Framing Phase – Insitebuilders

Part 24: Interior Wall Framing

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

Once the perimeter walls are in place and the first floor platform is secure, the interior walls are ready to be installed following the layouts shown on the floor plan.

Assembling the interior walls
Field carpenters determine the order of installation for the walls based on the working space available for assembly. Keep in mind that the chalklines on the subfloor mark the location of walls and top and bottom plates have already been cut to fit the line intersections.

Framing Phase – Insitebuilders

Schedules found on the construction documents list rough openings for the doors and windows. Header sizes for these openings vary with the span and the loads from the upper floor and roof framing. Structural headers and supporting columns that must be extended to the foundation are noted on the construction documents for special consideration.

Framing Phase – Insitebuilders

Bottom plates framed into the walls at the threshold of all the openings are cut after the double top plates for the upper floor framing have been finalized.

Filling in the details
Connections at the intersection of wall corners and end points are especially critical to stabilize the wall framing. The floor plan shows the location of the walls, but field crews determine how they interlock to prevent stress cracking once the interior materials are in place and finalized.

Framing Phase – Insitebuilders

The bottom plates of the walls that run perpendicular to the floor joist are nailed through the subfloor into the top of each supporting joist. When the walls run parallel to the joists, additional blocking may be required to prevent deflection.

Framing Phase – Insitebuilders

Lead carpenters are particularly aware of the need for blocking between the floor joists for columns, posts, and bearing walls. Solid blocking provides full bearing for structural loads that must be transferred from the upper floor and roof framing to the foundation.

Finalizing first floor wall framing
Once all the interior walls are in place, they are checked for proper nailing and structural integrity. The construction documents are used to check for missing connectors and excess nailing at the plates and studs. Too many fasteners or missing connections reduce the strength of the overall frame.

Framing Phase – Insitebuilders

When tie down straps and structural connectors are finalized the lower floor framing is ready to be tied together with the doubled top plates. Placement and specifications for these connectors vary with local conditions, see the National Association of Home Builders resources at http://www.toolbase.org for design guidelines.

Framing Phase – Insitebuilders

The top plates are installed to lap over adjacent walls so that they lock the framing together as a single structural unit. The additional top plate also strengthens the span between the studs making them less likely to deflect under loads from the upper floor and roof 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.

insitebuilders.com

 

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

The construction method shown in this SketchUp process model is called “platform framing” because the interior is enclosed by wood studs, spaced to carry vertical and lateral loads as a lightweight space frame and the top plates of the walls are installed as a platform to carry the upper floor and roof loads.

Outside wall thickness
Engineers specify spacing and stud sizes to support the structural loads acting on the house and local indoor air quality requirements. The thickness of the outside wall is therefore a function of the depth of the stud, with the space between the studs used for loose, batt, or foam insulation.

Framing Phase – Insitebuilders

For safety, the walls are braced against wind load or accidental collapse as they are assembled and moved into place. The erection sequence and details at the corners and openings are determined in the field by the lead carpenter.

Framing continues around the perimeter
Framing details around the doors and windows for the outside wall accommodate the stud sizes, wall thickness, and the loads carried by the shear panels and headers specified by the engineers.

Framing Phase – Insitebuilders

The top plates over the wall studs distribute upper floor and roof loads to the vertical members in the walls and the bottom plates and the floor joists below the subfloor.

For detailed information about wood framing methods and load tables, see the American Wood Council publications and guides at http://www.awc.org.

Framing Phase – Insitebuilders

Nailers used to attach interior and exterior materials, cabinets, built-ins, shelving, and brackets are framed into the walls. The size and placement of these nailers depend on the weight and locations shown on the floor plans.

Finishing the outside wall framing
Sheathing is nailed to the studs as the walls are being erected in areas that will be difficult to access once all the walls are in place. It would be a mistake to sheath all the outside walls before interlocking top plates and interior walls are installed because the frame would be inadvertently exposed to wind loads during construction.

Framing Phase – Insitebuilders

Safety is improved once all the perimeter walls are in place because they act as a guard rail around the work area. This is especially important in framing the upper floors of a larger building.

Framing Phase – Insitebuilders

Next, the outside walls are strapped to the floor framing and foundation. Note that details for the framing around the openings and the outside corners of the outer walls follow standard framing details that distribute structural shear and bearing loads to the floor and foundation.

Framing Phase – Insitebuilders

Standard structural connectors are used to tie the walls to the rim joists of the floor framing (See the Simpson Strongtie Catalog for wood construction). Spacing and location of these tie-down straps are specified by engineering calculations and the local building codes.

Tie-downs and sheathing are important because wind and earthquake loads will generate positive and negative pressures causing dynamic uplift and rotational stresses on the completed frame.

(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.

Insitebuilders.com

Part 22: Shear Wall Framing

December 15, 2014

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

The wall layouts follow the floor plan for the building’s design, but the overall dimensions of the framing as well as the framing members themselves are determined in the field by the framing crew doing the work.

Wall assembly
The construction method varies with the wall’s location, the size of the job, and the structural requirements. A full framing team is made up of a lead carpenter, framers, and at least one carpenter in charge of the actual cutting.

Framing Phase – Insitebuilders

The lead carpenter sets the layout and sequence of wall construction and the framers determine the cut lengths for the assembly as they erect the walls.

Lengths are either called immediately to a cutter as the wall is being assembled or listed on a cut-sheet so the pieces can be prefabricated as separate bundles. The pieces in each bundle are then marked for assembly and staged on the subflooring for different crews.

Framing Phase – Insitebuilders

The idea is to safely separate the work, allowing skilled carpenters to check dimensions and fit the members together as each wall is put into position.

Shear walls anchored to the foundation
Once the wall is assembled, it is tilted up and moved into place over the layout lines marked on the subfloor. The bottom plate is then nailed or bolted through the subfloor into the top of the floor joists.

Framing Phase – Insitebuilders

When regional wind or earthquake loads require special engineering, the shear walls are designed so that tie down anchors extend down to the floor framing to be bolted to the foundation.

Framing Phase – Insitebuilders

The shear walls also extend up from the foundation as part of the wall framing to be tied into the roof framing. In this way, the entire structure acts as a unified structural element. For this reason, the size and spacing of the nails securing the panels to the studs is critical to transferring lateral stiffness of the wall from the foundation to the roof.

 

(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.

http://insitebuilders.com

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

For jobsite safety, professional framers will install the plywood subfloor as soon as the joists have been secured. In high wind or earthquake zones, the joists and floor frame are strapped to the foundation at the ends of the girders and along the perimeter.

Staggered subfloor
The subfloor is laid in a staggered pattern so that its lengths are perpendicular to the direction of the joists. The plywood is then glued and nailed to the joists so the seams are centered on the length of the bearing surface.

Framing Phase – Insitebuilders

In some cases, interlocking panels and/or edge nailing to solid blocking are used to add strength to the floor framing. Solid blocking under bearing loads from above are also important.

In this example an opening is framed in the floor joists to provide access to the crawlspace. Interior access is important when you want to avoid frost lines or swales in the finish grade around the building.

Framing Phase – Insitebuilders

The enclosed crawl space is also prepared for future construction before the floor is sealed. This includes raking out rocks and debris and spreading sand or heavy mats to make it easier to service certain areas. Materials and equipment that would be difficult or impossible to put in the crawlspace are also staged for later installations.

Framing an open crawl space
The open crawlspace is framed over girders and foundation piers. The frame is again strapped to the foundation to structurally tie the frame to the foundation. Open crawl spaces allow drainage, shade, and natural circulation in warm, humid, or wet environments, but require insulation and soffits in cold climates.

Framing Phase – Insitebuilders

Access under the raised floor makes it easier to maintain or change mechanical and electrical systems, but it’s important to use pressure treated materials in extremely moist areas or if the joists are less than 18 inches from the finish grade.

Framing Phase – Insitebuilders

The crawl space is again prepared for future construction. This includes installing plumbing and mechanical systems under the floor and grading the backfill to slope away from the foundation piers and stem walls.

Finishing the open crawl space
Mechanical and electrical lines are drilled and fitted in the floor cavities before the subfloor is finalized. Here again phased construction models and careful planning help coordinate future installations, reduce costs, and speed the final construction.

Framing Phase – Insitebuilders

Once the joists are installed, insulation and soffits are fitted to the underside of the open framing. This reduces heating or cooling losses through the floor and seals the joists and insulation from moisture, insects, and other pests. Perimeter skirting prevents wild life from using the space for nests or burrows.

Framing Phase – Insitebuilders

Note that nail size and nail spacing vary with the loads imposed on the floor and the structural design of the building framework. Requirements will vary according to local codes and the loads imposed on the finished frame.

 

(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.

Insitebuilders.com

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

To begin framing the floor the top of the foundation stem walls and piers are first cleared of debris and any pockets in the reinforcing filled with grout to seal the surface. This includes wire brushing the anchor bolts to remove concrete or rust and make it easier to secure nuts and washers as the plates are drilled and fitted, flush to the outside face of the foundation wall.

Setting the sill plates
These sill plates serve three purposes. The first is to provide a uniform working surface along the top of a level stem wall, shims should not be necessary depending on the skill of the masons.

Framing Phase – Insitebuilders

The second reason for the sill plates is to protect the framing from deterioration due to moisture and insect infestations. Redwood and other insect resistant woods were once used, but the availability of these materials has been seriously depleted, making their use impractical for most modern constructions.

Instead, a non-arsenic chemical solution is drawn into wood fibers under pressure to protect it from moisture and oxidization. Micronized copper is added to this chemical to act as a termite barrier, reducing the possibility of rot and insect damage, see www.ufpi.com.

Framing Phase – Insitebuilders

Most importantly, the sill plates act as a bearing surface for the framing members that rest directly on the stem wall. The wood sill then absorbs the weight of the building and ties the framing to the foundation. Simpson Strongtie has a complete line of structural anchors with uplift load limits, see www.strongtie.com.

The sill plates are structural members
With the sill plates securely anchored and the drains and moisture protection installed, backfill is placed to provide a safe working surface around the foundation. It’s important that the backfill not add soil pressure high up on the wall until the floor framing is finalized. Once in place, the floor adds lateral strength to the top of the wall.

Framing Phase – Insitebuilders

Safety is again the number one concern on a professional jobsite. For this reason the framing team begins their work by setting up a designated cutting zone and a lay down area to stage cut materials. The work zone must be close enough to the carpenters so that they can call out dimensions and variations as they measure and place the joists and girders.

Framing Phase – Insitebuilders

Composite beams are glued and spiked together from standard milled materials according to engineering calculations. Field fabricating girders and beams in this way reduces the need for handling and transporting larger framing members.

Framing Phase – Insitebuilders

The joists are fitted into hangers to be flush with the top of the composite girders. Flush framing adds height to a basement or crawl space making it easier for mechanical and electrical contractors to access the underside of the floor.

Note that straps, clips, and anchors work together to tie the frame to the foundation and counter uplift loads. Earthquake and hurricane regions require structural connections engineered according to the environmental loads imposed on the building.

 

(To be continued…)

—————————

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.

Insitebuilders.com

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

The carpentry team begins the next phase of the construction after reviewing and accepting the completed foundation checklist. Once they start, responsibility shifts to their shoulders and any problems discovered once framing has started will only be complicated by delays and change orders.

Foundation drains and waterproofing

The framing begins by sealing the foundation stem walls, adding moisture and vapor barriers, setting perforated foundation drains, and placing filters over washed gravel to control ground water and wet soil conditions. Moisture protection has to be completed so that the foundation can be backfilled immediately after the floor joists are in place.

Framing Phase – Insitebuilders

To minimize petroleum based coatings, dimpled membranes are used to cover the foundation walls with a high recycle content HDPE material (See Superseal Construction Products). The membranes zip together to form a barrier against moisture that would otherwise penetrate the stem wall.

Framing Phase – Insitebuilders

The perforated drains are located near the bottom of the foundation footings to channel accumulated moisture to drywells, drain fields, or storm water systems. If flexible drain pipes are used, they’re laid over a compacted base to keep them from settling and clogging once the backfill is in place.

Framing Phase – Insitebuilders

Washed gravel is shoveled over the perforated drains and covered with fabric filters just before backfilling following national standards for moisture control.

Mobilizing the framers

Mechanical and plumbing supply and drain lines, electrical cables, and grounding rods are installed through the foundation walls and into the crawl space before the framing restricts access to the area under the floor. These lines penetrate the stem walls through special pressure sleeves and are bedded in trenches according to utility specifications.

Framing Phase – Insitebuilders

While the foundation is open, the crawl space should also be bedded with sand for later servicing by plumbing and electrical contractors or if there’s a basement the floor is prepared for a concrete slab.

Framing Phase – Insitebuilders

Carpenters begin by cleaning the anchor bolts and top of the stem walls in preparation for the sill plates. For safety, the site is cleared of all scraps, tools, and unnecessary materials before staging the work areas and equipment to support the framing team.

Framing Phase – Insitebuilders

For complex projects, knowledgeable contractors will use the site utilization plans (SUP) made during the preconstruction phase along with a simple deconstructible construction model to anticipate daily tasks and save time and materials.

The idea is to minimize material moves, repositioning, and cross traffic by thinking through the floor, wall, and roof framing prior to starting the work.

(To be continued…)

—————————

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.

http://Insitebuilders.com

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

Foundation Review (Foundation Checklist (PDF)
The formwork for the concrete footings is laid out on the floor of the excavation using the same workpoint and batter boards that were used to guide the excavation. The forms hold the poured concrete and steel reinforcing. Almost all steel reinforcing wire and rebar are now made from recycled material.

Foundation Phase – Insitebuilders

As soon as possible after the concrete has cured, the forms are removed, cleaned and reused in the framing for the house. This minimizes waste, reduces the cost of rigid formwork, and lowers consumption for a more sustainable approach to construction.

Foundation Phase – Insitebuilders

Building and stripping the forms and preparing them for reuse is a time consuming process that can be all but eliminated with the use of fabric forms. Fabric forms hang from horizontal screed boards and use the natural shape of wet concrete to shape the concrete.

Foundation Phase – Insitebuilders

The foundation stem walls for this house are constructed with standard concrete masonry units called “blocks.” The blocks are laid in a “running bond” using masonry tools and reinforced with horizontal and vertical steel. The steel is embedded in “grout” to form a solid structural system. Depending on site and soil conditions, the same walls could also be built using cast-in-place concrete or insulated forms.

Foundation Phase – Insitebuilders

Both masonry and concrete walls raise the frame of the house off the ground. This elevates the foundation and provides a crawl space or basement under the house to maintain and service the building during its life cycle.

Foundation Phase – Insitebuilders

A raised foundation reduces potential moisture penetration, mold and mildew, insects and insecticides, and makes it easier to add or modify the house as needs and requirements change over time.

Simplified Construction Modeling Tutorial
For anyone interested in the construction modeling techniques used for the Foundation Phase illustrations, see this quick tutorial.

The tutorial is one of more than 70 videos included in our book “Mastering the Art of 3D Construction Modeling.”

 

(To be continued…)

—————————

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.

Insitebuilders.com

 

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