Make Sure You Air Seal Your Modular Home

Why You Must Air Seal Your Modular Home

I’ve written in the past why it’s important to air seal your modular home.  It’s because air infiltration in the gaps where modules are joined can cause a great deal of heat loss.  If you want an energy efficient modular home, you need to air seal these gaps.
The modular manufacturer can control air infiltration within each of the modules, but when the modules are placed side by side or stacked on top of each other, significant gaps are created. It is just not possible to bring two modules together tightly when a cable is wrapped around each one while being lifted onto the foundation. In addition, even when the framing of one module is tightly butted up against the framing of another module, it is not possible to make the joint airtight.

What Can Happen When You Don’t Air Seal Your Modular Home

One of my first customers, Jim, hired a general contractor who didn’t take this seriously.  Jim’s home was a raised ranch with a drive under garage.  It was a good sized home, 28’ x 60’.
When Jim called me, it was after three winters of substantially higher heating bills than he expected.  His first comment was, “You said my home would be energy efficient.  But my heating bills are almost as high as for my previous home.”

Shows all connections where two modules are joined, both side to side and top to bottom, as well as where the modules sit on the foundation. The GC must air seal these against air infiltration.
The general contractor must air seal the modular home against air infiltration where two modules are joined, both side to side and top to bottom, as well as where the modules sit on the foundation

When we visited his home to complete an inspection, we expected to find that his contractors had not insulated the basement walls, as Jim and I had discussed while planning his home.  We also thought his contractors might have failed to put the attic insulation back in their bays after completing the button-up work.  Plumbers, heating contractors, and electricians often pull out some of the attic insulation so they can do their work.  Sometimes they forget to put it back, and the general contractor forgets to make sure they do.
But that’s not what we discovered.  So we performed a “smoke test” to see where air might be leaking.  What we found was that the joint where the front and back modules met in the basement and in the attic had not been air sealed by Jim’s contractors.  This gap at the “marriage wall” was creating a “chimney” effect, which was allowing the air to flow – and heat to escape – up through the middle of the house all winter long.  Although this was seriously compromising the energy efficiency of Jim’s home, we only needed a couple of hours to seal the marriage wall.
As we agreed, Jim called me after his next heating system.  He happily reported that his heating bill was substantially lower.

Have Your General Contractor Air Seal Your Modular Home

Ever since this experience, we’ve made sure to emphasize to our customers and their general contractors that they are responsible for completing the air seal where the modules join.  But we still find that some GC’s fail to do this task.  I strongly suggest that you ensure that your GC does.
For more information about why you must air seal your modular home, see The General Contractor’s Responsibilities for Building a Modular Home in my book The Modular Home.  For information about how to properly air seal a modular home check out this blog post and my Checklist for How to Air Seal a Modular Home.

Modular Home Set Responsibility

Responsibility for hiring the modular home set crew and crane should always be left to the modular dealer or manufacturer. A customer should refuse to hire the modular home set crew and crane, even if a dealer promises it will save substantial money.

A trained modular home set crew is working with an experienced crane operator to set the 4 modules on this two-story modular home.
A trained modular home set crew is working with an experienced crane operator to set the 4 modules on this two-story modular home.

Why You Should Never Hire the Modular Home Set Crew or Crane

The set procedures require a great deal of specialized knowledge, skill, and teamwork that a modular set crew acquires only through training, supervision, and experience.
Because of the size and cost of the modular units, as well as the risks associated with the modular home set procedure, whoever sets a home has substantial liability.
If a modular home set is done poorly, the general contractor’s job will be made substantially more difficult and the quality of the finished home may suffer as a result.
If someone on the modular home set crew is injured, the person or company that hired the crew could be held liable.

Why Would a Dealer Want You to Hire the Modular Home Set Crew and Crane

The goal of a dealer who asks the customer to hire the crane and the modular home set crew is to hold the customer responsible for any problems with how the house goes together. Since he neither built nor set the home, the dealer can disclaim responsibility for any problems. It is best to avoid dealers who operate this way.
For more information about hiring a modular home set crew, see Selecting a Modular Home Dealer and The General Contractor’s Responsibilities for Building a Modular Home in my book The Modular Home

Modular Manufacturers and Modular Dealers

Selecting a Modular Dealer and Modular Manufacturer

Inside the Pennwest/Manorwood Homes Factory
Inside a modular home factory. 

Shopping for modular dealers also means shopping for modular manufacturers. To make the right decision, you need to evaluate both the dealers’ services and the manufacturers’ homes. Even when a dealer and manufacturer are the same company (that is, when the modular manufacturer sells its homes through a company-owned retail center), you will want to evaluate the manufacturer’s services separately from its homes.
Most modular manufacturers, however, sell their homes through independent dealers. In this situation, it can sometimes be difficult for a customer to judge where the contributions and responsibilities of one end, and those of the other begin. Visiting model homes and talking with past customers will help, but your actual experience of the modular manufacturer’s attributes will be largely filtered through the dealer.

Underestimating the Importance of Modular Manufacturers

Building the Floors at the Pennwest/Manorwood Homes Factory
Building the floors on a jig.

In fact, customers seldom discover the true differences between modular manufacturers. For example, quality differences are sometimes difficult to identify when comparing dressed up model homes, which misleads many customers into thinking most manufacturers offer equal quality. Customers also have a difficult time sorting out whether price differences for a similar plan are due to the dealers’ retail prices or manufacturers’ wholesale prices. In addition, it often appears to customers as if different modular manufacturers are willing and able to build similar plans. Since most dealers work with their manufacturer to help their customers build any of the standard modular sizes and designs typical of the industry, it appears to customers as if what really matters when designing a home is how much design assistance the dealer provides. This overall experience leads many customers to conclude that the most important factors when shopping for a modular home have to do with the dealers’ services. Consequently, it is common for customers to feel they are buying a home from a dealer without regard to his manufacturer’s abilities. The personal contact provided by dealers reinforces this perception, making modular dealers the face of the industry.

Overestimating the Importance of Modular Dealers

Installing an Interior Wall Partition on the Pennwest/Manorwood Homes Assembly Line
Installing an interior wall partition with a crane.

Realizing that most customers attach greater importance to the role of the modular dealer than to the modular manufacturer, many dealers feel comfortable selling more than one manufacturer’s homes, and some even change manufacturers every year or two. They realize that most customers are buying a home from them because of the personal support and services they provide rather than because of the product quality and services offered by a particular manufacturer. Conventional builders feel the same. They know customers buy their homes not because they use a particular brand of window or cabinet or because they buy from a certain supplier. Customers purchase their homes because they provide superior craftsmanship and services for a fair price or because they offer a superior location.
There are exceptions to this categorization, and they almost always involve modular manufacturers who have been able to build an identifiable brand name for themselves. This tends to occur most often in communities close to the manufacturer’s factory. It is also enhanced when top-quality modular dealers forge long-standing relationships with a manufacturer. In these situations, the modular manufacturer’s reputation grows along with the dealer’s. The power of a dealer, however, is particularly evident when the dealer breaks this bond and selects another manufacturer, causing the manufacturer to adopt a new dealer. In this case, new customers are more likely to follow the established dealer (and his new modular manufacturer) than the old manufacturer (and its new dealer). This reinforces the feeling of many dealers that they are more important than the manufacturer.
Installing a Ceiling to the Module on the Pennwest/Manorwood Assembly Line
Attaching a ceiling to the module on the assembly line.

The fact that customers and dealers sometimes depreciate the contribution of modular manufacturers does not mean this is the wise thing to do. A smart customer will want to consider the real differences between manufacturers in specifications, craftsmanship, and warranty service. It is not that the manufacturers’ contributions are more important than their dealers’. It is just that you need to get the best that you can afford from both. You can only do this if you know what each is responsible for contributing.

The Relationship between Modular Manufacturers and Modular Dealers

A Few Pennwest/Manorwood Homes Roof Sections
A few roof sections ready for installation.

Customers are most likely to receive the best that a modular manufacturer has to offer when the manufacturer has a committed relationship with its dealer. That is why most modular dealers form a close affiliation with one or two companies. They may change modular manufacturers every few years for one reason or another, but they prefer to do business with the same company or two because it affords them and their customers several advantages. Other dealers choose not to form an alliance with any particular manufacturers. Instead, they switch from manufacturer to manufacturer every time they sell a home, selecting whichever manufacturer is willing to give them the biggest discount for the home. Sometimes they will pass along the savings to you; sometimes they will keep it for themselves. Either way, this dealer strategy can cause problems.
If a modular dealer is loyal to a modular manufacturer, the manufacturer is going to go out of its way for the dealer and his customers when there is a warranty-service need. It is not that a manufacturer who sells one home a year to a dealer will ignore its warranty obligations. But it will not assume the financial burden of correcting a problem unless it is convinced of its responsibility, especially if it heavily discounted the house to get the dealer’s sale. This may seem unfair, but manufacturers give preferential treatment to their most loyal customers in every industry.
Modular dealers often need the assistance of their modular manufacturer’s engineering and sales departments. This is particularly true when a customer wants to build a custom design or select some nonstandard features. Manufacturers may not always be able to do what the dealer and customer ask, but they will make an extra effort to help a loyal dealer. Sometimes this extra consideration is a big reason customers are able to get the house of their dreams.
Installing Drywall Mud on the Pennwest/Manorwood Homes Assembly Line
Applying drywall mud on an arched opening.

It is a challenge for anyone, not just a novice customer, to master all of the details (such as floor plans, standard features, optional selections, and prices) for one modular manufacturer. It is impossible to master them for several manufacturers at the same time. Each manufacturer will provide the dealer with its basic building specifications, but there will always be many details that are not contained in their lists. Dealers only learn of them by working closely with a manufacturer over a period of time.
Installing the Kitchen Cabinets onthe Pennwest/Manorwood Homes Assembly Line
Installing the kitchen cabinets on the assembly line.

When a dealer works with a new or little-used modular manufacturer, he does not always know what he is selling, since he does not always know what specifications are included in a given package. Likewise, the modular manufacturer may not know what the dealer thinks he is buying. Modular manufacturers and dealers learn a lot about each other’s expectations and preferences through each new home they sell. Many dealers have their own standards that they expect the manufacturer to meet, but there is little opportunity for this information to be shared when a dealer jumps from manufacturer to manufacturer. For example, when a dealer orders a 9-in-12 roof, he might assume that he will receive storage trusses, which will give his customer usable attic space. Consequently, he may include it in his contract with the customer. When it comes time to order the home with a new modular manufacturer, however, the dealer may not think it necessary to inform the manufacturer of this specification, since it was standard with his previous manufacturer. The fact that the dealer will be obligated to remedy his mistake will not make it any better for the customer.
For more information about what you need to know about the contributions of modular dealers and modular manufacturers, see Selecting a Modular Home Dealer in my book The Modular Home.

Why Wood Expands and Contracts in Your New Home

Why Wood Expands and Contracts

Your first heating season will remove much excess moisture from the wood and concrete in your new home. In the following years, your home will undergo an annual cycle of moderate expansion and contraction as the moisture content throughout your home increases and decreases across the seasons. This will be especially true if your home is located in a climate that experiences a lot of variation in temperature and humidity throughout the year – as is true of the northeast United States. The wood framing, doors, trim, and floors will shrink under conditions of low humidity (most often the winter) and expand under conditions of high humidity (most often the summer). This may cause wood fittings, such as at miter joints at the corners of windows and doors, to temporarily tighten or loosen. Usually, these conditions will return to normal when the humidity returns to normal.

Avoid Excessive Heat During the First Year

During the first year, use of a fireplace or a coal, pellet, wood, or other such stove at very high temperatures can lead to excessively fast drying. This can cause an unusual number of drywall cracks and nail pops as well as excessive warping, cupping, and shrinking of wood and other materials. The modular manufacturer, modular dealer, and general contractor cannot be responsible for any damage caused by these excessive heat conditions. Waiting a year before using these products at very high temperatures will help permit the wood and other materials in your home to dry slowly and normally.
For more information about why wood expands and contracts in your modular home, see Warranty Service for a Modular Home in my book The Modular Home.

Expect Moisture Condensation in Your New Home

Over the years we’ve received a few calls each winter from customers who’ve built a new modular home with us. One reason for their calls was the “ice dams” that had formed on the eave edge of their roofs. I’ll discuss this condition in a later post.  The other reason they called was concern about the moisture condensation on the inside of some of their windows.

Moisture Condensation: The First Heating Season

Moisture condensation often forms on the inside of windows and doors in new homes because of the drying out of the lumber and concrete foundation.
Moisture condensation often forms on the inside of windows and doors in new homes during the first heating season because of the drying out of the lumber and concrete foundation as well as by your daily cooking, bathing, drying clothes, and breathing.

Moisture condensation happens quite frequently at the beginning of a new home’s first heating season. This is true regardless of the type of wood frame construction. As much as a ton of moisture (yes, 2,000 pounds!!!) can be released by the lumber, concrete foundation, and drywall as they dry out. The condensation can appear as fog on the windows and can even freeze on the glass. Moisture condensation is most likely to appear on windows, rather than walls, because glass surfaces have the lowest temperature of any interior surface in a home. When the warm, moist air comes in contact with the cooler glass, the moisture condenses. The same action occurs on the outside of a glass of iced tea in the summer and on the bathroom mirrors and walls after you take a hot shower. If condensation occurs in your new home, you will need to provide ventilation to dissipate the moisture. Turning on the kitchen and bathroom ventilation fans each day or briefly opening a few windows, especially during the first heating season, should take care of the problem.

Moisture Condensation: Daily Living

Moisture condensation can also build up in a home after the first year because of normal living. If the problem continues, you should remind everyone in the family to use the bathroom ventilation fan when they are bathing and the range hood fan when they are cooking. Today’s tight homes are more prone to retain moisture from cooking, bathing, drying clothes, operating humidifiers, heating with fossil fuels, and breathing. Proper ventilation, however, will maintain the right amount of moisture in your home to balance comfort and safety. If an abnormally wet situation exists, use a dehumidifier. Otherwise, problems may result, such as peeling paint, rotting wood, buckling floors, insulation deterioration, mold and mildew, and even moisture spots on walls and ceilings. Remember, you are responsible for any problems caused by improper ventilation.

Moisture Condensation: Exterior Causes

Excessive moisture condensation can also be caused by conditions outside of the home itself, such as high winds during heavy rainfall or a snowstorm. Dampness in the basement, caused by poor exterior grading, a high water table, or other site conditions can also lead to moisture problems in the home. Again, if an abnormally wet situation exists, use a dehumidifier.
For more information about moisture condensation in your modular home, see Warranty Service for a Modular Home in my book The Modular Home.