Tag Archives: double bubble radiant barrier

A 100×100 Pole Building, Shingles to Steel, and Double-Bubble

This week the Pole Barn Guru answers reader questions about the possibility of a 100′ x 100′ pole building, the consideration of switching from asphalt shingles to steel roofing, and if one can reuse the “double-bubble” when replacing roof steel.

DEAR POLE BARN GURU: Can I build a 100 ft X 100 ft. pole building? JOHN in PENSACOLA?

DEAR JOHN: While 100 foot clearspans can be achieved using post-frame construction, most building uses do not have this sort of requirement. In general, it will be far more cost effective to get your 10,000 square feet with a rectangular footprint of 60 to 80 foot in clearspan width. If you are limited, by property constraints to 100 x 100, but do not necessarily have to have a clearspan, a row or two of strategically placed interior columns can assist in keeping your building investment down.


DEAR POLE BARN GURU: I’ve got a question for you finally. I have a house with asphalt shingles at the moment and was thinking about switching to steel. If I were to remove the shingles, would I need to place latticed boards to keep the steel roof off the plywood to provide room for air movement? I’d use whatever underlayment is approved for the steel, but looking at a lot of your posts and comments, it’s got me wondering if I’m better off just going back to asphalt shingles instead and saving a lot of extra work.

I’m curious if in the case of placing the steel on the underlayment could cause some issues with condensation that may or may not make its way down the underlayment and off the roof. Would hate for any condensation to find its way into the plywood and become locked in causing rot. SETH in GRAND FORKS

DEAR SETH: Let’s start by looking at downside of shingles – https://www.hansenpolebuildings.com/2015/03/shingle-warranties/ and from Tim Carter https://www.hansenpolebuildings.com/2018/10/ask-the-builder/

For condensation to occur on underside of steel roofing, warm, moist air from your attic must be able to come in contact with roofing. Your plywood with an appropriate underlayment provide a thermal break keeping this from happening. You do want to make sure you have adequate eave and ridge ventilation https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/

Here is an actual “how I did it” story for you: https://www.hansenpolebuildings.com/2018/06/how-to-install-a-steel-roof-over-shingles/


DEAR POLE BARN GURU: I’m replacing my screwed down corrugated steel roof because the installer kinked the metal in a few places. Can I use the same double bubble vapor barrier or must i replace the vapor barrier too? It has a few holes in a few places in addition to the staple holes they made when applying it. JAVO in PRINCE FREDERICK

DEAR JAVO: Double bubble or other reflective radiant barriers only work to control condensation when they are 100% air sealed. You would be money ahead to order your replacement panels with an Integral Condensation Control factory applied and throw away your old double bubble. Please read more here: https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/

Pole Barn Insulation, Oh So Confusing

Pole Barn Insulation, Oh So Confusing

How to best insulate any building can be confusing – with pole barns being right there with any other structural system. “Best” also has to include a balance between the upfront investment and the long term savings, throwing in the wild guess as to what future costs of heating and/or cooling might be. Energy costs are probably not going to get any less expensive, so using today’s costs in determination of the outcome should yield a conservative answer.

To me – a practical return is if I can have my investment returned within a seven year period or not. There are also some intangibles to be factored in, such as a well-insulated building being much quieter for the occupants.

Regular readers will recognize the volume of questions I receive from those who did not plan ahead for the eventuality of climate control and are now looking for solutions. This is an issue which can and should be economically planned for at time of construction.

Reader MATT in ROCKFORD got the ball rolling on this subject when he wrote:

“I am ready to build my dream garage but somehow I managed once again to stumble upon an area where people just can’t agree on a single solution. Insulation!!! There should be a single answer for each barn use. 1: Storage only use this… 2: Equine only use this… 3: Workshop/Garage with occasional winter heat use this… 4: Garage/Mancave/House with full time HVAC use this… Plus the difference is argued about whether to use a radiant barrier? Or vapor barrier and where to put them. Vapor barrier like Tyvek etc. outside, plastic vapor barrier inside between wall material and the studs. Up north, snow on steel. Down south sun blazing on the steel. To vent or not to vent is also important.

 I would like to have a person with proper insulation experience in the north and the south who can explain why and in which order ( pic or graphics would be fantastic ) of what is correct. And give definitive answers boasting absolute confidence instead of having an answer that seems wishy-washy. Many kit distributors like to sell things easy to ship (dbl bubble radiant barrier). Many builders like speed, convenience, and mark-up (radiant barrier). Seems like spray foam has issues too.

Ultimately I live in Alabama where humidity, mold, and insects are a definite issue. I am building my final dream garage/home and I am disabled with a limited income so I can’t afford to make a mistake.

 Ugh Please Help!

 I also forgot to mention or ask about insulation that follows the roof line like in a clearspan structure. Or using steel trusses or scissor trusses where the insulation may be next to the roof and there is no attic.   Thanks, Matt”

Matt ~

I feel your pain. Insulation and ventilation are areas where there are a nearly innumerable number of possible solutions, many of which both work and can be Code conforming. Over my nearly 40 years in the post frame building industry, my own feelings about how to properly insulate have changed – most due to the advent of new products, better research and the gaining focus on energy efficiencies.

Tune in tomorrow for the rest of the story!