Archive for the ‘interior’ category

Candle Soot: Shadowing and Ghosting

April 13th, 2013


Two years ago, we installed a new roof with ridge vents. Recently, we have noticed shadows on our ceilings in places where the roof trusses run. The house has cathedral ceilings as well as flat ceilings, and these “shadows” show up in all rooms. Also, along an exterior wall in our kitchen, we can see (from end to end) the outline of the roof truss, as well as vertical markings of studs. The markings in the ceiling and the walls look like someone lightly penciled in shadows of the trusses and studs. Can this be a result of the ridge vent that was cut in the roof?



What you are describing is textbook “shadowing” or “ghosting ” from candle soot. Does someone in your family burn those nice aromatic candles in glass jugs? Those are great soot producers.

M049 - Candle - Soot Generator


Candle soot is about as heavy as air. It moves throughout your home, aided by the forced air furnace. Outside walls and attic ceilings have plenty of insulation, but there is much less insulation on the framing edges. As a result, framing edges and fasteners are slightly cooler than the surrounding drywall.

When the air moves across the cooler surfaces, it slows slightly and deposits soot. The dark soot stains outline the framing with a shadowy or ghostly appearance.

So, stop burning candles! Or at least burn only very high-quality candles, and keep the wicks trimmed to 1/4 inch or less. Don’t burn candles in jugs – their combustion is starved of oxygen, so it produces lots of soot. You can find more information at in the Free Articles section; look for the article, Soot, Ghosts and Ugly Stains.

M050 - Candle - Trim Wick


Furnace fan, to distribute heat throughout the house?

January 31st, 2013


I have a two-story house with a basement, built in 1952. Is it a good idea to turn the furnace fan on, to distribute the heat throughout the house?

– Marian


H014 - Warm Air Furnace Fan and MotorYes and no. If you have a problem with a cool area when heating or a warm area when running the air conditioning, operating the fan continuously will even out the temperatures in your home. The downside is this will cost electrical energy to run the fan and cause some wear and tear on the fan. However, you can run a fan on a newer, high efficiency forced air furnace with an ECM or variable speed motor for little cost – about 1/10 the cost of a typical fan motor. Finally, I think your first step is to have a contractor inspect and adjust your system. At times, duct dampers can be adjusted to correct cold spots and air flow problems. Often you need to make a spring and fall damper adjustment for a two story home.

– Mr. Fix-It

Shadowing, Ghost Stains

February 17th, 2010

What causes “shadowing” on house walls? I always chalked it up to soot from candles, but I recently had a realtor call me about a house that had shadowing on studs, ceiling truss members, and nails/screws in the drywall. The house was built in 1995 and is a typical ranch-style in West Michigan. There appears to have been a “zero clearance” fireplace that may have been wood or gas. Any ideas?


You have it right, most gray stains that outline framing and fasteners on drywall are caused by soot from combustion. The soot is often from burning candles. The worst candles are the good-smelling ones in a glass jug because the flame lacks Oxygen for combustion. A gas fireplace can also cause soot inside a home.

The soot collects near framing and fasteners on outside walls because these areas are slightly cooler and the air slows as it passes by, depositing soot. You will also find soot on horizontal surfaces and around pictures where air flow changes direction.

Check out my free article:

Soot, Ghosts and Ugly Stains

Distributing Humid Air via A/C Blower

January 18th, 2010


I live in a 1200-square-foot condo that has radiant heat and an A/C blower located in the foyer. The A/C fan ducts are v-shape, no longer than 15ft, and go to the master bedroom, a second bedroom, the kitchen, and the great room.

Now that the air is more dry, if I place a humidifier in the foyer will it go up the air intake of my fan blower, thus sending the humid air to other areas in the condo?

The air intake is 36″ x 48″ and requires a filter. Can the humid air pass through the filter? Will it gum up the filters and/or cause other problems?



Humidity or moisture in the air moves at about 5 mph due to vapor pressure. You can place a humidifier anywhere in your unit – as long as the doors are open, it will move throughout the unit without the fan. If you choose to run the fan (without the A/C I assume) it will move the air quicker.


Sealing Space Between Kitchen Cabinets

January 16th, 2010


My brother-in-law and I installed new kitchen cabinets last spring. Everything turned out great, except for one oversight. A few wall cabinets have dead space in between them, and they are open at the bottom. It’s allowing outside air to come through the bottom of the cabinets. What kind of insulation might you recommend to fill these cavities? Would fiberglass be safe to use?



I assume you do not have solid drywall at the top of the cabinets to the attic and this is allowing air movement. You can seal the gap with anything that’s solid – drywall, wood, metal, or plastic. Fiberglass or insulation will not stop air movement.

You should also have a complete air seal from the heated space to the attic. In fact, you must have an air seal to prevent heat loss and moisture damage into the attic.


Clearing Sink Drains

December 9th, 2009


What is the best product to keep the kitchen sink draining properly? Also, what is the best product to open a stopped sink?



I don’t know of any reason to use any product in a kitchen sink to keep it flowing. If it is slow draining, I would remove the trap, clean it, and snake out the drain line after the trap.

Trap Plugged - Clean With Wire or ToolThe same process applies for a stopped-up sink. For a sink that may be blocked with hair – bathtub or bath sink, you can sometimes pull out the debris with a hooked wire or a small tool designed to stick in the trap and pull out the debris.

I don’t ever recommend chemicals. They don’t work well. If you fill a stopped-up trap with chemicals and it does not work – now you have to deal with the chemicals when you clean the trap – not a good think.

For a kitchen sink, you could try to pour a few gallon of boiling hot water down the drain – some folks think this may loosen cooking grease that may have accumulated.

Tips for Painting Ceilings

November 23rd, 2009


I have had bad experiences painting ceilings. I use good quality, semi-gloss paint and a roller. I always end up with lap marks and shiny spots. Any suggestions?


I suggest you try using flat paint specifically designed for ceilings. Semi-gloss tends to show lap marks and any uneven application. Flat paint is very forgiving and the better quality flat paints cover well and still can be cleaned.

You also need to practice your application techniques. With a roller evenly filled with paint, you should apply the paint in a “W” or “M” pattern over a 3 by 3 foot area. This spreads the initial, thick paint over a wider area. Then, work your roller up and down or left and right to even the coat of paint over the whole area.

Always try to paint from a wet edge so you new application blends in with the paint on the wall. When you lap new paint over dry paint, you run the risk of a lap mark. Finally, use lots of light so you can easily see how the paint is covering.