2x4 frame bottom plates issue

Discussion in 'Remodel Forum & Blog' started by lmei007, Apr 8, 2012.

  1. lmei007

    lmei007 Member

    Messages:
    159
    Location:
    Maryland
    I have interior french drain around the basement concrete wall. In many places the concrete are less than 1" in thickness. we couldn't go deeper because the foundation doesn't have footing.

    If we use Tapcon, it may damage the french drain and it may also not hold well. Is there another way to fix the bottom frame plate? or i can leave them without mechanical connection with concrete floor.

    Any suggestions?
  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,143
    Location:
    South*East
    You could fasten two 2x4's with 1/2" plywood in between flat against foundation wall and start your framing from there.

    John
  3. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,244
    Location:
    Land of Cheese
    Particularly if you are insulating, there would be nothing lost (except a little bit of square footage) if you build the stud walls further to the inside of the exterior walls. In many basements you will find that the concrete walls are not plumb from one end to another, so you will need to come inwards to keep everything straight anyway.

    If you are planning any plumbing below slab, don't forget that it will need to be inside of the footing drain also.

    I don't understand how a basement wall cannot have a footing......
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,503
    Location:
    Cave Creek, Arizona
    A basement wall without a footing is a disaster waiting to happen. Even if your anchors penetrated the "French drain" it would NOT damage it, unless you used a red clay tile pipe.
  5. lmei007

    lmei007 Member

    Messages:
    159
    Location:
    Maryland
    Are you saying fasten the 2x4's with the concrete wall?
  6. lmei007

    lmei007 Member

    Messages:
    159
    Location:
    Maryland
    you are right, the plastic pipes should be ok but if the concrete cannot hold the Tapcons well, why I need those Tapcons?
  7. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,244
    Location:
    Land of Cheese
    The tapcons I am familiar with would not have the shear strength to be suitable for this type of application. You need to think about things that happen in a house- I.E. kids roughhousing, furniture getting pushed against the wall, etc. One situation that I vividly remember was a carpet installer using a carpet stretcher. When he applied pressure against the baseboard, he pushed the entire finished wall in because it was not nailed properly.

    We always use 3/8" Red Head Wedge Anchors when setting walls on concrete. The bottom plate should also be treated lumber unless you are using sill plate gasket or something similar to keep the wood up off the concrete.
  8. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    I'm really shocked here...

    Who cares how the 2x4 stud wall SHOULD be built, if that house is honestly missing footings, why bother doing anything inside it?

    Bulldozer.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,503
    Location:
    Cave Creek, Arizona
    Do you have any idea how much force it would take to "shear" almost any fastener when the two surfaces are in contact with weight on them? That wall was NOT improperly nailed, it was not nailed at all.
  10. Dana

    Dana In the trades

    Messages:
    2,806
    Location:
    01609
    The studwall is not structural- it's not supporting the house, and only needs sufficient strength to hold the wallboard and cavity insulation. Mechanically ins a near-zero load. The gypsum is required as an ignition barrier against your wall-foam.

    Run your floor foam all the way to the wall foam, and tapcon the subflooring to the slab a foot or so away from the edge ~24" o.c. or so, then nail the studwall plate to the subfloor- DONE! It's not going anywhere.
  11. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,244
    Location:
    Land of Cheese
    But in this case the new wall might eventually be holding the house up, as the OP states that there is no footing under the basement walls. :p
  12. lmei007

    lmei007 Member

    Messages:
    159
    Location:
    Maryland
    I have asked few experts. I was told it was not illegal to build a house without footing if the foundation soil was very stable back in 1950s. There is no single crack on this 60yrs house. That indicates it can still stand up for another 60yrs or so. I am not worry about this. So when I put the french drain. I used two 2" pipes to avoid a deep trench. I think this house is sitting on an old beach. When i dug hole for sump pump basin, which is at least 5' away from the wall, I found i was on a beach with lots of small rocks/gravels. The basement is a full basement. it is unlike a refill layer.
    Last edited by a moderator: Apr 9, 2012
  13. lmei007

    lmei007 Member

    Messages:
    159
    Location:
    Maryland
    Great! I like this idea. Thank you indeed.
  14. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,986
    Location:
    North Vancouver, BC
    Seriously. Bulldozer?

    My home was build in the 60's. In North Vancouver and served many families well up until two years ago when we ripped it apart.

    No footings.

    None.

    No rebar in the foundation walls as well. This was common back in the day.

    There are many ways to attach to the bottom plate to the slab. Consider attaching some 1/4" cement board to the bottom plate first and set the 2"x4" with thinset. You might use some waterproofing over this one stud to stop moisture migration.

    Building the wall a little tight and installing over a 3/4" ridgid foam insulation works. If the new wall is not bearing any weight.

    Building the wall a little light on the measurement and using spray foam to attach it top and bottom works as well.
  15. Dana

    Dana In the trades

    Messages:
    2,806
    Location:
    01609
    johnfrwhipple: He's already building it with more than 3/4" of foam on both the wall and the slab, and it needs to be more than 3/4" in his climate. With only 3/4" he'd be putting the studs at risk for mold growth from either wintertime condensation on the cold foam.

    An interior vapor retarder would cut the wintertime load, but raise the average load from ground moisture, which he clearly has, so to be safe he has to skip the poly, and keep the average winter temp at the foam/fiber interface above the interior dew point of design interior temp of 21C/35% relative humidity, which is +5C. This would not meet code in Canada, which requires the foam/fiber interface to be above +5C at the outdoor design temp, not the winter average temp. But in any climate warmer than Saskatchewan it would lower rather than increase mold risk with this approach.

    His average winter outdoor temp is about -4C, so with R13 batts in the studwall and R3.75 (3/4" XPS) the average temp at the foam/fiber interface on the above-grade section would be:

    -4C + [(21C- -4C) x (3.75/(3.75+13)]= +1.6C

    which is well shy of +5C.

    Bumping that to 1" would be code-legal here, but only yields about +3C.

    At 1.5" XPS (R7.5) or 2" EPS (R8) hie's in good shape though:

    -4C + [(21C- -4C) x (7.5/(7.5+13)]= +5.1C

    Any condensate that forms on the above grade portion in the overnight hours or during cold-snap re-evaporates before reaching the stud plate.

    Vancouver's average winter temp is about +3C, but the wintertime interior moisture is also much higher, so it's safer to design for the dew point of 21C/40% RH air, which is +7C.

    With 3/4" XPS you'd have:

    3C + [(21C- 3C) x (3.75/(3.75+13)]= +7C, which is perfectly safe...

    ...but not code-legal without interior poly in Canada.

    To meet code in Vancouver (outside design temp= -4.5C), if you bumped that to 1.5"/R7.5:

    -4.5C + [(21C- -4.5C) x (7.5/(7.5+13)]= +4.8C

    That's close enough to code legal without the poly that it should fly with inspectors, but you could use unfaced low density R11s rather than R13s, or unfaced 2"/R8 EPS rather than R7.5 XPS if they're they type that want to quibble.

    In Vancouver I'd either do that, or use 2.5"/R10 EPS or 2" XPS held in place with furring through-screwed to the foundation on which to hang the gypsum for a thinner stackup.

    In my own home (not too far from diyfun) I went with 3"/R19 fiber-faced iso + furring. The footings in my house are fully saturated with water 4-5 months of the year (high water table), yet the foundation dries adequately through the somewhat-permeable facers of the foam to keep from rotting out the foundation sills. If I went with foil-faced or poly I'd have to jack up the house and insert membrane capillary breaks under the foundation sills to protect them from ground moisture.
  16. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,986
    Location:
    North Vancouver, BC
    I thought the question was about fixing the bottom plate to his concrete basement floor?

    JW
  17. Dana

    Dana In the trades

    Messages:
    2,806
    Location:
    01609
    It was about fixing the bottom plate to the concreted floor, but unless you'd read his other threads you wouldn't necessarily have known the rest of the construction details. The fact that he is putting down floor-foam and a subfloor, and wall-foam to boot changes what might otherwise be a good recommendation.

    The discussion about the wall foam was for your benefit, since the thickness you recommended was wholly inadequate for his climate & construction, (but fine for yours.)
Similar Threads: frame bottom
Forum Title Date
Remodel Forum & Blog Best way to frame concrete half wall in daylight partial exposure basement? Mar 12, 2014
Remodel Forum & Blog Recessed Wood Framed Mirror -- how to remove caulk without damage? Oct 23, 2012
Remodel Forum & Blog fixing wall that bows out past door frame Feb 8, 2010
Remodel Forum & Blog A-Frame heat improvements Dec 29, 2009
Remodel Forum & Blog Wooden Frame in Shower area.. How to Seal... HELP Sep 29, 2008

Share This Page