Tag Archives: soffit vents

Installing Steel Liner Panels in an Existing Pole Barn

Installing Steel Liner Panels in an Existing Pole Barn

Reader JASON in WHITEHOUSE STATION writes:

“ Hello! I have a post frame 30X40 Pole Barn that was built prior to me owning the house. Currently, the shop is not insulated. I would really like to insulate it, as it’s quite unbearable in the summer and winter. The building has soffit vents, a ridge vent, and two gable vents. With the way the building is set up with all that ventilation (possibly too much?), is putting in a ceiling with insulation on top my best bet? I know there are many options when it comes to insulation, but I am trying to determine what is best for my application. I am leaning towards 6 mil poly on the bottom side of the truss, ceiling liner panel over that with blown in insulation on top. My truss is 8′ on center. Is there a recommended length of panel I should use? Thank you for your help with this. I’m sorry if I asked too many questions.”

Mike the Pole Barn Guru responds:

Provided your building has roof trusses designed to adequately support a ceiling load, your best bet will be to blow in insulation above a flat level ceiling. If you do not have original truss drawings available to determine if they have a bottom chord dead load (BCDL) of three or more, then you will need to find the manufacturer’s stamp placed on truss bottom chords and contact them with your site address. With this information they should be able to pull up records and give you a yes or no. If you are yet unable to make this determination, a Registered Professional Engineer should be retained to evaluate your trusses and advise as to if they are appropriate to carry a ceiling and if not, what upgrades will be required.

If your building does not have some sort of thermal break between roof framing and roof steel (a radiant reflective barrier, sheathing, etc.) you should have two inches of closed cell spray foam applied to the underside of roof steel, or else you will have condensation issues (even with the ventilation). With trusses every eight feet (again provided trusses can carry ceiling weight), I would add ceiling joists between truss bottom chords every four feet and run 30 foot long (verify from actual field measurements) steel panels from wall to wall.

You do not have too much ventilation – and be careful not to block off airflow at eaves. You can omit poly between liner panels and ceiling framing.

Insulating an Existing Post Frame Building Attic

We are in an era where climate control of brand new post frame buildings is extremely common. It is also much easier to insulate (or plan for it) at time of construction, rather than having to go back and do it afterwards. 

For new post frame buildings, here is my Ultimate Guide to Post Frame Building Insulation: https://www.hansenpolebuildings.com/2019/11/post-frame-building-insulation/.

Loyal reader DAMON in SPOKANE is fortunate to have some parts of his existing post frame shop made easy for retrofit insulation. He writes:

“Hi,

First I want to say I love your web site, the information I’ve been reading is invaluable! I am located in Spokane County. I have a 24x24x10 post frame garage that was here when I purchased the house. The walls have commercial girts R19 insulation. I would like to heat this garage and use it as a woodworking shop. Right now the ceiling is open and there is no insulation. The roof is sheeted with OSB, then felt then steel roofing panels. There is no ventilation or overhangs to install soffit vents. The roof has 4:12 pitch.

I am considering one of two options. The first is to spray foam under the roof decking with closed cell foam, about 2″ which would give me about an R14. This would mean I would have to heat a larger air volume all the way up to the roof. Is this an effective method? Will the closed cell foam seal everything and hold the warm air in efficiently? I supposed I could install a couple of slow turning ceiling fans to push the warm air back down.

The second alternative is to add a ceiling. I was able to confirm that the garage was built with bottom load trusses. I could install joists and an osb ceiling and then go with a blown in insulation, maybe R38. Because there is no ventilation I was thinking of adding large appropriately sized gable vents to provide the ventilation since I do not have soffit vents nor a ridge vent.

Of the two options, is one a better consideration than the other? I know you’re probably pretty busy, I appreciate any time you have to help me with my decision.”

Mike the Pole Barn Guru responds:
Thank you very much for your kind words, hopefully you have been entertained as well as informed!

As your building was built with trusses designed to support a ceiling, I would recommend you pursue this route. You would need to add gable end vents in the upper half of each gable with a net free ventilation area of at least 139 square inches per end. Please keep in mind this is not vent dimension, but net free area only.

Your building’s roof trusses probably do not have raised “energy heels” so it would be most practical to use closed cell spray foam insulation along two feet closest to each eave sidewall (applied to top side of ceiling finish). I would recommend you blow a minimum of R-49 across the balance of the attic area as this will meet minimum recommended attic insulation levels from www.energystar.gov. Your spray foam applicator can make recommendations for the thickness of his or her product.

Also, please consider using 5/8″ Type X sheetrock for your ceiling. It will be less expensive than OSB and provides some degree of fire resistance.

Foil Insulation is Not Insulation

Foil Insulation Is Not Insulation

Products being incorrectly marketed and sold as “foil insulation” are actually nothing more than a radiant reflective barrier. They are not insulation. I have previously covered this very subject, so will not rank and rail more: https://www.hansenpolebuildings.com/2014/04/reflective-insulation-wars/

Today’s learning article has inspiration in this from reader BOBBY in GRASSTIN who writes:

“I have a 24×36 Morton Pole building built in early 80s. I am trying to insulate and heat the building. Currently I have ridge vent and soffit vents. I was not intending on putting a ceiling under the trusses. This fall I lined the whole building roof and walls with foil insulation and hung 2 natural gas infrared heaters as a temp fix. I currently have two 9×7 overhead garage doors which are un-insulated and leak pretty much on all sides and a sliding door on the table end which leaks. Needless to say my gas bill is atrocious and because I sealed the ridge vent and soffit vents with foil I have a bad condensation problem mostly because the heaters put out so much water. Aside from sealing the doors with new insulated doors, how should I tackle the insulation and the condensation problem? Do I spray foam the roof and leave the vents plugged? Or spray foam the roof and install ceiling and unblock the soffit and ridge vents? Or spray foam ridge and soffit vents and install Gable vents? Which would probably be cheaper than a ceiling. Would I lose all my heat out of the Gable vents? Newbie here and appreciate the help.”

Mike the Pole Barn Guru responds:

Lots of things happening here, so let’s dive right in.

Ditch your current heaters and replace them with vented units. There are efficient vented gas heaters available, providing same type of heat you are used to, but they exhaust all their combustion by-products outside through a wall vent. You’ll lose not only water vapor, but also carbon monoxide, nitrogen dioxide and other contaminants.

Use a high quality sealant over your building’s concrete floors: https://www.hansenpolebuildings.com/2018/11/siloxa-tek-8505-concrete-sealant/.

So far we have eliminated sources of most condensation, moving next to how to best insulate what you have.

Chances are very small your building’s trusses will support a ceiling. This would have been an ideal case, as it would have kept you from having to pay to heat an area above truss bottom chord level.

Replace your present overhead and sliding doors with insulated overhead doors. Tear out foil “insulation” and throw it away. Keeping eave and ridge vents sealed, use closed cell spray foam insulation across walls and underside of roof deck. An absolute minimum thickness will be two inches, providing approximately R-14. You will need to weigh benefits of greater R values against investment.

Me – if allowed by my Planning Department I would build another building properly designed to be energy efficient. Chances are it will be comparable in investment to what you are going to throw into a three decades old building, plus it will be brand new!

 

Minimizing Condensation When Building Over an Existing Foundation

Minimizing Condensation When Building Over an Existing Foundation

Reader ROSS writes:

enclosed overhangs“Hello, I have a question about venting of my building. I currently am in the process of building a shop myself. I had an existing foundation of 75 x 42 that had 8ft concrete walls all the way around. I’m building my building on top of this to give myself 17’ sidewalls. My concern is about my venting. I’m planning to have soffit installed along the building and am not sure if I should go with Gable vents or ridge vents. The building will be insulated with 3” fiberglass with a poly vapor barrier on the walls and with 1” 4×8 sheets of foam board on the roof with all the joints taped. My concern with ridge vent is will moisture condense on the exposed ridge cap and drip since it has to be left uninsulated for venting or will it be ok? I would rather not have any drips. My gut feeling tells me I need to have plenty of venting since 3 sides of the concrete are covered with dirt and already show condensation pretty regularly when the temp changes. With my soffits do I need to run vented soffit the full length of the building? Thanks your response will be greatly appreciated!”

Mike the Pole Barn Guru Responds:

I’d start with excavating around the foundation and properly sealing it from the outside, as well as sealing the slab floor. It sounds like you propose to place foam insulation board between the roof framing and the roof steel – not a good structural idea, as you are significantly reducing (if not eliminating) any shear strength afforded by the steel panels, as well as eventually contributing to leakage from the screws being able to “work” between the framing and the steel. You would be ahead to either use a radiant reflective barrier (less expensive, more labor intense) or Condenstop/Dripstop (read more here: https://www.hansenpolebuildings.com/2014/07/condenstop/) beneath the roof steel. Either one of these products can be adhered to the ridge caps as well.

The Building Codes do not allow for gable vents to be combined with eave or ridge vents. Your best bet is to run full vented soffits on both eaves, combined with ridge vents the entire building length. https://www.hansenpolebuildings.com/2014/02/pole-building-ventilation/