Ashley P

Home building 101, er, 404?

175 posts in this topic

So I'm "planning" to add on to our house.  I want to put a basement under the addition.  One difficulty is placing a basement wall near my existing foundation/footer.   Pouring a concrete wall into forms requires space on the "back" of the form to remove it after pour, that would push the basement wall well away from the existing house.  One way around that is to use a ICF like BuildBlock for at least the one wall that borders the current foundation.  That way the wall could be built almost directly against the dirt, I would even waterproof them as I lay them.  Consequently I'm studying what the cost of BuildBlock would be for A) that wall only, B) whole basement, C) both basement and ground level walls.

Benefits of BB vs wood frame:  they include insulation and mounting for "wall covering" (sheet rock), so you don't lose 3.5" of interior space and don't have to frame or insulate the exterior wall, and it's air tight. That helps to offset the high initial cost (yet to be determined).

However, while the concrete is advertised as having a beneficially high "thermal mass", I think it's a liability (when used above ground) since concrete conducts heat so well compared to insulating materials.  That triggered another brain spasm resulting in....heating/cooling the concrete?

Since my water coupled heat pump simply dumps 6 or so gallons H2O per minute out in the creek the whole time the unit runs, I've got a "free" source for water that COULD be used to again  heat or cool the house...what if I put Pex tubing into the ICF before poring the concrete?  (Above ground walls only, BTW.)  Downside would be initial cost, possible leakage into concrete which would leak out eventually, weakening the wall to some extent, and worst case water freezing in the wall (highly unlikely and very preventable).

Thoughts?

http://buildblock.com/

http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

 

 

Edited by Ashley P

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John, I'd "studied" putting a basement under this house.  One major obstacle is that the "back porch" is added on to this house and has a concrete slab floor.  That would make it practically impossible to put I-beams under the house as they'd need to pass through or under that concrete.  If I could just slide beams under and support this house, I'd probably do it, rent a skid steer and dig it out.  Even so, the addition would not be big enough and a stairwell would eat up valuable existing upstairs space.

70k feet is a *little* big....unless that's including a garage w/indoor 1/8 mile dragstrip.  :O 

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John, I've been thinking that a basement under this house could work.  If the basement was made a little larger than the current house I think we'd have enough space. The current "back room" on a slab is 1/2 as long as the house. If it were to extend across the entire length, and a basement were under that, we'd then in total be adding about 1600 sq.ft on, so killing some upstairs room for a stairwell wouldn't kill us.

 My brother had a house moved 15ish years ago and I payed attention to how that was done.  My house has some negatives to sliding I beams under it:  slab back room, poured foundation (not blocks to punch through), chimney, in floor heater.   Well, I  removed the heater some time ago, this weekend framed up the opening "correctly" so as not to interfere with beams.   Weather broke Saturday afternoon so I used an air chisel and child labor to remove the chimney down to the interior wall.   Prepping to remove part of the surround and get the rest of it out.  The back room has out "utilities", so I might need to put all that in a storage shed adjacent to to the house to keep the house operational.

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10 hours ago, JohnC said:

What will a basement cost?

looks like it would be expensive to do. 

I'm not sure.  lol   But it's less than a basement AND upper level addition, right? lol

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Aren't you on a chunk of land? What about building a new house next to the current one? A builder friend of mine once told me the actual construction cost wasn't really very much, like 50K to get you 3000sqft. 

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whats the chances of you digging it out and the entire house collapsing? I'm with Disney on this one. May be cheaper just to build a new shell.

 

Side note - I finally signed on a contract yesterday.

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1 hour ago, Disney said:

Aren't you on a chunk of land? What about building a new house next to the current one? A builder friend of mine once told me the actual construction cost wasn't really very much, like 50K to get you 3000sqft. 

My reasoning (against a new house next to it) is we'd be throwing away a house that's worth $40k(?), I can't/don't want to afford that.  And a basement under current house would "fix" a few energy problems...no more cold crawlspace and no more ductwork in the attic.

1 hour ago, mstrpth said:

whats the chances of you digging it out and the entire house collapsing? I'm with Disney on this one. May be cheaper just to build a new shell.

Very slim.  Ground around here has high clay content and is very stable.   If it were to be supported on 50' I beams the load would be 10' away from the hole.

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46 minutes ago, Disney said:

Wonder if you could sell the old house.

Sent from my SM-N910V using Tapatalk

Then it would have to be moved, which would involve the same "structural mover" type companies I'm looking into now....anybody heard of Toothman Structural Movers out of Springfield TN?

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Talked to them, ballpark $10k.  That would include lots of dirt removal for beam installation, which I was hoping to do myself to save costs.  Flip side, it would be much faster.  Hmmm....ways to get them down to $6k.....workers on site get free lunches w/ice cream?

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 It's not a complete dig, but I didn't understand his description of how he'd put in the cribbing.  That can be explained later in person.

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Tonight it was air chisel, one man, and two boys vs. interior chimney.  Chimney lost.  Now just the base is left under the house.  Wife is thrilled to have 32ft3 more kitchen!   Might not have to add on...lol

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Met with house mover.  He first said 11+k.  I said "what if I.....".   He said $9k.  Thinking that's fair and likely the way to go.  Now to see if the farmer was serious about letting me use his hoe... ;)   I'd need to remove the rear "back room" that has HVAC and water heater.  I think water heater can go in the kitchen where the chimney was and the HVAC can hang on the soon to be exterior wall.

I wonder what my HOA and building inspectors will say.  Oh, that's right......

 

 

 

 

 

 

 

 

 

...they don't exist!   Muwahahahahaaa!

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On 6/28/2016 at 2:55 PM, Disney said:

10K to dig out basement and install support beam? Sounds really cheap to me.

He's not excavating for that $9k price.  What I had not understood the other day regarded his digging under the house for cribbing.   He explained that today; the main beams will be supported about 6' inside the existing foundation, so they're cantilevered.  He likes to put the cribbing on the basement floor grade, so there's a lot of material to remove for four  4'x4' bases.  But I'd guess only 1/10th of the total volume.   My wife can't visualize mechanical stuff and she was trying to understand how much dirt would have to be moved.  I said, more than this house full.  lol

But I think that after 12 years of marriage and 5 kids I've about got her trained.  She's HAPPY with a hole in the wall where the chimney was, and she's FINE with putting the kitchen table in the living room and the washer/drier where it was.   Or, she's gonna wait till I've torn off the back room, have the HVAC hanging on the back wall, house hung 10 foot above a huge hole in the ground...and drive off.   Hmmmm.....better pull the coil wires about then...

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19 hours ago, Disney said:

Man, that sounds really fair to me. Let me know when I keep to come help video tape this for you.

call me and we'll make a full blown production out of it.

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