Tag Archives: setting trusses

Pole Barn Conversion, Condensation Concerns, and Setting Trusses

This week the Pole Barn Guru answers reader questions regarding converting a section of an existing building into living space, concerns about condensation in an insulated wall, and a concern about setting trusses too soon following a concrete pour.

DEAR POLE BARN GURU: Hello! We have a pole barn already built, 60×80, and we’ve decided to build living quarters in a 30×60 portion of the barn. We want to put a second level in the living quarters. We’ve done a 2ft monolithic pour that extends to the footings, around the exterior, 6-8inch thick concrete with steel grates underneath. We’ve done a 2ft by 3ft thick concrete footer underneath each pole. There are 16 total. Is this something that could be turned into engineered living space with a second story space (30×30)? Thanks in advance. KAITLIN in EDEN

DEAR KAITLIN: Most pole barns are built either without being engineered or to Risk Category I. For residential purposes, it would need to meet more stringent structural requirements of Risk Category II. You will probably have to add some perimeter slab insulation in order to meet Energy Code requirements. My best recommendation is to engage a Utah Registered Professional Engineer to do a physical evaluation of your existing building and to design needed structural upgrades.

 

DEAR POLE BARN GURU: Hello I recently built a post frame home and I have a question for you regarding the insulation on the walls. The exterior walls are 6×6 posts with 2×6 flat girts and a well-sealed WRB then steel. I used R-21 fiberglass with bookshelves girts on the inside of the wall then applied a 6 mil vapor barrier with acoustical caulk and tape to achieve a tight seal. Do you see any issues with this system in the long or short term as far as condensation and air sealing because of the lack of OSB or plywood sheathing on the outside? WESLEY in DULUTH

Installing a ceilingDEAR WESLEY: I have seen many far less well thought out wall systems without exterior sheathing not experience issues with condensation. As far as air sealing, you could get a blower door test done to find out exactly what your situation is. For extended reading, please see https://www.hansenpolebuildings.com/2020/10/blower-door-testing-your-new-barndominium-part-i/ and https://www.hansenpolebuildings.com/2020/10/blower-door-testing-your-new-barndominium-part-ii/

 

DEAR POLE BARN GURU: I am getting ready to pour my footing for my posts and am wondering how long I wait for the concrete to cure before setting the trusses, etc TRIPPE in NINE MILE FALLS

DEAR TRIPPE: We always suspend our columns eight (8) inches above bottom of holes and mono-pour footing and concrete encasement in a single pour (saves on paying for short haul charges). While concrete typically reaches 75% of compressive strength in seven days, when I was building we would pour one day and start building next day. For slabs on grade, it is recommended to not walk on them for 24-48 hours after a pour. Keep in mind, concrete compressive strength is in psi (pounds per square inch) and soil bearing capacity under footing is in psf (pounds per square foot). Most soil will support a maximum of 2000 psf or 13.88 psi, so your concrete (at 2500-3000 psi) is going to be much stronger, even after a very short time span, than soils beneath. You can increase concrete strength by ordering a higher cement mix and speed curing time by use of hot water (avoid use of chemical additives to speed curing).

Site Slope, Gable End Exhaust Fans, and Setting Trusses

Today’s Ask the Guru blog answers reader questions about building on a slope, a recommendation for gable end exhaust fans, and setting trusses into columns.

DEAR POLE BARN GURU: I always see pole barns being built on level ground. is there any reason my concrete slab, perimeter board, and exterior grade can’t slope 1/4″ per foot from the back to the front of my pole barn garage? I realize the bottom of my metal siding would probably have to be cut at an angle to match the slope. DAVID in WESTFIELD

DEAR DAVID: Could and should are two different animals.

Everything is going to be far easier working from a level site, where grade can be sloped away from building at 5% or greater (a 5% slope is six inches in 10 feet). You don’t want to have water from any direction running towards your building.

International Residential Code (2021 IRC) Section R309.1 and International Building Code (2021 IBC) Section 406.2.4 address concrete floor slope: “The area of floor used for parking automobiles or other vehicles shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway.” Floor slope by IBC only applies to “U” occupancy buildings of 1000 square feet or less. Actual slope requirement is unspecified however a generally accepted minimum is 1/8” per foot. Grade inside of building should be gradually built up to create this slope.

As far as cutting bottom edge of your steel siding to follow a slope, cutting each panel to precisely follow slope would be a difficult, if not impossible task. This also would leave a raw field cut edge in close proximity to ground and it will rust.

 

DEAR POLE BARN GURU: I have a 30×48 pole barn. 13′ at eaves/overhang and 19′ center height because of scissor truss. No windows. One man door and one garage door. It has closed cell insulation. Brown roof. Used for trailer/camper storage. Not a lot of work going on in this building. It stays a little cooler than the outside temperature but is humid with musty smell due to no ventilation. I would like to install a gable end louvered exhaust fan but everywhere i search i come up with different answers. I don’t need fast air movement, just replacement. i would like to know what size fan and air intakes are required to do this. Some of this information may be irrelevant but it was asked for among other inquiries. Thanks for your time and help. WILL in WINFIELD

DEAR WILL: You should plan upon three to six air exchanges per hour. With 23,040 cubic feet of interior space, you need 1152 to 2304 cubic feet per minute (cfm) as an exhaust. A professional HVAC provider can confirm amount of air intakes required, as well as set you up with an appropriately sized exhaust fan.

 

DEAR POLE BARN GURU: I have a question on installing trusses on a 16×40 pole barn. The bottom of all poles are square and measure what they should on the print. Knowing that the 6×6 poles are probably not straight, is there a trick to making sure that I install the trusses straight and square at the top? Always want to double check before Ii start lifting these 14 feet in the air. Thank you for any help. BOB in MOORCRAFT

DEAR BOB: This is one reason I like to build with my trusses directly attached to columns (using notches cut into columns to provide full bearing). After verifying trusses are exactly 16′ in length, trusses can be placed into notches, with outside of truss flush to outside of columns. This solves any width issues. Using recessed purlins, joist hung between trusses, purlins can be pre-cut to length of space between trusses, solving length issues. Once framing is completed, each roof plane can then be squared (read how here: https://www.hansenpolebuildings.com/2020/05/how-to-square-a-post-frame-building-roof/).

Can Wall Girts Be Installed Before Trusses?

Can Wall Girts Be Installed Before The Trusses?

In my travels over the years I have seen more than a few post frame buildings under construction. When I find one being constructed by a building contractor, if the wall girts are installed before the roof, it is an immediate giveaway to the builder having been a framer at one time.

Why?

Because the correct (and easiest) way to assemble a post frame building is to construct the roof first, then place the wall girts.
But does this sound counter intuitive??

Client ED from CLINTON wrote to Hansen Pole Buildings’ Mistress of All Things Being Delivered, Justine, recently:
“I do have another question.  I am very limited on Whidbey Island concerning  options for setting the trusses and I do not believe I will be ready for the trusses when they arrive on site, so paying the truss company to set them at the time of delivery is not an option. .  It appears that Hansen’s recommends that the trusses get placed after the skirt boards are installed and before the wall girts are installed.  Do you see any issue with installing the wall girts prior to installation of the trusses?

Mike the Pole Barn Guru Writes:

Well, there could be some issues.

The majority of our clients (as well as most professional post frame building installers) frame up portions of their roof on the ground and then lift entire bays using either post top winch boxes, or a crane. Having girts in place would make this an impossibility as the girts would be in the way of raising the trusses.

In the event you decide installing the girts first is the direction you really want to go, it is crucial to have the tops of the columns held in place along the length of the building at exactly the column spacing. It is far easier to have to custom cut a few girts to various lengths and be able to keep all of the purlins in each bay the same length.

There are always methods to our madness, which is why the Hansen Pole Buildings’ Construction Manual leads clients (or their builders) through the process of assembly in the correct order to make the process as easy and pain free as possible.