| Author |
Message |
Colin Gilboy
Senior Member
Username: colin
Post Number: 237
Registered: 09-2005
| | Posted on Tuesday, July 27, 2010 - 10:24 am: |    |
Flatness, Levelness, F-Numbers, Straightedge: What do the numbers mean? Recent changes to ACI 117 provide new procedures for straightedge measurements for floor slab flatness. Under the revised standard, 1/8 inch in 10 feet is not a standard option. Learn what each term means and how to specify floor slab tolerances in accordance with industry standards for each floor surface classification.
http://www.conspectusinc.com/downloads/Documents/publications-download-TT-A4010.htm
Colin Gilboy
Publisher, 4specs.com
435.654.5775 - Utah
800.369.8008 |
Marc C Chavez
Senior Member
Username: mchavez
Post Number: 387
Registered: 07-2002
| | Posted on Tuesday, August 10, 2010 - 12:35 pm: | |
I will certainly get the new version of ACI 117 However; the discussion in David's article missed (IMHO) a major point. I don't care how flat the SOG (or suspended slab) is the day it’s poured; I care how flat it is the day the flooring sub tells me they cannot warrant the floor because it is not flat enough!
The concrete crew falls back on ACI and says they can only do so much with wet concrete – on suspended floors - with metal deck and cambered beams blah blah blah and how I just have to lump it! Well I don’t!
My specification requires Ff and Fl numbers at the time of FINAL FLOOR FINISH (The ACI doc is limited to initial finish, the ASTM for the test IS NOT limited) and yes they have to grind or better yet use cementitious underlayment to get the floor as flat as we need it for various floor finishes. This places the cost of floor flatness squarely on the back of the GC and it does not become an “extra” that the owner has to pay inflated change order prices for.
Supercap, Dayton Superior, and others have studied the idea of simply bull floating the concrete (I’m being general here) and leaving – no steel trowel – no extensive finishing – THEN come back and float the entire floor with (very expensive) underlayment – and guess what …the cost is the same as spending all that labor on finishing and we get a flatter smother floor.
Don’t forget what you need on a floor is the end product NOT the product within three days of pouring! |
Ellis C. Whitby, AIA, PE, CSI, LEED® AP
Senior Member
Username: ecwhitby
Post Number: 67
Registered: 03-2003
| | Posted on Wednesday, August 11, 2010 - 08:20 am: | |
Years ago, one of my brothers worked in Hong Kong. During one of our may discussions on the differences in AE and construction practice between the US and teh "far east" he explained that the structural floors were typically poured 2 to 3 inches "below" the final finished floor elevation and that a "topping slab" was then placed, which was expected to be "dead flat". I do not know what system is used now.
Marc: I would be very interested to see a cost comparison of the "topping" method you describe versus the "traditional" method. To be most useful of course, the relative costs for each method would have to be figured out for the different regions in the US. |
|
4specs.com Home Page