You'd think that applying for a mortgage would be the same whether you are buying a newly built house or an existing one. But it's not, so buyers of brand-new homes need to understand the differences.

For one thing, the timeline can be far longer -- as much as six months, or sometimes even more. And the lender usually likes to see a little more earnest money on the table.

Typically with an existing home, the period from the application to closing is well-defined: usually 30 to 60 days. But when a new house is involved, the timeline is less clear-cut. It can be as quick as 15 days if you are buying an already finished inventory house -- and you have all your paperwork in order -- to as long as 180 days if you are starting from scratch.

That means that you might have to keep your financial nose clean for far longer than if you were buying an existing home. No big purchases that could cause your all-important credit score to drop, no moving big chunks of money around for whatever reason, no co-signing a loan for Junior's new car.

It's the seller who dictates how much of a deposit is required when the sales contract is signed. In the existing home market, the more money upfront, the more likely you are to catch the seller's eye as a serious buyer. But as little as $500 can sometimes hold the deal.

Builders, on the other hand, want more than the typical $1,000. Often, they require buyers to put up 5 percent of the contract price. And some builders want as much as 10 percent down before they will start construction.

Lenders want to see similarly large deposits on new houses, says Josh Moffitt, president of Silverton Mortgage in Atlanta.

When new construction is involved, Moffitt explains, lenders usually have to go through a "full-blown pre-approval" process. That means more work on their part.

A pre-approval also tends to remove as much as the risk as possible from the builder's shoulders – and the lender's -- and places it on yours. Since you have a larger down payment at risk, you are less likely to walk away from a house built to your order.

Pre-approval aside, the main concern of serious new homebuyers is rising interest rates. To protect themselves, the smart ones look for what's called "rate locks."

"Rate locks are important, especially when volatility is the norm," says the Silverton executive. "Up or down, we don't know. Going into a contract which doesn't close for four months creates a lot of exposure."

A rate lock guarantees that the interest rate you will end up paying will not be any higher than on the day you applied for your mortgage. Typically, a lender will hold the rate for 30 or 60 days. But after that, you are going to have to pay for what's known as an "extended lock."

How long and how much depends on your lender. But Moffitt says if the lender is quoting 4.5 percent today, you might have to pay an extra half-point to hold that rate for 180 days. Or the lender might agree not to go any higher than 5 percent if the hold is six months.

Whatever the cost, a rate lock is good protection. "You don't want to go to closing and find out your monthly payment is $300 more than you expected," Moffitt says.

It's also smart to make sure your rate lock contains a float-down rider. That way, if rates should recede during the time your new home is being built, the rate you eventually pay for financing will be lower. Again, good insurance.

Another difference between new and existing home processes is the appraisal. With an existing home, the appraiser looks over the property, finds comparable sales and comes up with a valuation. But with new construction, there is no house to appraise, perhaps not even a model.

Here, the appraiser makes his determination using the plans and specifications supplied by you and your builder, and comes up with a value based on what the house will look like when it is completed. Then, when construction is finished, he makes a final inspection to confirm the place is worth what he thought it was in the first place.

But the real challenge is finding acceptable comparables. In a major subdivision, where all the houses are pretty much alike, it's generally not difficult to find sales of similar houses. But nowadays, according to Moffitt, lenders don't want to see sales of properties that resemble the subject property as much as they do those of a more recent vintage. Or those that are close by.  

Consequently, neighborhoods, streets and even blocks can make a big difference in the appraiser's ultimate valuation. Or, if the lender says the most recent comps are more important than those that are equivalent to your house, sales from other school districts, on busy streets or lots not nearly as desirable as yours could come into play.

Why do houses in Vancouver neighborhoods with a high percentage of Chinese residents tend to sell for more when the house number ends in 8? And why do they sell for less when the house number ends in 4?

According to a study from the University of British Columbia, when the number on the house ended in 4, houses sold at a 2.2 percent discount. The reason, according to UBC: In Mandarin, Cantonese and several other Chinese dialects, the pronunciation of the number four sounds very similar to the word for "death."

There's even a name for the fear of No. 4: It's called tetraphobia. And it's why Richmond Hill, Ont., passed a bylaw this summer outlawing the number four in all new street numbers.

At the same time, when the number above the door ends in 8, which is phonetically similar to the word for "prosperity" or "wealth" in many Asian tongues, the house tended to sell for a 2.5 percent premium.

Gamblers are often superstitious, which is why you'd be hard-pressed to find a decent-sized casino hotel in Las Vegas with floor numbers four, 14, 24, 34 and 40 to 49. And of course, numerous office buildings throughout the country do not have a 13th floor.

Home sellers may not be afraid of certain numbers, at least not all of them. But according to real estate search engine Trulia, setting a price and "lucky" numbers go hand-in-hand.

"Setting the right asking price for your home isn't all science and it isn't all art," says Jed Kolko, Trulia's chief economist. "Sellers and agents pick numbers to signal their strategy, and to appeal to the traditions and superstitions of local buyers."

After studying the asking prices of all the homes for sale on the Trulia site for about a year starting in October 2011, Kolko discovered that after zero, as in $200,000, the number nine was the most popular, as in $199,999.

That is, of the non-zero ending digits in list prices, a whopping 53 percent of all prices ended in nine. The next most common number was five. "No other digit comes close to 9 and 5," Kolko says.

As it turns out, nine, in the vernacular of home buyers and sellers, is less than zero -- by more than $1.

And when house prices are reduced, according to the Trulia study, the lower price is more likely to have nine as the final non-zero digit than it was in the original price. In other words, the economist reports, when sellers are more eager to sell, they are more likely to price with a nine than, say, a one or two.

But apparently it's only sellers of lower-cost homes who subscribe to this pricing theory. When houses are priced over $1 million, buyers can't be fooled into thinking they have nailed a bargain with just one digit. Which is why only one in four homes listed for seven figures or more had a nine as the last number.

At the same time, it appears that nine is only popular in some markets. In upstate New York, for example, nine was the last non-zero digit in more than two-thirds of the listings. But nine was in less than a third of the listings in places like El Paso, Texas; Tacoma, Wash., Seattle and Honolulu.

Triskaidekaphobia -- fear of the number 13 -- is much more widespread. It appeared in the asking price of just 13 percent of Trulia's listings. That's not just at the end of the asking price, but anywhere in it. The number 13 appeared in home prices less than the numbers 12 and 17.

Then, of course, there's lucky number seven. House prices in Nevada are more likely to have a seven in the list price than anywhere else in the country. And whereas prices with triple sevens were found in just eight out of every 10,000 listings in the Trulia study, such a combination is three times more likely in the Silver State.

The numbers three and six represent both the good and bad in Christian numerology. And as you may have guessed, they resonate most in the Bible Belt, which covers most of the South.

The number 316, as in John 3:16, was 27 percent more likely to appear somewhere in a Bible Belt home's asking price than in houses elsewhere.

And good wins out over evil, at least when pricing a house, for the number 666 showed up in less than one out of every 10,000 listings. But 666 was still more common in Bible Belt houses than anywhere else.

Back to the number eight: It's so important in Chinese culture that the Beijing Olympics officially began at 8:08:08 p.m. on Aug. 8, 2008 (8/8/08), and that the United Airlines flight from San Francisco to Beijing is numbered 888.

Same thing for house prices. In neighborhoods without a large Asian population, Trulia found that the number eight was the last non-zero numeral in just 4 percent of the listings. But in neighborhoods with a preponderance of Asian residents, eight was the last non-zero digit in 20 percent of the listings.

Most people spend more than 50 percent of their time indoors -- children, some 90 percent -- so it is important to pay attention to the quality of the air in your home. And that means more than installing a few carbon monoxide detectors or testing for radon.

Mold can cause severe health problems, for example. Ditto for lead, a tainted water supply or hazardous household products. And since government at the state and federal levels can only legislate so much, it is up to homeowners to take whatever action is necessary to protect their families.

Indoor air pollutants come not only from what people have in their homes but also what they do there. It is well established, for example, that smoking can cause breathing problems. But so can furry pets and home projects that involve sanding, welding, painting or solvent chemicals like varnish and paint strippers.

Fortunately, there are simple steps you can take to find out the causes of poor indoor air quality and what to do about them.

-- Mold, sometimes known as mildew, grows where there are wet or damp surfaces. You can spot it easily when it grows out in the open, but often it is hidden behind walls or under the carpet. Either way, the telltale signs are the same: musty smells, watery eyes, runny noses, sneezing, itching, wheezing, headaches and fatigue.

To protect against mold, be sure your gutters are clean and not leaking, and that downspouts direct rainwater away from the house. Your yard should slope away from the building.

Repair leaking roofs, walls, doors and windows right away. Water is insidious, and can cause problems if left to stand. If your carpet remains wet for more than a couple of days, for example, it is best to toss it. It's also wise not to leave water standing in refrigerator drip pans.

Additionally, make sure the humidity in your home is not too high. If the moisture content in the air is more than 50 percent, turn off your humidifier and move your jungle of houseplants outside. Always make sure to run your bathroom fan when bathing or showering, and run your kitchen exhaust fan when cooking.

-- Unlike mold, you can't see, smell or feel carbon monoxide (CO), a deadly gas that can make you sick or even kill you. Signs of low-level CO poisoning include headaches, nausea, vomiting, dizziness, sleepiness, tightness in the chest and difficulty breathing. Many people confuse it with the flu.

To protect your house and family, install carbon monoxide alarms near each sleeping area and on each floor. But to make sure they never go off, never use the kitchen stove or oven to heat your house, and call a repair service if the flame on your range's gas burners is orange or yellow.

Also, don't use charcoal grills or run car engines inside your house, garage or basement -- even for a short time. They produce so much CO that even opening the windows and doors will not give you enough fresh air. In the same vein, never warm a vehicle while it sits inside the garage, even with the garage doors open. Start lawnmowers, snowblowers and other yard equipment outside, never inside.

At least once a year, hire a heating contractor to check your furnace, vents and other sources of carbon monoxide. Make sure your fireplace chimney is clean and in working order with an annual checkup.

-- Lead poisoning poses a serious health risk for children. Lead is not used as much in paint, pipes and other materials as it once was -- indeed, lead paint was banned in 1978 -- so houses built prior to 1950 are the most problematic.

If you are planning to remodel your older home, or have just finished a renovation, beware of dust or paint chips. Otherwise, look for cracking, chipping or flaking paint, or doors or window frames where paint is being rubbed away.

Also check for lead pipes, which are a dull gray in color and scratch easily with a key or penny, or pipes which are joined with lead solder. Water that flows through them can contain lead.

Your state or local health department can tell you how to check for lead at little or no cost, and most hardware stores carry low-cost lead testing kits. But if you find lead, don't try to remove it yourself. Getting rid of lead in the wrong way can make the problem worse, so find a certified contractor for the job.

-- Public drinking water is safe, but if you have a well or other private water supply, it's up to you to protect yourself. And since you can't see, smell or taste potentially dangerous microbes, you should have your H2O tested about every two years for bacteria, nitrates and perhaps pesticides at a laboratory.

You should also take care of your well. Have it checked by a professional if it is more than 20 years old. Make sure there are no gaps between the well casting and the material or ground around it.

-- When it comes to hazardous household products, buy only what you need, and read and follow the directions. Properly dispose of what you don't use, or give the leftovers to someone who can use it. Never burn or dump leftover containers.

Most of the information for the above comes from the Department of Agriculture's National Institute of Food and Agriculture (www.nifa.usda.gov). Other good sources include the Office of Healthy Homes within the Department of Housing and Urban Development (www.hud.gov/healthyhomes), the Environmental Protection Agency (www.epa.gov/iaq) and Healthy Indoor Air for American Homes (www.healthyindoorair.org).