How to Frame a Reverse Gable Porch
Reverse gable porches are an excellent way to protect any door from effects of weather – specifically rain and snow. I personally feel they are an underutilized great feature.
For more reading about reverse gable porches: http://www.hansenpolebuildings.com/2015/07/reverse-gable-porch/.
Today’s article has been sparked by reader DARRELL in ATLANTA who writes:
“How to frame a reverse gable over a door on an existing pole barn. Thank you.”
Mike the Pole Barn Guru responds:
Ultimately this will be a question you will need to have answered by a RDP (Registered Design Professional – architect or engineer) who provided sealed plans for your original structure, as they will have to verify ability of existing structure to support loads imposed by this reverse gable porch.
Most reverse gable porches are attached to a wall below the existing roofline. Structural design of new roof system will need to be able to accommodate weight of snow drifting against existing wall or sliding off from roof (depending upon whether reverse gable will be added to endwall or sidewall).
Siding will need to be removed from existing wall in area of reverse gable. A truss will need to be placed against this wall – usually it will be easiest for span of truss (and width of reverse gable) to be from one existing roof supporting column to another. If reverse gable will have overhangs, then this truss against existing wall needs tails 1-1/2 inches longer (measured horizontally) than width of overhang, in order to attach fascia boards. 2×4 (wide face to wind) siding backing needs to be added to this wall, approximately two inches above truss and following same pitch.
Your RDP can specify connection of truss to existing columns. It may be necessary to add a bearing block below the truss heels, in order to adequately support roof loads.
Two new columns will support new gable parallel to the wall including your door. For sake of preventing things from running into them, they should be no smaller than 6×6, and be fully concreted into the ground. A single truss will be notched into face of these columns 1-1/2″ opposite from existing main wall. If reverse gable has no overhang, neither will this truss. If endwall overhangs, this end truss attachment will be lowered (in comparison to main wall truss) by thickness of purlins, adjusted for roof slope. A 2×4 siding backing should be nailed to face of both top and bottom chords of this truss.
Depending upon span between these two trusses and roof loads 2×4, 2×6 or even larger purlins should be placed edgewise. They will butt into the side of truss against existing building and be attached with hangers. If no endwall overhang, attachment to opposite truss will be the same. If an endwall overhang will be included, then purlins run over second truss and are attached to top of it with Simpson H1 brackets. With an endwall overhang, solid 2x blocking will be placed between purlins, to prevent rotation. Solid blocking should be held 3/4″ out past 2×4 siding backing. With enclosed overhangs, soffit will attach to this solid blocking. With open overhangs, endwall J Channel will butt up against blocking.
Fascia boards and fly rafters of same dimension as purlins will need to be installed, if there are overhangs.
DEAR POLE BARN GURU: 
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
I would recommend using premanufactured wood floor trusses between floors (
For cases where strength of steel skin is not adequate to support loads, the International Building Code (IBC) provides for wall panels to be braced by adding either Oriented Strand Board (OSB) or plywood. This most often occurs when a wall (or walls) have large amounts of openings (doors and windows) or in cases where buildings are tall and narrow, or very long (usually width of three to four times building length). An engineer can determine the applicability of this as a design solution. Installation of added sheathing is generally fairly simple and requires (in most cases) minimal extra framing materials.
“Maybe you could have a chapter on how building a new building cost money. And that you shouldn’t expect other people have spent money to just give you their plans and all their knowledge that they spent their own hard-earned money on to get.”
There is no such thing as a “pole foundation engineering calculator” therefore, there is also no link to one. The design of post frame (pole) building foundations is one which is best left in the hands of RDPs (Registered Design Professionals – architects or engineers). When provided with all the pertinent information about your proposed building, they can design not only a structurally sound column embedment, but also your entire structure (which I whole heartedly recommend). 
The building official is also authorized and directed to enforce the provisions of this code. The building official shall have the authority to render interpretations of this code and to adopt policies and procedures in order to clarify the application of its provisions. Such interpretations, policies and procedures shall comply with the intent and purpose of this code.
In my humble opinion, a majority of these builders who had to change their construction were probably not building Code conforming structures! Think about this if you are considering investing in a post frame building from ANY builder.
While I appreciate your questions, we as a company and me as an individual do not provide free engineering services. In answer to your questions:
Wikipedia may consider a lean-to a simple structure, however there is far more involved than may meet the eye. Before diving deep into adding a lean-to to an existing pole barn (post frame building) a competent Registered Design Professional (RDP – engineer or architect) should be engaged to determine the adequacy of the existing structure to support the lean-to. Failure to do so can result in catastrophic failures – causing injury or death.
DEAR DAVE: Rather than working off from the dimensions of a building which best fit some prior client’s wants and needs, you will be far better ahead to work with one of the Hansen Pole Buildings’ Designers to come up with the dimensions and features which will best fit with your budget. If you can do a design which has some or all of both of the narrow (peaked) endwalls enclosed from roofline to the ground, it will normally be the most cost effective.
He or she takes into account all of the climactic loads placed upon your building – wind, snow and seismic, along with the allowable soil bearing capacity of your site in making the determination. The other factors they will have taken into account include the spacing of the columns, eave height, roof slope as well as the dead loads the building must support (not only the weight of the building as proposed to be constructed, but also future loads such as wall and ceiling finishes).
DEAR FAITH: This is a question which is best posed to the RDP (Registered Design Professional – architect or engineer) who designed your building and provided the sealed blueprints for you to build from. I am not aware of an engineered hanger which will do what you are looking to accomplish, however there may be a direction in which to head for a solution. By predrilling holes through the purlins from narrow edge to narrow edge, it might be possible to utilize a number of very long spikes or drive screws which could provide the needed resistance to uplift and seismic forces. In order to have adequate area for connectors, it might take going to a three or four inch wide purlin, which may turn out to work well aesthetically with your timber framed trusses. There will need to be blocking placed on top of the trusses, between the purlins to prevent rotation.
Always (may I repeat Always) construct only post frame (pole) buildings which are designed by a RDP (Registered Design Professional – engineer or architect) specifically for your building upon your site. You will always get piece of mind and usually the RDP will save you more money than what you invested for their design work. 
In the post frame building industry, Hansen Buildings deals with Registered Professional Engineers pretty much every day. It is thanks to years of schooling, field experience, and real life design work these design professionals perform which makes our pole buildings as safe as they are.
If he wasn’t a building official, it wouldn’t really matter much whether he gets rankled or not. If he was a supplier or subcontractor, fine, take the risk; if he can’t handle it, hire a new one. But you can’t hire new building officials. Get on the wrong side with one and run the risk of installing yourself on the person’s or jurisdiction’s blacklist. Navigating the regulatory quagmire is hard enough without painting a sign on your forehead which says “I am a jerk.”
Trust me on this one – getting into the jerk line at the Building Department is tantamount to waterboarding. Life…will….become….miserable.
I have heard of projects where during construction the engineer of record got calls from the contractor asking for interpretations to the cryptic red marks all over the structural plans. This is alarming because engineers do not release construction plans with red marks on them. If corrections are to be made, engineers make them in the office and reissue the plans. What has happened is an overzealous plans examiner took it upon himself to change the engineered plans via red marks and then issue the plans for construction without bothering to ask or tell the engineer!
In changing the engineer’s design, the Building Department superseded the actual registered engineer as the engineer of record and assumed all sorts of liability. If their risk manager ever got wind of this, heads would roll. And roll they should.
Oftentimes, engineers do nothing about this, especially if it is near an Act of Congress to obtain a building permit in the particular jurisdiction. Sadly sometimes the only way to obtain a permit is via the building department redoing the design and assuming the liability. Raising a stink could cause long delays in the issuance of a permit.
Before questioning the Building Official, weigh the costs. If the building inspector is a reasonable person, ask the question. If, on the other hand, the inspector is seemingly “out to get you”, maybe let the issue pass and then at the end of the project bring it up to his superior.
If you are a Building Official and reading this, please do give me feedback on “smoothing the road”. Trust me; I am on your side. My goal is always the same: To provide adequate support and education to clients to assist them in getting a well-designed pole building which is safe, sound…and built to code. 
An engineer is responsible for the analysis and design of the structure or framing system of a building or building component. While doing the building’s structural design, the engineer will take safety and performance into consideration. For performance or serviceability this is the design for vibrations from machinery, floor vibration or deflection which could cause discomfort, or even building deflection or sway. The occupants of a building might feel uncomfortable if the building sways or moves too much, especially on the upper stories.
