Tag Archives: post frame garage

How to Insulate My Post Frame Garage

How to Insulate

I fear “how to insulate my post frame (fill in the blank)” is going to be my most answered topic for the next decade. Energy efficiency is the “hot” topic right now and sadly there are more folks trying to solve what they already have, than there were those who planned for it correctly in the beginning.

Reader ERIC in FENELTON writes:

“Hello, I am wondering what the best and most cost effective way to insulate my post frame garage would be. I recently erected a 32’x48’post frame garage with glulam posts on 8’ centers, girts and purlins on 2’ Center’s, trusses on 4’ centers with 1’ overhangs with center soffit and ridge vent. Walls and roof are steel with double bubble between purlins and roof steel and tyvek between hurts and the wall steel. I will be building a wall to separate one of the bays as a metal shop for welding and fabricating. This will be the only bay that is heated and is 32’x21’. I am on a budget but my biggest concern is moisture. I installed the tyvek and double bubble hoping to positively effect the problem but am still hesitant to put fiberglass in the
walls but spray foam is out of my price range. I have seen some people cut 1 1/2” foam board to fit between the wall girts and either stop there or then frame traditional walls between the posts and add R13-R19 faced insulation. Is this an adequate way to insulate and will the foamboard keep moisture from the fiberglass? I will definitely be framing between posts and then covering with painted OSB regardless of the insulation method I choose. Also, I was leaning toward using fiberglass batts in the ceiling and then using the white liner steel under the trusses. They are 2×6 top and bottom cord trusses and rated for a ceiling. Fiberglass in the ceiling gives me the same moisture
concerns however. So I guess my question is, now that you know about my building, what is the best abs most cost effective way to insulate the portion of the building and avoid moisture? Spray foam is out of the question due to costs. I have been doing a ton of research but get different answers everywhere I go. Any help will be greatly appreciated. Thank you.”

Mike the Pole Barn Guru
As long as the Tyvek is well sealed, you will not be gaining moisture from the outside on the walls. What you need to create is a dry wall cavity. Completely fill the wall with unfaced fiberglass (you might consider using BIBs http://www.hansenpolebuildings.com/2011/11/bibs/)
and cover the interior of the wall with a well sealed vapor barrier (clear visqueen will do nicely). Cutting foam board is an exercise in
futility unless you can figure out how to completely seal it, if you
stop at this point.

For your ceiling – there is a good chance you will experience
condensation on the underside of the steel ceiling liner panels. With
your vented eave and ridge, blown in fiberglass is probably the best
answer. If you do not have raised heel trusses, you should probably look
at spray foaming the first couple of feet of the ceiling area in order
to reduce heat loss from not being able to gain full thickness of the

Extreme Efforts to Add Post Frame to House

Extreme Efforts to Match Post Frame to House

Reader JOSH from POST FALLS and I have previously communicated. He is doing what I refer to a piecemealing – putting together his own building by making repeated trips to the local lumber yard (learn more about piecemealing here: http://www.hansenpolebuildings.com/2014/03/diy-pole-building/.

Josh’s new post frame garage is adjacent to his home and he wants things to match up.

Josh writes:Construction Manual

“Thanks so much for your offer for help. The knowledge of other people’s questions on your site is a great resource. I’ll buy my next pole structure kit from you for sure.

Quick question. I have an 18″ overhang with 2×8 purlins and truss top members. My pole garage is next to my house and will be matching the exterior of the house. The varge rafter and fascia on the house are 2×6.  It looks like I can just trim the bottom off on the fascia side, but what is the recommended way to match the gable end to the house if the purlins on the garage are 2×8 instead of 2×6?

Also are the varge rafter and the facscia both 1×6? or 2×6?

P.S. I noticed you used grok in one of your answers to a question. Haha, first use of grok in a non-technical setting I’ve seen. You must have a technical background.”

Mike the Pole Barn Guru Writes:

My mission is to be informative and entertaining – if grok got a chuckle from you, then all is good! I also try to throw out some occasional words most people do not use every day, with the hopes it will expand the vocabulary of some.

Unless your pole garage is attached to your house, frankly no one except you or I would ever notice the fascias are not the same dimension. People just are not finely attuned to details such as these. If it is really important to you, you could cut the overhanging portion of the purlins down to 5-1/2″ by ripping a chunk off from the overhanging portion, without it negatively affecting the structural ability of the purlins to carry the load. Your Building Department may require a letter from the engineer who designed your building on this one, however.

I would go with two inch nominal material for both the varges and fascias – they will be far straighter and will tend not to wave as much between supports.



A Wood Floor in a Garage

A loyal reader writes:

“Hi. Good morning! As I read your post about a wood floor in a work shop, it reminded me of my research into a garage with a wood floor. I have often wondered, can this be done?

So I ask you, can this be done?

I am not a rich man, nor do I have much money. I have to be frugal with everything I do and everything I do must be durable and last for a very long time, life hopefully. Hence I am pondering building the things I want in stages.

The size up front will be 16×40. Maybe 20×40 if it’s not much more expensive. Later on, another building attached in the same size dimension ending with a 32×40 or a 40×40.

I would not mind having space in the attic to do things with, but the space I gave you can be used wisely for that anyway.

I will also tell you that I am not what the world considers a young man with a lot of time left on the Earth. I first and foremost need that garage.

I look forward to your answer. I would even like to have a price quote. I live in a mobile home that I once was pondering turning into a house with a garage. But most articles tell me it is not a wise thing to do.

Thank you,

P.S.- I live in central Alabama. Have a wonderful day!”

Mike the Pole Barn Guru says:

Yes, a garage can be built and designed with a wood floor. Whether or not it should be done is the true question – as it is not going to be an inexpensive proposition.

At my home near Spokane, Washington, I have a post frame garage which is built on a steeply sloping hillside (14 feet of grade change across 24 feet of depth). While the under structure is wood, it does have a concrete slab poured on top of the framing. In hindsight, I would have used fire retardant treated plywood on top of the joists and then sealed the top surface of the plywood. I say this because the concrete slab, in my humble opinion, has not held up as well as I would have liked it to over the past 25 years (it has numerous cracks and sprawls).

The IBC (International Building Code) specifies a uniformly distributed live load of 40 pounds per square foot (psf) (which would be the same as non-sleeping areas of a residence) for garage floors along with the requirement of: “Floors in garages of buildings used for the storage of motor vehicles shall be designed for the uniformly distributed loads of the Table (UBC 1607.1) or the following concentrated loads: (1) for garages restricted to passenger vehicles accommodating not more than nine passengers, 3,000 pounds acting on an area of 4-1/2 inches by 4-1/2 inches.”

This 3,000 pound concentrated load, if it was based upon beams every 12 feet and joists every two feet would equate out to a uniform live load requirement of 125 psf.

Garage floor parking surfaces must be made from approved noncombustible and nonabsorbent materials. FRTW (fire retardant treated wood)might meet with the approval.

Engineered post frame buildings, for any use, are designed to last not only your lifetime, but many lifetimes to follow – so they are a great permanent investment. If the ability to get the most bang for your investment is important, my encouragement would be to borrow a small amount to enable you to get the entire building footprint you ultimately desire, rather than doing the building in two phases. It is always far more economical to do the project once, than in multiple phases and there will be savings both in materials as well as your time to assemble.

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