Stains Around Registers Signal Leaks

January 9th 2012
Stains Around Registers Signal Leaks

With our heating systems running to keep our homes warm, many of us are probably noticing stains around heat registers and outside walls as well as inside walls and stair cases. These stains are caused from air infiltration and exfiltration.

Homes with forced air furnaces will have stains around the heat registers as well as outside walls. Stains on the carpet on inside walls and stair cases are caused from positive air being pushed out under outside walls and you carpet becomes a filter picking up all the impurities in the air as it passes under the wall. Note: This shows up more on light coloured carpet.

Some houses with forced air furnaces will have stains on carpet around heat register floor vents caused from air being pushed around the register when the register is closed. Keep in mind a register louver is for directing the airflow not to shut off or turn on. Also stains found in areas of staircases or stair wells and inside walls, indicate cold air return to the furnace is short cutting ways to get to the furnace blower, thus pulling air under the walls and around stair treads to cold air ducts running under the floor joists in the basement or crawlspace.

Electric, Hot Water, Radiant or Convection heated homes can have similar stains show up, but always on outside walls. This is caused by air leakage from the home (windows and doors, etc). Range hood fans, bathroom fans exhausting air out of the home and make up air or infiltration air coming in under the outside walls, thus staining light coloured flooring.


Outside, Inside Walls and Staircases

To repair the stains, remove carpet from carpet strip (smooth strip) and caulk with a draft stop caulking compound between the bottom plate of the wall and sub-floor. Make sure the area is clean first.

Heat Register Vents

You can also repair this around your heat register vents. Using duct tape, apply over metal heat register boot, under and onto plywood or shiplap sub floor, terminating under carpet by 1 inch. This should be done on light coloured vinyl floors as well to stop from staining. Duct tape should terminate on top of vinyl to protect out beyond the register vent.

How to Clean

The residue left behind from air infiltration and exfiltration can best be cleaned with a product called
Pink Solution, which is available at many home improvement retailers, including Windsor Plywood, as well as my HouseSmart Home Services office.