Part 43: MEP Rough-in Sequence

September 20, 2016

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

Mechanical systems bring the house to life. These include metered services provided by public utilities as well as onsite systems like air handling, waste water treatment, and drainage control.

MEP Phase – Insitebuilders

There are also alternative sources of power, water, and waste disposal that can be privately metered to track consumption. Off grid services include septic systems, well water, on-site drainage, grey water collection, alternative power sources, and LP or methane gas.

Indoor Air Quality
Indoor air quality is an important consideration during the installation of the mechanical systems because the building is sealed and will trap airborne volatile organic compounds (VOC) and other contaminants during the rough-in and finish work.

MEP Phase – Insitebuilders

The systems are installed sequentially to minimize contamination, damage, and rework. This includes the cutting and drilling associated with the concealed plumbing, HVAC equipment, line-sets, and ductwork, and finally the electrical wires, boxes, connections, and fixtures.

Building Systems Work Together
After the cabinets are installed and walls painted, the systems subcontractors return to install their plumbing fixtures, finalize the electrical lighting and connections, and clean and balance the HVAC system.

MEP Phase – Insitebuilders

Important is that the finished systems work together, with ventilation and drainage to remove waste, filtering equipment to condition the intake of air and water, and electrical fixtures balanced on engineered circuits to maximize efficiency.

MEP Phase – Insitebuilders

Note that some builders avoid PVC conduit and piping because of the environmental impacts of their manufacture and disposal, but equal consideration should be given to minimize galvanized, lead, copper, and adhesive materials that raise their own environmental concerns.

 

 (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.Close-In, 6.Roofing, 7.MEP, 8.Finish)

The objective of the Close-In Phase is to seal the house against the weather so that the mechanical, electrical, and plumbing (MEP) can be installed.

MEP Phase – Insitebuilders

A sustainable shell
The house wrap acts as a barrier against drafts and moisture, while insulated doors and windows are caulked and screwed to securely seal openings and minimize heat transfer.

MEP Phase – Insitebuilders

The trim and siding acts as a hard shell to protect the walls in the same way the metal roofing protects the waterproof membrane. The siding is made from a cement based fiber that is long lasting and durable, reducing maintenance, and increasing the product’s life-cycle.

MEP Phase – Insitebuilders

Metal roofing is manufactured from high recycle content steel, coated at the factory to prevent corrosion, and pre-painted to provide a reflective coating that reduces cooling loads in warmer regions or absorbs heat in colder climates.

MEP Phase – Insitebuilders

The resulting enclosure is long lasting and durable with a service life that will minimize maintenance, repairs, and future replacements.

Now for human comfort
Mechanical, electrical, and plumbing (MEP) systems add comfort to the house by supplying water, removing waste, providing heat, ventilation, cooling, and electrical power. They are installed in the following order:

1. Plumbing

MEP Phase – Insitebuilders

The pipes and fixtures supply water and gas and remove waste from the house. Because this includes large diameter pipes and fittings, the bulk of the plumbing is roughed-in to the framing before the other systems are installed.

2. Mechanical

MEP Phase – Insitebuilders

Heating, ventilating, and air conditioning systems use a combination of air handlers and compressors to distribute conditioned air into the building and vent out moisture and contamination. Indoor air quality depends on the efficiency of the balance and correct capacity of the components of the system.

3. Electrical

MEP Phase – Insitebuilders

Human comfort depends on a well designed electrical installation. This includes dedicated circuits, receptacles, lighting, and controls as well as telecommunication wiring. Because wiring for these devices can be easily damaged, the electrical components are the last to be roughed-in to the framing.

Note that experienced construction managers overlap and carefully coordinate the MEP installations as simultaneous tasks to speed the scheduled completion.

 

 (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.Close-In, 6.Roofing, 7.MEP, 8.Finish)

The last step in the Close-In Phase (the shell) begins once the flashing is complete and the work area is ready to start cutting roofing panels. Metal roofing with concealed fasteners is considered by many to be more aesthetically pleasing, but there are applications when exposed fasteners are more practical.

Close-In Phase – Insitebuilders

This includes buildings where additions or future changes are anticipated that will require removing roofing panels. Metal roofing with exposed fasteners are also easier to install and require no special tools or hardware.

Metal roofing with exposed fasteners
Once the underlying flashing is complete, the roofing panels are cut and mounted either directly to the roof deck or to furring strips laid over the temporary roofing membrane.

Close-In Phase – Insitebuilders

When weather conditions are either extremely cold or hot, the furring strips create an air space that prevents direct heat transfer from the metal panels through the sheathing to the interior. This air space also helps to prevent heat loss from the interior to the metal surface that causes ice dams from melting snow.

Rigid insulation is applied to the roof deck when batt or blown insulation is not installed in the attic or space between the ceiling joist and rafters.

Close-In Phase – Insitebuilders

Special roofing screws with EDPM washers penetrate the high point of the metal roofing, spaced according to manufacturer specifications, and engineered to counter uplift from wind loads.

Close-In Phase – Insitebuilders

The screws are long enough to secure the roofing panels, flashing, and the furring and rigid insulation, if used. Building codes require the screws to fully penetrate the roof sheathing so that the threads of their tips are visible for inspection from the interior.

Close-In Phase – Insitebuilders

Once the roofing is complete, exterior finishes and sitework are finalized. This includes touch up for prepainted trim, siding, and flashing as well as finish sitework, landscaping, vents, screens, and skirts around the pier foundation.

Sitework and landscaping that includes sprays, dust, insecticides, or other chemicals are always coordinated with the interior subcontractors to prevent contaminants from entering the building. “NO SMOKING” signs are also posted at all entries before the interior work begins.

 

 (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.Close-In, 6.Roofing, 7.MEP, 8.Finish)

Unless there are interior finishes, furnishings, or materials that require protection earlier in the schedule, the finished roofing is the last step in the close-in process.

Close-In Phase – Insitebuilders 

Timing depends on when mechanical and electrical rough-in is scheduled, since roof and wall penetrations are often necessary for vents, intake, and outflow lines that extend through the roof from the walls and ceilings.

The roof flashing
A professional roofing contractor begins work by setting up the site and the rooftop for the work. This includes the installation of toe boards, chicken ladders on steep slope roofs, and tie off points for personal fall protection.

Close-In Phase – Insitebuilders

Local building codes do not specify safety procedures for roofing contractors, but the United States Department of Labor, Occupational Safety & Health Administration requires fall protection on residential roofs for employees working six or more feet above a lower level (See Fall Protection in Residential Construction).

Roof flashing is a flattened fiber, elastomer polymer (EPDM), or sheet metal material shaped to prevent leaks by covering the joints, edges, and angles of the roof, especially where the roof comes in contact with a vertical surface that comes “through the roof.”

Close-In Phase – Insitebuilders

The flashing for metal roofs with concealed fasteners is an integral part of the roofing system and installed with proprietary methods, tools, and clips to ensure a secure seal.

Close-In Phase – Insitebuilders

Note that the roofing contractor will coordinate their work with the other trades to fit siding, trim, and other exterior finish materials over or under the roof flashing.

See the Metal Roofing Alliance website for information on different types of metal roofing, detailed specifications, and expert advice.

Metal Roofing with concealed fastener
A galvanized metal roof with concealed fasteners provides a seamless seal against moisture penetration, reducing energy costs and providing a much longer life cycle than other types of roofing. Color choices depend on climate and site conditions, white is the most reflective, while darker colors will absorb more solar energy.

Close-In Phase – Insitebuilders

The concealed fasteners anchor the metal panels to roof sheathing or furring strips depending on insulation requirements and local conditions.

The clips are screwed to the roof structure with tabs that bend over the panel edges, and are snapped to battens extruded in the panels. Once snapped into place, the roofing system is secure against wind loads, icing, and other weather related problems.

Close-In Phase – Insitebuilders

The installation of metal roofing is most efficient on houses with simple roofs, but there are a variety of special pieces that can be used to accommodate almost any configuration when the system is installed by a professional roofing contractor.

 

 (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.Close-In, 6.Roofing, 7.MEP, 8.Finish)

To minimize the possibility of damage from overhead work, the sunroom and skylights are installed before the roofing and after the clerestory and siding have been completed.

Close-In Phase – Insitebuilders

Installing a custom sunroom
Most sunrooms are available as kits with screens and glass set in an aluminum or vinyl frame (see the Better Living Guide to Sunrooms). These kits are sold by authorized contractors and are by far the easiest way to install a sunroom.

In this example, a custom-made sunroom is field constructed by skilled finish carpenters to fit an existing opening. Note that local codes may require detailed engineering drawings or specific factory labeling, indicating test results for positive and negative design pressures.

Close-In Phase – Insitebuilders

The frame must be weather resistant, carefully joined, and treated with a sealant and stained or painted before the glass is installed. In most climates, a clear, vertical grain pressure treated wood or composite, similar to that used for exterior decking, is the best choice for the framing material.

Close-In Phase – Insitebuilders

The rafters and stops are routed to secure the glass and are spaced to match the size of standard insulated and tempered glass panels. These panels are similar to those used for window walls in commercial buildings and are sourced from the same suppliers.

Installing the skylights
Skylights are often specified to replace windows in small rooms that require daylight and natural ventilation and are manufactured to meet energy and building code requirements.

Close-In Phase – Insitebuilders

Operable skylights must be placed away from nearby plumbing and exhaust vents to prevent cross contamination and the intake of harmful gases. Required distances are governed by local building codes.

When the unit is ready to be bolted to a curb that was built around the opening in the roof, flashing is installed by the roofing contractor, and the prefabricated flanges of the skylight frame are set to counterflash the roofing material and seal the opening.

Close-In Phase – Insitebuilders

As an alternative, flush mounted skylights are available to avoid ice or debris buildup against the curb, improve energy efficiency, and lower the visual profile of the unit on the roof (See especially www.velux.com).

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 (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.Close-In, 6.Roofing, 7.MEP, 8.Finish)

Siding installation begins by setting up a cutting and staging area for the work and clearing the site of debris or obstacles around the perimeter that might interfere with the scaffolding.

Close-In Phase – Insitebuilders

To minimize breathing the harmful silica dust that results when fiber cement siding is sawn with power saws, carpenters use shear or scoring tools to trim the material lengths to size(see James Hardie installation instructions).

Soffits and trim ready for siding
Since the siding must be nailed into the wall studs to secure it against possible wind loads, the work begins by locating the nails through the exterior sheathing and marking the vertical stud locations.

Close-In Phase – Insitebuilders

The siding is then cut to size and nailed to these stud lines in horizontal bands while maintaining a uniform spacing and exposure. Gecko gauges are able to clamp each row while holding the subsequent rows in place to control the dimension for the exposure.

Scaffolding makes it possible to adjust the work platform vertically and install the material safely and efficiently.

Close-In Phase – Insitebuilders

The joints in at the splice points and the ends that meet the trim around the corners and doors and windows are spaced for expansion. These joints are caulked to seal the gap prior to painting the exterior walls.

Safely installing gable siding and glass
Since stack scaffolding cannot be used to install the gable clerestory and siding, the pump jacks shown in the illustration are able to adjust to existing conditions. Important is that the base of the jack-poles must be attached to the frame of the building.

Close-In Phase – Insitebuilders

In this example, the poles are attached to the framing above the opening for the prefabricated sunroom.

Close-In Phase – Insitebuilders

Fall protection requirements are part of the project’s safety plan. According to the US Department of Occupational Safety and Health Administration, fall protection and safety rails are necessary to protect the safety of the workers whenever the nature of the work or the height of a scaffold is greater than ten feet (see the OSHA training manual here).

 

 (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.Close-In, 6.Roofing, 7.MEP, 8.Finish)

There are 15 tasks shown in the close-in phase for this example. Depending on the project and local conditions, many of these tasks must be completed sequentially. But others are often installed simultaneously.Close-In Phase – Insitebuilders

The key to scheduling the work is to assess potential equipment or material conflicts, safety concerns, and local conditions. Poor scheduling will cause delays for subcontractors, and the workers assigned to different teams.Close-In Phase – Insitebuilders

In most cases, the doors, windows, soffits, and trim are installed before the siding, but in some cases the weather will make it important to install the roofing before any of the other close-in tasks. In this example, the rolled roofing underlayment is sufficient to temporarily seal the interior.

Setting the Door and Windows
Windows are manufactured with an edge flange that is screwed to the rough framing around the wall opening. Wind loads determine the number of screws used along the sides of the door or window and are specified by local building codes or the project engineer.

Close-In Phase – Insitebuilders

Energy codes require doors and windows to be certified by the manufacturer to guarantee that they meet energy ratings for the glass and frame.

Insulating tape, similar to that shown on the familyhandyman website are installed along the sill and sides of the door and window openings before the units are set in place. Once secure the perimeter of the door and window frames are taped to complete the installation.

Close-In Phase – Insitebuilders

When weather conditions are extreme, metal “Z” flashing further seals the door and window frame to prevent moisture penetration.

Note that building codes require tempered glazing for glass doors and adjacent windows whenever inadvertent impact might occur.

Cement Fiber Trim to Match Siding
In this example, fiber cement boards are nailed to the framing at the corners, lower edges of the outside walls and around the door and window frames. For life-cycle and maintenance information on fiber cement trim and siding, see www.jameshardie.com.

Close-In Phase – Insitebuilders

The trim above the header spans the full width of the door or window frame and the horizontal joint is caulked to the vertical trim of the jambs.

Close-In Phase – Insitebuilders

Bathroom, dryer, and plumbing vents that penetrate the outside walls and the roof are coordinated with the mechanical subcontractors and completed before the siding is installed.

 

 (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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