Tag Archives: floor trusses

How Tall Should My Eave Height Be for Two Stories?

How Tall Should My Eave Height Be for Two Stories?

I have learned a couple of things in 40 years of post frame building construction. One amongst these is – most people are dimensionally challenged (no offense intended).

As much as some folks would like to believe, you cannot legitimately put two full height finished floors in a 16 foot eave height post frame building.

Now fear is a strong motivating force. Perhaps it is fear of a building “appearing” too tall or of OMG it will be too expensive keeping people from considering what it actually takes to create a Building Code conforming two story building.

Back in my early roof truss selling days, I had two clients who had relocated from New York state to North Idaho and were building new homes on adjacent properties. Both of them (and their spouses) were relatively short of stature and had decided to build their homes to Code minimum ceiling heights of seven feet. Their reasoning was it would be less space to heat and cool and they could chop two studs out of 14 foot long materials.

Missed in all of this was how much sheetrock waste would be created!

Sidebar – modern Building Codes allow seven foot ceilings under International Residential Code (IRC), however IBC (International Building Code) requires six more inches.

Now I am vertically challenged at 6’5” and would feel very uncomfortable with seven foot ceilings. In my own personal shouse, most ceilings on both floors are 16 feet high!

In today’s exciting episode we will learn together how tall eave heights should actually be to give reasonable ceilings in post frame buildings.

Setting a “zero point” at exterior grade (and assuming slab on grade for lower floor), top of slab will be at +3.5 inches.

To create eight foot finished ceilings requires 8’ 1-1/8” (allows for 5/8” sheetrock on ceilings).

In order to be able to run utilities (e.g. plumbing and ductwork) through second floor supports, I highly recommend prefabricated wood floor trusses (https://www.hansenpolebuildings.com/2020/01/floor-trusses-for-barndominiums/). Generally truss height will be about an inch for every foot of clearspan with a 12 inch minimum. 

In my own shouse, we have a 48 foot clearspan floor over our basketball court. And yes, those trusses are four feet deep!

Allow ¾ inch for OSB floor sheeting.

6-1/16″ for heel height of trusses with 2×6 top chord at 4/12 slope (provided you are using closed cell spray foam insulation between purlins)

If using blown-in insulation truss heel height should be R value of insulation divided by 3 plus 2″ to allow plenty of eave to ridge air flow above insulation.

At a bare minimum an eave height of 18’ 0-9/16” will be needed to create those eight foot ceilings.

Barndominium: One Story or Two?

Barndominium: One Floor or Two?

Welcome to an ongoing debate about whether it is more cost effective to build a one story or two story barndominium. Commonly I read people advising two stories is less expensive than a single story. Reader TODD in HENNING put me to work when he wrote:

“I’m curious why “Going to multiple stories will be more expensive than building the same amount of finished square footage on a single level”? Everywhere I read it says it’s cheaper to go up than out. For example wouldn’t there be more cost with bigger footprint of concrete, in-floor heating, roof trusses, and more steel on roof? Thanks.”


Mike the Pole Barn Guru writes:

It turns out Todd has requested a building quote from Hansen Pole Buildings, so I was able to work scenarios from his requested 40 foot wide by 48 foot long scenario. I arbitrarily merely doubled his building length when looking at a single story. It may have been more cost effective to have done this exercise by going greater in width and less in length (as one gets closer to square, there is less exterior wall surface to side, insulate and drywall).

Included were colored steel roofing and siding, commercial bookshelf wall girts to create a wall insulation cavity (https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/), dripstop/condenstop under roof steel to minimize or eliminate condensation (https://www.hansenpolebuildings.com/2017/03/integral-condensation-control/), ceiling loaded energy heel trusses (https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/) with ceiling joists for sheetrock, 24 inch enclosed vented overhangs, vented ridge and one entry door. In the two story version I added floor trusses and a four foot wide set of stairs.

In order to maintain eight foot finished ceiling heights, two stories requires a 21 foot eave and single story 10 foot. Engineered plans and delivery were included.

I did not include materials for a bearing wall at the floor truss center. Features listed above ran roughly $6000 more to go two floors. Also, with the two floor version, you will lose 50 square feet of usable floor on each level due to stairs.

In this particular instance best overall buy could come down to what you pay for your slab and in-floor heating. Labor to erect a single story will be less expensive (I would predict at least a $3000 difference). Some other thoughts – two story has 1/2 as much attic insulation and 45% more wall insulation. Two story (excluding interior walls) has 30% more wall to drywall. This added exterior wall surface will likely result in more windows.

Personally, I own three multiple floor post frame buildings, these are my considerations:

Accessibility roughly 10% of all Americans will spend time in wheelchairs in their lifetimes. My wife is a paraplegic and we cannot get into one of her son’s homes because it is a split entry. Two of her other sons have built ramps for her, but they also have multi-story homes and it greatly limits areas she can have access to. In our own shouse (shop/house), we added an elevator after her injury (elevators are NOT cheap).

Stairs in general – you are probably much younger than my 62 years, going up and down stairs gets to be a chore as we age.

Heating and cooling – unless each floor is on their own system, one floor is always either too cool or too warm. I put one of my own buildings on two separate heat pumps for this very reason.

In conclusion, whether one story or two, go with what best fits your wants and needs and your property. Love what you build and it will result in a happy ending.

Footing Size? A “Reverse Barndominium?” and a Loft Bedroom?

This week the Pole Barn Guru answers questions about the footing size for an open car porch and why a person should use a registered design professional, building a “reverse barndominium” where one build a post frame shell around an existing structure, and if one can build a loft bedroom in a footprint of 20’x 30′.

treated postDEAR POLE BARN GURU: I am building an open car porch, the inside will be connected to another building and on the outside I planning on using 3 – 8 inch x 8 inch x 8 feet posts 12 feet apart. The open car porch area is 24ft x 24ft and the roof is 6 on 12 with 2 x 6 rafters and joists landing on the outside plate. What size footing will I need for each pole? JAY in MORGAN CITY

DEAR JAY: This is a question best answered by the Registered Professional Engineer who designed your building, as he or she will be able to do a complete analysis including soil bearing capacity, design wind speed and wind exposure. With columns only eight feet long, I am guessing you are planning on using wet set brackets into concrete piers https://www.hansenpolebuildings.com/2019/05/sturdi-wall-plus-concrete-brackets/. I would not be surprised to see piers up to three feet deep and two foot diameter in order to adequate resist uplift forces.

DEAR POLE BARN GURU: Are you aware of anyone ever building a “reverse barndominium”? Usually barndominiums are built shell (outside walls) first then the interior, but what about building entirely around an existing structure? I really want to buy this historic house built in 1861. It is currently gutted down to the dirt floors, needs a roof, garage, etc. Why not just enclose the whole thing and DIY the interior without dealing with the outside elements? The primary structure is 19’x38′, but the side structure is an additional 20′ (39′ total wide) with a 6/12 roof. The eave height is 15.5′ and about 20′ at the ridge. The basement is about 4′ deep. I could go 42′ wide with a structure and have the exterior posts completely outside of the current footprint. The lot is 60’x150′ and I’m looking at a 40×80-ish building with a second story.

Is this feasible or have I succumb to the Dunning-Kruger Effect? I have attached an image of my sketchup drawing to give a better idea of my concept.

Thank you great guru. I love your philosophy and transparency throughout your blog posts. I have learned a lot at the cost of otherwise being productive at work. JAMES in WESTON

DEAR JAMES: Thank you very much for your kind words, although I am not as certain your employer would be as happy with me 🙂

Perhaps surprisingly, you would be far from the first person to attempt such a project. Is is entirely doable and actually becomes very similar to what people do with a PEMB (Pre-engineered metal building aka red iron) or a weld up barndominium, where a shell is erected and a building is built inside of a building. You just happen to have your insides prebuilt!

Outside of my loyal readers, most have never heard of the Dunning-Kruger Effect (https://www.hansenpolebuildings.com/2015/01/dunning-kruger-effect/)

 

DEAR POLE BARN GURU: I’m interested in a residential building approximately 20ft x 30ft. How tall would the walls need to be to include a loft bedroom with headspace to approximately 4ft from the sides? JUDE in DUPONT

DEAR JUDE: I will answer your question from a standpoint of you getting best value for your investment – meaning using both floors from wall to wall.

Assuming a concrete slab-on-grade for main level, bottom of framed ceiling would be at 8′ 4-5/8″ this allows for 5/8″ drywall on ceiling and 1/2″ at bottom to be able to account for any variances in your building slab and to keep drywall from soaking up moisture from floor, plus 3-1/2″ for actual thickness of a nominal four inch thick slab.

I would recommend using premanufactured wood floor trusses between floors (https://www.hansenpolebuildings.com/2014/09/floor-trusses/). Plan on a 20 inch thickness, plus 3/4″ for subflooring and 8′ 1-1/8″ putting bottom of roof trusses at 18′ 2-1/2″. In Pennsylvania I would recommend R-60 blown in attic insulation (just under 20 inches thick), resulting in needing a 20 foot eave height.

 

 

Floor Trusses for Barndominiums

In my last article I discussed limiting deflection for barndominium floors. Today I will take this one step further with a floor truss design solution.

Most of us don’t think too much about floors we walk upon – unless they are not level, squeak when we walk on them, or are too bouncy.

Traditionally wood floors have been framed with dimensional lumber (2×6, 2×8, etc.), usually spaced 16 inches on center. Often floor joist span limitations are not based upon lumber strength (ability to carry a given load), but upon deflection criteria. Building codes limit floor deflection to L/360, where “L” is span length in inches.

“Stiffest” (by MOE – Modulus of Elasticity values) commonly used framing lumber is Douglas Fir. A #2 grade Douglas-Fir 2×12, 16 inches on center will span 18’1” when carrying standard residential loads. An L/360 deflection event, would cause the center of one of these floor joists to deflect as much as 6/10ths of an inch!

Lumber is organic, so it varies in consistency from board to board. It also varies in size, and it is not unusual for a dimensional variance of over ¼ inch, from one end of a board to another. Combine this with probability some of these boards will be crowned with bow down and it means an uneven floor will result.

One of our friends lives in a fairly new home. In a hallway between her kitchen and sleeping areas, there is a good ½ inch dip in her floor – more than noticeable when walking across it!

I first used floor trusses in my own post frame shouse (shop/house) 25 years ago. My trusses were designed so they were only 1-1/2” in width (most spans up to this can be done with a 3-1/2” width), but these 30 foot floor trusses are only 24 inches in depth. They allowed me to create some unique interior areas, without a need for interior columns or load bearing walls.

When we built our post frame barndominium in South Dakota, we utilized floor trusses again – here to span 48’ (yes 48 feet)! We live upstairs in a gambrel building, with a clear-spanned half-court basketball court size garage/shop downstairs!

A few years ago, our oldest son Jake needed a new post frame garage at their home near Knoxville, Tennessee. His mom convinced him this plan would be so much better with a mother-in-law apartment upstairs. We used 4×2 (2x4s turned flat) floor trusses to span a 24 foot width!

I’d forgotten how fast a trussed floor can be done – until Jake ordered them for a second-floor  addition he put on his home when he moved back to South Dakota. In a matter of just a couple of hours, I framed this entire 24 by 32 floor by myself and was ready for sheathing. All ductwork and plumbing can be run through open truss webs, making for nice clean ceilings downstairs.

Considering a full or partial second floor in a post frame building? Don’t want posts or bearing walls down below to prohibit full space utilization? Then floor trusses may be your answer.

Make sure to allow adequate height for truss thickness. As a rough rule-of-thumb, I plan upon one inch of thickness, for every foot of span. While it will nearly always be less, it is better to design for having a couple of extra inches, than not enough.

Gambrel Barndominium Done Differently

What I Would Have Done Differently With Our Gambrel Barndominium

Pole Barn Guru BlogWhen we built our gambrel roof style barndominium 15 years ago we were in a position financially where we could have done most anything we wanted to. Our property was over two acres in size, so available space was not a determining factor. After having lived in it every day for going on four years, I have realized there are some things I would have done differently. For sake of brevity, I will only discuss main clearspan portions of our barndominium (it has 18 foot width sidesheds).

Footprint

Our center portion is 48 feet in clearspan width and 60 feet deep. Whilst this sounds really big, I wish we would have gone 60 feet wide and 72 feet deep. There is just never enough room and a portion of our half-court basketball court has been taken up with a workout area. Start parking a few vehicles inside and even smaller grandkids are looking for space to dribble and shoot the basketball.

Downstairs Height

16 foot high ceilings might seem like a lot. Doing it again I would go to 20. Makes playing basketball easier for those three point shots. At 20 foot, ceiling would not have been perfect for volleyball, but it would have made a serviceable practice are (given a larger footprint): https://www.hansenpolebuildings.com/2013/09/pole-barn-11/.

Floor Trusses

Yes we could have spanned 60 feet, we just would have had trusses about five feet in thickness. I would have specified a lesser deflection than our current L/360 however (read about floor deflection here: https://www.hansenpolebuildings.com/2015/12/wood-floors-deflection-and-vibration/). I also would have installed a diagonal (top chord to bottom chord) bracing system every 12 feet along building width, tying three trusses together across four feet. This would have further reduced deflection by spreading loads across a wider portion of the floor system.

Knee Walls

Our gambrel trusses are set directly at floor level. In order to have some semblance of sidewalls, we placed a knee wall in four feet from each side, reducing our usable width to 40 feet. While this made our space more functional, ever try to hang pictures on a four foot tall wall? Doing it again, I would opt to raise trusses up either four or eight feet above the floor level. Latter of these would have given wall to wall usable space as well as a more standard wall height.

Upstairs Ceiling Height

We have a 16 foot high ceiling now. While this works, it does make for a short ceiling in my wife Judy’s craft/sewing loft above a portion of our master bedroom. With a 60 foot span, we could easily have had 10 foot ceilings both above and below the loft. Of course Judy would have had to have found a 20 foot tall Christmas tree! (and she would!)

Whatever size barndominium you decide to construct – it will not be large enough. At a minimum I would encourage going no less than 10% greater in space than you think you need. Ready to get serious about planning your new barndominium? Call 1(866)200-9657 to get started now!

Multi-Story Pole Barns

Multi-story Pole Barns
Hansen Pole Buildings has developed a reputation for taking potentially challenging post frame (pole barn) building projects and developing them from concept to fruition. This leads many clients, with an interest in multi-story pole barns, to our doors.

Gambrel roof pole barnMy own post frame building home, along Lake Traverse South Dakota side, features both a second floor and a mezzanine (partial third floor) where my lovely bride has her sewing and quilting projects in various stages of assembly.

Our house Northeast of Spokane has two multi-story post frame buildings. Both of these happen to be constructed upon sites with a significant grade change. One of them has a 22’ x 24’ garage, with a studio apartment below and an office above (located in attic bonus room trusses). Tallest of these has been located near property rear. 40’ x 36’, it has a three vehicle garage space in lowest level, a full second floor, as well as a third floor (and a rooftop deck).

More reading about this building can be found here: https://www.hansenpolebuildings.com/2012/02/grade-change/.

Reader K.F. in ONTARIO writes:
“I would like to build a pole barn with a 10’ lower level and an 8’ upper area, with the dimensions 30×48. I would expect that the poles would need to be around 19-20’ long (above grade). That seems like a very tall pole (3x-2×6). What is the best way to build two levels and how does the upper floor go in?”

In my humble opinion, multi-story post frame buildings should always be designed by a Registered Design Professional (RDP – architect or engineer). Risks are far too great for an average person to safely and competently design a multi-story pole barn.

As to heights, one needs to look to how they desire to best utilize spaces being created. If interior columns are not an issue, a floor thickness of around a foot should be allowed for between levels. Don’t like having to maneuver around posts? Then floor trusses (https://www.hansenpolebuildings.com/2017/01/wood-floor-trusses/) might be a design solution. Roughly allow about an inch of truss depth for every foot of floor being spanned. Obviously, higher than residential weighted floors will necessitate a need for greater truss thickness.

Many multi-story post frame buildings are used residentially. If your proposed building will be climate controlled have roof trusses designed with raised heels (https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/) in order to provide full thickness of insulation from wall-to-wall. In colder climates, with a R-60 attic insulation recommendation, raised heel trusses could be as deep as 22 inches!

With a clearspan floor and raised heel roof trusses, ceiling heights desired by K.F. could result in sidewall heights of over 22 feet.

Not to fret – glu-laminated technology has allowed for one piece columns to be manufactured up to 60 feet in length. My own South Dakota building has columns as long as 50 feet.
As to how an upper floor goes in, this is where RDP experience comes into play. I have witnessed far too many instances of poor design practices of second floors without an engineer’s knowledge involved.

Looking for a multi-story pole building? Look to a post frame building kit supplier who works with a RDP to provide engineer certified plans for your building. Much better safe and standing, than flattened.

Pole Building Rooftop Decks

Post Frame Roof Top Decks

Question: Can decks be constructed upon a post frame roof top?

Answer: Yes, and it may prove far simpler than one might expect.

Our typical request from clients generally revolves around having a very slightly sloping roof and to use EPDM (ethylene propylene diene monomer) rubber as roofing over plywood. This solution might work, however very slight slopes tend to be problematic.

One of my own post frame buildings, located lakeside at Newman Lake, Washington, happens to have a rooftop deck. This particular building’s location happens to be perched upon the rear (farthest distance from our lake front) of our steeply sloping lot. The 30’x36’ building with a 10 foot wide enclosed shed off left sidewall has a total footprint of 40’x36’.

This building happens to be tall. Very tall – as in 40’6” from grade to roof peak. Besides garage level, it has two floors above. Upper floor clearspans a 30 foot width with floor trusses. This level also has a vaulted ceiling, provided by scissor trusses (I’ve written about this particular building’s roof trusses previously: https://www.hansenpolebuildings.com/2018/08/post-frame-scissor-trusses/).

Smoky MountainsKnowing this building would be very tall, and there would be a 180 degree panoramic lake view, it was planned all along to have a rooftop deck.  Adding to design challenges, we wanted this deck to be capable of supporting weight of a hot tub and its occupants!

This deck would cover an area between pairs of roof trusses/sidewall columns, a space of 12 feet along the building length. Sidewall columns were extended through the roof steel, to support glu-lam beams. These glu-lam beams had their opposite ends supported by a roof truss system designed to carry concentrated deck loads (along with snow and ceiling loads).

Where columns and glu-lams penetrated roof steel, a thick, high quality rubber and acrylic elastomeric roof coating formulated especially for steel roofing was used. After over 20 years of service, no leaks have been experienced. Other solutions may have been to use EPDM rubber boots and flashing to seal penetrations.

Interested in roof top entertaining upon your future pole building? It can be done, just ask your Hansen Pole Buildings’ Designer.

 

Friends Don’t let Friends Stick Frame

Oh the misconceptions arm chair engineers have when it comes to what can be done with post frame construction. For the most part – if you can imagine it, we can design it! Here is a case in point shared by our friend Neil:

DEAR POLE BARN GURU: I have limited floor plan on my lot, looking at a 24w x 64L size post frame building, 14 or 16 foot open height workshop area for lift and heavy truck work and a full second floor for an office, light storage, etc, (40psf live load). This would put the sidewalls between 20 and 22 feet. I believe I can clear span the 24 feet with modern engineered joists, but at this point does it still make sense to use post frame construction? Friends of mine have concerns about column loads, footing capacity, and suggested to just pour a full foundation, stick frame with it to 16′ and build a second floor and go up from there and put trusses on. NEIL in CLEVELAND

DEAR NEIL: Not only is post frame construction going to be the most practical solution, it will also be the most economical. Having to pour a continuous foundation is painfully expensive (read more here: https://www.hansenpolebuildings.com/2011/10/buildings-why-not-stick-frame-construction/). Another issue with trying to stick frame a 16 foot high wall – the Building Codes will not allow it unless you have an engineer sealed design, further adding to the expense.

While “I” joists might be able to span the 24 feet successfully, it will probably be much more practical to do with prefabricated wood floor trusses (https://www.hansenpolebuildings.com/2014/09/floor-trusses/), as they can be designed to limit deflection (read about deflection here: https://www.hansenpolebuildings.com/2015/12/wood-floors-deflection-and-vibration/)  and afford the ability to run duct work and plumbing through the webbing. In order to get everything you want to fit in your new building, you are probably looking at an eave height of around 27 feet. You will want to be talking with your Planning Department to see if there will be height restrictions.

Post frame building columns are very strong in the compression (weight bearing) direction and getting columns 32 feet long is not a problem, as glue-laminated columns are easily available in this length. Footings can be easily designed to support all of the live and dead loads which will be imposed upon them by your new post frame building.

On your second floor, if you intend to go with a 40 psf (pounds per square foot) live load, you will be restricted to residential use. Office space requires 50 psf and light storage is 125 psf. Design the floor for what you will actually be using the space for and have no regrets later!