# Why Are You Stuck on Bookshelf Girts?

Why in World are you Stuck on Bookshelf Girts?

“Why in world are you stuck on bookshelf girts. For instance with ‘normal’ pole barns one could SPF the walls and roof and have almost no heat loss through the lumber. One could argue your “bookshelf girts” and purlins between trusses makes the building VERY close to a “normal home”. Do you offer a traditional style built pole barn as there MUST be savings to be had.”

Mike the Pole Barn Guru writes:
There are as many ways to structurally design post-frame buildings as there are providers and builders. Our way of building happens to be very similar to what would be considered as traditional style in Western states such as Washington, Idaho, Oregon, California, etc.

We do happen to offer buildings with columns every eight feet, trusses every four feet – however very few clients ever pick this as an option.

We are always looking at ways to make our post-frame buildings more efficient and DIY friendly, without sacrificing performance.

Worst part of post-frame construction (and least easily to detect challenges in advance) is having to dig holes. By widely spacing columns (usually most cost effective is every 12 feet), number of holes having to be dug is reduced by roughly 1/3rd from eight foot spacings.

Let’s examine R-value, calculated using Type 1, conventional method.

For sake of discussion, we will use an 18 eave height (tall enough for two stories in most instances). I’ve chosen a flash and batt method, for sake of cost effectiveness of insulation.

R-value through cavity

Air film – inside 0.67

½” gypsum wallboard – 0.56

2” closed cell spray foam – 14

5-1/2” Rockwool – 23

Total R = 38.73

R-value through girts

Air film – inside 0.67

½” gypsum wallboard – 0.56

2×8 girt – 9.06

Total R = 10.79

On an 18’ wall, there will be 8 girts with an area of 1.5” x 12’ x 8 = 9.6 sft (Square Feet)

Total area of a bay = 18’ x 12’ = 216 sft

Hence girts makeup 9.6 / 216 = 0.044 (4.4%) of wall

10.79 x 0.044 + 38.73 x 0.956 = 37.5

37.5 / 38.73 = 0.968 (96.8% of a wall without girts)

How about pieces in say a 60’ long wall?

Splash planks:  1/12’ 3/16’

Girts: Exterior 2×6 8/12’ 24/16’ Interior 2×4 8/12’ 24/16’
NOTE: Exterior girts may fail in deflection, especially at wall corners where forces are greater

Columns (excluding corners): 7/22’

Truss carriers (will vary depending upon roof load): 2×12 2/12’ 6/16’

Me:

Splash planks: 5/12’

Bookshelf girts: 2×8 40/12’

Girt blocking: 2×4 10/16’

Columns(excluding corners): 4/22’

Your version has me handling 74 pieces of lumber, with 1582 bd.ft. (board feet) of lumber vs. 59 pieces with 984 bd.ft. of lumber

Your wall sets outside of external wall girts at Building Line and creates an 8-1/2” thick framed wall. On a 40’ wide building, net framed interior clear width is 38’7”.

My wall has outside of columns at Building Line, so only 5-3/4” is lost on each side. Net framed interior clear width is 39’0-1/2”

In summary, my being stuck on bookshelf wall girts loses only 3.2% to thermal bridging, reduces holes to be dug (per sidewall) by 43%, reduces pieces to be handled 20% and board footage of lumber used by 38%, while delivering a greater net usable interior space.

# Termite Resistance of Stone Wool Insulation

Termite Resistance of Stone Wool Insulation

Could you possibly share whatever information you might have on a product that is termite proof/termite resistant to insulate my slab on my building.

The only thing I have found somewhat useful is Cellofoam. It’s a EPS product that is infused with insecticide.”

Mike the Pole Barn Guru says:

Solution – Rockwool Comfortboard 80.

Rockwool Technical Innovations released a bulletin in August 2019, wherein they had recently completed third party testing at University of Hawaii to determine termite resistance of stone wool insulation. Insulation samples were tested to AWPA E1-09, “American Wood Protection Association Standard Method for Laboratory Evaluation to Determine Resistance to Subterranean Termites”. Test involved exposing insulation samples to 400 Formosan subterranean termites for a 28-day period then measuring weight loss of material, termite mortality rates and visually evaluating sample damage. Results were then compared to a control sample of Southern Yellow Pine untreated and Southern Yellow Pine treated for termite resistance with ACQ, type D.

Test results indicated stone wool insulation proved to be termite resistant per this rigorous test making material appropriate for use under conditions of very heavy termite hazards.

Laboratory observations made during testing moted termites initially investigated stone wool, but then covered it with sand within first week. This is an avoidance behavior evidenced by termites wanting to isolate something undesirable, such as an unacceptable food material.

Material weight loss of stone wool was only 1.22% compared to 4.85% for treated wood and 50.92% for untreated wood.

Both IRC (International Residential Code) and IBC (International Building Code) address foam plastic insulation use in areas where termite infestation probability is ‘very heavy’ and restrict its use when installed on exterior face or under interior or exterior foundation walls or slab foundations located below grade. To use foam plastics in these applications and geographies, it is required all structural members are made of non-combustible materials or pressure preservative treated wood, or an approved method of protecting foam plastics and structure from termite damage is used.

# Condensation Control, Ventilation or Insulation

Most Builders Do Not Understand Condensation Control, Ventilation or Insulation

Crucial to proper performance of climate controlled buildings of any sort is condensation control, adequate ventilation and insulation. Sadly, most builders do not understand how to come up with a proper design solution.

Reader AARON in WISCONSIN DELLS writes:

“Hello, I was wondering if you had a minute for a quick question ? I have read posts for countless hours regarding vapor barrier between trusses and roof steel and I can’t find the answer I’m looking for. I’m building a 44×96 that will have in floor heat in South central Wisconsin (by Madison) so we have cold winters and humid summers. Walls will be spray foamed. I will be applying a vapor barrier (poly) to the bottom of roof trusses and then putting a metal ceiling on and spraying fiberglass insulation above the ceiling. Fully vented ridge cap and 2’ overhangs with vented soffits around the entire building. The builder did not put any vapor barrier down between the roof steel and the trusses so the steel is directly on the trusses. Could this end up creating a moisture issue or will I have enough air flow in the attic space that I do not need the vapor barrier between the roof metal and trusses ? Thank you very much for your time.”

Thank you for reaching out to me Aaron, I am always available to answer questions.

Your builder sadly did you no favors in not having a means to prevent condensation on your roof steel underside. It also requires having an actual thermal break, not just a vapor barrier. Your best solution now is to have two inches of closed cell spray foam applied directly to the underside of your roof steel, making certain they do not block ridge vents. Without this thermal break, expect to end up with damp insulation.

If your builder installed vented soffits on your building’s end overhangs, you need to find a method to block them off – otherwise your attic will not vent properly.

In regards to ceiling vapor barriers, Joe Lstiburek (building scientist and founding principal of Building Science Corporation) says plastic vapor barriers should only be installed in vented attics in climates with more than 8,000 heating degree days. Even in South central Wisconsin, you are not to this point.

You’ll want to verify a correct ratio of air intake from soffits to air exhaust at ridge (chances are good your builder did not). At least 40% and no more than 50% of your attic’s net free ventilating area (NFVA) should be at the ridge. You may need to block off some of your sidewall eave vents to get the ratio correct.

I would also recommend you blow in rockwool insulation in your attic rather than fiberglass. Fiberglass insulation loses R value when outside (attic) air temperatures are low and is also affected by even small amounts of moisture.