A Day In The Sun

By
Home Inspector with JRV Home Inspection Services, LLC HOI 394

"Toasted" roof shinglesThere is nothing like a beautiful sunny day to enjoy. The warm light raises ones spirits as high as the sun itself.  There are many days where I find myself atop a roof, a gentle breeze brushing my sun warmed face and I think how nice it would be stay up there a while longer.

As most everyone knows, while that sun light may feel great, too much can be detrimental to ones health. With houses, the sun can be a blessing and a curse. Warm light through a window is a delight on a cool morning. But on that same warm roof top perch, the shingles are baked continually. If left on to long they can become similar to overdone pieces of toast.

Ugly black stains mean excessive moisture, condensation and decay for this roof sheathingBelow the roof covering is the attic which becomes like an oven from the baking being done from above. It has long been known that an attic without a means of relieving the built up heat will cause numerous problems for the building. Attic ventilation has been the answer for many, many years. The other reason for venting is to dry out the attic when the temperature drops. Moisture diffuses into the attic from the conditioned spaces below. It must be dissipated or it can collect, condense and cause decay.

Recently I found the results of excessive moisture which has been accumulating and condensing on the roof sheathing in an attic. The entire slope was in this condition. You can see the soffit vents in the photo. The vents were properly installed and as best that I could tell were open. The ridge vent was checked and found to be clear. When all systems appear to be properly installed and working the culprit should be looked for below the insulation and inside the house. 

In an attic where the ventilation is working and not being over whelmed the roof sheathing should look like the second photo.

This sheathing is almost pristine, hard to believe it is the same attic.Or should it?

The second picture is from the same roof but the opposite slope. The difference is dramatic. The reason for the difference is the roofs orientation to the sun. This slope faces the sun, while the other is shaded. There was some confusion as to why this would be happening because the clean side of the roof was shaded by large trees.

Trees in Connecticut loose their leaves in the fall. The sun is unobstructed for a good five months during the cold weather. This issue, as I mentioned, is more of a cold weather phenomenon. As the sun can dry out a puddle, so can it dry out the underside of a roof.

The sun has in this instance been a benefit to one side of the roof. Unfortunately the condition of other side of the roof doesn't look so bright. 

Posted by

James Quarello
Connecticut Home Inspector
Former SNEC-ASHI President
JRV Home Inspection Services, LLC

 ASHI Certified Inspector

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Rainmaker
694,665
Clint Mckie
Desert Sun Home, commercial Inspections - Carlsbad, NM
Desert Sun Home, Comm. Inspection 1-575-706-5586

Hi James,

Looking at the decking there needs to be the proper venting. The more the venting the more the moisture can escape and dry out faster. But you already knew this. :-)

Have a great day in Connecticut.

Best, Clint McKie

Jan 13, 2013 08:35 PM #4
Ambassador
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Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Jim, this is such a good point.  "Proper" attic ventilation will only deal with "normal" excess moisture conditions and if there is too much moisture by-passing into the attic bad things will happen in spite of "good" ventilation.

Jan 13, 2013 11:24 PM #5
Ambassador
3,103,752
Paul S. Henderson, REALTOR®, CRS
RE/MAX Northwest. - Tacoma, WA
Tacoma Washington Agent/Broker & Market Authority!

Nobody can argue the effects of the sun; both good and bad. We all have to learn moderation and preventive care with both our bodies and our homes... 

Jan 14, 2013 12:18 AM #6
Rainer
284,418
Steven Cook
No Longer Processing Mortgages. - Tacoma, WA

James -- that is a startling contrast between the two sides of the roof!  Is there anything that can be done to keep it from getting worse/doing the same thing after repairs?

 

Jan 14, 2013 02:40 AM #7
Rainer
208,325
Sajy Mathew
Coldwell Banker Residential Brokerage - Lancaster, PA
Making your real estate dreams become a reality!

Amazing that happened on two sides of the same roof.  My parents had an issue with their home but the whole roof needed treated.  Ventilation was the problem there.

 

 

Jan 14, 2013 04:31 AM #8
Rainer
264,020
Robert Sole
REM Inspections LLC - Winter Springs, FL

It is apparent that there is a moisture problem somewhere in the home.  If there isn't any obvious reason in the area surrounding the home, then the moisture must be coming from inside the home and migrating into the attic.  One thing is certain, if the problem isn't solved, the one side of the roof will not last as long as it should.

 

Good post.

Jan 14, 2013 06:05 AM #9
Rainmaker
2,539,966
Myrl Jeffcoat
GreatWest Realty - Sacramento, CA
Greater Sacramento Real Estate Agent

Excellent information on the sun, roofs.  I've been fortunate with my roof.  It was supposed to be a 15 year roof, but has lasted in reasonably good condition beyond that.  Still, I suspect my friendly roofer, will need to park his truck in my driveway within a couple years.

Jan 14, 2013 10:44 AM #10
Rainmaker
217,052
Rob Ernst
Certified Structure Inspector - Reno, NV
Reno, NV-775-410-4286 Inspector & Energy Auditor

One of the other theories is the more ventilation the more stack effect. The more stack the more damp air from the home and crawlspace end up in the attic. Ventilation is one solution but the source of the moisture should also be looked into. 

Jan 14, 2013 11:20 AM #11
Anonymous
Rooftop ventilator

Roof ventilators are easy to install and configure to meet the demands of fresh air changes in the house. These are light weight and strong and can be fitted to all types of buildings which include both commercial as well as residential buildings. The eco-ventilators find use in industries, factories, warehouses, workshops and even for domestic purposes. Roof ventilation is a much misunderstood topic, for it seems counter-productive to all the energy-saving weather-sealing and insulation efforts we invest in as building improvements.


for more details
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Jan 14, 2013 02:33 PM #12
Rainmaker
270,119
Steve Warrene
Your Town Realty - Lower Burrell, PA
Pittsburgh Real Estate Investment Specialists

It's a shock to see the same roof with that big of a difference in results. 

Jan 14, 2013 06:45 PM #13
Rainmaker
687,134
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Clint, When moisture over whelms the ventilation, which it has in this attic, adding more ventilation does not solve the problem. The moisture is finding its way into the attic because the ceiling is not well seal against leakage. There can also be other contributing factors such as over use of humidifiers or an excessively wet basement. Ultimately there are usually several reasons for a condition like this one to be occurring. 

Charlie, Exactly. Often this problem is thought to be the ventilation itself. 

Paul, Well said and so true.

Steven, If properly repaired it won't happen.

Sajy, If the whole roof was effected, it was probably ventilation all though I have found that is very rarely the case. 

Robert, Since I inspected this home, I can say there wasn't a moisture problem. In fact I made a point of looking for many of the known culprits. The house is baseboard heated, no humidifiers any where in use. Three occupants, one a toddler. The basement was dry, but a crawl space under an addition did have some infiltration. I strongly suspect the insultion and bypasses. 

Jan 14, 2013 08:28 PM #14
Rainmaker
687,134
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Myrl, Thanks. Roof coverings can last longer than stated...or less :)

Rob, I disagree, stack effect and ventilation are not the cause for this issue. It seems stack effect has become the theory du jour. While you are correct a damp crawl space will certainlty effect the attic, so will over humidification, which is fairly common here. As I have stated already, this is not a ventilation issue. By passes and fiberglass batts are my prime suspects. Holes in the ceiling at the attic let conditioned air through, which then coindenses on the roof. Keep in mind air passes into the attic in the summer as well, but the attic and the weather are warm, thus no condensation. 

Rooftop Ventilator, Roof ventilation is generally well understood, the causes for the issue shown, however not as much.

Steve, I thought it would be eye opening. 

Jan 14, 2013 08:42 PM #15
Rainmaker
217,052
Rob Ernst
Certified Structure Inspector - Reno, NV
Reno, NV-775-410-4286 Inspector & Energy Auditor

I would agree bypasses and holes in the air barrier are a reason for getting moisture into the attic. Majority of moisture movement in a structure is due to air movement. The house is most often under negative pressure, so you would think the air wouldn't make it's way into the attic if that was the case. The stack effect is occurring due to the buoyancy of air and moisture.The second law of thermodynamics explains this. In the summer you can actually test for reverse stack effect where the hot air from the attic is forcing it's way into the home. Air sealing is the way to go but controlling of the source is the important issue. 

Jan 15, 2013 09:08 AM #16
Rainmaker
687,134
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Rob, Moisture movement and air movment are really one and the same. 

"The stack effect is occurring due to the buoyancy of air and moisture.The second law of thermodynamics explains this."

The stack effect is due to temperature differentials between the interior of the building and exterior which create differences in air density. Warm air is bouyant compared to colder air and as we know can hold more moisture. Air movment is less often due to thermodynamics than air pressure differntials. That being said, the engine that drives the moisture into the attic is a combination of air pressure and temperature differentials, BUT without a means of access the the warm conditioned air would never get into the attic. Therefore the bypasses are the root cause for moisture and air transport into the attic. 

On another forum recently on attic moisture, one of the guys put up a great link. Check it out 

http://www.greenbuildingadvisor.com/blogs/dept/building-science/lstiburek-s-rules-venting-roofs

Jan 15, 2013 08:13 PM #17
Rainmaker
233,523
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

James - gotta chuckle at that attic ventilator comment.  I just wrote a comment to Charles explaining how I'm not trying to rip off his ideas with my posts... same to you, buddy :-).  

I just wrote a comment on Charles' blog, which I'm just going to copy and paste here as well.

One other important component to consider in these cases is the ductwork for the furnace.  I'm at IW2013 right now, and I sat through a great class yesterday put on by Jim Nemastil and Marko Vovk, where they made a big deal about leaky furnace return ducts in basements being a major contributor to attic moisture  problems.  I've done a ton of attic troubleshooting inspections, but I've never really considered what an impact leaky basement return ducts could make in an attic.

As soon as I get home, I plan to do some experiments on my own house.  Fun stuff.

Do you have any plans to attend any IW conferences in the future?  I sat through almost all technical classes at IW last year, and I found it so-so.  This year I attended mostly business classes, and I have so many great ideas for growing my business that I think my head is going to explode.  I'll definitely be attending IW2014 - I'd love to see you there.

Jan 16, 2013 11:30 AM #18
Rainmaker
687,134
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Reuben, I don't see it in any way as ripping off, just great minds thinking alike :) 

Interesting about the return ducts. I am curious how they came to this conclusion. This house has baseboard heat. As for IW, we'll see what happens this year as to whether I attend. 

Jan 16, 2013 09:53 PM #19
Rainer
27,008
Stephen Gaudet
Gaudet Inspections - Manchester, NH

Good article James.  Usually it's bathroom fans causing that problem.

 

Jan 16, 2013 11:33 PM #20
Rainmaker
233,523
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

If I can reproduce the results, I'll definitely follow up with a post on that topic explaining how it works.

Jan 17, 2013 12:06 AM #21
Rainmaker
490,619
Donald Hester
NCW Home Inspections, LLC - Wenatchee, WA
NCW Home Inspections, LLC

Jim, I see that exact same effect here and we are very dry. The north facing roof creates the condensation and freezes. It is almost always bypass, the pink panther issues and people not using their ventilation properly.

Jan 17, 2013 04:36 AM #22
Rainmaker
687,134
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Stephen, Thanks, they are one of the more obvious causes.

Reuben, I'd be interested no matter what the results. 

Don, It"s the usual suspects most every time. 

Jan 17, 2013 05:47 AM #23
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