Dear Pole Barn Guru: Vapor Barrier & Compaction Questions

Welcome to our newest feature: Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment. 

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DEAR POLE BARN GURU:  Will 5/16″ foil/bubble/foil work as a vapor barrier/insulation against the condensation problem you address? SWEATING IN POLAND, IN

DEAR SWEATY: The product you are referencing is a “double bubble” product, which has two layers of air cells trapped between aluminum foil facings. As long as the seams are securely taped tight, the product you have referenced should perform adequately as a vapor barrier.

Personally, I wouldn’t spend the extra money for the “double bubble” as it adds no appreciable R-value, and could potentially cause issues with the steel being able to function properly as a diaphragm.

For less cost and easier installation, I would recommend “single bubble” vapor barrier with aluminum facing up, white vinyl facing down. This product is available with a tab on one side, with an adhesive pull strip attached. This allows for positive sealing between rolls, without the need to try to tape.

DEAR POLE BARN GURU:  I’m having a pole barn constructed do I need to level the site first and put the stone down before they start? The contractor says he doesnt want me to do that until they put the barn up. AWW SCHUCK, INDIANA


From a builder’s standpoint, I would agree totally with your contractor, unless your site was leveled AND properly compacted, prior to construction starting.

 Whether making the site level or not, prior to building remove topsoil and stockpile for later use in finish grading. In frost prone areas, remove any clays or silty soil from within the future building “footprint”.

 Now why would I prefer to build on a site which is out of level? The holes for the building columns need to extend the distance specified on the plans into native soil (or the compacted equivalent). If fill is brought onto the site, and has not been compacted, then it increases the depth of the holes your builder must dig.

 When you do level your site, replace subsoil removed from around building with granulated fill to help drain subsurface water from building. Distribute all fill, large debris free (no pit run), uniformly around site in layers no deeper than six inches. Compact each layer to a minimum 90% of a Modified Proctor Density before next layer is added. Usually, adequate compaction takes more than driving over fill with a dump truck, or earth moving equipment.

 Also refer to my blog on adequate compaction – enter “compaction” into the search box in the upper right – scroll down a bit to find more information on how to do this.  Good Luck!




2 thoughts on “Dear Pole Barn Guru: Vapor Barrier & Compaction Questions

    1. Peggy ~ Post frame buildings can be designed to attach to the top of either a partial or full concrete basement with relative ease.


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