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Insulation tips


Houses built before 1940 were rarely insulated, and if they were the products originally used may have settled or deteriorated over time, allowing heat to escape and the cold air to creep in. 

Here at  InsulationGo you will find some tips to guide you through your old-house insulation project.

  • DO install batts and blankets at right angles to the first layer.
  • Be very careful moving around in your attic. Watch out for overhead rafters, and walk only on ceiling joists. If you have room, lay a plywood panel across the ceiling joists to walk or kneel on.
  • DO wear goggles, a dust mask or respirator, gloves, long sleeves and long pants when working with insulation.
  • DON'T disturb existing insulation - especially loose-fill. Moving it around can create gaps where air can leak through.
  • DON'T put insulation over recessed light fixtures, ceiling fans or ventilation fans. If you're using loose-fill insulation, use sheet metal to create barriers around the openings. Keep all insulation at least three inches away from chimneys and gas flue pipes.
  • DON'T cover attic vents, and leave at least one inch of air flow between the insulation and the roof.
  • DON'T forget to insulate and weatherstrip the attic opening.
  • Determine if you have insulation. It's easy to confirm whether or not you have attic insulation—usually loose fill between ceiling joists or exposed batts of colored fiberglass. You can also check your exterior walls for a series of patched holes.
  • DO place the vapor barrier towards the warm side of the insulated area - facing downward on the attic floor or to the interior side of the wall.
  • DO add a polyethylene vapor barrier on the floor of a crawlspace to reduce condensation from ground moisture.
  • DON'T add a second vapor barrier to additional layers of insulation - this can trap moisture inside the first layer. Use loose-fill or unfaced batts or blankets; if only faced batts are available, cut facing every few inches to allow air to pass through.
  • When sunlight enters your home, it is mostly ultraviolet radiation, which transfers easily through glass. Once it hits an object the sunlight becomes radiant heat. To capitalise on all this free energy and gain extra warmth, open your blinds and curtains during the day and let that natural heat wash over you. Don’t forget to shut your winter-weight curtains when the sun sets to keep that warmth in.

  • Consider the different insulation materials available including polyester, glasswool, polystyrene etc. There are a range of prices but you tend to get what you pay for and some are more difficult or unpleasant to work with than others - for example glasswool/fibreglass insulation can cause skin allergies and so you'll need goggles, face-mask and complete coveralls. We recommend non-itchy polyester insulation for DIY.
  • Choose the best format for your home. There are sections, rolls of blanket, loose fill etc. For underfloor and walls self-supporting sections are best and safest for DIY install. In ceilings we recommend blanket rather than sections so there is no heat loss through the joists, while for confined ceiling spaces that are hard to reach loose-fill is a suitable option.
  • Measure up carefully. Take care to measure well so you order the correct insulation widths for underfloor or walls as the insulation needs to fit well between the joists.
  • Don't buy too much. For ceilings a good starting order for blanket insulation is 75% of the house's footprint - you can always order an extra bale but returning surplus might be a problem.
  • Avoid gaps: Heat flows through gaps like a sieve so the quality of your installation makes a big difference. Gaps around the edge of wall insulation can reduce its effective R value by approximately 3% for every 1mm gap and missing sections of insulation in ceiling, wall or underfloor severely compromises the whole project.
  • But keep the safety gaps: You need to maintain clearances around incandescent downlights, chimneys and ducts.
  • Mind your step: Maneuvering yourself and large bales of insulation around in a ceiling is a challenge. Any money you may save installing insulation yourself can be lost by a misstep resulting in a foot through the ceiling.
  • Existing Foil Insulation: Foil conducts electricity and on several occasions when our advisors are measuring up underfloor insulation they have discovered the whole underfloor foil has been electrically live. Take extreme care when working with foil near electrical wiring to avoid serious injury.
  • Electrical Wiring: Underfloor and in the ceiling there is wiring that needs to be safely managed when installing insulation for your personal safety to avoid electrocution. For DIY underfloor insulation we recommend you use self-supporting forms of insulation that require no staples.
  • Downlights: To avoid creating a fire hazard, it is critical that insulation is installed correctly around downlights, chimneys and power cables.
  • Install New Windows: If your home is still outfitted with windows from the 90’s, you might want to consider a change. Today’s technology has contributed to incredible advancements in insulated windowpanes and frames that will make a huge difference on your utility bill. Look for an energy star logo or check out triple pane or gas filled pane window types that insulate from within the glass. It's a great investment and will increase your home's value while decreasing your energy bill.

  • Work with another person and maintain contact throughout both the assessment and installation process.

  • Avoid installing insulation in hot weather and at the hottest part of the day.

  • Properly insulated attic can shave 10 to 50 percent off your heating bill. And it works the opposite way for warm climates; in summer, it helps stabilize your house's indoor temps to keep cooling needs in check.

  • Stop using your attic for storage. Why? Because the simplest and cheapest way to insulate an attic is to add material to the floor. But if the floor is covered in plywood, you can't stuff enough insulation beneath it to do the job sufficiently—not even in warm climates.

  • Fix roof leaks. Water is insulation's enemy!!!! It creates a breeding ground for mold and mildew and ruins the air-trapping pockets that block heat flow. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.
  • Illuminate dark corners of the attic using portable battery-operated lanterns or clip-on workshop lights.
  • Work from the perimeter of the attic toward the door or hatch so that you don't trample all over the insulation you just put in.

Old houses can be drafty places, and warm air can leak from a multitude of areas. Check and see where you may be losing heat in your house. Chimneys and fireplaces without working dampers are typical. Other areas to consider are air leaks though cracks around windows, ducts, electrical outlets, and recessed lighting. 

Note that the primary site of heat loss is through the top of the house. Heat rises and can escape though roofs that are not adequately insulated.

Most heat loss is typically through the roof. Since warm air has a tendency to rise and cool air to fall, insulating the attic is the place to start. If the attic is unfinished, the insulation should be installed on the floor. If the attic is used as a living space, say a home office or play room, the insulation should be placed between the rafters.

One of the biggest mistakes here is installing insulation without a proper ventilation path between the insulation and the building exterior. Don't block the soffit, ridge, or gable vents in the roof. This can create moisture problems

An insulation's R-value—the material's thermal resistance or resistance to heat flow—depends on what region of the country you live in and what part of the house you are insulating. The higher the R-value the better the material insulates.

When retrofitting an old house with insulation, one of the most important points is to avoid creating moisture problems.

Mold growth, peeling paint, and even rotting wood are all signs of high moisture levels.