TOP 10 Blunders that rot your house, waste your money, and make you sick.


ONE
VAPOR BARRIERS ON BASEMENT INSULATION WILL ROT YOUR WALLS
We anticipate a house’s walls to get wet during construction, either from the weather or from the materials (that’s why joint compound is called mud). But they also can get wet once the house is finished and occupied. Wet walls have to dry. There are two types of wall that can get wet: regular walls over the ground and basement walls under the ground. In addition, there are two sides to a wall: an indoor and an outdoor it’s smart to design walls to dry to both sides, but drying to at least one side is a pretty significant objective. A vapor barrier on the inside of a wall means that the wall can dry only to the outside. This is OK for ordinary walls in cold climates (like Canada, where there are only two seasons: last winter and this winter), but it’s not OK for underground room walls, not in any climate. Basement walls can’t dry into the ground because—you guessed it—the ground is wet. Because basement walls can dry only to the in-side, covering the inside of a finished basement wall with a sheet of plastic is a bad idea. Wet basement walls wrapped in plastic can’t dry. We must build walls so that they can dry during wet seasons. By using extruded polystyrene foam for insulation, you can eliminate the inside condensing surface and prevent water intrusion from the outside.


TWO
VENTED CRAWLSPACES ARE MOIST ENOUGH TO GROW MUSHROOMS
Many years ago, we didn’t insulate crawlspace floors, and we didn’t air-condition houses. Crawlspaces were warmed by the houses themselves. Now that we protect and insulate floors, crawlspaces are within a degree or two of ground temperature. During nearly all of the summer, this temperature is below the dew point of the outside air, even up north. Airing and ventilating a crawlspace allows moist outside air to condense on cool crawlspace surfaces. As a result, the ventilation air is wetting the crawlspace rather than drying it. It’s like opening a basement window in June: The walls sweat.And wet walls turn into moldy walls quickly. The whole point of airing a crawlspace is to remove humidity. If we could import hot, dry air from Tucson to vent moist crawlspaces in Tupelo, venting crawlspaces would be a great idea. But for Tupelo air to vent Tupelo crawlspaces, the air needs to be dry enough to pick up moisture, and it needs heat to evaporate the moisture. This isn’t going to happen, and here’s why: Tupelo air isn’t hot and dry. Neither is Toledo air, Tallahassee air, nor Toronto air. A crawlspace is just a mini-basement and should be treated as such. It’s like a basement for a hobbit. You should condition the air in your mini-basement. Make it part of the house because, regardless of what you may think, it already is. Heat it in the winter and cool it in the summer with a supply duct or grille. Don’t insulate the floor; insulate the outer limits and install a continuous ground cover to keep out humidity.
THREE
DUCTS AND AIR HANDLERS IN ATTICS WASTE MONEY AND SUCK IN BAD STUFF





Why put the heating and cooling system outside the space that it needs to heat and cool? We insulate walls to R-19 and ceilings to R-50, yet we slip an R-4 sleeve over ducts and call it good. Where were the adults when this choice was made? What’s more, ducts leak. Let me rephrase that. Ducts leak a lot—about 15%. It’s like installing a large exhaust fan in the attic to suck conditioned air out of the house and pull unconditioned air in through the cracks. If radon were a valuable commodity, we could mine it this way. And think about winter. Heating bills go through the roof, and escaping air heats the top story, melting snow and forming ice dams. Goodbye, heated air; hello, water damage. You can’t make ducts and air handlers tight enough so that they won’t leak (don’t even think about duct tape). The least you can do is put them in a conditioned zone such as the basement or a conditioned crawlspace, or you can move the attic insulation up to the roof.


FOUR
USING JOISTS OR STUDS FOR DUCTWORK ROTS FRAMING
A panned stud or joist cavity is an air return that uses framing members,sheet metal, and drywall as ductwork (photo above). Why is this bad? Because the air is pulled through a leaky framing cavity instead of a duct, contaminants come along with it. The result is that air will be sucked from any leak available to equalize the pressure (drawing below). In a humid climate, the house will suck wet air into the wall cavities. If the house has a vapor barrier inside the face of the drywall, the water will stay inside the wall (air will make it through the cracks). Wall cavities are a bad place to store water. If the stud-bay or joist-bay return is in the garage, pollutants such as carbon monoxide or vapors from gasoline or solvents can be sucked into theliving space. If the air return is in a furnace room, combustion gases can besucked out of the flue (backdrafting). Here’s the test: Turn on the HVAC unit and spend a romantic candlelit evening with your significant other. Burn those cloying perfumed candles; the fine soot particles in the candles act wonderfully as tracers for airflow. Next day, look for stains on the carpet at the baseboards near a studcavityair return. Air is being sucked into the wall under the baseboard, filtered by the carpet, and marked by the soot. If we did plumbing this way, we’d flush our toilets into the floor framing.




FIVE
WINDOWS AND DOORS WITHOUT PAN FLASHING CREATE A WATER-INJECTION SYSTEM
There are only two kinds of windows in the world: windows that leak now andwindows that will leak later. The only things that leak more than windows aredoors. And the more expensive the door, the more it leaks—especially bigFrench doors with sidelites. And sliding doors. I know, I know, I can hear thesalesman already: “My windows don’t leak. They were tested at the factory.”Right, they didn’t leak at the factory. But they will leak after they’re in a house.
If not today, then tomorrow.Windows are like people; their characteristics change as they age. As windows and people get old, they leak. I don’t leak now, but I will someday. Windows and doors need a dependable backup system: a gutter. These gutters are known as pan flashing, that thing with a back dam, end dams, and a slope toward the outside. They’re simple to install; many come in two pieces that slide together (Jamsill; 800-526-7455). Just don’t put a hole in it because a dab of silicone won’t seal the hole. Silicone is like people: When it gets old …








SIX
DON’T LET BRICK WICK WATER INTO WALLS
I hate brick. No, I don’t—I love brick. I hate bricklayers. No, I hate lazy bricklayers who don’t ventilate cavities and clean up mortar droppings. Let me rephrase that. The old way of installing brick worked. There was a 1-in. cavity behind the brick with air inlets at the bottom, outlets at the top, and a clear pathway connecting the two. Why is this important? Because brick essentially is a dense sponge. When it rains, brick gets wet.Now, let’s pause for a minute to review the second law of thermodynamics:Water moves from hot to cold and from wet to dry. OK, back to the brick. What happens when brick is rained on? Brick gets wet, and we know that water moves from wet to dry (inward toward the dry part of the brick). Now what happens when the sun comes out? Yup, water moves from hot to cool (inward toward the cool part of the brick). If the cavity behind the brick is vented properly, the ventilation air intercepts the flow of moisture and carries it out the top of the wall. No problem. If the cavity is vented improperly, however, water vapor is driven inward, toward the cool, dry house, and through the vapor-permeable exterior housewrap and plywood sheathing; it then condenses on the interior plastic vapor barrier. Here, the water sits and waits for mold to drink it. If the vaporbarrier is leaky or if there isn’t one, the mold eats the drywall instead. If you’re going to install brick, make sure there’s a clear cavity vented at the top and bottom. If you can’t use brick responsibly, don’t use brick.

SEVEN
STUCCO NEEDS TO DRAIN
Stucco is a simple product. A few thin coats of reinforced mud provide a strong, goodlooking protective layer for a house. The entire key to successful stucco is drainage:There must be a drainage space between the stucco and the tar paper that the stucco isinstalled over. This used to be easy because in the old days, tar paper was more robust than it is now: It weighed more, was thicker, and had higher rag and cellulose content. The first coat of stucco would swell the tar paper. After the stucco and tar paper dried, the tarpaper shrunk back and debonded from the back of the stucco. The resulting wrinklesformed a drainage space. Today’s tar papers and housewraps don’t debond because theydon’t swell enough. Because they don’t debond, they don’t drain, and worse, theylose their water repellency over time. To apply stucco successfully with contemporarytar paper, use two layers of tar paper. The first will act as a bond break, and the secondwill act as a drainage plane between the two layers.

EIGHT
WITHOUT THE RIGHT PATHWAY, CONDITIONED AIR GOES TO ALL THE WRONG PLACES
Let’s see. We duct conditioned air (supply air) to a bedroom on the second floor and place the returnair grille in some other room on the first floor. So how does air get back to the return when the bedroom door is closed? It’s sucked under the door. According to my calculations, for this to occur efficiently, the gap at the bottom of the door should be roughly 1 ft. to prevent pressurization of the bedroom. Why is pressurization bad? Because uncontrolled air changes are bad. If your bedroom is pressurized, conditioned (paid-for) air is being pushed through the walls and ceiling. If the pressurized air is moist, water is being pushed into the walls. Remember, wall cavities are a dumb place to store water.Because a knee-high gap at the bottom of the door is unlikely to sell houses, we (repeat after me) ignore the problem. Air rushes under the door, is filtered by the carpet, and creates racing stripes at every door opening. Again, those romantically sooty candles enhance this effect. The retrofit solution at my house was throughwall vents.




NINE
AERODYNAMICALLY COUPLED GAS APPLIANCES CAN’T EXPEL ALL TOXIC GASES
More than 10,000 people visit emergency rooms each year with carbon-monoxide poisoning, and more than 500 people die from it annually. A little more than half of these cases are the result of automobile-exhaust inhalation; the rest are caused by consumer products. About 100 people die yearly because of malfunctioning gas furnaces and water heaters. We’ve come a long way since the caveman days, but when it comes to managing combustion by-products, we haven’t advanced much. Back then, we’d put a hole in our cave, light a fire, and hope the smoke would leave. We’ve advanced from a hole in the cave to aerodynamically coupled gas appliances. We’ve put a pipe over the fire and stuck the pipe through a hole in the ceiling to vent smoke.
In typical gas water heaters, the chimney isn’t connected to the top of the water heater;there’s a gap. Building scientists call this gap a bad idea. Everyone else calls it a draft hood.Except in Germany, where things always are ordered and precise, combustion by-products don’t follow arrows past the draft hood, especially if your house, range hood, or clothes dryer sucks(see No. 4). If your house sucks, the result is called backdrafting, sucking toxic gases into your breathing air. Installing appliances this way is crazy. You should use only sealed combustionwater heaters and furnaces, which are vented directly to the outside. And by the way, they should have a dedicated supply of combustion air piped directly to the flame (drawing above right), also with no holes in the pipe.



TEN-The most dangerous thing to do to your house
UNVENTED GAS SPACE HEATERS AND FIREPLACESPRODUCE COMBUSTION EXHAUST THAT DOESN’T BELONG INSIDE
You’d never run your car in an enclosed space, would you? So why would you run a gas heater or fireplace in one? I’m not talking about portable space heaters, which everybody knows are dangerous in enclosed areas; I’m talking about actually installing an unvented gas heater or fireplace permanently. Sure, they’reinexpensive, but the potential price tag is very high. At Building Science Corporation, we call this the Kevorkian option. Let me explain: There’s really no such thing as an unvented gas space heateror fireplace. The combustion by-products, quite simply, are vented into the room, then into your lungs and shuttled to your brain. This is bad.
When installed, maintained, and operated according to the fine print on their warning labels, gas space heaters and fireplaces have a pretty good safety record। But the potential for mistakes is too great.A window should be open when these heaters or fireplaces are on, but if it’s cold out, many people won’t open a window. Unvented gas heaters and fireplaces can’t be the primary heat source, but if their thermostat is set at the wrong level, they become the primary heat source. What’s more, the room size necessary for a 30,000-Btu unit is unfathomably large. Why in the world would you want to increase your risk ofcarbon-monoxide poisoning? Let’s revisit my cave analogy: We’ve got a fire in the cave and a hole in the ceiling for ventilation. Using an unvented gas appliance is like plugging the hole in the ceiling. By this time, we should have figured out that it makes sense to locate the fire outside the cave. One more thing: Unvented gas space heaters and fireplaces are illegal in five states. Sealed-combustion appliances, good. Unvented combustion appliances, bad. Period.

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Is Your old Wiring Safe?

Some materials used in old houses are better than their modern counterparts, like three-coat plaster versus drywall. When it comes to electrical wiring, though, older does not mean better.
Electrical materials and safety devices have improved considerably over the past century. Is old wiring safe? It may be. Or it may present a shock, electrocution,or fire hazard due to deterioration from age, poorly executed modifications, or lack of capacity to meet modern power demands.

Older wiring that’s in good shape, however, can continue to serve, and selective upgrades can be used to meet today’s needs. A visual inspection of the panel and exposed wiring is the first step
in evaluating an electrical system. Although I can’t possibly describe everything that could go wrong with old wiring and how to fix it, I can describe some of the signs of an electrical system that needs repair or replacement.

RED FLAGS IN THE FUSE BOX AND BREAKER PANEL

1. Coins or slugs behind the fuses. In this case, a penny is not a sign of good luck, but rather a sign that the wiring may have been damaged by the bypassed overcurrent protection.

2. Hacked panel covers. Circuit breakers are designed to work only in specific panels. To save
money, mismatched and oversize breakers may have been installed, and the panel cover
modified to fit.
3. Rust. On screws, wire, armored cable, or the box itself, rust is a sign of deterioration. Rust can create poor connections and potential safety hazards.
4. Melted wire. Exposed copper wire is dangerous because it can cause arcing, shock, and electrocution. Melted insulation is a sign of overheating.

Armored cable, or BX, also was used in early electrical systems. Originally designed to protect the wires inside, the armor also acted as the grounding conductor in later versions of the cable.
Loomex, a predecessor of the nonmetallic (NM) sheathed cable used today, became available in
the late 1920s. Nonmetallic cable first had only two wires with a tar-soaked cotton jacket. Later, a grounding wire and plastic sheathing were added. The insulation on the wires was made more heat resistant in 1984. This cable, used widely today, is labeled NM-B. When current travels through a wire, the friction creates heat that can damage the wire’s insulation. Consequently, all wiring is protected by fuses or circuit breakers. In early electrical systems—5-, 20-, 25-, and 30-amp—Edison fuses provided this protection. The second generation of overcurrent protection is the circuit breaker. A circuit breaker is a switch that senses when there’s
too much current and opens, interrupting the circuit. The advantage of breakers is that they can be reset after the problem has been fixed. If a fuse melts, it has to be replaced. When I inspect old wiring, I begin at the fuse box or breaker panel.

First, inspect the panel As greater demands were made on old electrical systems, fuses would
melt due to overloads. People often installed an oversize fuse, or installed a coin or metal slug to bypass the fuse and keep it from melting. When I evaluate a fuse box, I take out each fuse and look for a coin or slug. If I find one, I know the wiring on that circuit probably is damaged and needs to be evaluated further before it can be deemed safe. Likewise, if I find a bunch of 30-amp fuses in a box, there is a good chance the circuits are overfused. Thirty-amp or larger circuits are
used for 240v appliances or for subpanel feeders, so there should be only a pair of 30-amp or larger fuses for each of these circuits. I also check the gauge of the wires on each circuit to determine if the fuse size is appropriate. If the homeowner intends to keep the fuse box as
the main panel or as a subpanel, I install type-S inserts before I replace the fuses. The inserts make it impossible to install oversize fuses.

Homeowners with newer electrical panels sometimes install oversize circuit breakers on overloaded circuits. Using the coffeemaker and toaster at the same time no longer trips the breaker, but it’s likely that the wiring has been overheated and damaged as well. I’ve also found electrical panels missing covers. This makes resetting a breaker unsafe. And I’ve seen the cover notched to accommodate a breaker not designed for the panel. This is dangerous because breakers and panels work together as a system, and only breakers listed for use in a specific panel are acceptable. If the cover is missing or has been hacked up, I buy a new one or have a new one made, replace the mismatched breaker, and carefully inspect the wiring for that circuit. Inside all electrical boxes, I look for rusted metal, melted plastic, exposed copper on the hot and neutral wires, and loose connections.

Look for failing wires After I inspect the fuse box or breaker panel, I look at all the accessible wiring, usually in the attic and basement. I check for signs of deterioration or of improper
modification. If I find bare wire where the insulation has fallen off, or brittle insulation that will
fall off soon, I know there’s a risk of shock, electrocution, and fire. I inspect modifications to
knob-and-tube wiring. Original splices should have a neat layer of friction tape and should be supported by knobs on both sides. Nonoriginal splices should be made in electrical boxes. Open
splices can fail and arc. The National Electrical Code (NEC) does not allow knob-and-tube
wiring to be buried in insulation, although some jurisdictions do, as long as it has been inspected by an electrician and there is a sign warning that the wiring is present. (Go to
www.finehomebuilding.com for more on old wiring and code issues.) I begin my evaluation of armored cable at places where it’s exposed to moisture because rust is the most common cause of deterioration. I also make sure the fittings that connect the cable to electrical boxes are not
rusted or loose. Rust and bad connections impair the grounding path. If I spot rusted cable, I test the quality of the grounding path with a special tester. (Go to www.finehomebuilding.com for more on these testers.) With NM cable, I first check to see if the sheathing is deteriorating
or has been chewed by rodents. Then I look in a few boxes to see how the grounding conductor is terminated. During the transition to grounded circuits, some electricians clipped off the ground
wire or wrapped it back onto the sheath. If grounding outlets are installed in a system without a
grounding wire, I replace the outlet with a nongrounded or GFCI (ground-fault circuit interrupter) receptacle. Some NM cable installed in the 1960s had aluminum conductors.
If I find branch circuits with aluminum wiring, I inspect all connections. Because aluminum expands and contracts,it can work itself loose. I make sure that all the switches and outlets are rated for aluminum wiring. I also look inside junction boxes and behind outlets and switches. Looking in these areas, I can tell if past electrical work was done properly.

THREE MYTHS ABOUT OLD WIRING

Myth #1 Knob-and-tube wiring must be replaced

When the opportunity presents itself—during a remodeling project, for instance—I usually recommend replacing old wiring. Some insurance
companies won’t issue new policies or will charge higher premiums for houses with knob-and-tube wiring. However, if it is inspected, proves to be in good condition, and meets your needs, there is no
reason to rewire your house.

Myth #2 Old nongrounding circuits are unsafe

Most new appliances, lamps, and tools have two-prong plugs that don’t need a grounded outlet. These two-prong plugs are double-insulated, reducing the chance of shock or electrocution
and the need for a grounded circuit. What is unsafe is using an adapter to make a three-prong plug work in a nongrounded outlet. If you need to plug in a surge protector or other grounded device, run a new circuit that has an equipmentgrounding conductor.

Myth #3 GFCIs won’t work with old wiring

A GFCI receptacle will work fine in an old electrical system even if the circuits don’t have a
grounding conductor. The GFCI self-test button will work, too. Because there’s no grounding
conductor, though, a plug-in continuity tester won’t trip the breaker.

Rewire or upgrade? After I inspect an electrical system, I have to decide whether to recommend
rewiring the house or just doing selective upgrades. If much of the cable sheathing or conductor
insulation is in bad shape, if there are no fixture boxes, or if testing shows poor connections, I recommend a rewire. If only one or two areas have deteriorating insulation and it looks as if the original installation and any modifications were well done, and the results of voltage-drop testing
are acceptable, then selective replacement or upgrading is an option. Folks often worry about nongrounded circuits. If wiring is in good shape and grounded outlets aren’t needed—for three-prong plugs or surge protectors—these circuits are fine. Older wiring and the small outlet boxes that often were used with it can be difficult to rework. If you need or want to add GFCI outlets,
for example, you may find it difficult to install the GFCI in a small box without damaging the old
wires. In this case, I install a junction box at a point where the original wiring is in good shape, and splice and run new cable to the outlet. If the outlet box is still too small, I remove the old electrical box and install an old-work box. If a house’s wiring is in good condition but is overloaded, adding a few new circuits is the best solution. Installing new circuits to serve the kitchen-counter and bathroom outlets, computers, dishwashers, and garbage disposals
takes a significant load off existing circuits and costs much less than rewiring the house.
If I’m adding new circuits, I have to decide if the fuse box or breaker panel has enough capacity
and breaker spaces to handle new circuits. If the service is an original 120v, 30- or 60-amp fuse
box or breaker panel, or if I need to add branch circuits to a fuse box, I recommend upgrading to a modern panel and 200-amp service. It is also time to upgrade the service when the load calculations show a demand larger than the existing service or when no space is available for new circuits. Finally, if the panel is rusted or if the hot buses are badly pitted, it’s time to upgrade. If all you need is one or two additional 20-amp circuits, and the panel has capacity and breaker
space, there’s no reason to replace a panel just because it is old. Looking at the condition of wires, and their supports and connections, is a big part of inspecting an old electrical system. If you inspect the wiring in your house and still have concerns, call an electrician who has expertise in old wiring and has the special equipment to test the safety and reliability of the circuits and overcurrent protection.

Poor additions. Other than knoband-tube, wires should be in a cable or conduit. Loose current-carrying wires are vulnerable to damage.

Missing electrical box. Switches,outlets, and splices should be installed with electrical boxes.

Chewed cable. Rodents can be a problem with nonmetallic cable. Chewed cable should be repaired or replaced.

Bad connections. During an inspection, all connections should be checked. Because the armor on this BX cable acts as the grounding conductor, a bad connection means poor or no ground.

Deteriorating sheathing. The insulation on old wiring can be brittle. Brittle insulation crumbles, exposing wires and creating a hazard. Small areas of deteriorating cable can be fixed; lots of deteriorating cable should be replaced.

Clifford A. Popejoy

www.onerenohome.com

Painting

Most people think that painting the interior of a house is a job that requiresjust a couple of tools, a high level of boredom, and very little experience.
Only after they’ve come to the end of their messy
first job do they begin to wonder about that old guy in painter’s
whites they once saw working at someone else’s house. How could he paint an entire room in a seamlessly choreographed sequence of brush and roller strokes before his second cup of coffee and not spill even a drop of paint? I’m not that old guy yet, but I am a painting contractor. People always ask me how they can improve their painting techniques. If you consider the act of painting on par with a trip to the dentist, the answers ahead will provide some Novocain to ease the pain of your next painting project.
I like to move all furniture out or to the center of the room and cover it with plastic. To protect the floor, I roll out 4-mil plastic and tape it to the baseboard. Unless I’m painting the ceiling, it’s necessary to cover only the first 3 ft. or 4 ft. of floor from the wall. Blue masking tape is best; it adheres to most surfaces and peels off cleanly for up to 14 days. The green tape can stay on even longer. Next, I make sure walls and trim surfaces are clean, stain-free, and smooth. Nail holes, bumps, and cracks can be patched; for anything less than 1⁄4 in. deep, I use lightweight joint compound, which dries quickly.

It’s a good idea to start any job with a quality primer. (For more on primers, see “Don’t Skip the Primer,” FHB #161, pp. 60-63). Stains including ink, crayon, water, and smoke soot can be blocked by a stainkilling primer such asBenjamin Moore’s Fresh Start acrylic primer . After applying the primer, be sure to spot-prime thesame area with the finish paint before applying the final coat. Otherwise, the spot will appear shiny when the wall is viewed from an angle.


For a topcoat, there are two things to consider: latex vs. oil, and type of finish. Oil paint is made with an alkyd-base resin and cleans up with mineral spirits. I use it in kitchens and bathrooms because it is impervious to water. Latex paint is made from acrylic resins andcleans up with water. Because of their good durability and easy cleanup, I use latex paints everywhere else.
Pro painters have different preferences, but I like to paint the walls first, then the trim. Ican roll out the walls quickly and not worry about any spray landing on the trim. Once the walls are finished, I wipe down the trim with a damp rag and start on it. I don’t mask off the trim when I cut in the walls, but masking is certainly a good option if you’d rather not worry about getting wall paint on the trim. Any one of the low-tack tapes works well.
Lap marks on walls are the visible transition between the textures made by a brush and by a roller.
I cut in with a brush first, then try to roll as close to the trim as possible. I switch between cutting and rolling to ensure that the cutting stayswet, which also helps to eliminate marks. You’ll also find that the greater the paint’s sheen, the greater the likelihood of lap marks, which is a big reason to use flat paint on walls. Ropes, another type of lap mark, are caused by squeezeout from the roller’s edge and can be remedied by a lighter touch when rolling out a wall. After loading the roller with paint, I use short, easy strokes that overlap each other by at least half.
HOW DO I PAINT A PANELED DOOR AND NOT GET LAP MARKS?Paneled doors should be primed with a highquality primer to eliminate bleed-throughstains. Multiple finish coats (usually two) may be necessary to get good coverage.
Ask your paint supplier to tint the color of the primer as close as possible to the color of the finalcoat paint. Again, the secret to stopping lap marks is to use a smooth last stroke with little paint and light pressure.
1. Start by painting at the top of the door, panels first, then rails, then stiles. Here, lesspaint is better to prevent drips; two coats lightly applied are better than than one heavycoat that drips or sags.
2. Be sure to keep the paint’s leading edge wet to prevent brush marks. A final lightstroke across the panel faces and along the intersections of the rails and stiles will eliminate sags and brush marks.

3. When you reach the door knob, use even less paint to get a seamless stroke pattern.The trick is to brush around the knob with continuous strokes and avoid stops. Masking or removing the hardware is also an option.
4. Be sure to check your work for drips, particularly in recessed areas and along door edges. As long as the paint is still fairly wet, drips can be erased with a light brush stroke.

BY FRANK SINICROPE

Floor Sanding

Sanding a floor is nasty work. It's noisy and dusty, and it takes a fair amount of practice to do it right. It's one of the most frequently subbed-out jobs. But a lot of people are willing to take it on for the first time, as owners of tool-rental shops will readily attest. Here are some tips, and a few precautions.

Preparation—Take everything that isn't nailed down out of the room. Cover the builtinswith plastic sheeting, and tack sheets of plastic across any doorways. Rolled-up towelslaid against the bottom of the far side of doors in rooms being sanded will also help to contain the dust.

Sweep the floor clean and set any protruding nails at least in. below the surface. Repairloose boards or squeaks with nails driven into joists. If there's room under the floor, Ilike to fix squeaks by driving screws through the subfloor to draw the hardwood tightagainst the underlayment. These screws have to be 1/4 in. shy of the total thickness of the subfloor and the flooring. You'll need a dust mask while you're sanding. You may want to wear some ear protection, too. Wear shoes that don't have crevices in the soles that can pick up grit. Sneakers or running shoes are good, but avoid the ones with black soles—they can leave scuff marks that are hard to remove.

The tools—It takes two basic kinds of sanders to finish (or refinish) a floor: a drum sander and a power edger. Both are available at tool-rental shops, and both require some muscle and practice to use correctly. The drum sander, or floor sander, is used tosand most of the floor (photo facing page, top). It is a formidable machine. Even thesmaller versions weigh about 125 lb., and they look like a cross between a lawn mower and a steamroller. They need their own 15-amp circuit to operate an 8-in. drum that rotates at about 5,000 rpm. When this drum is fitted with coarse-grit paper and lowered onto the floor, it wants to take off like a dragster.

If you hold it in one place, it is inclined to eat its way through the floor and into the basement. It's not a machine to be taken lightly. But it's the only tool for the job, and with some practice, an operator can develop the required light touch.

The first-time user should practice on a section of floor thatwon't be in direct view.
Try a bedroom floor or part of a room that will be covered with arug. And sand only with the grain. As in any sanding job, you start with coarsegritpaper and work up to the fine grit. It takes quite a few sheets of at least three differentgrits to do an entire floor. Sheets are sold at the rental shops, and you can generally return the ones you don't use. Take plenty. If you are refinishing a floor that's coveredwith paint, begin sanding with a very coarse paper—12 to 20 grit.

For a new floor, start with 24 to 40 grit. The drum sander is designed to make a slightly deeper cut on the left side of the drum (drawing facing page, top). This delicate angle allows you to feather the edge of the cut on the right side. To benefit from this feature, you should start sanding on the right side of the room, and work toward the left. Begin about a third of the way up the floor (drawing facing page, center), and gradually lower the drum to the floor by letting up on the handle. It's important that you walk forward as you do this so the drum won't dig in in one spot.

The weight of the machine will do the cutting. You want to make sure that the drum smoothly engages and disengages with the floor. As you near the wall (about 1 ft. away), begin lifting up the drum, and then lower it again as you back up over the same path. You're towing the sander now, and this is when it does its best cutting. Move to the left in 2-in. to 4-in. increments, making a forward and a backward pass over each section. When you've covered two-thirds of the floor, go to the left wall, turn around and sand the remaining third in the same manner. Take care to feather the slight ridge where you changed direction.

Sometimes a floor will be so uneven that it has to be sanded diagonally to the strips. Do this very carefully, and only with the coarsest paper. Start in one corner and move from right to left until two-thirds of the floor is covered. Go to the opposite corner, reverse direction and finish the remaining third. Then sand the entire floor in the direction of the grain with the coarsest paper.
Since the drum sander can't reach in close to walls, corners and other tight areas, you'llhave to sand these surfaces with an edger (photo bottom right). This powerful discsander has grips for both hands built into the body. When it's tilted back on its wheels, the disc is lifted off the floor. When allowed to tilt forward, the machine begins its work. Like the drum sander, it is a difficult tool to use correctly without some practice. Try it out where you can't do too much damage. The edger has a light mounted on the frontof its chassis that helps you see what you're doing. If you're renting one, check to see that the bulb works—frequently they don't. Unlike the drum sander, the edger makesits deepest cut on the right-hand side (at about one o'clock), and should be movedacross the floor from left to right.

A standard pattern for moving the tool is the semicircular path shown in the drawing, bottom right.There are other ways to operate an edger, too. Do whatever works best for you. Sand the areas missed by the drum sander with the same or a slightly finer grit. When the entire floor has been sanded with coarse-grit paper, fill any holes in the floor. I use a lacquer-base filler blended to match the species of wood that I'm finishing, and I spotfill nail holes and cracks between boards with a putty knife. If it's a top-nailed floor with a lot of nail holes or a parquet floor with numerous gaps, I trowel on the filler with a concrete trowel and wipe away the excess with a burlap rag. When the filler has dried, the floor can be sanded with medium (40 to 60-grit) paper.

When you've finished with the drum sander and edger, check for shiners—nailheads turned silvery from being sanded. Set them, and refill the holes.
Final sanding should be done very carefully with 80 to 120-grit paper. Feathering is mostimportant now because any ridges will show in the finished floor. When the floor has been completely drumsanded with the last paper, clean up the corners. For this task, the professionals I know use a common paint scraper, sharpened to a razor edge with a file or stone. Most of the time you should pull the scraper with the grain, but for hard-to-reach crannies you may have to work it at a 45° angle. This is acceptable practice, but never pull across the grain. When the scraping is done, hand-feather the perimeter with a sanding block wrapped with the final grit.

Cleanup—Sweep the ceiling, walls and floor as clean as you can with a good broom. Next,lightly dampen a medium-sized towel with paint thinner, lacquer thinner or alcohol,wrap it around the broomhead, and go over the entire floor with it. This is called tackingthe floor, and it will collect most of the fine dust that still remains. Thoroughly vacuumthe edges and corners using a crevice attachment, and you're ready to apply stains,sealers and finishes.