BlueTex insulation in workshop

[Dudley Wireman]

I’m new to this forum so I apologize if I’m posting in the wrong area. I searched under workshops for an answer to my question, but couldn’t find an answer so I’m posting here…

I’m building a new wood working workshop on my property in Virginia. It’s a metal 30x40 with 11’ walls on a concrete slab. I’m researching insulation for the building. I see spray foam is the preferred method in this forum but that may cost to much for the entire uilding. Could also do batt insulation with a vapor barrier. However, I came across BlueTex which is a double bubble with a vapor barrier.

Has anybody used this or have experience with it? I am planning on using a mini spit for heating and cooling. With temperate climate here not sure if BlueTex will keep it comfortable enough year round.

Thanks in advance for comments.

Dudley

[Jim Becker]

"Double Bubble" type insulation is fine in the south for helping to control radiant heat transfer, but it's not going to provide robust insulation properties (R value) that folks typically want for conditioned space. One of the reasons that closed sell spray foam is so highly regarded for metal buildings like this is that you can put on an inch to 2 inches in the walls and get most of the R value you could want along with serious air infiltration sealing, moisture barrier including eliminating condensation issues on the inside of the metal walls and very positive stiffening of the structure. You don't need a lot of the stuff to do that. In some cases, folks will do just an inch of the closed cell foam for those properties and add less expensive fiberglass to round out the job. Up top, spray foam is king when it comes to keeping the structure open and retaining heat/cooling. If you choose fiberglass or foam sheeting, etc., you need to insure that air flow remains on the inside of the metal siding/roofing to avoid condensation issues which can lead to rust, etc.

I'm planning on a new shop building here at our new property and it will either be metal or wood post frame. If metal, spray foam gets the nod 100%. If wood post frame, it could go either way, but I still favor the spray foam for the benefits I mentioned.

[Dudley Wireman]

Thanks, good advice!

[Bobby Robbinett]

That silver bubble type stuff will not provide much if any retention of your conditioned air. You could put it on the bottom of your roof deck if you go with a metal roof. It would help with the radiant heat transfer from the hot metal on the outside and take some of it away on the inside, but you would still need to insulate with either fiberglass or foam to make it right. If you put it on your roof deck you could get by with 3” pink fluffy over the roof deck and walls. That is what I have and it works great. You can get 100ft long rolls of 3” thick by 48” wide fiberglass for $250 or less each.

[Mike Stelts]

Here's an article by a well-known energy efficiency expert published by Nebraska Dept. of Energy. I think it will definitively answer your question.

[Steve Rozmiarek]

I personally think insulating metal buildings is a compromise at best no matter what you do. I think we've done tried all the systems at one time or another, and yes Jim and Bobby are right, that radiant barrier product is pretty much useless for R value. It does decrease the "baking" effect on sunny days, but that's about all.

What we do depends on the buildings intended use. If it will just 100% always be a shop, the fibreglass batt product is ok. Downside, it traps condensation which then causes problems later if not installed right. The most common instal is over the girts/purlins, under the steel, which stops airflow that will help condensation compounded by the lower R value where the insulation is squished between a framing member and the steel. This is easy, but way less than ideal. Depending on the building design, this can be decreased, but never fully eliminated.

Sprayfoam is better for sure, but it has down sides too. Replacing a damaged panel is a major problem if the building has been foamed, and it's expensive. You have to make sure to use closed cell too, or condensation will still occur and become a tremendous problem. It is a much better insulation though, and simple to install, so it is the leading contender generally.

Most of our buildings are a mixed use. It's common to have an uninsulated zone and a full climate controlled area for a shop or barndominium. If the space is legit uninsulated, I use a tyvek wrap between the framing and the steel, which does all the good things it typically does on a house, but adds the benefit of condensation "control". It doesn't stop it 100%, but it becomes much less common as it dramatically slows the air movement next to the steel. A barndominium or insulated shop can also benefit from the tyvek, and if the girts are installed bookshelf, you can place them on 24" centers and just fibreglass batt the cavity. However, you have to be careful spraying foam over tyvek if you decide to do that in the future because it will sag as it sets and not adhere properly on vertical surfaces.

More common for us is to use tyvek, then fibreglass, then frame an interior wall system, with more fibreglass, ending in a wall that is 2x6 plus 2x4 thick and R32 or so. This allows insulation from vibrations in high wind (all metal buildings do that), so drywall will survive better, and really high R value. The thicker walls can be a design feature, and it is still cheaper than spray foam. Ceilings are just dealt with as they would be in a house then, fibreglass or cellulose on top. This system is bulky though, and pretty much means you are building a building, in a building.

Like I said, steel sided buildings are an insulation compromise. They go up cheap, but when finishing the interior you pay the consequences. Luckily, depending on your use, you can generally find a reasonable solution.

[Jim Becker]

Good comments, Steve, and yes, as always, it's a compromise situation at multiple levels. I will say, however, that in the context of many folks here discussion their shop needs, these buildings are often dedicated shop buildings with more and more of us investing in HVAC systems, especially mini-split heat pumps which are uber-efficient. So getting it right is pretty important. Buildings with non-metal exteriors are easier since there isn't the extra complication of considering condensation which we both have noted as a factor for metal clad structures. If my future building ends up being clad with some kind of wood product sheathing, such as LP Smartside, I'll likely opt for fiberglass and a vapor barrier because I can install it myself economically. (other than blown-in for a ceiling application which I would absolutely contract out) If I opt for a building that's metal clad, either a metal or wood post-frame structure, spray foam will likely get the nod for the extra benefits. I don't know that I'd personally do a structure in a structure for my application, but for larger buildings that are, as you note, multi-use, I can absolutely see the benefits there to do that.

[Steve Rozmiarek]

Good comments, Steve, and yes, as always, it's a compromise situation at multiple levels. I will say, however, that in the context of many folks here discussion their shop needs, these buildings are often dedicated shop buildings with more and more of us investing in HVAC systems, especially mini-split heat pumps which are uber-efficient. So getting it right is pretty important. Buildings with non-metal exteriors are easier since there isn't the extra complication of considering condensation which we both have noted as a factor for metal clad structures. If my future building ends up being clad with some kind of wood product sheathing, such as LP Smartside, I'll likely opt for fiberglass and a vapor barrier because I can install it myself economically. (other than blown-in for a ceiling application which I would absolutely contract out) If I opt for a building that's metal clad, either a metal or wood post-frame structure, spray foam will likely get the nod for the extra benefits. I don't know that I'd personally do a structure in a structure for my application, but for larger buildings that are, as you note, multi-use, I can absolutely see the benefits there to do that.

You definitely understand the complications Jim. In a perfect world, you'd just sheet your building with ZIP or Weatherlogic, then wrap and steel over that. Leaves all the options available but it costs more.

We are dealers for a major brand red iron building manufacturer. If you order one of them to be used for a conditioned space, like a church or gym, they have some clever ways to deal with the insulation issues. They are a bit complicated and the building has to be designed that way from the beginning though.

[Ronald Blue]

The way I did mine isn't the consensus here but it's very satisfactory for me. I have a 30 x 56 x 14 pole building with a radiant heat in a slab. Fiberglass in the walls and ceilings. Before the insulation went up the walls were lined with plastic as a vapor barrier because I've heard that moisture will condense on the metal walls. The walls are 6" kraft faced and the ceiling is blown in fiberglass with at least R-56. The lower 4' of the walls is 3/4' strand board for durability and the upper 10' and ceiling are lined with white exterior tin. Electrical is all ran in conduit on the surface. It was by my calculations about one third the cost of spray foam. The white on the interior is also very beneficial in reflecting the light as well. I was reading Steve's comments and thought I would add that after the plastic was installed in the walls that the walls were the "bookcased". Lateral 2x6's two foot on center between the posts. It is amazingly quiet and tight now. Before it was finished on the inside even a light sprinkle of rain sounded like rock's beating on the tin. Now a hard down pour is barely noticeable. There really isn't a wrong answer as long as the right techniques are used.

[Bill Dufour]

Radiant barriers are really just to keep solar heat gain to a minimum. They have almost zero insulation value in the traditional sense. For my climate they do help a lot in summer. It is not cold enough here to do much good in winter.
Bill D.

PS: my roof deck, under asphalt shingles runs 125-145 F in summer. Un vented garage was 100-110 at about 6' off the floor. So only 5-10 degrees above outside temperatures. I could fell the radiant heat on the top of my bald head inside the garage during the day.

[John K Jordan]

Here's an article by a well-known energy efficiency expert published by Nebraska Dept. of Energy. I think it will definitively answer your question.

What a fascinating article! It's a shame how low people will stoop for profit. Need to get that guy to branch out and investigate a few other scams.