Tag Archives: engineer sealed structural plans

Spray Foam, Crawl Space Floors, and Column Sizes for Shed

This week the Pole Barn Guru answers reader questions about spray foam application of a vapor barrier, finishing a crawl space floor, and to go with 3 ply or 4 ply columns– this is dependent upon many things.

DEAR POLE BARN GURU: New Construction – Can spray foam insulation be spray over a vapor barrier blanket in the roof of a pole barn, too increase insulation rating?

Thank you, TERRY in WILSONVILLE

DEAR TERRY: In your part of our world, most often roof condensation is controlled by use of what is known as a “Condensation Control Blanket” – a thin layer of fiberglass bonded to a white vinyl backing. When laps are properly sealed (rarely done right) it does make for an effective vapor barrier, although it provides minimal, at best, insulating value.

I am not a fan of spray foaming to any flexible barrier in walls or roofs (https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/).

My first choice would be to design your building to be capable of supporting a ceiling, use raised heel trusses and blow in fiberglass insulation. With raised heel trusses you can get full thickness from wall-to-wall and you do not end up heating dead space between roof trusses. Roof steel should be ordered with a Integral Condensation Control (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/) and adequate ventilation provided at eaves and ridge.

Second choice would be to omit condensation blanket and Integral Condensation Control and use two inches or more of closed cell spray foam directly to underside of roof steel. This will not be nearly as effective as choice number one.

 

DEAR POLE BARN GURU: After reading several articles on your website I’m leaning towards building a single story post frame home with about a 4 foot crawl space so that I get benefits of a floor not hard on the joints and access to any plumbing or electrical if things go wrong. I would also like to build as close to a passive or net zero home (within a reasonable budget) but was wondering how to do that with a dirt floor crawl space. I’ve read that the best way is to keep crawl space within the envelope of the home but I’ve only read of a vapor barrier that is covering the dirt floor. Thanks for all your help. TODD in HENNING

DEAR TODD: Thank you for being a loyal reader. My knees and your joints must be related – as nothing pains me more than standing on a concrete floor for even relatively short periods of time.

Most crawl spaces are created with dirt floors, face it, they are low budget and meet Code with a 6mil black Visqueen Vapor Barrier installed. Now retired Hansen Pole Buildings’ Designer Rick Carr built himself a hunting cabin over a crawl space a year ago and decided to take a slightly different route. He opted to do a thin layer of concrete to cover ground in his crawl space, with an idea of being able to roll around using a mechanic’s creeper, should he need to work on sub-floor utilities. Here is an excerpt from part of Rick’s planning: https://www.hansenpolebuildings.com/2019/03/pole-barn-cabin-part-ii/

 

DEAR POLE BARN GURU: I am putting up a 60x135machine shed. 18 ft sidewalls, I’m wondering if the 3 2×8 laminated columns are enough or if i should spend 2900.00 more to go to 4 2×8 columns. thanks, SHANE in ASHTON

DEAR SHANE: Your question leads me to believe you are attempting to make a hundred thousand dollar plus building investment, without benefit of fully engineered structural plans.

Column sizes will be dictated by effects of column spacing, design wind speed and exposure (an Exposure C site being subjected to 20% greater wind forces), roof snow loads, dead weight of roof system (including any ceiling), roof slope as well as proper diaphragm design of your building shell.

I will implore you to please, please, please build only from a fully engineered plan. Think of it as an investment into one-time insurance. I only want to see you put this building up one time.

Putting Everything Under One Post Frame Roof

Putting Everything Under One Post Frame Roof

I have been an advocate of one larger roof, rather than an enclosed building with a roof only side shed for years. This allows for greater headroom in ‘shed’ area without having to deal with pitch breaks (transition from a steeper slope main roof to a flatter shed roof), making for easier assembly. In almost all instances, this will result in a less costly design solution.

This also happens to be a lesson I have tried to impart upon our Hansen Pole Buildings’ Design Team, however they have been slow to embrace this concept.

Reader RYAN in SUN RIVER writes:

Hansen Pole RV Storage“I have plans to build a 52x48x14 this spring.  The idea is 52×48 roofline 4/12 pitch. Under that roof is a 16×48 open side for rv parking and then 36×48 enclosed with concrete floor.  My original thoughts are to 2×6 stick frame the wall separating the open area from the enclosed area after the pad is poured (any suggestions). 16×12 insulated door and a 4’ man door on the front gable end and a 3’ man door to get in from under the open area towards the rear.

How much would you charge to draw this up with your building techniques?  

I am planning on sourcing materials local but wouldn’t mind a quote from you either.”

I do like your idea of having your enclosed portion and roof only under one gabled roof, rather than a smaller gable over enclosed portion and balance as a shed roof off one side. You gain headroom, it is easier to assemble and usually less costly.

I would frame separation wall with wall girts, rather than stick framing and having to add on horizontal framing to attach wall steel. Code also will not allow for a stud framed wall greater than 10 feet in height without it being engineered. To minimize possibilities of water from your RV area migrating into enclosed areas, your concrete should be two separate pours, with RV parking slab slightly lower at main building wall and sloping away from it.

Your choice of having a four foot wide person door is one you will not regret. For a minimal added investment you will save your knuckles repeatedly. 

As for building plans, we are not a plans’ service, however your investment in a new Hansen Pole Building does come with complete third-party engineer sealed structural plans, along with verifying calculations. This alone will usually save you thousands of dollars in engineering costs, plus you have our roughly 20,000 buildings of experience to arrive at what will be your most practical and cost efficient design.

Why people think they are somehow going to get a “better deal” by sourcing materials locally is beyond my comprehension. We have buying power an average individual (or contractor even) is never going to have, plus our control over materials being provided allows our engineers to be certain what they specify on plans, gets delivered to your building site. Some materials we have produced only for our clients – you cannot buy them elsewhere. 

For continued reading on this subject: https://www.hansenpolebuildings.com/2014/03/diy-pole-building/

Unknowedgeable Post Frame Building Suppliers

Reader JEREMY in STAFFORD SPRINGS is experiencing challenges with unknowledgeable post frame building suppliers. I will share his own words with you:

“I am currently attempting to price out for a metal building, post frame or conventional stick built. The dimensions we are looking at is a 40×60 with a 12 foot roof. I am having a hard time locating post frame construction components locally, and when I go to the local supply houses it seems that they are no more or even less knowledgeable than I am with this construction technique. So I figured I would start reaching out. I have a few questions. Do you sell components individually, such as wet set post anchors, laminated columns, roof trusses? Do you design plans that will satisfy code requirements? I live in Stafford Springs CT, which is in Tolland County. I have not spoken with the inspectors office at all yet. I would rather do my research first and come to them prepared.”

Well Jeremy, thank you for reaching out to us. Your dilemma is not unlike those faced by potential post frame building owners everywhere. For being as “simple” as they may look, post frame buildings are very complex structures, involving literally hundreds of pages of background calculations – very few providers have capabilities to do this type of analysis. Post frame buildings are ALL we do – unlike lumberyards and big box stores who, in trying to be all things to all people, end up generally being nothing to anyone.

Hansen Buildings Construction ManualIn order to keep our prices as reasonable as possible, we typically provide only complete post frame building packages. This allows for minimization of shipping expenses and potential freight damage, as well as us not having to provide $200 of Technical Support on a product we make only $100 on (we provide unlimited free Technical Support during construction, if our nearly 500 page Construction Manual and your engineered plans leave you with any uncertainties).

Every Hansen Pole Building comes with third-party engineer sealed structural plans and supporting calculations based upon climactic data for your area.

In your not too distant future I would encourage you to visit with your local Planning Department (https://www.hansenpolebuildings.com/2013/01/planning-department-3/) and Building Department (https://www.hansenpolebuildings.com/2019/01/building-department-checklist-2019-part-1/ and https://www.hansenpolebuildings.com/2019/01/building-department-checklist-2019-part-ii/).