Concrete Deck Blocks Compressive Strength

[Francis Vineyard]

Can you provide the code section(s) that requires a minimum compression strength for concrete deck footings?

2015 IRC Section R507.8.1 sends you to Section R403 for depth and sizes. Additionally Table R402.2 does not list Deck Post Footing.

R507.8.1 Deck post to deck footing. Posts shall bear on

footings in accordance with Section R403 and Figure

R507.8.1. Posts shall be restrained to prevent lateral displacement

at the footing. Lateral restraint shall be provided

by manufactured connectors installed in accordance

with the manufacturers’ installation instructions or by a

minimum post embedment of 12 inches in

surrounding soils or concrete piers.

 

[JBI]

Concrete deck footings are a 'foundation' and the table does list 'foundations'.

"Basement walls, foundations and other concrete not exposed to the weather"

 

[Francis Vineyard]

John, thanks for the quick response.

I needed specific language to argue though different elements they are understood to be interdependent for design purposes. Perhaps the IBC definition should be satisfactory.

SHALLOW FOUNDATION. A shallow foundation is

an individual or strip footing, a mat foundation, a slab-on grade

foundation or a similar foundation element.

DEEP FOUNDATION. A deep foundation is a foundation

element that does not satisfy the definition of a shallow

foundation.

 

[mark handler]

The minimum average net compressive strength per ASTM C90, 2014 edition, is 2000 net psi.

I do not thave the standards with me but look in the code standards.

 

[steveray]

I'd go with 402.2 too.......

 

[north star]

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From the DCA 6 - Prescriptive Residential Wood Deck Construction

Guide, based on the 2012 IRC:



FOOTINGS [ R403 ]:

See Figure 12 and Table 4 for footing size, footing thickness

and post attachment options and requirements. All footings

shall bear on undisturbed soil at least 12 inches below the

undisturbed ground surface or below the frost line, whichever

is deeper. Contact the authority having jurisdiction to

determine the specified frost line. Bearing conditions shall

be verified in the field by the building official prior to

placement of concrete. Where the building official

determines that in - place soils with an allowable bearing

capacity of less than 1,500 psf are likely to be present at the

site, the allowable bearing capacity shall be determined by

a soils investigation.

Also, see Figure # 12 on Page 13 for Typical Footings.

Here is a link to the DCA 6 Deck Construction Guide.

http://www.awc.org/pdf/codes-standards/publications/dca/AWC-DCA62012-DeckGuide-1405.pdf





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[ADAguy]

The AWC indicates 2,500 PSI, note that post footings are concentrated point loads vs spread footing loads.

 

[Francis Vineyard]

The AWC indicates 2,500 PSI, note that post footings are concentrated point loads vs spread footing loads.

In accordance to what code section? The footings referenced R403 and assumes compressive strength!

And according to Mark's post (#4) it could be 2,000

 

[mark handler]

In accordance to what code section? The footings referenced R403 and assumes compressive strength! And according to Mark's post (#4) it could be 2,000

The minimum average net compressive strength per ASTM C90, 2014 edition, is 2000 net psi.I do not thave the standards with me but look in the code standards.

minimum average, It maybe higher