Tag Archives: attic ventilation system

Will My Post Frame Building Support a Ceiling?

Will My Post Frame Building Support a Ceiling?

One of my frequently received questions – wanting to add a ceiling into a post frame building and wondering if the building will support the added weight. Other frequent questions include condensation issues and ventilation, so this reader has hit upon a trifecta.


Reader BRYAN in SWANTON writes:

“I am having some condensation issues. And I was curious about insulating the building. Also wanted to ask if my building is able to have a ceiling installed. Thanks for the fast reply.”

 

 


By any chance have you recently poured a concrete slab-on-grade inside of your building? If so, until concrete fully cures, it will expel a great deal of moisture inside of your building. Solution – open your doors to allow moisture to escape and keep them open until condensation issues no longer exist. Read more here: https://www.hansenpolebuildings.com/2018/01/condensation-roof-steel/.

 

If you poured a slab without a well-sealed vapor barrier underneath, it will contribute to excessive moisture challenges. If no vapor barrier, top of slab should be sealed: https://www.hansenpolebuildings.com/2018/11/siloxa-tek-8505-concrete-sealant/

 

Your new post frame building and its trusses were not ordered to be able to support the added weight of a ceiling. It may be possible to upgrade your trusses with an engineered repair to be able to carry a bottom chord dead load of five psf (pounds per square foot) or more. Plan upon an investment of $295 (plus sales tax if applicable), even if a truss repair cannot be designed. Contact Justine at justine@hansenpolebuildings.com if you are interested in going this route.

If you are able to get a repair to install a ceiling, this newly enclosed attic area will need to be adequately ventilated. This may be a possible solution: https://www.hansenpolebuildings.com/2018/07/my-pole-barn-needs-ventilation/

In order to insulate, best solution (although costly) may be to use closed cell spray foam insulation. If you purchase an insulation kit for your overhead door, you will need to change out door springs in order to handle the added weight.

 

 

Venting an Attic Without Soffit Air Intake

Venting an Attic Without Soffit Air Intake

Loyal reader KEN has an attic space with only air exhaust points – a vented ridge, and no air intake. His dilemma, how to adequately ventilate his attic without vented soffits.

Ken writes:

“I finally was able to make contact with the manufacturer of the open foam like material used under my ridge as a vent. The following is cut and pasted from their technical material: Net Free Area 1”nom.Thickness 8.5 sq.in.per lin.Ft.per side (17 sq.in .per lin.Ft.ridge).  Since I have a 60 foot ridge, that would equal 1020 sq. in. or 7 sq. ft. 

Given the ridge vent, do you still recommend 3 sq. ft.  venting on each end?

You note that an 18×24 would provide 140 sq in (or 0.97 sq. in.), but 18×24 is 432 sq in.  Do the louvers and other components reduce that by a factor of 3, just wanting to confirm.  With a 3 sq. ft. requirement, I would need a vent nearly 3 times an 18×24.  Maybe it just comes down to not the ideal but what can be practically installed. 

In order to prevent rust at the cut line, should I caulk the outside seam where the louver comes through the wall?”

Mike the Pole Barn Guru writes:

Another way of thinking about ventilation – view it like a straw. Obviously with best (and most) straws each end has an opening. What happens when a hole exists somewhere between ends? A reduction occurs in your ability to draw up water or soda. A similar effect happens when different vent types are employed over a shared air space.

Air and water are similar, their flow follows a path of least resistance. In a properly designed and installed attic ventilation system air flow travels from intake vents to exhaust vents, flushing out warm, humid air along roof deck (think underside of roof steel). However, if two or more different types of exhaust vents (gable and ridge) are used above a shared attic air space, one exhaust vent will likely to interrupt air flow to the other. In this arrangement it becomes another intake vent for a primary exhaust vent – leaving large sections of attic space incorrectly vented.

I would be inclined to seal ridge vent off and utilize gable vents. Dimensions of gable vents are overall unit dimension, not net free area (reduced from overall size by both exterior framework and louvers). Each endwall may require multiple vents in order to achieve an adequate airflow.

Caulking cut edges of endwall steel would certainly not hurt. A suggested caulking would be TITEBOND Metal Roof Translucent Sealant.