1 of 23

foundation workbook

Open Building Institute

2 of 23

foundation workbook

details

3 of 23

6 mil polyethylene vapor barrier

4” of gravel

4” concrete slab

12”

12”

6”

6”

housewrap

foam sill gasket

PT sill plate

2” EPS

2x6 wall

vinyl flashing

vinyl clapboard siding

finished grade

frost protected shallow foundation : slab on grade : detail

MASA or MASAP mudsill anchor

SEE QUESTIONS FOR ENGINEER IN THE NEXT TWO PAGES

4 of 23

frost protected shallow foundation : slab on grade : questions for engineer

QUESTION FOR ENGINEER (1 of 2)

Simpson describes several code compliant installation options for their MASA anchors. Our case is actually a combination of 3 of their options: a) we have a double 2x sill; b: we have double studs (every 4 ft); and c) we have 7/16” osb attached to the wall panels.

7/16 osb

double studs

concrete foundation

double sill/bottom plate

OUR CASE

MANUFACTURER RECOMMENDATIONS (click images for link to source)

5 of 23

frost protected shallow foundation : slab on grade : questions for engineer

QUESTION FOR ENGINEER (2 of 2)

Simpson makes two versions of this anchor:

  1. MASA seems to be designed to wrap around the sill plate - or be installed with a single leg up (attached to stud)
  2. MASAP appears to be indicated for SIP construction (attached with 2 legs up)

So MASAP seems to be the one we would want for our panelized system, but has 1 major setback: it doesn’t lay flat on the forms (as MASA does). The question is then if we can use the MASA anchors with 2 legs up (instead of the MASAP) and increase the schedule?

6 of 23

6 mil polyethylene vapor barrier

4” of gravel

4” concrete slab

12”

12”

6”

6”

housewrap

foam sill gasket

PT sill plate

2” EPS

2x6 wall

Post-installed concrete anchors

vinyl flashing

vinyl clapboard siding

finished grade

frost protected shallow foundation : slab on grade : detail

QUESTION FOR ENGINEER

Can a 2x6 sill plate (supporting 2x6 walls) overhang the rigid foam insulation 2”?

7 of 23

foam sill gasket

2” EPS

exterior door

vinyl flashing

PT 2x4

PT 1/2” plywood

butyl flashing tape

⅜ x 6 trimboard

(to cover flashing tape)

finish concrete floor

frost protected shallow foundation : slab on grade : door detail

8 of 23

9 of 23

6 mil polyethylene vapor barrier

4” of gravel

4” concrete slab

12”

12”

6”

6”

through-wall

vinyl flashing w/ back dam

concrete anchor

housewrap

foam sill gaskets

2x4 mudsill

2” EPS

2x6 wall

frost protected shallow foundation

10 of 23

6 mil polyethylene vapor barrier

4” of gravel

4” concrete slab

12”

12”

6”

6”

through-wall

flashing w/ back dam, doubles as thermite shield and insulation protection

concrete anchor

housewrap

foam sill gaskets

2x4 mudsill

2” EPS

2x6 wall

frost protected shallow foundation

11 of 23

6 mil polyethylene vapor barrier

4” of gravel

4” concrete slab

12”

12”

6”

6”

through-wall

flashing w/ back dam, doubles as thermite shield and insulation protection

concrete anchor

housewrap

foam sill gaskets

2x4 mudsill

2” EPS

2x6 wall

frost protected shallow foundation

12 of 23

frost protected shallow foundation

6 mil polyethylene vapor barrier

4” of gravel

4” concrete slab

12”

12”

6”

6”

through-wall

flashing w/ back dam, doubles as thermite shield and insulation protection

concrete anchor

housewrap

foam sill gaskets

2x4 mudsill

2” EPS

2x6 wall

13 of 23

6 mil polyethylene vapor barrier

4” concrete slab

foam sill gaskets

concrete anchor

through-wall

flashing w/ back dam, doubles as thermite shield and insulation protection

12”

6”

housewrap

4” of gravel

12”

6”

2” EPS

frost protected shallow foundation

14 of 23

frost protected shallow foundation

15 of 23

uninsulated foundation

6 mil polyethylene vapor barrier

4” concrete slab

foam sill gaskets

concrete anchor

through-wall

flashing w/ back dam

12”

6”

housewrap

4” of gravel

12”

16 of 23

foundation workbook

dimensions

17 of 23

380”

188”

2” rigid insulation

exterior turned-down footing

12” x 18”

4” concrete slab

12”

18”

4”

12”

12

4”

thickened slab (stairwell)

12” x 12”

72”

132”

48”

½” = 1’

FRONT

frost protected shallow foundation : slab on grade : dimensions

18 of 23

12”

18”

4”

12”

12”

4”

1” = 1’

Footings

19 of 23

foundation workbook

sill plate

20 of 23

½” = 1’

FRONT

frost protected shallow foundation : sill plate

2x6 : 96”

2x6 : 96”

2x6 : 96”

2x6 : 47”

2x6 : 95”

2x6 : 96”

39”

2x6 : 96”

2x6 : 96”

2x6 : 54.5”

2x6 : 52.5”

74”

2x6 : 100.5”

2x6 : 52.5”

39”

Expansion door

21 of 23

foundation workbook

anchors

22 of 23

QUESTION FOR ENGINEER

The IRC requires:

  • Anchors spaced a minimum of 6’ apart
  • A minimum of 2 anchors per plate section
  • One anchor no more than 12” from each end of a plate section

According to this, if we used, for example, 12’ boards for our sill plate, we’d only need 3 anchors per board. However, regardless of the length of our sill plate boards, the bottom plate on our wall modules is usually 48” (some are shorter). The adjacent studs on wall modules are nailed together per the IRC (see IRC section R602.10.4.4 Panel Joints). Does the bottom plate of the modules count as a sill plate for code purposes and does this mean that we need to use 2 anchors per module? Or only the actual sill plate counts (in which case we could use 3 anchors per 12’ board)?

48” wide

wall module

48” wide

wall module

48” wide

wall module

12’ long sill plate

2 anchors per module?

0r 3 anchors per 12’ board?

Adjacent studs of wall modules nailed together

per section R602.10.4.4 of the IRC

23 of 23

technical: foundation

concrete anchors

  • MASAZ - Zmax finish, compatible with pressure-treated lumber
  • Specifications (scroll down for Spacing Tables and Load Tables)
  • Code Compliance Report