Chapter 9: Sill Plates
1. Introduction
The importance of proper installation of the sill plates cannot be overemphasized. They carry a large part of the structural load and must be adequately and continuously supported. They must be installed level and with square corners so that all the rest of the structure may be easily squared, plumbed, and leveled. A sill sealer, gasket, or grout should be used between the sill plate and the foundation to prevent air and water infiltration.
2. Safety Issues
- Review the Morning Safety Huddle Talking Papers for Ladders with the volunteers
- Use safety glasses with power tools and while chipping any rough edges from the concrete foundation.
3. Prior Tasks to be Completed Before Starting
- Foundation backfilled.
- Steel beam installed.
- Beam pockets grouted.
- Smooth off or remove any bumps on the top of the foundation.
4. Recommended Staff/Crew Assignments
- 2 people lay out sill plate perimeter on top of foundation.
- 2 people install 2 x 4 plate on beam.
- 2 crews of 3 cut, drill, and install sill plates.
- 2 persons level and install washers and anchor bolts.
5. Order/Tasks to be Completed
____1. Lay out sill plate perimeter on top of foundation.
____2. Install 2 x 4 plate on top of beam.
____3. Cut, drill, and install sill sealer and plates.
____4. Install anchor bolts, washers, and nuts.
____5. Level / shim sill plate and retighten nuts.
6. Tools/Equipment List
- Circular saw
- Drill and 5/8" bit
- Hammers
- Laser level
- Square
- Pencils
- Chalk box
- 100 ft tape measure
- Extension ladder
- Extension cord
- Staple gun
- Rotohammer drill
- Safety glasses
- Gloves
7. Material List
- Nails 8d, 16d
- 2 x 4 lumber for steel beam if applicable
- 2 x 6 lumber treated for sill plate
- Sill sealer (150 ft)
- Construction adhesive (Liquid Nails)
- ½" x 6" expansion anchor bolts
- Steel shims
- Foam sealant
8. Quality Checkpoints
____1. Sill plate level and straight.
____2. Agree with plan dimensions.
____3. Corners square.
____4. Diagonal measurements right.
____5. Continuous support - grout as needed.
9. Construction Drawings and Text
NOTE: The following drawings, diagrams, and text are to be used on the job site when a question arises as to methods and procedures associated with the task. The notes on the drawings have been geared toward use as a quick reference. If a more in-depth explanation is needed, please read the text description. But most importantly, consult your Habitat Site Supervisor and Construction Manager for advice as needed.
Lay out perimeter of sill plate on the top of the foundation wall. This should align with the outside of the foundation.
Trial locate both rear (or front if instructed by HFHSL construction staff) corners of the sill plate. Then measure forward from one rear corner and mark an arc at the distance for that side. Then, measure from the opposite rear corner the diagonal distance that will ensure a square corner and mark where this distance crosses the previous arc. That is the front corner point for the sill plate. The diagonal distance will likely be provided on a detail sheet but can be calculated by:
Diagonal distance = the square root of the sum of the square of both sides
This is a very easy calculation if you have a calculator that has square and square root functions.
Then locate the other front corner and the other corners of the sill plate perimeter in the same manner. Caution should be taken on a brick veneer house as the foundation will be approximately 4 inches longer and the sill plate should not cover the foundation where brick will be laid.
Adjust sill plate layout for best all-around-fit on your foundation.
Snap chalk lines on the foundation marking the outside edge of the sill plate.
Select the longest treated 2 x 6 available to minimize joints. No piece shorter than 8' 0" should be used when possible. Do not use severely warped or crooked pieces. If warped lumber must be used, a chalk line can be snapped on the convex edge and then a cut can be made to give a straight edge. This straight edge will be the outside edge of the sill plate.
Starting along the long walls (usually the side walls) place the square end of the 2 x along the rear plate line. Mark anchor bolt locations with lines across the 2 x 6. Measure the distance from the chalk line to each bolt centerline and mark the centerline of the bolt location on the 2 x 6 for drilling.
Cut plate to length and drill 5/8" holes at bolt locations.
Sill sealer can be stapled to the underside of plate.
Install plates as finished. Continue until all plates are installed with washers and nuts. NOTE: It is preferred but not necessary for there to be an anchor bolt within 12" of any end of a board. At these locations you may need to drill (in place) holes with a hammer drill to set a 6" expansion anchor.
Toenail butt joints and corners with (2) 8d nails.
If the foundation high point and required shims have already been measured and marked on the foundation, install shims at each bolt location as the plates are installed. If this has not been done, then use a laser level or level and shims to level the plate. Final level check should be made with nuts tight.
Extreme gaps can be filled by 2 layers of sill seal or foam sealant.
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Page last updated Saturday, May 3, 2008 at 6:39:51 PM
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