Part 34: Begin Closing in the Framing

(Introduction, Syllabus, 1.Prelims, 1-4Precon, 2. Excavation, 3.Foundation, 4.Framing, 5.Close-In, 6.Roofing, 7.MEP, 8.Finish)

Once the temporary roofing is in place, doors, windows, insulation, and exterior finish materials are installed along with the final roofing to waterproof the shell of the building. Labor and materials must be carefully coordinated during this phase to complete these tasks efficiently, prevent conflicts in the schedule for the various trades, and ensure the safety of the workers. 

Fall Protection and Construction Safety

The traditional framing methods shown in this example mean materials are exposed to the weather for a longer period of time so care must be taken at the end of each day to protect them from moisture and deterioration.

This longer framing schedule also increases the possibility of accident or injury, making construction safety and the use of proper equipment essential, even on simple residential jobsites.

Safety management includes fall protection harnesses, tether lines with limiters, toe boards, spotters, material hoists, ladder ties, scaffolding, and common sense. 

Multitasking the Exterior Finishes
Careful scheduling is important to efficiently coordinate the multiple tasks and subcontractors working on the project during this phase.

A simple bar chart helps visualize the scope of the work needed to complete the close-in. The length of the bar represents the estimated time to complete each task, and the horizontal position of the bar on the chart indicates its relative sequence and timing.

The Tasks Include
1. Finish carpenters: The work begins by completing the framing so that the exterior surfaces of the house can be wrapped with a vapor barrier and sealed with trim and siding.

This includes the walls and roof for the dormer, framing for the mechanical enclosures, and adding nailers and blocking to support the trim, siding, and the flashing and roofing. 

2. Doors, windows, and glass: Once the framing is finalized, a vapor barrier is rolled out and stapled to the sheathing to wrap the house. Openings are then fiber-taped to complete the seal before the doors and window frames are inserted and screwed to the rough openings (See also Dupont Flashing Systems).

3. Siding and trim: Trim is then installed at the corners, base of the exterior walls, and around the doors and windows before the siding begins. In this example, a pre-painted cement fiber siding is shown set against the trim to protect the framing from the weather.

4. Finished roofing: Roof vents, skylights, and the prefabricated sunroom are finalized along with flashing for the metal roofing. Bathroom skylights and the sunroom enclosure are installed by the finish carpenters.

Two types of metal roofing will be illustrated in this example: the first with concealed fasteners and standing seams; and the other an exposed fastener system using special screws with neoprene washers. Both types of roofing are placed over sleepers and runners attached to the roof sheathing through the waterproof underlayment.

(To be continued…) 

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 The material presented in this series has been taken from our book, “How a House is Built: With 3D Construction Models” The book includes annotated illustrations, captioned text, videos, models, and the 2D Preliminaries. 

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Part 33: Completing the Roof Framing

(Introduction, Syllabus, 1.Prelims, 1-4Precon, 2. Excavation, 3.Foundation, 4.Framing, 5.Roofing, 6.Shell, 7.MEP, 8.Finish)

The advantages of the open ceiling that results from traditional roof framing include the more expansive “feel” in the room below and the space gained for lofts or light shelves that is normally lost to trusses.

Sheathing ties the roof together
As the framing for the hip roof is completed, sheathing is nailed to the roof rafters to stiffen the frame and tie the roof together as a unified structural system.

Note that the sheathing is laid in a staggered pattern and that nail spacing is again specified in structural calculations according to local building codes.

Impregnated asphalt felt is rolled out immediately after the sheathing is finalized. The material is lapped and tacked into place with flat-washer-roofing nails to temporarily waterproof the framing below. Special high-density and reflective polyethylene sheets are used instead of asphalt felt on larger commercial roofs.

Slope change at bathroom roof In this example, a shed roof is framed over a separate section of the floor plan. The shallow slope of the shed roof raises the ceiling height in the room below.

Hangers for the rafters are secured to a ledger along the upper ridgeline of the roof. The rafters then span to bear on the top plate of the perimeter walls. Jack rafters are cut to fit the diagonal at the valley intersection.

The angle and configuration of the compound cut at the valley make it possible to use full penetration toe nailing through the rafter in lieu of a manufactured structural connector.

To minimize waste, blocking is cut from the dropped ends of the rafters as the roof framing is completed.

Sheathing and underlayment complete As soon as the sheathing is completed, the asphalt felt underlayment works to waterproof the framing until the roofing contractors can begin their installation.

Experienced carpenters manage the effects of rain, snow, and jobsite moisture in order to prevent damage to the framing members and the possibility of embedded mold and mildew that can occur in regions with high humidity.

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(To be continued…)

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The material presented in this series has been taken from our book, “How a House is Built: With 3D Construction Models” The book includes annotated illustrations, captioned text, videos, models, and the 2D Preliminaries.

Part 32: Framing the Hip Roof

(Introduction, Syllabus, 1.Prelims, 1-4Precon, 2. Excavation, 3.Foundation, 4.Framing, 5.Roofing, 6.Shell, 7.MEP, 8.Finish)
 

The framing for the hip roof requires compound cuts along the ridge lines at the intersections of the sloping hip roofs. The angles for these cuts are derived from the plane or slope at these intersections.

Calculating the hip ridge beam
The pitch of the hip’s ridge beams was once determined using a “rule of thumb” and some intuitive guessing on the part of a lead carpenter, but Simpson StrongTie has since set up an online calculator that makes the field-work much easier. The calculator can be found here.

Start the calculation by inputting the slope of the Main Roof and the Hip Roof. The pitch of the main roof is the same as the longer north-south slope that has already been erected. The hip roof is the triangular portion of the roof that remains to be constructed.

After you press “CALCULATE,” The results are shown on a table.

For this roof the 12:12 pitch of the main and hip roofs result in a 35.3 degree pitch for the ridge beams on each side of the hip roof.

Setting the hip ridge beams
The geometry of the roof means that these hip beams slope from the end of the cantilevered ridge to each corner of the wall framing. In this example, the angle is about 35 degrees.

Structural connectors are used to secure the ends of the hip ridge beams at the cantilevered ridge and the wall corners. These connectors are important because they counter the lateral and uplift loads imposed on the roof by strong wind or seismic activity.

Setting the hip jack rafters
Once the ridge beams are in place, “jack rafters” are cut at a compound angle so they fit to the side of the hip beam. A jack rafter is a short rafter used to complete the framing for the roof at a hip or valley.

 

Cutting the compound angle requires an experienced carpenter because the cut must match the pitch of the main and hip roofs as well as the angle of the ridge along the intersecting planes.

Skilled carpenters start with the lower jack rafters, testing their cuts and creating a template that they then use as a guide to complete the framing. Once the rafters are in place, the overhangs are trimmed to receive the structural fascia and the roof sheathing is added to stiffen the framing.

Note that fall protection is not always required for residential construction, but it is critical for safety regardless of the height of the roof and local codes.

 

(To be continued…)

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The material presented in this series has been taken from our book, “How a House is Built: With 3D Construction Models” The book includes annotated illustrations, captioned text, videos, models, and the 2D Preliminaries.

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Part 31: Intersecting Hip Roof

(Introduction, Syllabus, 1.Prelims, 1-4Precon, 2. Excavation, 3.Foundation, 4.Framing, 5.Roofing, 6.Shell, 7.MEP, 8.Finish)

An intersecting ridge beam is framed into the rafters on the north side of the house. This beam is designed as a double cantilever, extending out over two columns to support loads at each end.

Cantilevered to intersect with the rafters
The intersecting ridge beam bears on columns that carry the roof loads down to the foundation wall. Solid blocking is added between the floor joists under the columns to maintain full bearing.

The cantilever transfers the weight from the roof to the column, minimizing the load on the rafters at the intersection.

The framing members of the composite beams and columns are spiked and glued so that they “sandwich” each other at the rafter connection, similar to a furniture maker’s mortise and tendon joint. This reduces the need for moment connectors, making it possible for the pieces to be bolted together.

Once the ridge beam is in place, sheathing is nailed to the rafters to strengthen the frame and enclose the loft. 

Cantilevered to support the hip connection
On the opposite end, the ridge beam extends out over a second column to support the hip connection, eliminating the need for a truss or bearing wall at this point.

The cantilever transfers the loads from the hip connections back to the column and down to the foundation.

Once the ridge beam is in place, sheathing is completed on the north roof so that “jack rafters” can be connected to sleepers lag bolted into the rafters of the main roof.

Structural clips are used along the ridge beam and the interior bearing walls to counter the uplift loads that occur in the valleys at the roof intersections.

 

(To be continued…)

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The material presented in this series has been taken from our book, “How a House is Built: With 3D Construction Models” The book includes annotated illustrations, captioned text, videos, models, and the 2D Preliminaries.

Part 30: Setting Rafters and Sheathing

(Introduction, Syllabus, 1.Prelims, 1-4Precon, 2. Excavation, 3.Foundation, 4.Framing, 5.Roofing, 6.Shell, 7.MEP, 8.Finish)

Roof sheathing is added to stiffen the steeply pitched roof against lateral loads caused by wind and earthquake. An opening for a dormer on the north side of the roof is left open and will be framed after the intersecting hip roof is completed.

Framing the opening for the dormer
The opening allows carpenters to stage tools and equipment on the loft floor and have direct access to the work for the intersecting roof.

The framing for the dormer is framed similar to the opening in a wall, with a header, sill, and reinforced jambs to carry loads down from the roof and walls.

Short rafters are clipped to the ridge beam and the interior bearing wall to counter uplift loads from the dormer once it is in place.

Roof sheathing stiffens the roof framing
The edges of the sheathing are supported by structural clips inserted between the rafters along the horizontal joints. These clips stiffen the edges against long term loads from weather and dead weight of the roofing.

The sheathing is placed in a staggered pattern to minimize continuous joints and distribute the roof loads evenly across the rafters.

Each sheet is cut to fit the rafter spacing and the edges are nailed following a designated nail pattern. Nail placement and spacing are specified by the engineering calculations and the requirements of local building codes.

Safety lines and harnesses are not always required by residential codes for single story construction, but the added support makes it possible for carpenters to move quickly across the roof and repel along the roof edges.

Toe boards and chicken ladders give the carpenters a better footing and are nailed into the rafters as an underlayment to temporarily waterproof the unfinished framing.

(To be continued…)

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The material presented in this series has been taken from our book, “How a House is Built: With 3D Construction Models” The book includes annotated illustrations, captioned text, videos, models, and the 2D Preliminaries.

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Part 29: Setting Rafters

(Introduction, Syllabus, 1.Prelims, 1-4Precon, 2. Excavation, 3.Foundation, 4.Framing, 5.Roofing, 6.Shell, 7.MEP, 8.Finish)

Traditional roofs are framed using rafters that extend from a ridge beam down to the top plates of bearing or perimeter walls. The slope of the rafters shapes both the ceiling and the profile of the house.  

Rafter framing at the main roof 
Structural connectors similar to those used in the floor framing are used to tie the rafters to the ridge beam and the top plates of the bearing walls. The connectors counter uplift and lateral loads imposed on the house by wind or earthquake.

The connectors are predrilled according to engineered nailing patterns that prevent over nailing in the field. High strength “joist” nails are used instead of common framing nails to secure the rafters at the connector.

It’s important to tie off or block ladders at the top and base of the work area to prevent falls caused by displacement or slippage. The slope of ladder should be about 75 degrees or approximately one unit horizontal for every four units vertical.

For example a 24-foot ladder should be set out approximately 6 feet at the bottom of the ladder. See safety requirements and hook attachments for construction ladders at www.wernerladder.com .

Outlooks support the rake rafters
Rake rafters support the overhang at the gable ends of a roof. These rafters extend beyond the face of the perimeter walls and are held in place by outlooks (or outlookers) that are “let in” to the top of the main roof rafters.

The rafters are notched to receive the outlooks so that the top of the outlook is level with the top of the rafter. The outlooks cantilever beyond the face of the wall to support the rake rafters. Outlook spacing depends on the length of the overhang and the wind load requirements of local building codes.

Placing the rafters 
Rafters are precut to match the required slope of the roof. Though structural connectors make it structurally unnecessary, many skilled carpenters prefer to cut bird mouths into the rafter at the bearing points to provide a flat surface for the roof loads.

The end of the rafters cantilever past the perimeter walls to a structural fascia according to the requirements of the overhang. The fascia is structural because they tie the rafters together as a single unit and distribute roof loads to neighboring rafters.

Blocking is added between the rafters at the perimeter wall to prevent fire on the outside of the house from entering the space between the rafters through the soffit.

(To be continued…)

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The material presented in this series has been taken from our book, “How a House is Built: With 3D Construction Models” The book includes annotated illustrations, captioned text, videos, models, and the 2D Preliminaries. 

 

Part 28: The Ridge Beam

(Introduction, Syllabus, 1.Prelims, 1-4Precon, 2. Excavation, 3.Foundation, 4.Framing, 5.Roof, 6.Close, 7.MEP, 8.Finish)

The perimeter wall sheathing is completely nailed before roof framing begins. The sheathing stiffens the frame, finalizing bearing points, tie downs, and connectors as a unified structural system in preparation for the roof loads.  

Preparing supports for the ridge beam 
Because of the open ceiling in this example, these preparations also include framing beam pockets into the shear and gable walls that support the main ridge beam. These triangular walls are shaped to follow the slope of the rafters.

The ridge beam bears on vertical extensions of the shear walls and the sheathed gable walls work to resist movement perpendicular to the axis of the roof line.

Note that the shear walls are embedded between the gable walls so that a length of the ridge beam is fixed into position. The upper portion of the shear walls are bolted to the lower wall using tie downs and the structural nailing pattern. The sheathing on both sides of the shear wall transfers lateral loads through the wood frame to the foundation.

Once in place, the roof supports extend from the ridge beam and rafters down through the loft floor to the tie downs at the foundation stem wall. In some cases, steel straps are added to strengthen the moment resistance of the stud walls.

Setting ridge beam
After a final check, the area is cleared of unnecessary tools and materials and the ridge beam is ready to be set in place.
 
Options for lifting the ridge beam include a floor hoist as shown in this construction model or a light duty crane similar to those used by sign contractors or tree service companies.
 
Overhead safety is again of primary importance. Critical concerns include marking safe zones for workers, a safety observer to watch the lift as the beam is positioned, securing equipment, assessing unusual site conditions, and the experience of the carpentry crew.    


(To be continued…)

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The material presented in this series has been taken from our book, “How a House is Built: With 3D Construction Models” The book includes annotated illustrations, captioned text, videos, models, and the 2D Preliminaries. 
 

Part 27: Final Preparation for the Roof Framing

(Introduction, Syllabus, 1.Prelims, 1-4Precon, 2. Excavation, 3.Foundation, 4.Framing, 5.Roof, 6.Close, 7.MEP, 8.Finish)

Almost all residential roofs are framed using prefabricated trusses rather than more traditional conventually framed ridge beams and rafters. As noted above, truss roofs offer speed and labor efficiency and are designed by truss manufacturers using simple computer programs. The framing members are then prefabricated and delivered to the jobsite to be erected as an interlocking framing system.  

Traditional roof framing
As an alternative, traditional roof framing is field fabricated, maximizing the use of the space under the roof, but it also requires more time and attention to detail than component or truss framed roofs. Engineering is also more complex with roof slopes, spans, and the thickness required for insulation governed by the depth and spacing of framing members.

Traditional framing takes both experience and carpentry skills not often found in production residential construction. It is shown here for educational purposes. Though not difficult to build, this type of construction is best assembled by seasoned builders working for owners who value the space and visual interest of open ceilings and clerestory windows.  

Sheathing stiffens the frame
Once the top plates and loft framing are in place, sheathing is added to the outside of the exterior walls to stiffen the frame. The sheathing is nailed to the studs and plates to resist lateral loads and uplift forces from wind and earthquake.

The spacing of nails along the edges and centers of the sheathing varies with the anticipated loads on the structure.

Spacing is determined by engineering calculations that take into account the location, exposure, and wind and earthquake requirements of local building codes.

The geometry of the roof framing
The entry roof is a good example of the geometry of the traditional roof framing method. Note that the framing members form simple triangles with the floor or ceiling joists acting as the bottom chords of the truss and the rafters acting as the top chords or hypotenuse of the triangle.

Shear walls extend from the foundation tie-downs up through the loft floor, all the way to the ridge beam in order to unify the structural system.

Note that fall protection become increasingly important when framing a traditional roof, making safety and careful planning primary concerns during this phase of the construction.    

(To be continued…)

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The material presented in this series has been taken from our book, “How a House is Built: With 3D Construction Models” The book includes annotated illustrations, captioned text, videos, models, and the 2D Preliminaries.