Inspecting Your Attic for Your Protection


Fiberglass is the most popular type of insulation being the insulation of choice in over 70% of homes.  Fiberglass is literally a fiber spun from molten glass, and silica sand is the main ingredient in glass production. Glass fiber is used in applications as varied as boat hulls and fire-resistant fabrics, but according to the National Association of Certified Home Inspectors, the predominant use for fiberglass is in thermal insulation.


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Fiberglass Insulation

Fiberglass Insulation is an insulating material made from fibres of glass arranged using a binder into a texture similar to wool. The process traps many small pockets of air between the glass, and these small air pockets result in highFiberglass Roll of Insulation thermal insulation properties. Glass wool is produced in rolls or in slabs, with different thermal and mechanical properties. It may also be produced as a material that can be sprayed or applied in place, on the surface to be insulated. The modern method for producing glass wool was invented by Games Slayter while he was working at the Owens-Illinois Glass Co. (Toledo, Ohio). He first applied for a patent for a new process to make glass wool in 1933.

When fiberglass batts are installed in an attic, the batts will be installed in layers installed at a 90 deg angle to minimize gaps in the insulation.  Blown fiberglass insulation is becoming the insulation of choice for most home builders as there are no gaps as fibers will fill any voids just by gravity.

To start off, determine what R-value is recommended for your home based on your location. You can find this information from the Department of Energy. If you aren’t familiar with R-value, it’s basically an insulating material’s resistance to heat flow, measured by its thermal resistance or R-value. The higher the R-value, the more effective an insulating material is. Your home’s R-value score will guide you toward the type of insulation you need.  Homes built in Ontario in 2020 will have a minimum of R-60 insulation installed.

Cellulose Insulation

Cellulose insulation, made with recycled newspaper using grinding and dust removing machines and adding a fire retardant, began in the 1950s and came into general use in Canada during the 1970s. Residential cellulose insulations are generally derived from wood, and more specifically from paper: recycled newspapers, cardboard, office paper, and other common waste paper products. For this reason, cellulose insulation is considered an eco-friendly home product.  During the manufacturing process, cellulose insulation is treated with borates, which are Class I fire retardants. Class I refers to ordinary combustibles such as wood and paper, as opposed to Class II combustibles, such as flammable liquids, grease, gasoline, oil, etc.  I personally recommend cellulose insulation to clients who have problems with rodents.   Typically the cellulose insulation will look like a desert when inspecting the attic, while fiberglass will often be riddled with mouse trails and holes.   It would appear that mice do not like the Fire Redardent used in cellulose and would rather find a new home filled with fiberglass insulation.

Roxul Insulation  ( Rock Wool Insulation )

ROCKWOOL insulation is made from natural stone wool and harnesses its power to help reduce heating and cooling costs, maintaining steady temperature within rooms.  While fiberglass insulation tends to soak water up like a sponge, Roxul is incredibly water resistant. If you worry about mold or mildew growing in your insulation, or you live in an area that is prone to floods or other storm issues, then Roxul is the better choice.   Roxul also offers better sound proofing qualities and is approved for use in various fire separation assemblies.  Stone Wool insulation is a type of mineral wool and is completely resistant to rot, mould, mildew and bacteria growth.

Vermiculite Insulation

Vermiculite is a naturally-occurring mineral composed of shiny flakes, resembling mica. When heated to a high temperature, flakes of vermiculite expand as much as 8-30 times their original size. The expanded vermiculite is aAsbestos Testing - Barrie Home Inspection light-weight, fire-resistant, and odorless material and has been used in numerous products, including insulation for attics and walls. Sizes of vermiculite products range from very fine particles to large (coarse) pieces nearly an inch long.

Asbestos in Vermiculite 

A mine near Libby, Montana, was the source of over 70 percent of all vermiculite sold in the United States from 1919 to 1990. There was also a deposit of asbestos at that mine, so the vermiculite from Libby was contaminated with asbestos. Vermiculite from Libby was used in the majority of vermiculite insulation in the United States and was often sold under the brand name Zonolite. If you have vermiculite insulation in your home, you should assume this material may be contaminated with asbestos and be aware of steps you can take to protect yourself and your family from exposure to asbestos.  Barrie Home Inspection will test your vermiculite at a Certified Lab for as little as $80.00 for one sample.

Styrofoam Insulation

Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam (XPS), commonly called “Blue Board”, manufactured as foam continuous building insulation board used in walls, roofs, and foundations as thermal insulation and water barrier. This material is light blue in color and is owned and manufactured by The Dow Chemical Company.

Rigid foam insulation, whether it is expanded or extruded polystyrene, does have to be covered if it is installed in the interior of a building. This wall covering must have a minimum fire rating to protect the insulation from quick combustion during a fire. Because this type of insulation is made from plastic, it is combustible and may give off highly toxic fumes when burning. These fumes can overcome occupants of the home during a fire, even before the fire itself.  You are allowed to use uncovered styrofoam in both attics and crawlspaces.  Plain white styrofoam has to be covered and the coloured styrofoam will have instructions printed on the panels.  The Blue Styrofoam panels for instance must be covered to reduce flame spread rating and the developement of toxic fumes if exposed to fire.

Spray Foam

Spray foam is typically the same as styrofoam as far as flame spread rating goes, majority of spray foams are required to be covered.  Most professional spray foam installers will attach a label identiying the product used to easy find location like the main electrical panel.  Spray foam can also be used in attics and crawl spaces with the need to cover.

Types of Insulation

Blanket: batts and rolls


Mineral (rock or slag) wool

Plastic fibers

Natural fibers

Unfinished walls, including foundation walls

Floors and ceilings

Fitted between studs, joists, and beams.


Suited for standard stud and joist spacing that is relatively free from obstructions. Relatively inexpensive.

Concrete block insulation

and insulating concrete blocks

Foam board, to be placed on outside of wall (usually new construction) or inside of wall (existing homes):

Some manufacturers incorporate foam beads or air into the concrete mix to increase R-values

Unfinished walls, including foundation walls

New construction or major renovations

Walls (insulating concrete blocks)

Require specialized skills

Insulating concrete blocks are sometimes stacked without mortar (dry-stacked) and surface bonded.

Insulating cores increases wall R-value.

Insulating outside of concrete block wall places mass inside conditioned space, which can moderate indoor temperatures.

Autoclaved aerated concrete and autoclaved cellular concrete masonry units have 10 times the insulating value of conventional concrete.

Foam board or rigid foam




Unfinished walls, including foundation walls

Floors and ceilings

Unvented low-slope roofs

Interior applications: must be covered with 1/2-inch gypsum board or other building-code approved material for fire safety.

Exterior applications: must be covered with weatherproof facing.

High insulating value for relatively little thickness.

Can block thermal short circuits when installed continuously over frames or joists.

Insulating concrete forms (ICFs) Foam boards or foam blocks Unfinished walls, including foundation walls for new construction Installed as part of the building structure. Insulation is literally built into the home’s walls, creating high thermal resistance.
Loose-fill and blown-in



Mineral (rock or slag) wool

Enclosed existing wall or open new wall cavities

Unfinished attic floors

Other hard-to-reach places

Blown into place using special equipment, sometimes poured in. Good for adding insulation to existing finished areas, irregularly shaped areas, and around obstructions.
Reflective system Foil-faced kraft paper, plastic film, polyethylene bubbles, or cardboard Unfinished walls, ceilings, and floors Foils, films, or papers fitted between wood-frame studs, joists, rafters, and beams.


Suitable for framing at standard spacing.

Bubble-form suitable if framing is irregular or if obstructions are present.

Most effective at preventing downward heat flow, effectiveness depends on spacing.

Rigid fibrous or fiber insulation


Mineral (rock or slag) wool

Ducts in unconditioned spaces

Other places requiring insulation that can withstand high temperatures

HVAC contractors fabricate the insulation into ducts either at their shops or at the job sites. Can withstand high temperatures.
Sprayed foam and foamed-in-place





Enclosed existing wall

Open new wall cavities

Unfinished attic floors

Applied using small spray containers or in larger quantities as a pressure sprayed (foamed-in-place) product. Good for adding insulation to existing finished areas, irregularly shaped areas, and around obstructions.
Structural insulated panels (SIPs)

Foam board or liquid foam insulation core

Straw core insulation

Unfinished walls, ceilings, floors, and roofs for new construction Construction workers fit SIPs together to form walls and roof of a house. SIP-built houses provide superior and uniform insulation compared to more traditional construction methods; they also take less time to build.






Over the years the Standard for the R Value of insulation has increased to R-60 or over 20 inches of blown fiberglass insulation.  Ever since the energy crisis of the 70’s adding insulation to your attic has been the most economical way to save heating energy.  Most attics are either truss or rafter construction, with the maximum opening at the soffit area being 8 inches.


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When you add 20 plus inches of blown or batt insulation at the eave of your roof you are effectively blocking any air movement generated by your vented soffit around your home.  The Ontario Building Code requires an unobstructed vent area not less than 1/300 of the insulated ceiling area. When the roof slope is less than 1 in 5 and roof is constructed with roof joists the unobstructed vent area shall be 1/150 of insulated ceiling area.  Not less 25%Installing Soffit Baffles in Attic of the required vent area shall be located at the top and bottom of the space.

The solution to allowing air movement is the installation of soffit baffles, this can be made of wood, styrofoam or cardboard.   These baffles allow the air from your vented soffit to freely flow into the attic area.  In the winter warmer air will rise up and discharge through your roofs upper vents,  the escaping warm air being replaced by cooler outside air entering from your vent aluminum soffit at the bottom of the space.

Heat and moisture can enter your attic from a number of places.  Most common areas are any penetrations made into your insulated ceiling, which may include; pot lights, electrical boxes, exhaust fans, light fixtures and any gaps left during construction.  Another common area where heat and moisture can enter your attic is when a bathroom exhaust fan is discharging from your roofs vented soffit.  If the vented soffit is not blocked off on both sides of bathroom exhaust then the warm moist air will simply rise passing through the opening in the soffit vent and enter the attic.  Barrie Home Inspection has found many homes where the roof sheathing has moisture stains from the warm moist air contacting the cold wood sheathing in the winter.  This can lead to wood rot or even mould.

 Note: Some experts say that soffit vents can be omitted if gable vents are installed at opposite ends of the attic.  They claim that with this type of ventilation there has been no evidence of any problems.

Ice Dams

Lack of insulation and/or blocked soffit vents are generally consided the common causes of “ice dams”.  An ice dam forms when the roof over the attic gets warm enough to melt the underside of the layer of snow on the roof. The water trickles down between the layer of snow and the shingles until it reaches the eave of the roof, which stays cold because it extends beyond the side of the house. There, the water freezes, gradually growing into a mound of ice. The flatter the pitch of the roof, the easier it is for an ice dam to get a grip. Gutters at the eaves can also trap snow and ice. If snow and ice build up high enough in the gutter, it can provide a foundation for an ice dam.

Water from ice dams can back up enough to enter your living space.  Ice dams can also damage your roof covering and should be dealt with as soon as you notice ice dams forming.  Ice dams can be removed by gently running hot water over the dam.   You can install heating cables.   Using a snow rake to remove built up snow can also help remove ice dams, and will remove source of water feeding your ice dams.


Vapour Barrier - Protect Your Attic

Vapour barriers are required for insulated assemblies to prevent water vapour from entering attic or roof spaces.  In Ontario a 6mm polyethylene vapour barrier is required to be installed on the warm side of the insulation.   This vapour barrier prevents any moisture being carried into attic area with any heat loss radiation of air.  Vapour barrier is required to be continuous.

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Vapour Barrier – Protect Your Attic

Water vapor wants to move from warmer to colder air. That means in the winter time water vapor inside the home wants to move to the colder attic space. In the summer the warm humid air will want to move to the interior of a cooler home.Inspect your attic for any signs of moisture.  Inspect your attic insulation for any signs of discolouration, this would be from moisture and is a good indication you have an air leak into attic area.  Recommend moving insulation to look for any visible unprotected openings in vapour barrier.

Leaks in Vapour Barrier

The most common areas where leaks are penetrating your vapour barrier are electrical boxes, chimney penetrations and plumbing penetrations.  You can repair or improve the seal around these openings by securing poly vapourBathroom-Exhaust-Fan-Not-Insulated barrier around the opening and sealing with caulking.  Newer homes require any exhaust vents passing through  a unheated space to be insulated and protected by vapour barrier.  Many older homes have no vapour barrier over bathroom exhaust fanss and the exhaust duct is not insulated or protected with a vapour barrier.  In the winter the warm moist are being exhausted by your bathroom fan will enter the cold attic and most likely warm air will be turned into condensation.   This can eventually block your exhaust vent and even leak back into exhaust fan housing causing water damage.

Attic Hatch Seals

The entrance to the attic is an important part of preventing vapour leaks into your attic.  While most subdivision homes have a peel and stick foam seal which prevents heated humid air from entering the attic.   Many times during an attic inspection the wood supports around attic entrance are cover with mould from the air leakage at the hatch.  Also on some homes the attic entrance support for insulation has been damaged or knocked down, this prevents the blown in attic insulation from protecting area around hatch.

Adding Used Insulation

Cottage attics will sometimes have older fiberglass insulaiton batts added on top of existing insulation.  Older fiberglass batts often came with kraft paper vapour barrier attached, which when put on top of existing insulation can actually trap moisture in your insulation.   If you want to salvage used fiberglass insulation remove the vapour barrier prior to installing.

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Attics if not properly ventilated can develop the right conditions for mould growth — hot, humid, and an abundance of sheathing.   Look for restricted soffit vents in the attic, stuffed with insulation or with deformed cardboard baffles or any exhaust ducts discharging directly into the attic area.   Wood rot can start when 20% moisture level is reached.

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Mildew requires certain factors to develop. Without any one of these, it cannot reproduce and grow. The requirements are a food source (any organic material), sufficient ambient moisture (a relative humidity of between 62 and 93 percent), and reasonable warmth (77 °F (25 °C) to 88 °F (31 °C) is optimal, but some growth can occur anywhere between freezing and 95 °F (35 °C)). Slightly acidic conditions are also preferred. At warmer temperatures, air is able to hold a greater volume of water; as air temperatures drop, so does the ability of air to hold moisture, which then tends to condense on cool surfaces. This can work to bring moisture onto surfaces where mildew is then likely to grow.

Black Stains on Sheathing

When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black.  This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood.  This problem can be caused by inadequate ventilation, blocked soffit vents or moisture laden air entering the attic.  Here are some of the common areas where moisture can enter your attic:

Non-airtight can lights,Moisture Staining on Attic Sheathing

Access hatches not being weather-stripped,

Missing fire stopping around wires and pipes running into the attic space,

Missing fire stopping around HVAC equipment vents,

HVAC equipment venting directly into attic,

Standing water in condensate trays,

Missing fire-stopping around chimneys,

Dryers venting into attics,

Bathroom, laundry and kitchen exhaust fans venting into attics,

Missing ceiling vapor retarders.

Moisture Control

In the form of vapour, air always contains a certain amount of water. The higher the air temperature, the more water that can be taken. When the maximum amount is reached, the air is saturated.

The air will contain too much vapour when the temperature drops, which is emitted in the shape of water. This is what we call condensation. Cool surfaces like cold walls, the roof, windows, doors and domes will cool down fastest.

The laws of physics govern how moist air reacts in various temperature conditions. The temperature and moisture concentration at which water vapor begins to condense is called the “dew point.” Relative humidity (RH) refers to the amount of moisture contained in a quantity of air compared to the maximum amount of moisture the air could hold at the same temperature. The ability of air to hold water vapor increases as it warms and decreases as it cools. Once air has reached its dew point, the moisture that the air can no longer hold condenses on the first cold surface it encounters. If this surface is within an exterior wall cavity, the result is wet insulation and framing.

Frost in Attic

Many homes in Canada suffer from ice accumulation in attics, which most homeowners will often ignore it unless it causes a huge problem – mostly because they aren’t aware it’s happening until there’s an issue. Ice dams are causedFrost in Attic by warm and relatively humid air leaking from inside a home into an insufficiently ventilated roof space, condensing, and forming ice. 

Frost on your attic sheathing is caused by; high humidity in the home,  poorly ventilated attic and air leakage from house into attic area.  Addressing these issue will resolve your “frost in attic” problem.

Having your attic inspected by Barrie Home Inspections can identify potential problems and recommend the corect procedure to prevent any of the above mentioned problems occuring in your attic.


In Ontario a minimum of 25% of your attics required vents must be located on the upper area of roof.  Choosing the right type of roof vent is instrumental in ensuring your attic ventalation system will perform as required.  Barrie Home Inspections will provide information on the various types of roof vents available for your roof.

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Wind TurbinesWhirlybird parts view

Turbines were commonly called whirlybirds and were extremely popular in older homes, mainly due to the fact that they usually were spinning offering home owners a false sense of security.  Experts now think that as the turbinespull the hot humid air out of your attic, they also draw more heat from your homes insulated area.  The other issus with wind turbines is that they allow snow and rain to enter your attics insulation.  Barrie Home Inspections has found many attic areas with moisture compacted insulation directly below the turbines.

Most professional roofs will install passive type roof vents rather than the older Whirlybird vent.

Your house needs to breathe. The attic is where all the heat from the house builds up and is crucial for the air vapors to be expelled from the house to prevent mold. If the air is not expelled from the attic, it will cause problems such prematurely deteriorating shingles from a hotter roof decking. Mold, any moisture can be a problem with no ventilation.

Ridge Vents

Ridge vents are very effective at venting out moisture and hot air from your attic due to their size, and when they are used in combination with soffit vents, they are very efficient. Ridge vents do not create hot or cold areas in your attic as other types of vents do, so you don’t have to worry about parts of your roof aging faster than others. This can help to extend the life of your roof, and it is a good reason to install this type of vent.  Newer styles of ridge vents have curved channels to reduce this risk or are comprised of a mesh like material which prevent the entry of snow and rain.

Many roofers, when installing ridge vents, will install the same colour shingles on top of vent, making vent almost impossible to see from the ground.  When installed, the ridge vent runs along the entire length of the ridge of your roof. It’s not highly noticeable and blends in, leaving your roof looking sleek and beautiful. The ridge vent is often combined with soffit venting for the best results.  No wind is needed for these to work effectively.

Box Vents

Box roof vents are very popular and often found on subdivision roofs.   They are usually spaced evenly at the top section of your roof.   Cut outs are made in roof to create an opening for the box vent.  Box vents are almost always Box venting for attic installed on custom roof lines where other forms of vents would not be possible.  Many homes in Ontario have front covered porches where there is no attic access and the porch roof is unheated, so a box vent will allow any heat and moisture entering the unheated space to exhaust to the exterior.   This type of ventilation came into being because of the early failure of porch roof shingles due to trapped heat and moisture.

Box vents can be bought in a colour that will match your shingles and they also come in a variety of sizes.  The most common size is 18 in by 18 in.  Depending on the typical snow load for your area, box vents may become completely covered with snow which can negatively affect your attics ability to exhaust unwanted heat and moisture.  Dented or partially crushed box vents should be replaced immediately.

During home inspections Barrie Home Inspection frequently finds newly shingled roofs with issues.  Home owners have to get their roof replaced in order to sell the home.  Unfortunately many home owners will shop around looking for the cheapest roofer available.

The consquences for hiring the cheapest roofer will usually result in the following items being noted on your Home Inspection Report:

  • reused flashing that is bent, paint finish is peeling and open nail holes
  • caulking is cracked and open on flashing joints and exterior cladding joints
  • nails not caulked in flashing
  • valley flashing finish is peeling
  • exposed nail heads on shingles
  • shingles not installed properly at eaves and sides of roof.  ( large overhang and ragged edge where shingles have been cut )
  • water and ice shield not installed


If your home has any type of fibeglass insulation there is a 95% chance you have mice living in your attic.   Mice love fiberglass insulation and have no problem entering your attic to take up residence.  Mice can walk up a brick wall and squeeze through the smallest openings in soffits, vents, pipe penetrations or exhaust vents.

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When conducting home inspections,  Barrie Home Inspection Service  often finds mouse holes and trails scattered around the insulation in the attic.  People are shocked or surprised but for a mouse setting up residence in your attic is like the snow birds heading to Florida.  They have easy access, able to come and go in the hunt for food and water, and you never see them.  Once its starts getting crowded in your attic mice will start entering your wall cavities Mouse Trails and Tunnels though voids and any unsealed openings finding ways to enter your home.

The average mouse has about 5 to 10 litters in a year and it only takes a month for the young mice to become independent.  If left un-checked  your attic could easily become overrun with mice.  Since mice are nocturnal you may even catch sight of one entering your attic area around dusk when they will be out foraging for food and water.  Your attics is a desirable location to a mouse. Attics are protected from the elements, are free from predators and are much cleaner than the hole in the ground their less fortunate mouse-cousins live in.

Mice can chew your electrical cables and your plastic plumbing lines.  When this occurs you will have to hire a tradesman to remove damged wiring or plumbing and repair.  Some of the issues having mice in your attic are:

  1. a build up of urine and feces contamination
  2. substantially damaged attic insulation
  3. structural damage i.e. chewed trusses, ceiling joists, rafters, beams etc.
  4. electrical damage
  5. water damage through exposure to outside elements
  6. fluctuating heating and cooling bills
  7. ceiling collapses due to urine and moisture buildup
  8. entry by other animals through mice-burrowed holes.  Squirrels will enter you attic if possible and they can chew wood like a beaver.   Prevention is the key to protecting your home, once a squirrel gets into your home it will be hard to persuade him to move along.  Any wood trim on your homes exterior maybe damaged by a squirrel trying to reenter a home.