Technical Manual

Inc.

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APPENDIX 4D

SMARTJACK® SYSTEMS

Chapter 4

Miscellaneous Structural Support Products

Design Example

Step 1

- Determine the load which will be supported by the girder in pounds per linear foot:

Girder Load (plf) = (Span 1 (ft) + Span 2 (ft)) x Floor Load (psf) ÷ 2

Note 1:

Typical residential wood-framed construction may have an approximate floor load (dead

load + live load) = 55 psf

Note 2:

This equation assumes a floor system which does not support any load bearing walls or

columns.

Step 2

- Determine the load on the SmartJacks

by multiplying the calculated Girder Load (plf) by the

spacing of the SmartJacks

SmartJack Load (lbs) = Girder Load (plf) x SmartJack

Spacing (ft)

Step 3

- Verify that the calculated SmartJack

load is less than the allowable capacity provided by the

various system components as well as the well-compacted crushed stone base and the bearing soils.

Note 3:

Without a detailed soil investigation, typical installations should assume no more than

1,500 psf allowable soil bearing pressure. This would equate to an allowable soil capacity of

6,000 lbs for a 2’x2’ poured concrete footing or a 2’ cube of well-compacted crushed stone.

Extremely soft soils may prohibit the use of a crushed stone base or require that a larger poured

concrete footing be utilized.

Step 4

- Size the new girder by entering the following table with both the SmartJack

Spacing (ft)

and the calculated Girder Load (plf). Choose a girder that has an Allowable Load (plf) greater than the

calculated Girder Load (plf).

Rev. 9/23/15