general ballpark to have the following items done.

    1) Pour foundation and 3 walls
    2) Make cutout in existing foundadtion for an opening
    3) I Assume you would need to install bracing in existing foundation where it was cut out.

    The digging, framing and other construction things are not a problem for us. I'd just like to know a general ballpark for those items listed above.
  7. w_boughnerValued MemberMember

    for cost or method.

    cost footing and foundation 120-200 linear foot pending on height

    cuting the concreat - for a 3x7 mandoor we charge 800 for with out re-bar 1000 with re bar.

    and if you leave 10 inches of solid concreat between the top of door to brick you dont need a lintel. but if you have a block foundation you will defonatly need a lintel
    Last edited: Mar 22, 2010
  8. cm11599psWell Known MemberMember

    $$$ lol

    Right now we have my in laws living in the lower section so this isn't a plan that is happening any time soon. I'm just looking for a ballpark monetary figure so that I know if it's even worthwhile saving for.
  9. w_boughnerValued MemberMember

    and those prices are going rate in southern ontario and the foundation prices are just foundation not excavation
  10. cm11599psWell Known MemberMember

    Well, as long as it doesn't come out to be TOO much then my wife will be happy. She is very supportive of me and loves to have cool things in the house like this.
  11. jdhefModeratorModerator Member

    No need to brace exist foundation. Since the foundation is below the slab, there would be no need to cut it out. You would just remove the portion of the wall for the opening down to just below the slab (which should be the top of foundation), then cover it over with the new slab.
  12. w_boughnerValued MemberMember

    in that case you would have to pin and re-enforce your slab to the existing foundation
  13. cm11599psWell Known MemberMember

    I totally forgot that my coworkers long time boyfriend does all things concrete. I gave her the dimensions of what I'd like to do and she's gonna give me an estimate in a day or two!

    This project is a LOOONNNNNGG way off but I'd like to know if it's financially possible before trying to save for it.
  14. w_boughnerValued MemberMember

    well i hope it works out for ya
  15. jdhefModeratorModerator Member

    Should be no reason to pin the slab to the foundation. There is no lateral load so the foundation isn't going anywhere and there will be no stress transfered to the slab since it just floats.