Wisconsin Administrative Code › Department of Safety and Professional Services › SPS 301-399 - Safety, Buildings, and Environment › SPS 320-325 - Uniform Dwelling Code › Chapter SPS 321 - Construction Standards › Subchapter V - Foundations › Section SPS 321.18 - Foundations

Current through June 24, 2024
(1) GENERAL.
(a)
Design.
Foundation walls
					 shall be designed and constructed to support the vertical loads of the
					 dwelling, lateral soil pressure, and other loads without exceeding the
					 allowable stresses of the materials of which the foundations are
					 constructed.
(b)
Lateral
					 support at base.
Lateral support such as floor slabs or framing shall
					 be provided at the base of foundation walls.
(c)
Lateral support at top.
Lateral support shall be provided at the top of the foundation walls
					 by one of the following:
2. Structural
					 analysis. A system designed through structural analysis.
3. Anchor bolts.
a. Structural steel anchor bolts, at least
					 1/2 inch in diameter, embedded at least 7 inches into the concrete or grouted
					 masonry with a maximum spacing of 72 inches and located within 18 inches of
					 wall corners.
b. A properly sized
					 nut and washer shall be tightened on each bolt to the plate or sill.
c. When vertical-reinforcing steel is
					 provided in masonry construction, as required under sub. (3), the location
					 requirements under subd. 3.a. shall be modified as necessary so anchor bolts
					 are placed in the same core as the reinforcement without exceeding the limits
					 of subd. 3. a.
d. Alternate
					 foundation anchorage, designed and spaced in accordance with structural
					 analysis and as required to provide equivalent anchorage to the requirements of
					 subd. 3. a., is allowable.
4. Other mechanical fasteners.
a. Mechanical fasteners used in accordance
					 with the manufacturer's testing and listing.
b. When vertical-reinforcing steel is
					 provided in masonry construction, as required under sub. (3), the location
					 requirements under subd. 4. a. shall be modified as necessary so the fasteners
					 are placed in the same core as the reinforcement without exceeding the limits
					 of subd. 4. a.
(d)
Floor framing
.
1. Floor framing shall be fastened to the
					 sill plate by one of the following methods:
a. Mechanical fasteners used in accordance
					 with the manufacturer's testing and listing.
b. In accordance with structural
					 analysis.
c. In accordance with the
					 fastener table printed in ch. SPS 325 Appendix A.
Note:
Per s.
						SPS
						321.22(1), sill plates are not
						required on foundation walls of poured concrete or on masonry walls with
						mortar- or grout-filled cores or on masonry walls with a solid block top
						course.
2.
a. Where the floor framing is parallel to the
					 foundation wall, solid blocking or bridging shall be installed in at least the
					 first adjacent joist space at a spacing of no more than 32 inches on
					 center.
b. Blocking and bridging
					 shall be the same depth as the joist.
c. Fastening of the blocking or bridging
					 shall be in accordance with structural analysis or the fastener schedule in
					 Table 321.02-2.
Note:
The floor-framing elements required in
						this section are intended to provide lateral support to the top of the
						foundation wall. See s.
						SPS
						321.22(9) for further requirements
						relating to floor framing, including for bridging of floor framing to provide
						restraint against rotation or lateral displacement of the floor framing.
(e)
Soil lateral load.
Unless designed through structural
					 analysis, soil lateral loads shall be determined from Table 321.18-A.
Table 321.18-A
SOIL LATERAL LOAD
Description of Backfill
									 Materiale
Unified Soil Classification
Design Lateral Soil
									 Loada PSF per Foot of Depth
Well graded, clean gravels; gravel-sand
									 mixes
GW
30c
Poorly graded clean gravels; gravel-sand
									 mixes
GP
30c
Silty gravels, poorly graded gravel-sand
									 mixes
GM
40c
Clayey gravels, poorly graded gravel-and-clay
									 mixes
GC
45c
Well-graded, clean sands; gravelly sand
									 mixes
SW
30c
Poorly graded clean sands; sand-gravel
									 mixes
SP
30c
Silty sands, poorly graded sand-silt
									 mixes
SM
45c
Sand-silt clay mix with plastic fines
SM-SC
45d
Clayey sands, poorly graded sand-clay
									 mixes
SC
60d
Inorganic silts and clayey silts
ML
45d
Mixture of inorganic silt and clay
ML-CL
60d
Inorganic clays of low to medium
									 plasticity
CL
60d
Organic silts and silt clays, low
									 plasticity
OL
b
Inorganic clayey silts, elastic silts
MH
60d
Inorganic clays of high plasticity
CH
b
Organic clays and silty clays
OH
b
aDesign lateral soil loads are
						given for moist conditions for the specified soils at their optimum densities.
						Actual field conditions shall govern. Submerged or saturated soil pressures
						shall include the weight of the buoyant soil plus the hydrostatic loads.
bUnsuitable as backfill
						material.
cFor relatively rigid walls,
						as when braced by floors, the design lateral soil load shall be increased for
						sand and gravel type soils to 60 psf per foot of depth. Basement walls
						extending not more than 8 feet below grade and supporting flexible floor
						systems are not considered relatively rigid walls.
dFor relatively rigid walls,
						as when braced by floors, the design lateral load shall be increased for silt
						and clay type soils to 100 psf per foot of depth. Basement walls extending not
						more than 8 feet below grade and supporting flexible floor systems are not
						considered relatively rigid walls.
eSoil classes are in
						accordance with the Unified Soil Classification System, ASTM D2487, and design
						lateral loads are for moist soil conditions without hydrostatic
						pressure.