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How To Fix Roof Condensation

Make Sure Roofers Are Necessary For Your Pocketbooks Sake

How to Stop Metal Roof Sweating / Condensation / Dripping

According to the website HomeAdvisor, nationally the cost for repairing an asphalt shingle roof is about $575. The average cost for a new asphalt is $6,000 on average. Nationwide Insurance places those costs at $690 on average for repairs and more than $7,000 for replacement.

Signs of a roof leak and other problems with moisture in your home include mold, water spots ceilings or walls and wet and swollen insulation.

Winter roof damage dangers:

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Technical Reviewers & References

Fighting Condensation Factor #2 Move Wet Air Out Through Natural Ventilation

Natural ventilation uses local wind and temperature differences between the inside and outside of the building. This is an area that falls within the realm of the architect and the builder, and its effectiveness is based on their design.

Most of us count on using natural ventilation in agricultural and suburban buildings, but its often misunderstood. A well-designed system will take into account the sources of moisture present in the building local wind and climate conditions throughout the year, air exchange, control and flexibility.

It requires properly calculating ridge and eave venting, as well as placement. Chris says quite often the need for venting is underestimated, most typically at the eaves. The sum of the openings at the eaves should equal that at the ridge.

Unfortunately, this isnt always done correctly. Because a ventilation system is only as good as its weakest point, as Chris says, the wet air is not moved effectively.

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Beware The Flat Roof: Flat Roof Moisture & Condensation Warnings Prevention Cures

The accompanying text is reprinted/adapted/excerpted with permission from Solar Age Magazine – editor Steven Bliss.

This article, “Beware the Flat Roof, it calls up a whole new breed of moisture problems” explains how to avoid moisture and condensation problems under flat-roofed and low-slope roofed buildings.

The text below paraphrases, quotes-from, updates, and comments an original article original article “Beware the Flat Roof” by Steven Bliss.

A Home Mustnt Abuse Its Cover

10 Roof Problems and What to Do About Them

Building codes have some requirements that attempt to prevent the problems of ice dams and attic condensation. But codes dont address all the issues, and many houses are built without following building codes. First and foremost, its your builder or designers job to understand the relationship of humidity and air movement when designing and constructing the house so these problems dont occur, according to insurance company State Farm.

State Farm recommends making sure exhaust fans and dryer vents dont discharge into the attic. Minimizing fixtures that penetrate via ceiling fixtures and sealing those already made is also recommended. Taking these steps will not only help prevent condensation issues but can help reduce issues with ice dams as well.

Owners of homes with skylights have to be very vigilante for potential winter damage leading to a roof leak. They can allow for melting snow to puddle. That can lead to water that rots the structure around the skylight. It can also cause dry wall damage.

Heavy snow build up around skylight

Maybe the most obvious cause of leaks, which can happen at any time of year, is simply broken shingles. Even if the damage looks underwhelming, such a cracked or curled shingles, it can lead to significant problems for your home. Damages could include rotting the wood sheathing beneath a roof. That can significantly add to the cost of repairs.

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The Following Measures Can Be Taken To Relieve And Prevent Condensation Issues:

  • An attic with effective vapour barrier preventing moisture from entering the attic.
  • Sufficient insulation within the attic to keep heat within the home and out of the attic.
  • Adequate attic ventilation provided by a proper ventilation system of intake and exhaust venting.
  • Insulating pipes within the attic that may come into contact with warm air from inside the home.
  • Installing connector plates on metal goosenecks or PVC goosenecks.

If you have issues with water dripping from your bathroom vent fan, its wise to turn on the fan at least 10 minutes before showering or bathing and let it run for 10 minutes afterwards. This will help remove all remaining moisture from the bathroom space and pipe so it doesnt condensate within the pipe and drip back down.

Ultimately, moisture issues are complex and vary from home to home. While there is no standard solution for any given issue, calling us and asking for one of our expert technicians to inspect and assess your moisture concerns is the best place to start!

A Simple Solution To Metal Panel Condensation

If youve ever gone outside before sunrise, youve likely noticed dew on the grass or on your car windows. This is condensation. While we may have learned the basics of this naturally occurring phenomenon in science class, we may need a quick refresher.

Condensation occurs when theres more water vapor than the air can hold. When the water vapor is cooled off or compressed to its saturation limitat which point the vapors molecular density reaches its maximum thresholdit turns into liquid. Warm air can hold more moisture, but as it cools it reaches its saturation limit and water droplets form. While not a problem on the grass or your car , condensation on metal panels CAN be a problem for your customers. The good news is theres a simple solution.

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Why Is My Metal Roof Sweating

Condensation forms when warm, moisture-laden air hits a cold surface. In the case of metal roofs, it happens when warm, moist air from inside the house is driven into, and trapped inside of, the cavity beneath the roof. When the metal roofs temperature drops at night, the air condenses on the underside of the roof.

How Does Condensation Form

Condensation Under Your Metal Roof: Causes, Fixes, Prevention

Condensation forms when warm, moist air collides with cold surfaces. Ultimately, the cold surface cant hold the excess water and so condensation forms on the surface.

We often see this happening on windows and other glass surfaces that act as a barrier between inside spaces and the outdoor air and world.

For example, imagine a cold winter morning and youre starting your car. The cold air outside of your car cools down your windshield, so when you start the car youre creating an environment where the windshield is much cooler than the air inside your car.

The warm air from inside your car heats the windshield until the outside of the windshield starts to warm up. The cold air outside the car meets the warm windshield and condensation forms. To get rid of the fog you need to turn on the cold air to lower the windshields temperature and offset the difference between the outside air temperature and inside windshield temperatures.

Now lets look at an example of harmful condensation.

Imagine youre taking a shower and the hot, moist air comes into contact with the colder bathroom walls. That clash causes condensation drips on your walls .

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Where Does Roof Condensation Occur

Roof condensation can occur anywhere in an attic or crawlspace. It can form on rafters, around windows, on floor joists, around bathroom vents, and between attic insulation and the ceiling underneath.

If you were to notice water spots around your bathroom exhaust fan, there could be condensation forming on the duct that carries warm air through the attic space and to the outdoors. You could have condensation forming on roof rafters, then running down those rafters and collecting near the floor. You would see water spots along the corners of the ceiling in such a case.

Depending on where the roof condensation is occurring, you might not even realize its happening. Sometimes roof condensation is enough to be a problem, but not bad enough to observe without going into the attic and inspecting.

What Causes Roof Condensation

Moisture can be sneaky. If youve got a roof that doesnt leak, you may think youre protected from moisture damage. But the truth is that condensation is one of the chief forms of moisture damage in roofing systems.

The straightforward way of determining roof condensation causes is lack of ventilation. But that answer raises many questions, like how to vent roofs well enough or what to do when roofs cant be vented.

There are two different roofing paradigms when it comes to these issues: one for steep slope and one for low slope. The physics are the same for each , but the concerns and practices for each differ.

In steep slope roofs with attic space, ventilation is a reasonable tool to counter the risk of condensation. But in low slope roofs with no attic space, ventilation is typically inadequate.

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Flat Roof Leak Points And Condensation Problems

It’s a fact that flat and low-slope roofs demand careful detailing and good workmanship.

While a flat or low-slope roof can offer a long service life, 20 years or more, a small mistake can lead to a big leak. Flat roofs and low slope roofs also face potentially serious condensation problems that can in turn lead to costly rot or mold damage in buildings.

Our photograph at left shows severe alligatoring on a nearly-flat “low slope” roof that also was relying on tar and roof cement to try to stop parapet wall leaks.

The most common flat and low slope roof leaks occur at flashings and roof penetrations such as at plumbing vents, chimneys, and roof-mounted air conditioners or heat pumps.

Very common also are leaks at parapet wall flashing and parapet wall caps. Roofing industry spokesmen say that up to 90 percent of flat and low slope roof leaks occur because of poor detailing, poor workmanship, or abuse by other tradesmen working on the roof.

Roof flashing details that are not designed to absorb thermal or other building movement can lead to cracked broken metal flashings that leak badly into the building.

See THERMAL EXPANSION of MATERIALS for a table of the coefficient of expansion of common building materials including brick, concrete, mortar, and stone.

Other flat and low slope roof leak problems are caused by lack of expansion joints or counterflashing where needed.

Sketch at left showing common flat roof leak points is provided compliments of Carson Dunlop.

Winter Is Often A Roof Leak Culprit

12 Roof Repair Tips: Find and Fix a Leaky Roof

During the winter, at least in colder climates, one of the leading causes of roof leaks is something called ice dams. The name is pretty self explanatory. Ice dams are, essentially, caused by ice that forms at the edge of a roof after thaws and re-freezing. These issues are exacerbated by temperature differences on a homes roof. These ice build-ups cause melting snow to pool on a roof and eventually leak into a home.

Damaging Ice Dams

There is a complex interaction among the amount of heat loss from a house, snow cover, and outside temperatures that leads to ice dam formation. For ice dams to form there must be snow on the roof, and, at the same time, higher portions of the roofs outside surface must be above 32 while lower surfaces are below 32 , according to the University of Minnesota.

There are a few methods for preventing ice dams, such as making sure to use a broom to remove snow from the roof. If the snow doesnt pile up no ice dams can form. Its a simple as that. Be careful while clearing the snow from a roof. Being hasty or using the wrong tools can damage shingles.

Homeowners should also make sure that gutters are clear, preferably before a freeze, because backed up water in those drains can contribute to ice dam formation.

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Fighting Condensation Factor #1 Keep Moisture From Getting In

The first factor focuses primarily on the site preparation. If you have a smart architect and/or builder who is attuned to your buildings intended usage, they can situate your building and provide the correct features to prevent moisture from entering in the first place. These include:

  • Build your structure in an elevated position with good natural drainage
  • Place a vapor retarder under floor
  • Ventilate enclosed building when concrete is being poured, and continue to ventilate until it is cured
  • Use heaters that are vented to the outside
  • Provide adequate drainage of surface water away from the building, and provide underground tile to lower the water table or remove water from gutters draining into the tile
  • Be aware of other potential sources of moisture

Can Condensation Cause A Ceiling To Collapse

Once condensation causes moisture spots on the ceiling, homeowners usually begin to worry. Not only are condensation stains unappealing and unsightly, but they are also severely detrimental to the structure of your home and the health of your household.

Having these stains on your ceiling is proof that your condensation problem has progressed further into your home and is causing serious damage. A collection of water gathering between your ceiling and roof adds weight and stress, as well as encourages rotting in other parts of your homes structure.

The beams and drywall, for instance, will be under extra pressure and can soon become weak or begin actively sagging. This decay can result in a complete ceiling collapse which is both expensive to repair and dangerous to endure.

Identifying the roofing issue that is causing the condensation on your ceiling is vital to preventing this catastrophe before it begins. Ceilings can only handle so much weight before they begin to crack and then finally collapse, which is the extremely-possible worst-case scenario.

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Things To Know About The Stack Effect

Roofs are vulnerable to condensation anytime warm, moist interior air rising up through a building comes into contact with a cold roof assembly.

“In areas with more heating days per year, generally in the north, wintertime becomes problematic. When humid air from the interior makes contact with the underside of the roof surface, the water vapor it’s carrying turns into liquid water,” explains Jose F. Ponce, technical specialist with Professional Roof Consultants. “Think of a cold drink sitting out on a summer day. The same phenomenon happens with roof systems.”

Now is a good time to look for warning signs. Keep an eye out for drips, usually observed at midday when the sun is shining and the membrane’s temperature is on the rise, recommends Craig Tyler, architect and specification developer for Carlisle Construction Materials. Don’t assume dripping is from leakage.

Roof cuts and thermographic imaging can also detect moisture, in addition to other strategies.

“Cracking noises can sometimes be heard when walking on the roof during wintertime, as a thin layer of ice breaks,” he adds. “On structural concrete and possibly wood planks, or plywood, moisture drips may not be observed. But frozen moisture can be detected in the form of spongy, buckled, or warped insulation beneath the membrane.”

Remedial action depends on the intensity of condensation, but it can be as severe as system replacement, Tyler says.

What Causes Condensation Problems On The Underside Of Metal Roofs

Best Condensation Solution for Metal Roofing

To understand what causes condensation, we reached out to Chris Davis, President of DripStop. Chris explains that there are two important things to remember with condensation, and they may seem somewhat counterintuitive:

  • Warm air holds more moisture than cold air
  • Warm air is actually lighter than cold air

Essentially, condensation occurs at night, when the temperature inside a building is warmer than outside. Warm, wet air rises and meets the cold roof and cools. As it cools, it cant hold as much moisture. That excess moisture ends up as drops of condensation on the roof: Picture a cloud of moisture floating overhead between the rafters.

This video shows what a significant condensation problem can look like.

There are essentially three factors to be considered in the fight against condensation lets take a closer look at each of them.

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What Causes The Problem Of Roof Condensation During Winter

With a slope or flat roof, one of the things that must be kept in mind is the threat of moisture condensation during the late fall, winter, and early spring. Several factors combine to create this problem, which can rot timbers, cause mold growth, aggravate allergies, and more. However, one of the most obvious and disturbing things that can be caused by condensation is the appearance of roof leaks.

Condensation Leak

Dripping ceilings are almost always blamed on leaks in the roof, but condensation can cause this effect even when the roof’s outer surface is completely intact. That’s because once the condensation builds up enough, it starts to drip out off of the saturated beams and out of the insulation. Since the interior ceiling isn’t waterproof, the condensate drips on through. This can cause damage not only to the ceiling, but to whatever equipment or stock is beneath the dripping points.

A few factors work together to make condensation a bigger problem during cold weather. Warm air tends to hold more moisture, and it also likes to rise. This brings moist air from the building up through the ceiling. Moisture also likes to condense on cold surfaces, and the area between the ceiling and the roof is full of these surfaces. Finally, a lack of ventilation gives the moisture no way to get out of this semi-enclosed area. This leaves the moisture with nowhere to go but back into your building in the form of rain-like drops.



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