Tag Archives: vapor barrier

Building Insulation: Vapor Barrier

Insulation is one of the topics, once brought into conversation, seems to make most folks’ eyes glaze over.  Many know enough to ask about R Value, and understand “the higher the better”.  Or so they think.  Sometimes you need to stop a minute and go back to the source of what I call “the need”.  This is the way I teach our Building Designers, and clients as well, to think about any feature or addition to their pole building kit when they design their new building.  What are you going to need for your building?  Don’t just throw a bunch of stuff in and on there because it “my neighbor put it on his building”.  What are your needs?  Obviously we all choose features we want on our building, “just because”.  Just because it looks nice, gives the building a classier look, a lower profile, or we think the eagle on the weathervane hovering over the cupola is “pretty cool”.  This is all well and good, but insulation is not one of those “pretty parts” of a building.  Necessary yes, but what type and where do you put it?

When I designed my most recent pole building for my own use, I researched several types of insulation, and ended up using not one or two, but three different types of insulation, and each of them for their own specific purpose in relation to cost.  In other words, “what is the cost value” for each of them?

The types of insulation I looked at ranged from what most folks think of when you say “insulation”: fiberglass insulation, to foam board, spray on foam and B.I.B.’s (Blow in Blanket) along with the reflective type vapor barrier insulation in various configurations and applications.  I ended up putting reflective radiant barrier under my roof steel, wrapped my entire outside of the building in a reflective radiant barrier, put reflective radiant barrier under the heated concrete floor, fiberglass insulation in the interior walls, and then B.I.B.’s in the exterior walls.  Wow, I hear clients saying, “How do you know what to put where?”  Easy – once again it goes back to the “need”.  Over the next couple of days I will cover a few of the insulation choices out there, so get out a sheet of paper, make yourself a grid, and next time you need insulation, ask yourself these easy questions to decide “which insulation you are going to put where” in your new pole building.

First question, what is R value? For those of you who are not familiar with R values, it is simply the measure of resistance to heat flow. R-1 is equal to the resistance of a 1” thickness of wood. Insulation materials have tiny pockets of trapped air. These pockets resist the transfer of heat through material.  The ability of insulation to slow the transfer of heat is measured in R-values.  The higher the R-value, the better insulation’s ability to resist the flow of heat through it. Before you consider these products, read the test reports carefully.  In order to achieve the full promised values, the products must be installed in the center of an appropriate dead air space.

Second question, what are you going to be using your building for?  This will help you to determine what type of insulation you are going to need.  Of course, your “need” for insulation also depends on where you live.  If you are in Minnesota where I have my newest building, and want to change the oil in your car in January, putting reflective radiant barrier in the roof and even on the walls is probably not going to keep me warm.  No heating system is going to keep up with the heat pumping out of my building!

And, if you live in Knoxville, Tennessee and are OK working in your shop with coveralls on a few hours a week, your insulation answer will be greatly different than if you want to sit in your new shop in your shirtsleeves with your buddies watching the Super Bowl come January!

So your first project is this: take a sheet of paper and write down all the things you want to “do” within the confines your new building, including keeping pets, horses, or other animals at the right temperature.  Also make a list of other reasons we put insulation in spaces – noise for one.  Do you need good sound abatement for the “practice garage” for your son’s rock and roll band?  Is the loft bedroom right above where you work on motors or have a workshop with noisy machinery?

Once you decide on what your needs are for insulation, you can just match it to the Insulation Grid we’ll be making over the next several days.  I’ll be back tomorrow to start with the simplest of all insulation: reflective radiant barrier which includes a vapor barrier.  Winter is coming, so stay warm!

Lying or Just Plain Stupid?

Yesterday afternoon, one of our senior building designers sent me this instant message:Kid ready to make a bad decision

“So what do you do with a customer who is being sold a bill of goods by his contractor? Starting from, client was told he needed to pour footings and build with 2×6 studs because pole buildings ‘move too much’. All the way to – ‘you need to sheet your walls and roof with plywood before you put steel on’. This is because of security and dust coming through the walls. Not to mention on the roof for a vapor barrier.”

It amazes me the ignorance about pole buildings after over 80 years of solid pole building construction.

A bit more about this particular client’s building. It is 40’ x 80’ with a 14’ eave height. The client initially contacted the builder to get a labor quote only –  to construct a Hansen Building kit.  The client specifically asked for one of our pole buildings.  The builder told this client a pole building would be way too complicated to construct and the stick frame building would be less expensive.

Let’s look at the realities of the situation. To construct a stick frame building will take excavating a trench around the perimeter of the building to below the frost line (and it DOES freeze deep in Maine). A footing must be formed and poured. With a wall this tall, I’d imagine at the least it would have to be eight inches thick and 16 inches wide with rebar in it. On top of the footing will need to be formed up a foundation wall. This foundation is going to be a minimum of four feet tall, due to the frost depth. The wall should probably be an eight inch wall, but assuming six inch thick, three truckloads of concrete will be used for the footings and foundation! With the pole building, holes are augered in the ground and around five yards of concrete are required for the backfill. Pretty low tech and saves a bunch of money in equipment, materials and labor.

A kicker the contractor may not have considered, or has ignored….the maximum stud wall height allowed (according to code) without engineering is 10’. His building is going to need to be designed by a registered professional engineer in order to meet code requirements.

As far as “movement”, steel roofing and siding has shear values nearly equal to those of 7/16” osb or ½” plywood. Imagine the steel as being very thin, very strong plywood. It is the sheathing of a building which holds the frame stable, not the framework. With steel and plywood virtually equal for strength, it takes away the “movement” issue. Our Hansen pole building office is 44 feet high from ground to roof peak and has no noticeable movement in even the extreme wind loads of South Dakota.

Moving on, let’s address the issue of “eliminating dust”.  Each steel panel overlaps the adjacent panel which prevents dust infiltration. Base trim (aka “rat guard”) keeps dust from entering around the base of the building. All other steel edges have trims which cover possible infiltration areas. The eave edge of the roof steel and under the ridge cap are sealed by form fitting closure strips, which seal those areas.

The only place for dust to enter either style of building is going to be via an open door! Same goes for security – your building is only going to be as secure  as the quality of the doors. Chances are the builder is going to provide entry doors with wood jambs, which is an invitation to enter via a good swift kick. The commercial steel doors we provide have steel jambs as well.  No one is going to break those jambs with a kick.

As for a vapor barrier, our buildings come standard with a reflective radiant barrier for under the roof steel. With our exclusive PSA (pull strip attached) adhesive strips, proper installation assures the elimination of condensation. A side benefit being the increased insulation value and the reflective radiant barrier is superior against heat gain. Using plywood on a roof proves to be expensive, adds weight to the roof system and requires the use of asphalt felt paper or other similar and materials to create a water tight seal.

If ignorance is bliss, this particular contractor is either very happy, or he is feeding a line to the client. If the first, he is doing no justice to the client, if the second, he’s worse yet.  My guess is… stick framed is all he knows.  He is just too lazy to try something “new”, easier….and cheaper for the customer, while being just as solid, air tight and long lasting.