Tag Archives: metal trusses

What Bubble Insulation Brand do you Recommend, if Any?

What Bubble Insulation Brand do you Recommend?

Reader ERICA in WEST COLUMBIA writes: “Is there a specific bubble insulation brand you recommend? We will be using this as our vapor barrier in the roof. I’ve seen posts about this type of insulation disintegrating, so I’m wondering if the claims are exaggerated or if in fact it could be a certain brand. Also we are wanting to have cathedral ceilings throughout our building. Our roof is made with metal trusses and wood purlins. We are using bubble insulation and some type of batt insulation. What is the best method to vent if we are not going to have an attic space?”

To use batt insulation between roof purlins requires a minimum of an inch of continuous air flow between roof deck (roof steel) and insulation. To achieve this, you would need to add framing (such as 2×4 placed flatwise) running from eaves to ridge, then another layer running opposite direction. You could then use a reflective radiant barrier (bubble wrap) between overlays and batt insulation between purlins, up to depth of purlins. This requires vented eaves and a ridge vent.

Instead, look at spraying two inches of closed cell spray foam directly to underside of roof steel (between purlins), then fill balance of purlin cavity with unfaced rockwool batts. This will get you a higher R value and save on material and labor for a lot of 2×4. You should not vent either eaves or ridge in this case.

As for bubble ‘insulation’ – it is not insulation, at best (when completely sealed) it is an effective vapor barrier. There have been real problems with white vinyl facing of reflective radiant barriers flaking off over time. We had this same problem with our first supplier (and, of course, they went bankrupt before problems showed up). After selling millions of square feet, we stopped offering any reflective radiant barriers to our clients.

Read more about reflective radiant barriers here: https://www.hansenpolebuildings.com/2014/04/reflective-insulation-wars/

Edge Dimples, Metal Truss Spacing, and Monitor Buildings

This Wednesday the Pole Barn Guru discusses reader questions regarding panels with “edge wave/dimples,” metal truss spacing for an ag building, and monitor building widths.

DEAR POLE BARN GURU: Good afternoon, on a few jobs we’ve had installed the lap leg on it has had edge wave/dimples along the panel, with no rhyme or reason as to where the dimples are. This is causing the panel to not lay 100% perfect and have small gaps along it as well if you look from the side. When looking at the panel on the ground it appears you do not see the wave/dimples. It is 29ga az50 galvalume painted, 3/4″ high rib exposed fastener ag panel. Do you know what could possibly be causing this? I attached a picture as well. Thank you! Tyler

DEAR TYLER: Most often this is caused by handling issues before steel is on ground at your jobsite – after first time I had to deal with it I made it a point to double check overlapping edges of all skids for damage before driver sped away to his or her next delivery. Any appearance of a wave on this edge and back on truck it went.

Your randomness issues appear to be from jobsite handling however they oftentimes can be bent back carefully by covering wave with a soft cloth and using a pair of pliers. Even if slightly over bent back, it will lay flat once screws are installed on side away from overlap.


DEAR POLE BARN GURU: Putting up a metal truss pole barn that calls for 12′ post centers and want to use 16′ centers for the truss using 16′ 2×6 for the purlins 30 cups per bay. Looking to get more length to barn this way. Minimum wind and snow load central Mississippi agriculture barn building housing mostly hay. Will this work or is 12′ max on metal truss bay width? 3 bays 16′ would garner me 50′ length with overhang or two 12′ bays on the end and 16 bay in middle would get me 42′ of length with foot overhang. Would either be sturdy enough for this application. TOMMY in ACKERMAN

DEAR TOMMY: Those welded up steel trusses are designed to support bare minimal loads at 12 foot on center. Spacing them any farther apart is nothing short of a recipe for failure. Also, unless you have access to some very high strength 2×6 for purlins, they would be over stressed in bending and deflect noticeably. If you want or need a longer building, invest in more trusses.


second floorDEAR POLE BARN GURU: Monitor barns -is it crazy to think/have 14 foot “wings” and 24 wide center? Thinking 52 wide with 14-24-14 sizing. Seems most have narrower center. Is there a reason? STEVE in WEISER


DEAR STEVE: Not crazy at all, we have had clients with raised center of monitor as wide as 80′. Ultimately it comes down to what dimensions work best for your wants and needs.

Often monitor buildings are used for horse stall barns, where raised center is an aisleway. In this scenario 12-16′ center widths work very well for aisles.

Roof Purlins for a Bar Joisted Lean-To

Roof Purlins for a Bar Joisted Lean-to

Reader JIM in MOORESBURG writes:

“First, I have spent the last 3 hours reading around your site and am impressed. I appreciate the manner you answer questions on your site”, respectful and factual with no hint of disrespect (even if deserved) in your replies. Professional and well done! Second…My question is about correct purlin sizing/spacing on a lean-to shed roof 48ft long 25ft deep with 12ft bar joist spacing spanned by these purlins. (this is an open front machine shed). I wish to size for the snow load that occurs here (mountains of East Tennessee!) about once every 15 yrs which is 2 ft of snow. Purlins will be bolted into “U” shaped brackets welded to the tops of the bar joist similar to the design used on many kit pole barn metal trusses. My attempt to calculate purlin size/spacing results in using 2x8x12′ purlins at 24″ spacing but too many assumptions on my part to be comfortable yet other detail…Bar joists attached to post (in ground) adjacent to an existing wood barn. Roof Metal is Type “R” deep rib. Yes…this is DIY with materials from my surplus pile:) thanks.”

Thank you for your kind words. Our eldest son and his lovely bride lived in Maryville for many years, so I know where you are and have driven in your area.

Two feet of snow should give roughly a 25 psf ground snow load (https://www.hansenpolebuildings.com/calculating-loads/). Without an engineer’s review, your attempt at calculations look as though they should be plenty adequate – PROVIDED:

Roof slope of existing wood barn and lean-to are the same and in the same roof plane.

Otherwise you will have either an accumulation of snow at a steeper-to-flatter roof plane, a slide off load, or drifting to account for. If any of these are your case, then you should contract a Registered Professional Engineer for an accurate structural design. Any of these situations could easily cause an overload of your bar joists as well and should be validated.

Cost of a Pole Barn Home, Metal Trusses, and Rafter Connections

Today the Pole Barn Guru answers reader questions about he cost of a pole barn home, the possible life span of metal trusses, and connecting wing trusses or rafters to posts on a “monitor” style building.

DEAR POLE BARN GURU: Is it possible to build a small pole barn home for $100K or less? KERI in ELM GROVE

DEAR KERI: Assuming land and utilities (water, sewer, electric) are not included in this budget then yes. Ultimately it will depend upon your tastes and how much you are willing to DIY. I have seen reports of DIYers completing their post frame homes for under $50 a square foot.

This article should prove helpful for you to start forming a budget of your own: https://www.hansenpolebuildings.com/2019/07/how-much-will-my-barndominium-cost/


DEAR POLE BARN GURU: How long will a pole barn building with metal trusses last? ZACH in ONEONTA

DEAR ZACH: A fully engineered post frame building with wood trusses, built to match it’s plans should last longer than any of us who are alive on this planet will be around. With metal trusses, it will all depend upon if those trusses have been designed by a competent engineer, were fabricated by certified welders under strict quality control standards and are properly installed to specifications on your engineer’s plans. Done correctly, you should not have concerns regarding longevity.


DEAR POLE BARN GURU: On a Monitor style barn, how are the mono trusses for the “shed” roofs attached to the inner posts? On a laminated post could they be notched into the center 2×6 layer? Obviously they would have to be sized accordingly. How are your buildings typically done? How is that for 1 question? JOHN in FRESNO

DEAR JOHN: Nicely done! Most monitor style barns utilize dimensional lumber rafters for spanning each wing, rather than mono trusses. Regardless of whether trusses or rafters, they are attached to each side of main building (raised center) columns, with blocking between to provide for a landing place for any roof screws landing between members.



Dear Pole Barn Guru: Do You Have House Floor Plans?

Welcome to 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.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: Could you send me some house floor plans that you have made or that you have? We just are not very good at coming up with the sizes. We have looked at a double wide house that we really like but we are not sure if thats something we could find and some how send to you. BAFFLED

DEAR BAFFLED: As we provide the structural building shells, and not any non-structural interior walls, we have no “house floor plans”. A good way to come up with sizes is to take a tape measure to the rooms in the house or apartment you live in now. Same with the double wide you liked – go measure the rooms. Do paper cutouts of different pieces of furniture (to scale) and place them on rooms drawn to scale. There are also numerous FREE room planning tools on the net. One source is: https://freshome.com/2010/08/18/10-best-free-online-virtual-room-programs-and-tools/

DEAR POLE BARN GURU: Where do I place screws for exposed fastener applications? SCREWED IN SCHENECTADY.

DEAR SCREWED: A properly installed screw will be down in the flat of the panel. (Some companies errantly install them on the high part of the ribs).  At this location the steel panel has solid wood right below and good compression on the washer can be obtained. With thermal movement in the panel, the screw will be put into shear, not bending, and the hole thru the steel panel will slightly elongate.

When we tested full sized roofs, under controlled laboratory situations, we found repeatedly cycling horizontal loads (which simulated wind) into the roof system, also caused the holes in the steel panels to elongate, when using the industry standard #9 or #10 diameter screws. The mechanical engineer, Merle Townsend, who did our testing, designed the “Diaphragm screw” as a result of this actual testing.

As long as this slot does not exceed the diameter of the washer, the hole will remain sealed. In order to prevent undue slotting, only “Diaphragm screws” should be used to attach through screwed steel roofs.

Additionally, the diaphragm shear capacity and shear stiffness is based on the screws being installed in the flat of the panel. If screws are installed in the top of the rib, the diaphragm would be much more flexible and would not be as strong.

DEAR POLE BARN GURU: Do you sell metal trusses?  If not, can you recommend someone?  We live in Hastings MN. HARRIED IN HASTINGS

DEAR HARRIED: We do not. We’d need to know more about how you anticipate using them, to be able to give you a better idea. Unless you are looking at a tremendously huge span (over 100′) steel trusses are generally not cost effective.

For relatively small span residential and commercial applications, where trusses will be placed every two feet, some metal connector plated wood truss fabricators are also offering light gauge steel trusses.

In some parts of the country (especially Arkansas and Alabama) there are a plethora of folks who manufacture welded up steel trusses made from angle iron and rebar. There may be some questions as to the engineering and integrity of these products, as most of them are utilized in buildings which do not require building permits.