Chapter 11: Exterior Framing / Polystyrene

Installing the Blue polystyrene is typically a quick job that volunteers enjoy doing because of the lightweight material and the ease of application. Doing this task correctly is important to make the house more energy-efficient in the long run, so it is good to apply carefully. The "Blue Board" adds an additional R value to the house. Because it is easier, this is typically done before the walls are raised but may be completed after the walls are raised.

2. Safety Issues

• Review the Morning Safety Huddle Talking Papers for Deck Work with the volunteers
• Assure that no workers are positioned on the ground along a wall being raised
• Work at all times facing the leading edge of the deck. Work in a crouching position when within three feet of the leading edge
• Assure that windows, doorways not currently in use and floor openings are barricaded as soon a practical.
• Build and install a set of steps following the detail sketch in the Construction Manual as soon a possible after creating a door opening in the exterior wall.
• Volunteers should be instructed in proper use of power tools and safety precautions.
• Wear ear & eye protection when using power saws.
• Discard bonding material from bundled lumber. The corners may be very sharp and can cause injury.
• Use a ladder that will reach the work. Move the ladder with your work & don't lean. Place ladders on solid footing and have someone holding the ladder when mounting and dismounting the ladder.
• Habitat requires that hard hats be worn if any work is being done overhead.

3. Prior tasks to have been completed before starting

• Floor joists installed and subfloor laid.
• Materials on site.
• Foundation backfilled.

4. Recommended Staff/Crew Assignments

• One person to be safety supervisor.
• A crew of 3 to build headers (unless window and door framing has been prebuilt).
• A crew of 3 to be the saw crew.
• The remaining volunteers can be divided into crews of 5 - 6 to assemble and sheath walls and then to apply blue board and house wrap.

6. Tools/Equipment list

• Hammers
• Nail aprons
• Sledge hammer
• Tape measures
• Pencils
• Chalk box
• String
• Cat's paw
• Prybar
• Carpenter's square
• Speed square
• 6 foot level
• Twelve-Gauge Drop Cords (50'-100' as needed for power at site)
• Reciprocating saw
• Compound miter saw
• 2 saw horses
• Heavy-duty Power Strips
• Circular Saw ( 7 ¼")
• Extension Ladder (16')
• Step Ladders (8')
• Step Ladders (6')
• Table Saw (for cutting window nailing strips if not provided)
• Safety glasses
• Hard Hats
• Stapler

7. Material List

• 2 x 4 lumber, long lengths for plates
• 2 x 4 lumber, precuts for framing
• ½" sheathing, OSB or plywood
• 1" blue polystyrene board
• 8d nails
• 16d nails
• 2 x 4 lumber, long lengths for bracing
• Button cap nails
• Tyvek tape
• 5/8" Gypsom board (if applicable)
• Drywall tape (if applicable)
• Joint compound (if applicable)
• Sill seal
• Gable trusses (if applicable)
• 2 x 6 lumber (if applicable)

8. Quality Checkpoints

____ Chalk line layout is correct
____ Plates laid out correctly
____ All studs properly crowned
____ Walls built with correct nailing pattern
____ Fire blocking installed (if applicable)
____ Wall sheathing installed correctly and with correct nailing pattern
____ Gable ends built and attached (if applicable)
____ Blue insulation board nailed securely (to wall studs, not just sheathing)
____ Blue insulation board seams are staggered so that they do not coincide with sheathing seams
____ Blue insulation board seams taped (if instructed by HFH staff)
____ Raise walls and brace
____ Tape house wrap at corners
____ Apply any sheathing or blue board not previously installed
____ Check for plumb and straighten walls

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.

Framing Layout
Measure in 4 inches from the outside of each edge of the subfloor and snap a chalk line to identify the location of each exterior wall. Long 2 x 4 lumber should be used for the bottom plate and top plate. If your longest one does not span the length of the wall, butt multiple pieces together. Ideally, but not required, each butt joint should occur at a stud location or header location. Using a tape measure, pencil, and speed square mark the framing layout on the bottom plate.

It is best to layout the longest walls first so that they extend the full length of the house less one inch. Making it one inch shorter than the full length will allow for sheathing from adjacent walls to cover the end for additional strength. An exception to this rule is if you are instructed to build and raise the gable trusses with the front and back walls. In this case, the side walls are built last.

According to the plans, locate all windows and doors. The rough opening should be marked on the plate. The rough opening for both a door and a window will be 2 inches greater than the stated dimension. Mark these points on the plate and then additional marks 1 ½" away from the opening. Make lines across the plate and put a "J" between the marks for "jack stud". Jack studs support headers. Make additional marks 1 ½" from the jack stud and mark with an "X". This will be the "king stud, a full precut stud. Proper window and door location is necessary even if the framing for these has been preassembled.

If the wall extends to the edge of the subfloor, hook the end of the tape measure over the end and make a mark at ½" and at 2" from the end. This will mark the first stud and allow for the sheathing from the intersecting wall. The studs are typically laid out at 16 inches on center. The next stud will be marked between 15 ¾" and 17 ¼". Some people will move the tape measure back ¼" off the end so that it can be marked at 16" and 17 ½", then continuing every 16 inches the length of the wall. Others will put a nail at 15 ¾" and then mark every 16 inches the length of the wall. Shorter walls are done last and are laid out in the same manner. The second stud may be offset so that the second stud center is 16" from the outside of the wall it intersects. Use a speed square to make lines across the plate at each mark. An "X" should be put between each set of marks at each location where a precut stud will be used.

At each end that extends to the edge of the sill plate, an additional 2 x 4 should be marked next to the end stud. It should be turned sideways and should be flush with the inside edge of the plates so that it forms an "L". This will allow for more surface area to nail into from the intersecting wall, will provide a drywall nailer, and will allow space behind it for insulation.

Transfer framing layout to the top plate using the speed square.

Framing
Long walls should be built and raised first. Shorter adjoining walls are built later. It is important not to try to build too many walls at one time as this can lead to increased confusion and limited working space.

click to enlarge

click to enlarge

Walls taller than 8 feet require fire blocking to limit the potential of a fire spreading. After the wall has been framed and before it is sheathed, measure 8 feet from the bottom plate on both ends. Snap a chalk line between these points. In each stud cavity, install a 2 x 4 block cut to size (most will be 14 ½"). The first should be placed with the top edge aligned with the chalk line. The next should be placed with the bottom edge touching the chalk line. This staggering pattern should continue the length of the wall and will allow nails to be driven through the studs into the blocking without interference from previously installed blocks.

If the plan calls for cornice work on a second floor wall or porch beams, see plans and HFHSL staff for details.

Before sheathing the wall, the wall needs to be temporary secured to the deck and squared. Move the wall so that the bottom plate is at the chalk line on the deck. Toenail 16d nails through the bottom plate into the subfloor. This should be done through the surface of the bottom plate that will be facing up when the wall is raised. Nails should be placed every 6 - 8 feet. Measure the wall from corner to corner and then measure the opposite corners. Move the top plate until these two measurements are equal. Then, toenail 8d nails into the top of the top plate every 6 - 8 feet. Leave the heads up for easy removal later. The wall is now square.

If the plan calls for you to raise the gable trusses when raising the walls, the gable trusses should be assembled as explained in the chapter on trusses prior to the installation of the sheathing. It should include the 2 x 4 used as a nailer. The end wall may need to be raised several inches to ensure the the front of the wall and the front of the gable truss are flush. To do this, the 8d nails toenailed into the top plate will need to be removed. Prior to doing this, nail a brace from the outer edge of each end of the top plate diagonally to the bottom plate. This will ensure that the wall remains square. It is also important to install a cap plate to the end wall prior to attaching the gable end. If this is not done the wall will not be the proper height. It would be wise to stop the cap plate 3 1/2 inches shy of each end of the top plate so that the cap plate of the side walls can be slid in later. Once this is done, the gable truss can be attached by nailing 16d nails through the nailer into the cap plate every 12 inches.

Sheathing

Drawing 9: Plywood Sheathing Click to enlarge.

Sheathing, OSB or plywood, is laid onto the framing so that the long sides will be vertical when standing. Prior to applying sheathing, chalk lines are snapped every 16 inches to assist with nailing. Each edge should fall on the midpoint of a stud, except the end piece that will cover the entire stud. The sheathing should not extend beyond the bottom of the bottom plate. Nail with 8d nails every 8 inches, 6 inches on the perimeter. The end piece of sheathing cannot be installed if the end of the wall will be joined to a wall that is already standing. It will be installed after the wall has been raised and will extend 3 ½" beyond the framing to tie into the existing wall for additional strength.

It should be noted that if the gable ends are attached to the end wall prior to sheathing, then the sheathing should be installed so that it spans the intersection of the and gable truss and the rest of the roof.

If you are building a townhouse style home, the party wall or common wall for each home will by sheathed with 5/8" "X" rated gypsom board rather than plywood or OSB. Prior to applying the gypsum board, you will very likely put a diagonal metal brace on each end of the wall for stability. After the gypsum board has been nailed to the framing, a layer of joint compound is applied to each seam followed by drywall tape. Use a tapers knife to run additional compound over the tape and to remove excess.

Window openings and door openings should be cut using a circular saw as the sheathing is applied, unless HFHSL staff requested that it not be cut out for security reasons. If it is cut out later, a reciprocating saw is used and it is more difficult.

Installing Blue insulation board
Measure the height of the exterior wall. Normally HFH will have 4 'x 10' sheets available. Since the wall (along with the rim board) will be almost 9', trim the short end (4' end) of the board to fit. Use a sharp utility knife and a straightedge to cut the board.

Install the board starting at a corner. Each board has markings that should be aligned with the studs in the walls. The seams should not coincide with the seams of the sheathing as this will not provide as good of protection from water. It is best to nail into it through the sheathing into a wall stud, so the first piece should be installed and trimmed along the 10' length accordingly. The blue board will extend beyond the bottom plate sufficiently to cover the rim board when standing. Using button cap nails, nail every 12" along each edge, and at the intermediate 16" on center studs; nail vertically every 2' min. Use caution not to step on the unsupported blue board as this could lead to injury. Trim around door openings and window nailing strips. HFHSL staff may ask you to tape the insulation board seams with Tyvek tape.

If the gable truss is being raised with the end wall, blue board should not be installed until after the wall is standing so that 2 x 4 strongbacks can be attached directly to the wall to prevent the wall from hinging at the intersection of the wall and the gable truss when the wall is raised.

Install sill seal

Staple sill seal to the bottom plate before raising the wall.

Raising the Walls
When the wall has been prepared, stop all other work. All volunteers will help assist in raising the wall and stopping all other projects will reduce risk of accident. Pull 8d nails anchoring top plate to subfloor. Using claw of hammer, raise top plate and place scrap lumber every 10 feet so that the volunteers can reach under and grasp wall. A long 2 x 4 should be nailed to the outside top edge of either end of the wall with one 16d nail. These will be used for bracing and nailed to the rim board. Keeping backs straight and lifting with their legs, the volunteers will slowly lift the wall to the upright position. No one should be on the outside of the wall when it is being raised. The volunteers will continue to hold the wall until it is secured to the floor joists and braced. Make sure that the bottom plate lines up with the chalk line. A sledge hammer may be needed to make adjustments. When properly located, nail 16d nails through the bottom plate, 2 into each floor joist. Using level, brace the wall with long 2 x 4's nailed from the top of a stud and into a scrap 2 x 4 which has been nailed into a floor joist. These braces should be approximately every 10 feet. Try to place bracing so as not to interfere with the construction of other walls. This will reduce moving bracing.

When two adjacent walls have been raised, ensure that the end of each is plumb and nail the two walls together with 16d nails approximately every 12 inches. Continue until all walls have been raised and secured to each other. Remove all 16d nails that acted to secure bottom plate prior to raising (they will all be bent).

Straightening walls
When all walls have been raised, they should be checked for plumb with a level and then straightened. To straighten a wall take a scrap 2 x 4 and nail it to the inside of the top plate at either end of the wall. Use another nail in each scrap to string a line the entire length. Use another scrap 2 x 4 and test to see if it fits all along the wall. If the string is farther from the wall than the width of the 2 x 4, the bracing needs to be adjusted to move the top of the wall in. If the 2 x 4 does not fit between the string and the top plate, push the top farther out by adjusting the bracing. Continue this process until all walls have been straightened.

There are several techniques to help straighten a wall by pulling it in or pushing it out if it can not be moved manually.

To push a wall out a long 2 x 4 is nailed to a cleat attached to a floor joist. The 2 x 4 is placed at approximately a 45 degree angle and should be resting on a stud of the wall. Hit the end down with a hammer. As the 2 x 4 moves down the stud, it will push the wall farther out.

To pull a wall in, nail a 2 x 4 at a 45 degree angle from a cleat attached in a floor joist to a stud in the wall. The 2 x 4 needs to have the wider side facing down. Another shorter 2 x 4 is placed between the cleat and the wall and should be stood vertically and the top should touch the underside of the longer one. Use a hammer to drive the top of the shorter one away from the wall. This will bow the longer 2 x 4 pulling the wall in. Another method is to push a wall in.

A long 2 x 4 is nailed to a stake in the ground outside the wall and the other end is laid against the outside of the sheathing. It should be at a 45 degree angle. Again, the wide side of the 2 x 4 should be facing down. Pull down at the center of the 2 x 4. The board will bow and the end against the sheathing will slide down. Letting go of the board, the board will straighten pushing the wall in.