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| The Mechanical phase of construction often includes the house frame, wiring, plumbing, HVAC system (heating, ventilation, air conditioning), windows, doors, subfloor, insulation and roof. Photos © Mark M. Hancock / DFWmark.com |
This post is part of the New Build Construction 101 series, which includes: Pre-pour, Mechanical (this post), Punch List, plus a bonus Pre-Closing Walkthrough for new homes.
If you're interested in a new-built house, I'd strongly suggest these two posts too: Want to Buy a New-Built House?, New-Build Home Basics
The Mechanical Phase
The Mechanical phase of construction involves everything from after the foundation is poured to before drywall is installed. It often includes the house frame, wiring, plumbing, HVAC system (heating, ventilation, air conditioning), windows, doors, subfloor, insulation and roof.
After the slab has been poured it takes as much as 100 days to get to the mechanical phase. For many upscale homes, it takes six months total to have a move-in ready house under “normal” conditions. Volume builders can go from slab to complete in as little as three months while some fine home builders will need a year or more.
Some builders hire outside engineers such as Burgess Group to check the property twice before the buyers take possession. Most builders have a one- or two-year workmanship warranty and warranty the structure for 10 years.
Private “phase inspection” is the preferred option for new construction home buyers. It ensures the buyer has a nonbiased, trained professional look at the progress at each critical step of the process. It does cost more but is worth the price to ensure no mistakes occur. At the very least, private inspection needs to be done two weeks before closing. The private inspection is vital to ensure the home is truly “move-in ready” on closing day.
Many builders will have an informal buyer walk-through for a “punch list” with the builder or project manager shortly after the private inspection. The punch list ensures all items that need attention are addressed before closing.
A punch list is a list of problem items or errors to repair or replace. Essentially, it is work that remains to be done. Historically, contractors would pierce or punch a hole in the repair document to indicate the work was completed.
The punch list inspection is informally called a “blue tape” inspection. The buyer and builder or project manager inspect the property together and place pieces of blue painter’s tape on any known errors. Afterward, repair crews can locate and repair the problem or error.
The final walk-through is held shortly before closing and ensures the work promised on the buyer’s punch list was completed.
Framing
An engineer inspects the work to ensure it meets the standard of 90 MPH wind speed in the DFW (Dallas / Fort Worth) area. On the Texas coast, 120 MPH is the standard to handle tropical storm winds. This extra resistance is accomplished by incorporating more metal ties. Metal post straps mount to the foundation and metal hurricane clips join the roof to the walls.
Each metal post strap is rated at 500 pounds of uplift. Builders don’t want a house to blow over or lift from the concrete. Hurricane clips are in rafters to transfer energy throughout the structure and hold the roof onto the house directly above the post strap.
The addition of a solid load-bearing wall helps with wind shear and racking (tilt). Oriented Strand Board (OSB) is a kind of particleboard. It is used to strengthen walls from wind shear. Plywood is stronger but it costs more.
Leaded or lateral braceLateral bracing helps prevent twists and buckles or structural failure of the building. This bracing is asymmetrical to the studs and disburses load force diagonally throughout the structure via 1 x 4” wood braces or metal “X” braces.
After the frame is up, an engineer checks and tells the builder what to fix. This process continues refining through inspections until the frame is correct. Repetitive inspections motivate the builder to get it right the first time.
Anchors
Construction anchors provide resistance to potential uplift and overturning forces from both winds and earthquakes. While there are eight major types of foundations depending on the predominant construction of an area, two major anchors are used in new-house construction. Mud-fill anchors fold over the wall frame to hold it onto the foundation after the pour. Anchor bolts are set in the cement while wet.
Major House Frame Components
Stud
Studs are the vertical (up and down) timbers or metal supports in walls. Studs run between the floor and ceiling and are spaced either 16 or 24 inches on-center (measured center to center) – depending on the builder. Drywall is attached to the studs.Heavier objects such as TV mounts, mirrors, cabinets and more are mounted directly to the studs because the drywall can’t support the weight of these objects.
An electronic stud finder tool can be purchased at any home improvement store for a reasonable price. It allows homeowners to locate the studs behind drywall sheets. Better stud finders will have additional features such as electrical wire detection.
When locating studs for a project, it is handy to use painter’s masking tape and mark the studs to avoid having those marks directly on the wall. Remove the tape when the project is complete.
RafterRafters are a series of angled timbers or metal that extend from a ridge or hip toward a downward slope. The purpose of rafters is to support the roof deck and associated loads. A pair of rafters (left and right) are called a “couple.”
A “ridge” is the topmost peak of a convex joint on a roof. All subsequent convex joints are “hips.” All concave (curved inward) angles are called “valleys.” The roof “pitch” is the steepness of a roof as stated in a ratio of each inch of rise per 12 inches in depth. The roof pitch equals the rise divided by the span. For example, a 1/12 roof is relatively flat while a 12/12 pitch has a 45-degree rise.
Hips and valleys can be undersized from architect specifications, and that is where the problems start because it is difficult to see these problems.
JoistJoists are the horizontal timbers or steel that span open spaces and are supported by beams. The joists in turn are typically found in a parallel series to support the structure of a floor or ceiling.
Joist hangers are made of metal and hold joists in place. The hangers typically wrap around three sides of the joist to strengthen a load-bearing connection. They are often installed incorrectly because they must have a nail or screw in each hole to be code compliant.
PlatesThe bottom plate is the lowest horizontal timber or metal support of a stud wall frame. It is attached directly to the floor system. It carries the stud loads to the slab or floor joists.
Top plate is the upper horizontal timber or metal support of a stud wall frame that supports the roof structure. It carries vertical forces from the rafters to the wall studs.
Double top plates transfer loads from ceiling joists through the stud walls and bottom plate to the foundation. Double top plates are used on load-bearing walls while stud wall with no top load can have a single top plate.
In addition to structural integrity, builders want the header to be oversized and not sag over time.
Load bearing wallA wall is load bearing if the weight goes from the roof to the floor or an engineered wall to resist lateral forces. Both load-bearing and engineered walls should be left alone to ensure the house’s safety integrity.
If bolts are visible on interior walls at the floor, it’s considered load bearing because it has anchors in the foundation.
Plans may say one thing and construction workers don’t always pay attention to the plans because they want to get it done quickly. It’s vital to have a professional inspector check for these anchors and appropriate plates and any lateral braces on load-bearing walls.
A “Frame Punch” tries to fix something already done such as improper lateral braces. This must be completed during the mechanical phase of construction.
General Protocols
Window placements are written on the floor to ensure workers know where they will be installed later.
Gas lines are steel to prevent puncture. There are metal nail guards near places where nails might be driven close to a gas line. When needed, sleeves rather than actual pipe are placed in the foundation. This allows the pipe to be more easily replaced later. Additionally, steel and iron rust and degrade when in direct contact with cement. Plastic sleeves minimize this problem.
Radiant Barriers
Radiant barriers are 4 X 8’ sheet building materials. They are typically made of aluminum and installed in attics. They block and reflect radiant ultra-violet (UV) heat rather than allowing it to pass into the attic. This reduces the amount of summer heat gained in the attic and lost from air conditioning.
Better radiant barriers reflect as much as 97% of solar radiation, which equates to about a 30°F temperature shift in the attic. This also allows all ducts to move cooled air more efficiently with less strain on the whole HVAC system.
In warmer areas, the radiant barrier allows builders to reduce A/C requirements by as much as a half ton. Because heat always moves from hot to cold places, it also helps in the winter to block heat from escaping the house.
A standard new home is awarded a 100 HERS rating (Home Energy Rating System). The HERS index is the construction industry standard for inspection and calculation of a home’s energy efficiency. The HERS system ranges from a zero-energy home (the best and extremely rare) to 150 HERS or more.
The goal for most modern upscale builders is in the range of 50 HERS or less. Most existing homes are in the 130 to 150 range.
Additional batt insulation made of fiberglass will be in the walls while loose-fill fiberglass insulation is blown into ceiling cavities. Treated insulation also helps combat mildew, fungus and moisture.
These aim to increase the R-value of the house. The R-value is a measurement of a building material’s thermal resistance per unit area to resist conductive flow of heat from a hot to a cold area. R-values are additive per layer and are measured in inches or meters of thickness. Rigid foam sheets are more expensive than loose fiberglass but often have higher R-values.
During the mechanical phase of home construction, visitors may see green film over vents. The film allows for pressurized testing to ensure there are no leaks in the HVAC system.
Builders try to construct an air envelope in the building and pressurize the whole house to check for leaks. Leaks cause lost energy and more expense. They also allow moisture and pests to enter the house.
Building a Better House
Builders endeavor to get it right the first time by inspecting during the process of construction. Fewer mistakes and earlier detection of any mistakes saves money for the builder and eventually for the buyers.
In rural areas outside of a municipality, NOBODY watches home builders. There are no codes and no inspections. Meanwhile, city inspectors create accountability for builders to produce minimum-standard houses. Consequently, some custom builders can cut corners and don’t have the same accountability in rural settings. As always, it’s important to find and work with people (builders, contractors, etc.) who do the right things even when nobody supervises.
Plumbing
Plumbing, HVAC and electricity take about six business days to install in one house. Drains are in the foundation. Water lines are run over foundation rather than under it if possible. It’s MUCH less expensive and easier to replace and repair sheetrock rather than sections of the foundation.
Copper was the traditional plumbing system. However, copper can’t expand when it freezes. Instead, it breaks and causes multiple layers of damage. The rigid nature of metal makes it difficult to install or move for redesigns. Additionally, copper pipes will corrode over time.
Traditional water systems have main delivery lines which branch out to various outlets. Each split is an opportunity for a system failure and hidden leak. It also takes a skilled pro to repair, replace or divert any of these lines, which will need to be soldered.
Cross-linked polyethylene (PEX) is the accepted standard for many builders as well as home flippers and advanced DIYers (Do It Yourself). It is a flexible plastic tubing developed in 1968 and made popular in the 1980s for radiant floor heating systems. After it was chemically reformulated by adding antioxidants to resist the higher chlorine levels in U.S. water supplies, it could transport potable water and gained acceptance in construction. About 10-12 years ago it became the industry standard.
PEX lines are normally colored. Red is always hot. Blue is always cold. White and gray lines can carry either temperature but often transport cold water in new-built houses. PEX is not suitable for outdoor use because UV rays break down the plastic.
Another difference from the traditional plumbing system is the PEX manifold to divert water. Rather than a main line, the PEX lines move through a manifold (vaguely like an electrical circuit breaker). This allows individual lines to connect directly to the outlet fixture rather than having multiple branch lines (PEX can also branch with the correct fittings). PEX system advantages include:
• Very few metal fittings with a lower chance of expansion breaks and leaks.
• PEX doesn’t corrode over time.
• Color-coded lines ensure easy identification of line temperature.
• Water runs silently through PEX to eliminate the “water hammer” noise of metal pipes.
• Can be connected to existing lines if correct fittings are used.
• It is DIY friendly if correct tools and connectors are used.
• Stable manufacturing cost – it isn’t subject to copper availability and price futures fluctuations.
Tankless Water Heater
Tankless water heaters were originally a government initiative. They save energy but have a higher initial cost than a traditional tank-based water heater. Builders are expected to exclusively install tankless systems by 2025 to save tanks from going into landfills.
These systems heat water as it flows through a heating device rather than attempting to maintain a constant temperature for an entire tank of sitting water.
Most builders use tankless water heaters as the standard. They are more energy efficient, require less storage space, last longer, offer endless hot water, use less water if multiple units are used and are safer than traditional tank water heaters.
Cold water must still run out of the line when first used after sitting dormant, but it creates an endless supply of hot water after the line temperature changes.
The circulating system of heated water creates “instant hot” water. The system needs to be scaled from time to time to remove the mineral buildup. Circulating hot water systems removes the need to clear cold water from the line. Circulating hot water systems are not as energy efficient as a standard tankless system.
Homeowners don’t want to hear about maintenance, but all systems must be maintained. Tank systems require annual maintenance and sometimes twice annually depending on the water quality. Tankless systems also require maintenance, but not as much as tanks. They must be descaled of mineral buildup periodically. Once annually is the manufacturer’s recommendation.
Termite Protection
While the studs are still visible, buyers may notice the bottoms of the boards are green. The green color indicates the wood was treated with Bora-Care. Both the wood and concrete are treated.
Bora-Care treatment is for termite and other wood-eating insect prevention. Unlike traditional pesticide treatments, it’s relatively benign to humans while it is deadly to pests. The active ingredient of Bora-Care is borate salt. If borate salt is ingested by wood-eating insects, those pests are unable to get nutrition from their food, and they starve to death. Because it works on the insects’ biology, they can’t develop a resistance. The deaths of others alert the colony to avoid that property. Additionally, some pests won’t even attempt to eat the wood due to the treatment.
It comes with a 10-year warranty. Homeowners will need to take additional measures afterward. However, lines are run through the walls to allow pest treatments later from outside the house without ever exposing the entire house to pesticides.
Preparing for the next steps
Once sheetrock is on the walls, builders can often hand over keys within 45 days. Other builders use cabinets as a benchmark date for as much as 75 days before closing. The project manager will tell you when it is about time to list a home for sale and optimize timing without a homeless period of expensive temporary housing.
If you’re ready to make the move to a new-built house, you have the right to have your best interests represented by a licensed REALTOR. The builder’s sales agent represents the builder – not you. The builder planned to pay a REALTOR fee. This cost is built into the purchase price. Don’t PAY for services that you don’t get! Contact a qualified REALTOR before you sign anything at the builder’s office. Otherwise, you possibly waive your right to no-cost representation.
DFWmark is certified as a New Home Sales Agent, Green Home Sales Agent in addition to having the Military Relocation Professional (MRP) and Graduate, REALTOR Institute (GRI) designations. I can ease the strain of finding your new-built home with my proprietary research information as well as help you liquidate your current house.
Please continue this Construction 101 series to the Punch List inspection.
I’ve Got Your Six!
Radiant BarriersRadiant barriers are 4 X 8’ sheet building materials. They are typically made of aluminum and installed in attics. They block and reflect radiant ultra-violet (UV) heat rather than allowing it to pass into the attic. This reduces the amount of summer heat gained in the attic and lost from air conditioning.
Better radiant barriers reflect as much as 97% of solar radiation, which equates to about a 30°F temperature shift in the attic. This also allows all ducts to move cooled air more efficiently with less strain on the whole HVAC system.
In warmer areas, the radiant barrier allows builders to reduce A/C requirements by as much as a half ton. Because heat always moves from hot to cold places, it also helps in the winter to block heat from escaping the house.
A standard new home is awarded a 100 HERS rating (Home Energy Rating System). The HERS index is the construction industry standard for inspection and calculation of a home’s energy efficiency. The HERS system ranges from a zero-energy home (the best and extremely rare) to 150 HERS or more.
The goal for most modern upscale builders is in the range of 50 HERS or less. Most existing homes are in the 130 to 150 range.
Additional batt insulation made of fiberglass will be in the walls while loose-fill fiberglass insulation is blown into ceiling cavities. Treated insulation also helps combat mildew, fungus and moisture.
These aim to increase the R-value of the house. The R-value is a measurement of a building material’s thermal resistance per unit area to resist conductive flow of heat from a hot to a cold area. R-values are additive per layer and are measured in inches or meters of thickness. Rigid foam sheets are more expensive than loose fiberglass but often have higher R-values.
During the mechanical phase of home construction, visitors may see green film over vents. The film allows for pressurized testing to ensure there are no leaks in the HVAC system.Builders try to construct an air envelope in the building and pressurize the whole house to check for leaks. Leaks cause lost energy and more expense. They also allow moisture and pests to enter the house.
Building a Better House
Builders endeavor to get it right the first time by inspecting during the process of construction. Fewer mistakes and earlier detection of any mistakes saves money for the builder and eventually for the buyers.
In rural areas outside of a municipality, NOBODY watches home builders. There are no codes and no inspections. Meanwhile, city inspectors create accountability for builders to produce minimum-standard houses. Consequently, some custom builders can cut corners and don’t have the same accountability in rural settings. As always, it’s important to find and work with people (builders, contractors, etc.) who do the right things even when nobody supervises.
PlumbingPlumbing, HVAC and electricity take about six business days to install in one house. Drains are in the foundation. Water lines are run over foundation rather than under it if possible. It’s MUCH less expensive and easier to replace and repair sheetrock rather than sections of the foundation.
Copper was the traditional plumbing system. However, copper can’t expand when it freezes. Instead, it breaks and causes multiple layers of damage. The rigid nature of metal makes it difficult to install or move for redesigns. Additionally, copper pipes will corrode over time.
Traditional water systems have main delivery lines which branch out to various outlets. Each split is an opportunity for a system failure and hidden leak. It also takes a skilled pro to repair, replace or divert any of these lines, which will need to be soldered.
Cross-linked polyethylene (PEX) is the accepted standard for many builders as well as home flippers and advanced DIYers (Do It Yourself). It is a flexible plastic tubing developed in 1968 and made popular in the 1980s for radiant floor heating systems. After it was chemically reformulated by adding antioxidants to resist the higher chlorine levels in U.S. water supplies, it could transport potable water and gained acceptance in construction. About 10-12 years ago it became the industry standard.
PEX lines are normally colored. Red is always hot. Blue is always cold. White and gray lines can carry either temperature but often transport cold water in new-built houses. PEX is not suitable for outdoor use because UV rays break down the plastic.
Another difference from the traditional plumbing system is the PEX manifold to divert water. Rather than a main line, the PEX lines move through a manifold (vaguely like an electrical circuit breaker). This allows individual lines to connect directly to the outlet fixture rather than having multiple branch lines (PEX can also branch with the correct fittings). PEX system advantages include:
• Very few metal fittings with a lower chance of expansion breaks and leaks.
• PEX doesn’t corrode over time.
• Color-coded lines ensure easy identification of line temperature.
• Water runs silently through PEX to eliminate the “water hammer” noise of metal pipes.
• Can be connected to existing lines if correct fittings are used.
• It is DIY friendly if correct tools and connectors are used.
• Stable manufacturing cost – it isn’t subject to copper availability and price futures fluctuations.
Tankless Water HeaterTankless water heaters were originally a government initiative. They save energy but have a higher initial cost than a traditional tank-based water heater. Builders are expected to exclusively install tankless systems by 2025 to save tanks from going into landfills.
These systems heat water as it flows through a heating device rather than attempting to maintain a constant temperature for an entire tank of sitting water.
Most builders use tankless water heaters as the standard. They are more energy efficient, require less storage space, last longer, offer endless hot water, use less water if multiple units are used and are safer than traditional tank water heaters.
Cold water must still run out of the line when first used after sitting dormant, but it creates an endless supply of hot water after the line temperature changes.
The circulating system of heated water creates “instant hot” water. The system needs to be scaled from time to time to remove the mineral buildup. Circulating hot water systems removes the need to clear cold water from the line. Circulating hot water systems are not as energy efficient as a standard tankless system.
Homeowners don’t want to hear about maintenance, but all systems must be maintained. Tank systems require annual maintenance and sometimes twice annually depending on the water quality. Tankless systems also require maintenance, but not as much as tanks. They must be descaled of mineral buildup periodically. Once annually is the manufacturer’s recommendation.
Termite ProtectionWhile the studs are still visible, buyers may notice the bottoms of the boards are green. The green color indicates the wood was treated with Bora-Care. Both the wood and concrete are treated.
Bora-Care treatment is for termite and other wood-eating insect prevention. Unlike traditional pesticide treatments, it’s relatively benign to humans while it is deadly to pests. The active ingredient of Bora-Care is borate salt. If borate salt is ingested by wood-eating insects, those pests are unable to get nutrition from their food, and they starve to death. Because it works on the insects’ biology, they can’t develop a resistance. The deaths of others alert the colony to avoid that property. Additionally, some pests won’t even attempt to eat the wood due to the treatment.
It comes with a 10-year warranty. Homeowners will need to take additional measures afterward. However, lines are run through the walls to allow pest treatments later from outside the house without ever exposing the entire house to pesticides.
Preparing for the next steps
Once sheetrock is on the walls, builders can often hand over keys within 45 days. Other builders use cabinets as a benchmark date for as much as 75 days before closing. The project manager will tell you when it is about time to list a home for sale and optimize timing without a homeless period of expensive temporary housing.If you’re ready to make the move to a new-built house, you have the right to have your best interests represented by a licensed REALTOR. The builder’s sales agent represents the builder – not you. The builder planned to pay a REALTOR fee. This cost is built into the purchase price. Don’t PAY for services that you don’t get! Contact a qualified REALTOR before you sign anything at the builder’s office. Otherwise, you possibly waive your right to no-cost representation.
DFWmark is certified as a New Home Sales Agent, Green Home Sales Agent in addition to having the Military Relocation Professional (MRP) and Graduate, REALTOR Institute (GRI) designations. I can ease the strain of finding your new-built home with my proprietary research information as well as help you liquidate your current house.
Please continue this Construction 101 series to the Punch List inspection.
I’ve Got Your Six!
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