×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Stoop with no Foundation Wall

Stoop with no Foundation Wall

Stoop with no Foundation Wall

(OP)
I'm in the Midwest and we typically detail stoops with foundation walls that are extensions of the building foundation wall. I'm currently working on a project with 1000's of feet of storefront where a door could be inserted anywhere along the storefront. We are trying to figure out a way to have a stoop without the additional 4ft tall foundation wall parallel to the building foundation wall. I will be doweling the stoop slab into the building foundation wall, I'm just worried that will act like a hinge. I've heard that on the east coast they use a detail similar to this with no stoop walls. Anybody have a suggestion?

Thanks!

RE: Stoop with no Foundation Wall

Use 4 feet of non-frost susceptible (well graded granular with less than 6% passing a no. 200 sieve) fill below the stoop slab. An alternate would be to provide 2" Styrofoam under slab. Keep water from building up under the slab by providing drain tile in either case. This will prevent creation of ice lenses under the slab. Dowel the stoop slab to the foundation wall.

Have the GC coordinate the joints in the slab placement as information becomes available.

I hope this helps.

RE: Stoop with no Foundation Wall

I've seen retail centers where the entire front area was a structural slab with a void below (using metal deck or cardboard void forms).

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: Stoop with no Foundation Wall

I got started in the midwest and "grew up" with the same detail which I miss dearly, truth be told. I subsequently moved north to Canada where heave us more of an issue and several variants are used:

1) Shallow frost protected apron slab with edge thickening (non-expansive soli).
2) Thin suspended slab with a grade beam and screw piles out front and void form below (expansive soils).

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Stoop with no Foundation Wall

In Maine I see a lot of option 1 that KootK posted with an option 3 being drilled holes below grade with precast frost posts or poured concrete posts using sonotubes (more common in residential).

Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com

RE: Stoop with no Foundation Wall

I misread your question. With the solution that I had previously suggested, I would still have a continuous frost depth foundation wall parallel with the building foundation. Having a parallel frost depth foundation wall and a slab on grade does not necessarily prevent slab heave unless it is bridged with a structural slab with a void underneath (as JAE suggests) or an insulated slab or non-frost susceptible fill with drainage below the slab on grade. Slab should also slope away from the building.

RE: Stoop with no Foundation Wall

Another option that may/may not be cost effective: a few scoops with a backhoe down to frost...fill with lean concrete to elevation less the slab thickness. "Sidewalk slab" poured on top. You've got a nice mass of concrete bearing at frost elevation, supporting your sidewalk slab. Doubt that would go anywhere. Smooth trowel on the lean concrete with a layer of visqueen between the two allows initial shrinkage of the sidewalk slab. Dowel into bldg side foundation as you stated.

I also like option 1 suggested by KootK so long as the subgrade is fill not susceptible to frost (verify composition with geotech?). I like the idea of extending the "non-frost fill" down to 4' and beyond the plan extents of thickened edge stoop slab by a few feet (give contractor a min dimension).

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources