Attic Moisture Sources

Attic moisture sources can be difficult to diagnose.  The sources can range from framing voids, compromised ceiling vapor barrier, electrical or plumbing penetrations, attic hatches or the ever increasing volume of recessed lighting fixtures.  One of the most common attic moisture source is something that is quite easy to identify: bathroom exhaust fan vent hoses.  All too often these exhaust mechanisms are poorly installed or improperly vented to the outside.  Thus creating a significant source of heat & moisture that is introduced to the Attic space with each shower and bath use.

Take a look at the photo below.  You can clearly see that there are 2 individual bath fan vent hoses that are sharing a single exhaust vent.  Neither looks properly fastened to the Gooseneck roof exhaust vent and the other is simply pointed at the penetration in the roof sheathing.  Around these hoses you can see the evidence of moisture and the subsequent damage to the wooden trusses and plywood.  The frost that his building on the plywood & nail heads is a direct result of the moisture these hoses are contributing to the Attic space.

The remedy is simple.  Install an individual gooseneck roof exhaust vent for each and every bath fan, clothes dryer and kitchen hood exhaust fan that is exhausted through the attic.  Make sure that the connection at the fan source & roof vent is secure to prevent air leakage.  It is easy to replace older metal pipes with the newer pre-insulated flexible hose that can be cut to length and snaked through the attic to meet your needs.  IDEAL is happy to provide this service to your bath fans during our Attic insulation upgrade services.  Call today for your FREE inspection.

bath fan moisture sources

bath fan moisture sources

Properly air seal pot lights

Pot lights.  Everyone loves them.  They are chic, minimalist and used frequently in both new construction and renovations.  Unfortunately they represent a penetration in the ceiling vapor barrier that when improperly air sealed can be a source of unwanted heat and moisture into the Attic space.  To properly air seal pot lights one must first install an I-C rated pot light, gasket-sealed tight to the ceiling drywall.  Then a poly boot should be installed over the light, preferably by an electrician who can properly fish electrical wires through the boot while installing the light itself.  Next the poly boot should be sealed with caulking to the ceiling vapor barrier.  The flanges of the poly boot may also be tape sealed for extra assurance of proper air seal, as in the photo below.  If these steps are followed to completion both contractor and homeowner can rest assured that this potential source of heat and moisture is mitigated, saving future headaches down the road.

properly air seal a pot light with poly boot and tape seal

properly air seal a pot light with poly boot and tape seal

Drip flashing can help prevent rotten plywood under shingles

When roofing your home it’s important to consider all factors of a proper Roofing system.  The underlay, venting and flashing all play a role in how well your roof will shed water and prolong the life of the asphalt shingles.  Drip flashing can help prevent rotten plywood under shingles.  It is installed along the Eaves of the roof, the lower horizontal edges of any roof, and is designed to prevent water from creeping back up under the shingles as it travels towards the eaves trough.  This is particularly important in lower sloped roofs where water is shed at a lower rate.  Just as any penetration in a wall such as a window or door must have proper flashing, the Drip flashing plays an important role in prolonging the health of your roof deck and subsequently the shingles.

the absence of drip flashing can lead to water penetration and damage to wood substrate

the absence of drip flashing can lead to water penetration and damage to wood substrate

Trees overhanging roof can cause damage

Too often trees are planted too close to the home and/or grow to overtake the roof line.  Trees overhanging roof can cause damage to the roof shingles as well as issues in drainage.  Rubbing can cause excessive granule loss leading to shingle failure.  Debris such as branches, leaves, sap and seeds can end up in the Eavestrough and eventually clog the Downspouts.  Make sure to prune your trees back away from your Home to prevent damage and prolong the life of your roof.

trees overgrown roof can cause damage

trees overgrown roof can cause damage

 

Roofing Downspouts

Potential granule loss at downspouts

Prolonged water flow from roofing downspouts draining on to a lower roof line can result in excessive granule loss and potentially lead to more serious water ingress issues. Extending your down spouts to meet the nearest eavestrough or re-directing a downspout directly to ground level can help avoid these issues and extend your shingles lifespan. At IDEAL we are happy to consult with you to address these issues as well as any and all of your roofing needs.

focused water runoff from upper downspouts to lower roof lines can lead to excessive granule loss

focused water runoff from upper downspouts to lower roof lines can lead to excessive granule loss

R-value

R-value is the unit of measurement used to gauge a material’s ability to reduce the rate of heat flow.  Everything has an R-value and in insulation it is used to rate the effectiveness and quality of products.  Different products have different R-value characteristics which are often compared by inch-depth.  A standard fiberglass batt has a different R-value per inch-depth than loosefill fiberglass, cellulose, JM Spider or spray foam insulation.

We use insulation most commonly in residential construction within the wall and ceiling cavities.  Its purpose is to hold heat within the conditioned spaces, the interior of your home, and slow down the rate of transfer to the outdoors.  Walls are most commonly insulated with Fiberglass batts which have the lowest R-value per inch-depth.  JM Spider Custom insulation is an innovative system that creates a higher r-value per inch-depth using loosefill fiberglass and resin.  Spray Foam insulation, in either ½lb open-cell or 2lb closed-cell offers the highest r-values.  Spray Foam is also excellent in areas that are difficult to insulate traditionally such as Floor Joists & Cantilevers.

For Attics the standard remains loosefill fiberglass insulation.  At IDEAL we utilize Climate Pro insulation developed by Johns Manville, one of the largest insulation manufacturers in North America.  Climate Pro is formaldehyde free and offers ease of installation to ensure your attic will be insulated to a quality standard with minimal heat loss.

Insulation within finished wall and floor cavities are difficult/impossible to improve without renovation.  Flat ceiling attic spaces on the other hand are readily accessible and often easy to upgrade the insulation R-value.  During an attic upgrade inspection IDEAL will identify the current R-value of your attic insulation and specify the additional loosefill fiberglass insulation required to achieve our recommended R-Value of 50.  Ventilation and vapor barrier performance is also considered and scope of work quoted. By increasing your attics insulation you can expect increased comfort within your home and potential savings on your energy bill.

Air sealing attic

One of the most important factors in keeping a healthy energy efficient home is to ensure the entire envelope of your building is air sealed. Much like a balloon, poking holes in your homes building envelope will let air escape.  As heat rises, an area of prime concern is the ceiling vapor barrier, or air sealing attic floor.  Problems can occur within Attics when the warm moisture laden air from your living spaces (cooking, showering, inhabitants, etc.) meets cold air circulating in the attic.  As warm, moist air collects on the underside of the roof freeze-thaw weather actions cause wood rotting and ceiling stains from dripping water.

There are many sources of penetrations in your ceiling or attic floor such as framing voids, ducts, plumbing stacks, bath fans and of course the attic hatch.  Pot lights are common ceiling penetrations that are best sealed with a pre-formed poly boot, fitted over the light by an electrician during   installation.  It is important to note that only IC-rated potlights should be used in Attic spaces so they are safe to be in contact with insulation.  Insulation alone in an attic does not act as vapour barrier to stop living space moisture escaping into the attic. At IDEAL Insulation our attic inspectors check all of these examples of penetrations in your attic floor. We weather-strip and insulate all attic hatches to ensure the least amount of air leakage from this source into your attic.  All identifiable penetrations are sealed in the attic with poly repairs or canned hilti foam if required.

In an attic with an extensively damaged vapour barrier IDEAL can remove your current attic insulation and then install spray foam to the attic floor.  2lb closed cell spray foam is used which contains the required moisture resistant properties.  You can insulate the entire attic floor with spray foam or install loosefill fiberglass insulation over top of the cured foam to reach the desired completed R-value.

Attic air leaks source Fine Homebuilding

Attic air leaks source Fine Homebuilding

Diagram legend

  1. Potlights
  2. Electrical cable penetrations
  3. Access hatch
  4. Gaps near chimneys
  5. Plumbing vent pipe
  6. Unsealed soffit
  7. Utility chases
  8. Duct penetrations

 

 

 

 

Attic insulation article

Read a great article on the Construction Instruction website discussing some of the same factors we do here on our IDEAL blog.  You can read the full article HERE.    There is also a nice visual representation of Attic insulation factors that you can view HERE.

Highlights include:

– proper vapor barrier seal between living spaces and Attic

– installing Air chutes, or styro-foam baffles, along the perimeter of the Attic space to ensure proper air flow intake from the soffit cavity

– insulating up to and over the external wall plates to ensure full coverage of the Attic floor

– the importance of an R-value of R50 in colder climates

 

Soffit ventilation

Attic inspections consider 3 major factors:  R-value (measure of thermal resistance) of current insulation, Continuity of ceiling vapor barrier and Ventilation.  Ventilation is evaluated in 2 ways: Intake (usually in through the soffit cavities) and Exhaust (through vents installed high on the roof’s ridges).  Your home’s attic and roof depend on proper ventilation to exhaust heat and moisture from the attic space.  Whenever ventilation is limited, or out of balance between intake and exhaust, issues arise such as condensation.

Most homes draw intake ventilation through the Soffit cavity.  The soffits are the underside of the roof where it overhangs the exterior walls of the building.  Older homes, prior to the 1970’s had soffits made out of sheets of plywood that often had very few or sparse vents cut into them.  The adoption of perforated aluminum soffits came in conjuncture with an understanding of the importance of Attic ventilation that for decades became the standard in new home construction.  Unfortunately all too often in the renovation market contractors install new aluminum soffit over top of existing wooden soffit, greatly limiting air flow.

In cases where Attic intake ventilation is limited due to wooden soffits, aluminum covering wooden soffits or plywood stops installed between the attic and the soffit cavity we must pursue additional measures. These measures may involve attempts to bash out plywood stops from the Attic side.  Not a very effective technique but sometimes successful.  Removing the wooden soffits and replacing with new perforated aluminum soffits.  We can often remove the plywood stops from the outside where access is improved with the existing soffits removed.  The best way to address the intake ventilation issue but surely a costly exercise.

The third is the installation of Lower roof intake vents.  This practice has become much more commonplace in Calgary since it has been adopted by New Construction developments in adherence to local fire regulations.  High density residential construction is no longer permitted to utilize perforated aluminum soffits so they install lower roof intake vents during construction.  In the renovation market we can use the same intake vents to create ventilation in Attics where the soffit cavities are poorly vented.  Intake vents are installed around the perimeter of the roof, or specifically in problem areas, down near the edge of the roof.  Always above the exterior wall plate and preferably above the finished height of the current/new attic insulation.  This allows fresh air to be drawn into the Attic space, above the perimeter of the Attic insulation so it can then cycle through the attic and exhaust up through the vents installed at the ridges.

lower roof intake vents allow for Attic intake ventilation through the lower parts of the roof

lower roof intake vents allow for Attic intake ventilation through the lower parts of the roof

 

Attic Rain

CBC Calgary recently reported on an unfortunate instance of Attic condensation termed “Attic Rain”. You can read the article HERE. As Attic insulators we come across this phenomena during the Winter months.

It is caused by a combination of 3 factors: penetrations in ceiling Vapor barrier, insufficient Attic insulation and insufficient Attic ventilation. The first cause is difficult to remedy. Once your attic is insulated it is very difficult to find vapor barrier penetrations, akin to a needle in a hay stack. The most prudent process is to remove all current insulation, seal penetrations using poly or spray foam and then re-insulate.

The second issue is much more easily addressed. Low spots or missing insulation can be topped up with new insulation during a simple attic upgrade. These low spots can cause excessive heat loss in a localized area resulting in moisture concentrating in a specific area. During winter months this moisture will freeze to the underside of the Roof, the coldest place in an Attic. During the day when the temperature rises the frost can melt. This cycle of freeze-thaw is what eventually leads to condensation, or Attic rain.

The last issue can also be remedied, but involves a detailed investigation of both Intake and Exhaust ventilation. Most houses draw fresh air into their Attic spaces through the Soffit cavity. Newer houses now utilize Lower roof intake vents that are installed on the roof. This is due to recent changes in Calgary’s fire code. Air is expelled from your Attic through exhaust vents that are installed near the top, or ridges, of your roof. Your attic relies on this air exchange to help equalize the temperature between inside and outside of your Attic, as well as expel moisture. Improper venting will cause heat and moisture to become trapped in your Attic space. The build-up of this heat and moisture is what feeds the freeze-thaw cycle during the Winter months and can lead to condensation and Attic rain.

IDEAL recommends that you take a look into your Attic space once a year for signs of condensation and air movement. We are happy to schedule an inspection where our qualified team will visit your home to assess these factors and positively contribute to your Homes comfort and quality.