Tag Archives: eave strut

Steel Ridge Cap to Roofing Overlap

Hopefully no one wants to create a roof with leaks. Reader MIKE in HARBOR CREEK wants to make sure he is doing things correctly. He writes:

“How much overlap do you have to have with roofing and ridge cap? Is 2.5″ enough and then you use metal to metal screw you do not have to penetrate the purlins?
Ty”

I cannot vouch for how other building providers assemble their buildings, so I will go with how we do it.

To calculate a building’s roof steel length we take one-half of the building’s span (or horizontal measure from peak/ridge to the outside of columns) and multiply this times a factor for roof slope. 

For slope factor – multiply slope by itself and add 144. Take the square root (use a calculator) of this number and divide by 12.

Example to calculate slope factor for 3.67/12:  [3.67 X 3.67] + 144 = 157.47. Square root of 157.47 = 12.549. Divided by 12 = 1.0457.

For a 40 foot width gabled building with a 4/12 slope this length would be 21.082 feet (call it 21’1”).

Outside of columns at eave we have a 2x of some sort as an eave strut, with a width of 1-1/2 inches and roof steel must overhang this by 2-1/4 to 2-1/2 inches. Using 21’1” for our roof steel length, this means the top edge of roof steel will now be four inches from the peak/ridge.

Standard steel ridge caps are generally very close to 14 inches in overall width, giving somewhere around three inches of overlap on each side. Placed in this overlap will be either a form fitted outside closure strip or a vented closure (https://www.hansenpolebuildings.com/2015/11/ridge-cap-foam-closure-strips/). Either of these products properly installed will prevent weather (rain and/or snow) from being driven beneath the ridge cap into your building. You can read a little more on correct placements of closures here: https://www.hansenpolebuildings.com/2015/11/outside-closure-and-vented-closure-installation/.

By using metal-to-metal stitch screws to attach the ridge cap to high ribs of roof steel, there is no need to have to miraculously hit any ridge purlins with screws. Here is a brief tale involving a builder who went off on his own tangent https://www.hansenpolebuildings.com/2011/12/stitch-screws/.

In summary Mike, provided you have a 2-1/2 inch overlap, have used proper ridge closures and stitch screws your life will be good and you will have a happy end result!

Whiskey Tango Foxtrot! Is It Ventilation?

Whiskey Tango Foxtrot! Is it Ventilation?

I really enjoy good food. In order to continue doing so and avoid weighing significantly more than I should, I do a treadmill run nearly every morning. To keep from expiring from utter boredom of exercise, I have wall mounted my flat screen LED television within easy viewing distance. With subscriptions to Amazon Prime and Netflix, I have yet to run out of movies and series to view. Most movie selections are either fairly old, or were box office challenged. One of these movies was 2016’s Tina Fay starring in Whiskey Tango Foxtrot, with a budget of $35 million and a box office take of $18.3 million.

Well, this article isn’t about how Tina Fey carried this movie. To be precise, it’s a movie title conveying my expression upon doing some recent reading.

Back in 2016 I had penned an article (https://www.hansenpolebuildings.com/2015/06/overhang/) mentioning a specific pole building company by name. A representative of this company recently contacted Hansen Pole Buildings’ owner Eric to let him know they did not appreciate being named. I was even kind enough to have included a live link to their website in my article, providing them with free press.

While editing, I happened to peruse their website. When a Whiskey Tango Foxtrot moment hit me…..

Under ‘Building Features’ I found this gem, “(Our standard roof to eave or gable design creates a fully ventilated structure making boxed overhangs an option, not a necessity)”.

I had to read it several times to fully get my head around what I thought I had read.

In order for this statement to be true, roof steel high ribs would need to remain unobstructed – allowing a free flow of intake air. This could possibly pose a challenge if one desires to keep small flying critters from entering a dead attic space.

In my humble opinion, this attempted ventilation intake ranges from laughable to totally ridiculous. However, I have found, nearly anything can be spun to sound like a benefit. What should be happening between roof steel and eave strut – placement of an Inside Closure (https://www.hansenpolebuildings.com/2015/12/the-lowly-inside-closure/), to seal these openings.

IBC (International Building Code) 2015 Edition tends to agree with me.

“1203.2.1 Openings into attic.

Exterior openings into the attic space of any building intended for human occupancy shall be protected to prevent the entry of birds, squirrels, rodents, snakes and other similar creatures. Openings for ventilation having a least dimension of not less than 1/16 inch and not more than ¼ inch shall be permitted. Openings for ventilation having a least dimension larger than ¼ inch shall be provided with corrosion-resistant wire cloth screening, hardware cloth, perforated vinyl or similar material width openings having a least dimension of not less than 1/16 inch and not more than ¼ inch.”

Thinking about a post frame building other than from Hansen Pole Buildings? Before possibly throwing away your hard earned cash, give us a call – if we feel someone else’s building has a better value than ours, we will be first ones to tell you to invest in it.

 

Avoid Metal Building Insulation

One More Reason to Avoid Metal Building Insulation

 

Photo isn’t showing the inside of a Hansen Pole Building. This view happens to be inside of an eave sidewall looking up underneath a post frame building roof. White vinyl facing happens to be underside of a product commonly known as Metal Building Insulation, having actual R values so low it should be more appropriately described as Condensation Control Blanket.

For previous words of wisdom in regards to Metal Building Insulation, read more here: https://www.hansenpolebuildings.com/2015/05/metal-building-insulation-3/.

This particular building can be found in Western Washington. 20 years old, construction was done by current building owners. A horse barn, building has a concrete slab floor, other than in horse stalls. Each side of building has open (no soffits) overhangs.
Now our challenge – certain days, with high humidity and fog, building has a problem with water ‘leaking’ along first purlin inside building.

My take regarding the problem’s root cause:
Properly installed in a roof, each roll of Metal Building Insulation should be stretched two inches past eave strut (eave purlin). Fiberglass adhered to vinyl facing should be removed from these two inches, folded back over top of intact fiberglass, then fastened securely to eave strut top until steel roofing installation. This takes a bit more effort than merely cutting rolls off flush with eave strut outside and calling it a day.

My guess, this building’s owners were not given instructions advising how to properly install Condensation Control Blanket, so it was done a quicker and easier way. This leaves a raw edge of fiberglass above the eave strut. When those chilly high humidity days occur, underside of roof steel in eave overhang has condensation collecting. Some of this moisture then contacts raw fiberglass edge and wicks up into building. Please note, in photo the apparent puffiness of insulation between sidewall and first purlin up roof. This would be an indicator water has sat above white vinyl vapor barrier.

A solution exists – remove screws from roofing above fascia and eave strut. Insert form fitted inside closures above eave strut, making certain no fiberglass remains exposed to overhang. More information about inside closures here: https://www.hansenpolebuildings.com/2015/12/the-lowly-inside-closure/)

Replace screws (using larger diameter than original screws). Roofing should be screwed to both sides of high ribs into fascia board. We recommend use of 1-1/2″ Diaphragm screws as a replacement.