Tag Archives: Rafters

How to Cut Shed Rafters

How to Cut Shed Rafters

Reader MICHAEL in MILACA writes:

Building a Loafing type pole shed, I have a question how to cut the rafters? I am building a 24 x90 loafing shed and I am using a 1-3/4″ x 24″ wide x 28 foot long LVL for the rafters. I do I figure the right field cut for this? I am using a 2/12 roof pitch.”

This excerpt from Hansen Pole Buildings’ Construction Manual should get Michael going:

Chapter 40: Cutting Rafters

Most Common Mistakes:

  1. Failing to learn to use a framing square. 
  2. Ignoring adage to measure twice before cutting.
  3. Overlooking cutting so rafter crown is up when installed.

Using a Framing Square to Mark Rafter Slope

With rafter crown up, place framing square on wide face. See Figure 40-1 

“12” location will be a constant for any roof slope. Adjust other “leg” of framing square to match roof slope needed.


Figure 40-1: Using A Framing Square to Mark Rafter Slope

To determine rafter length, multiply distance traveled horizontally by rafter, by appropriate slope factor from Table 40-1

For other slope factors – multiply slope by itself and add 144. Take square root (use a calculator) of this number and divide by 12.

Example to calculate slope factor for 3.67/12:  [3.67 X 3.67] + 144 = 157.47. Square root of 157.47 = 12.549. Divided by 12 = 1.0457.

Table 40-1                               COMMON SLOPE FACTORS

Roof Slope Slope Factor
2/12 1.0138
3/12 1.0308
4/12 1.0541
5/12 1.0833
6/12 1.118
7/12 1.1577
8/12 1.2019

Example below: 36’ wide pole and raftered “grid” style barn with a 4/12 roof slope.

See Figure 40-2


Figure 40-2: Column Spacing For Grid Barns

Here rafter has an 18’ horizontal distance (1/2 of 36’ building width) times 4/12 slope factor 1.0541 = 18.9738’ (18’ 11-11/16”) See Table 40-2

DECIMAL OF A FOOT TO INCH CONVERSION
Feet Inches Feet Inches
      0.9167 11 0.0781 15/16
      0.8333 10 0.0729 7/8
      0.75 9 0.0677 13/16
      0.6667 8 0.0625 3/4
      0.5833 7 0.0573 11/16
      0.5 6 0.0521 5/8
      0.4167 5 0.0469 9/16
      0.3333 4 0.0417 1/2
      0.25 3 0.0365 7/16
      0.1667 2 0.0313 3/8
      0.833 1 0.0260 5/16
0.0208 1/4
0.0156 3/16
0.0104 1/8
0.0052 1/16

Table 40-2

My Drill Stem Pipe Barn Sways in Light Winds

My Drill Stem Pipe Barn Sways in Light Winds

“Recently my husband and I decided we would try building a pole shed row barn for our horses out of structural drill stem pipe. We used 2 7/8 pipe columns on 12’ centers with 2 3/8 pipe columns supporting the (over hang, non-stall) side of the barn. It is 60×24, with 12’ tall center poles and 10’ tall short walls. The rafters are welded 2 3/8 pipe with 6” clips with the 2×6 purlins bolted to them with hex bolts to support the 26g r panel roof. We ended up putting the columns (poles) 3’ in the ground with 1 (and some of them got 2) bags of concrete in the hole with the remaining dirt backfilled. We also had the pad built up after the poles were set so there is about a foot of sand as well. The poles all have a base of red clay. We didn’t know what we were doing so we ended up not doing any footers or anything like that. So my question is, is this sufficient for the columns and if not how do we add support after they’re already up? My concern is this thing falling on our horses. We have significant movement (in my opinion) and racking so far, even after putting the roof on; however, it did get better after the roof went on. I can still shake it if I go to swinging on one of the columns. We can also we some cracking in the ground around the poles when it goes to moving after we’ve been pushing on it. There are no walls on yet, but we plan on adding a wall on each end and possibly the whole backside of the barn where the stalls will go. The front will stay open. Stalls will be welded to the vertical columns using 2 7/8 pipe so the entire structure will end up being held together at the base like it is at the top. I just worry about it buckling somewhere and coming down because we didn’t put our poles in the ground good enough. Please let me know your thoughts and what we can do to provide more strength. I’ll send some pictures so you can understand what I’m talking about. Thanks for any advice 🙏

 

I will add, we had around 25mph wind gusts today and I did notice it swaying and vibrating some but I wouldn’t have been able to tell if I hadn’t of leaned against one of the poles.”

 

Many thanks,

 

Bethany

Thank you for reaching out to me. Your building has a plethora of challenges, some can be solved, others you will have to make do with best you can.

Although not a current challenge, building upon a red clay base is likely to result in some long term negative consequences. Why would clay be an issue to build upon? Clay expands and contracts depending upon the amount of moisture present. When wet – clay expands, when dry it shrinks. These movements will cause buildings to move as well – not a good thing.

If your intent is for your building to be a permanent long-term structure, my best recommendation is to engage the services of a Registered Professional Engineer who can make recommendations as to how to properly reinforce what you have to make it structurally sound.

Issues include (but may not be limited to):

Lack of adequate concrete backfill/encasement under and around vertical pipes. This can be tackled by digging out around each column down to where you have current concrete and backfilling with more pre-mix. Required diameter can be determined by whomever you hire as an engineer.

Pipe columns may be inadequate in diameter for proper stiffness.

Adding properly engineered walls will increase stiffness. Should you happen to enclose your two ends and a single sidewall, your resultant will be a three sided building and they have an entire set of challenges all their own (for extended reading: https://www.hansenpolebuildings.com/2014/03/three-sided-building/).

Builder Warranty Example

Example Builder Warranty

Disclaimer – this and subsequent articles on this subject are not intended to be legal advice, merely an example for discussions between you and your legal advisor.

I cannot express strongly enough how important to both builders and their clients to have a written warranty in any agreement. 

WARRANTIES: There is no warranty applicable to the building and is expressly in lieu of all other warranties available under any State or Federal laws, expressed or implied, including any warranty of all labor, material, product and taxes will be paid for and there will be no potential lien claim against Purchaser’s property upon completion of the work and following final payment by Purchaser to Seller.

Products supplied by third party suppliers, manufacturers and sub-contractors to the project are warranted only to the extent that the suppliers and manufacturers of those products provide a warranty.

In the event that a defect is discovered in one of these products, Seller will assist Purchaser in securing repair or replacement of these products under the warranty provided by the third party supplier or manufacturer. Warranty work is work which was correctly and completely done initially, but becomes non-operational or dysfunctional following occupancy or use by Purchaser. No retainage or holdback will be allowed for warranty work.  

Seller expressly warrants to the original noncommercial purchaser(s) and only the original purchasers.  

That if any part of a Seller constructed post frame building, as covered by this warranty, proves to be defective due to materials or workmanship, under normal use and service, for two (2) years, that defective part will be repaired or replaced, subject to the terms and conditions contained in this Warranty.

Seller hereby assigns to Purchaser all rights under manufacturer’s warranties. Defects in items covered in manufacturer’s warranties are excluded from coverage of this limited warranty, and Purchaser should follow the procedures in the manufacturer’s warranties if defects appear in these items. 

 For ten (10) years.

Any solid sawn or glu-laminated (pressure treated to a minimum UC-4B) structural columns that fail due to decay or insect damage, unless said column has been exposed to animal wastes.

The original building roof structure, if damaged directly by snow loads because of the failure of any prefabricated roof truss or trusses to meet design specification. Subjecting your roof system to greater loads than those set out on the face of this Agreement, any unspecified ceiling loads, or modifying the trusses in any way voids all Warranties.

Any major structural defects which are defined as being an actual defect in a load-bearing portion of the building which seriously impairs its load-bearing function to the extent that the building is unsafe. For purposes of this definition, the following items compromise the structure of the building:

  1. Load bearing columns,
  2. Floor or ceiling joists,
  3. Beam, trusses and rafters.

For Two  (2) Years:

Any roof leaks due to defects in material or workmanship, expressly excepting where the building has been connected to an adjoining structure, in roof valleys, or at roof slope changes to which cases, no warranty applies. 

Any other building parts which prove to be defective in material or workmanship.

This warranty period shall commence on the date of the acceptance of the building by the Purchase or Purchaser’s occupancy of the building, whichever comes first.

This warranty contained wherein is void in situations where:

  1. Installation is not made in accordance with the instructions supplied by Hansen Buildings.
  2. The actual operation or use of the product varies from the recommended operation or intended use.
  3. There is a malfunction or defect resulting from or worsened by misuse, negligence, accidents, lack of or improper performance of required maintenance by the original purchaser.
  4. The building is altered or added onto, unless by Seller.
  5. Seller is not notified within twenty four (24) hours of problems due to snow loads.
  6. Purchaser fails to take timely action to or damage.
  7. Anyone other than Seller’s employees or agents or subcontractors have been on the building roof.
  8. Purchaser fails to make final payment per terms of sale.

Equipment such as fans, HVAC, gutters, downspouts, walk door locksets, other equipment not manufactured by Seller, site work, concrete, doors, windows, interior finishes, mechanical or electrical systems are excluded from this warranty.

The Purchaser expressly agrees to fully and timely pursue all available remedies under any applicable insurance agreement before making claim under this warranty.

In the event Seller repairs, replaces or pays the cost of repairing or replacing any defect covered in this warranty for which Purchaser is covered by insurance or a warranty provided by another party. Purchaser must assign proceeds of such insurance or other warranty to Seller, to the extent of the cost to Seller, of such repair or replacement.

Any claims for defects under warranty must be submitted in writing to Seller within the warranty period and promptly after discovery of the claimed defect, describing the defect claimed and date of building completion, before Seller is responsible for correction of that defect. Written notice of a defect must be received by Seller prior to the expiration of the warranty on that defect and no action at law or in equity may be brought by Purchaser against Seller, for failure to remedy or repair any defect about which Seller has not received timely notice in writing.

Purchaser must provide access to Seller, during normal business hours to inspect the defect reported and, if necessary, to take corrective action. A reasonable time should be allowed for inspection purposes. If, after inspection, Seller agrees, at its sole option to repair or replace only the defective materials or workmanship within the first three months from date of building completion at NO COST to the Purchaser. Thereafter Seller shall assume the cost of material and labor for any warranty work upon advance payment by the Purchaser of a one hundred dollar service payment for each incident under this warranty. The obligation of Seller, under this warranty, shall be performed only by persons designated and compensated by Seller for that purpose, and is subject to all other provisions of this warranty.

The provisions of this Warranty are the full and complete warranty policy extended by Seller, and are expressly in lieu of all other warranties, expressed or implied, including any warranty of merchantability or fitness for a particular purpose. These warranties may not be transferred or assigned. The liability of Seller shall not exceed the cost to Seller for repairing or replacing damaged or defective material or workmanship, as provided above, during the warranty period. 

THE WARRANTY STATEMENTS CONTAINED IN THIS LIMITED WARRANTY SET FORTH THE ONLY EXPRESS WARRANTIES EXTENDED BY SELLER FOR ITS BUILDING AND THE PROVISIONS HEREOF SHALL CONSTITUTE THE PURCHASERS EXCLUSIVE REMEDY FOR BREACH OF THIS WARRANTY. IN NO EVENT WILL SELLER BE LIABLE TO THE PURCHASER FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND FOR BREACH OF AN EXPRESS OR IMPLIED WARRANTY ON THE BUILDING; PROPERTY DAMAGE, PERSONAL INJURY , OR ECONOMIC LOSS IF OCCASIONED BY SELLER’S NEGLIGENCE, EVEN IF SELLER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. 

Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitations or exclusions may not apply to you. This warranty gives you specific legal rights and you may also have other rights which vary from state to state. 

Purchaser shall promptly contact Seller’s warranty department regarding any disputes involving this Agreement.

Seller and Purchaser agree that this limited warranty on the building is in lieu if all warranties of ability or workmanlike construction or any other warranties, express or implied, to which Purchaser might be entitled, except as to consumer products. No employee, subcontractor, or agent of Seller has the authority to change the terms of this warranty.

Stretching Stick Frame Construction

Post frame (pole building) construction is popular due to efficiencies of materials (ability to do more with less) and speed of construction.

Reader RAYMOND in BARLING is trying to find a way to make stick framing cheaper, he writes:

“24×64 pole barn in question. 4 pitch.  I am just comparing the cost of alternate designs.

Using 2×6 rafters with purlins across top for metal. Can I part from the standard 24 OC of rafters and expand to 30 OC (since more support from purlins)?

Furthermore, is it possible to use 30 OC studs all around, instead of poles (since more support from purlins on walls)

I would really appreciate your wisdom.

Thanks!!”

Mike the Pole Barn Guru says:

Let’s begin with, “since more support from purlins on walls”. Studs in stick framed walls will not resist wind loads perpendicular to a wall any better due to lateral support from purlins (actually girts) installed horizontally.

Your rafters are also going to be unable to support greater roof loads due to purlins being attached.

Building Codes have prescriptive requirements limiting what can and cannot be done with conventional (stud wall) framing, without having to have a fully engineered building. This would include studs and rafters being no greater than 24 inches on center. They also preclude wall heights of over 12 feet (you did not mention any heights however it should be kept in mind).

International Residential Code (IRC) Table R8702.4.1(1) provides rafter spans for common lumber species with a roof live load of 20 psf (this happens to be Code minimum whether snow is present or not). Being as you are in Arkansas, we will assume the minimum load as well as no ceiling being attached to rafters. With rafters 24 inches on center your rafters would need to be 2×8 #2 Southern Pine at a minimum. You would also need to provide ceiling joists or rafter ties to resist outward push of rafters on bearing walls. In order to get full value from rafters, ratio of rafter ties measured vertically above the top of stud walls to the height of roof ridge would need to be 1/7.5 or less. At a 4/12 slope ridge height would be 55.64″ meaning rafter ties could be located no more than 7-3/8″ above top of stud wall, so plan on then being at least 20 feet in length. A ridge board must also be provided as well as a collar tie, gusset plate or ridge strap (please refer to IRC R802.4.2).

Stud walls also mean you would need to make provisions for structural headers above any opening in any load bearing exterior wall. With post frame construction openings can be placed between columns in exterior walls, eliminating structural headers (this assumes trusses are placed aligned with wall columns with roof purlins on edge).

For stud wall construction, your concrete slab on grade will need to have an appropriately thickened edge in order to support weight of walls, or a continuous footing and foundation will need to be poured.

Ultimately post frame construction, not stick wall construction, is most probably going to be Raymond’s best route to go when considering investment and ease of construction.

Crawlspace Skirting, Adding Spray Foam, and Rafters

Today the Pole barn Guru discusses crawlspace skirting, adding spray foam, and building with rafters instead of trusses.

DEAR POLE BARN GURU: I am planning on building a post frame home with a standard wood framed floor structure. It will have a crawlspace below but will not have concrete stem walls. The building site slopes down, some of the crawlspace may be excavated below grade, some areas will be above grade. Looking for ideas for skirting the crawlspace to provide the most appealing look at exterior side and keep out water and pests. TRENT in WALLA WALLA

DEAR TRENT: In areas where your building’s crawl space would involve excavation below grade, it might behoove you to place a permanent wood foundation between columns (https://www.awc.org/codes-standards/publications/pwf-2015).  In other areas most of our clients have run steel siding down to four inches above grade, just like typical post frame construction.

DEAR POLE BARN GURU: Looking to spray foam the Hansen pole barn we built.

I have some questions.  We ordered the kit with roof insulation and it was installed when built. I’m thinking of leaving the ceiling open so the trusses are exposed. Can the foam be sprayed over the insulation? If the insulation is removed can the foam be sprayed directly to the roof? If so do I just close off the ridge vent? On the side walls do I just close off the top that opens to the eaves? MARK in MT. AIRY

DEAR MARK: Make sure to use only closed cell spray foam. I have heard arguments both for and against using spray foam against either a weather resistant barrier (such as Tyvek) in walls or a reflective radiant barrier. For this one I would defer to an answer from whomever will be doing your foam application, since they will have to warranty their installation. Certainly you can spray foam directly to inside of steel panels – I did this in a recent addition to my own post frame building home. You will need to close off both vented ridge as well as soffit.

DEAR POLE BARN GURU: Is it possible to build a pole building roof structure with rafters rather than trusses? FRED in GREENBANK

DEAR FRED: As long as building can have either interior columns, or single sloped (within reasonable span limits) it can certainly be raftered, rather than trussed. Please see this prior article in regards to pole and raftered buildings: https://www.hansenpolebuildings.com/2012/08/stall-barn/

 

“Rafter”Spacing, Old Posts, and Electrical Wiring Solutions

Today the Pole Barn Guru answers questions about “rafter” spacing, how to best dispose of old posts, and where to run electrical wiring.

DEAR POLE BARN GURU: Can I place rafters 48” apart on 24 x 40 pole barn with steel roof? DAVE in BAY CITY

DEAR DAVE: I will interpret your “rafters” to be Midwestern casual term for roof trusses. If so and properly designed to support required loads, trusses could be placed every four feet. In order to support roof steel, purlins would need to be laid either across top of, or joist hung in between roof truss top chords.

You should consult with an RDP (Registered Design Professional – architect or engineer) who will be providing plans for your building for determination of required loads, purlin spacing and size.

 

Ask The Pole Barn GuruDEAR POLE BARN GURU: I have a telephone post fence that I no longer want. How to I dispose of it? It is big and heavy. MINETTE in LUCAS

DEAR MINETTE: Whether large or small challenges, or a question doesn’t even pertain to post frame buildings, I do my best to answer them all and give best possible advice.

I’d start with trying to give it away using Craigslist and/or Facebook – you just might find a taker!

 

DEAR JUSTINE: (Ha ha! Fooled you as reader JAMES questioned Hansen Pole Buildings’ wizardress of all things materials – Justine, who forwarded it to me):

I have a construction question… I need to run wiring in the walls of the pole barn, and I wanted to be sure that drilling through the poles wouldn’t be a problem. I can either run all the wires up into the ‘attic’, then down where they are needed, which wouldn’t require boring holes through the poles, but would use a lot more wire, or I can run horizontally, and bore holes through the poles.

What is the recommended way? Are there limits to how many/large the holes can be?

Thanks. JAMES in LEBANON

DEAR JAMES: An article has been written specifically to address your question: http://www.hansenpolebuildings.com/2013/08/electrical-holes/

 

 

 

Attaching Horse Stall Posts to Trusses

Attaching Horse Stall Posts to Trusses – Just Say No!

Horse housing can be a significant piece of pie for post frame (pole barn) builders and building kit suppliers when economies are good. From 2007 to 2012, as U.S. economy tanked, horse populations decreased by 10%! Well, economies are cyclical and with a strong recovery a need  for stall barns has increased.

What surprises me – only a very small number of what I would term “best designed” stall barns – designed with sufficient airflow for healthiest horses, are being built. These buildings do not have prefabricated roof trusses, instead they are built using poles (columns) and dimensional lumber rafters. For more reading about pole and raftered stall barns: https://www.hansenpolebuildings.com/2012/08/stall-barn/.

I scratch my head when I see clients investing in clearspan buildings to be used for equine housing. I am most familiar with pole and rafter buildings with poles every twelve feet, to accommodate building horse stalls. Reader SCOTT in DAYTON writes in as one of these who now facing some challenges of trying to correctly construct stalls in his clearspan building. He writes:

“I am installing dividers and horse stalls in a clear span structure. Interior posts need to be added two of which will attach to one of the rafters and serve as supports for the dividers and a stall front. Each post will consist of three 2×6 cribbed boards with treated lumber for the below grade pieces. The tops of the posts will be saddles so that I can through-bolt into the rafter. My question is: how do I set these so that they are neither supporting or hanging from the rafter? Do I dig the holes just shallow enough so that the top of the posts will be snug to the rafter or just hang them and fill the holes with concrete? Thanks!”

Mike the Pole Barn Guru responds:

Even after nearly 20 years as a Midwest import I am still not used to prefabricated wood roof trusses being referred to as “rafters”. Unless you have prior truss manufacturer engineer sealed approval you should not be connecting columns to truss bottom chords. While it may seem added support of a tightly fitting column might be an assist, under a snow load it may actually place loads upon truss in spots not designed for support and can lead to a catastrophic failure.

You may want to consider using either a solid sawn pressure preservative treated column, or a glu-laminated column with bottoms treated for structural in ground use, as opposed to nailing up a three ply 2×6 column where members can separate over time.

I’d be prone to place columns deep into the ground and completely backfill the holes with premix concrete, stopping columns well below trusses.

 

 

A Stone Base Floor? Trusses vs Rafters, and Entry Door Install

DEAR POLE BARN GURU: I have a 40 x 24 pole barn with a 4 inch stone base floor. Can I place 2×4 grid framing 24 in on center with 3/4 inch T&G 4 x 8 sheets for light weight shop usage? No vehicles. JEFF in SYCAMORE

DEAR JEFF: Some ifs – if your site is drained so as to not have excess moisture beneath the building, if the subgrade is thoroughly compacted and if you have a well-sealed vapor barrier underneath, then it might work. Be prepared for the possibility of frost heaving. Both the framing and the sheathing should be pressure preservative treated to a minimum UC-4B level to prevent possible deterioration.

 

craigslist pole barnDEAR POLE BARN GURU: You compare scissor trusses to conventional trusses, but I see nothing about using beams instead. I’m aware of only one post frame supplier that provides beam systems in lieu of trusses. Are there any down sides to using beams and avoiding trusses all together? RACHEL in ST. LOUIS

DEAR RACHEL: My only guess would be you mean rafters, not beams. Or it could be your intent is a ridge beam supporting rafters. In any case, the answer is going to come down to time, money and reliability. If an alternate system to prefabricated wood roof trusses is to be used, it should most certainly be a design which has been thoroughly reviewed and sealed by a Registered Professional Engineer. Obviously prefabricated wood roof trusses are most highly prevalent because they offer the advantages without the expense of time and labor.

DEAR POLE BARN GURU: Can I install a 36″ steel entrance door before the exterior girts are applied? DONAVON in EAGLE GROVE

DEAR DONAVON: In most cases, the columns on one or both sides of the entry door are trimmed off above the door and supported by a wall girt which runs between two roof supporting columns. If your particular application has framing on both sides of the door which is attached to the roof system, then it would probably be possible to install the entry door prior to the wall girts. I am not seeing any apparent advantage to doing so and it would add to the possibility of inadvertent damage to the door.

 

Deep Fascia Overhangs

The definition of Fascia from the sum of all human knowledge (Wikipedia):
“Fascia (/ˈfeɪʃə/) is an architectural term for a vertical frieze or band under a roof edge, or which forms the outer surface of a cornice, visible to an observer.

Typically consisting of a wooden board, uPVC or non-corrosive sheet metal, many of the non-domestic fascias made of stone form an ornately carved or pieced together cornice in which case the term fascia is rarely used.

The word fascia derives from Latin “fascia” meaning “band, bandage, ribbon, swathe”. The term is also used, although less commonly, for other such band-like surfaces like a wide, flat trim strip around a doorway, different and separate from the wall surface.
The horizontal “fascia board” which caps the end of rafters outside a building may be used to hold the rain gutter.”

In layperson’s terms, the fascia is the outside member of an overhang which is extended past the eave side (where the rain water drips or snow slides off) off a building.

For most residential structures, the fascia board is a 2×6 or 2×8, which provides an overall fascia height approximating five to seven inches depending upon slope of roof, etc.

Open OverhangsThere are some cases where it is advantageous to increase the height of the fascia, these would include (but are not limited to):
Aesthetics (aka looks) – some people like the look created by a deep fascia overhang.
Supporting signage – on commercial buildings having a deep fascia on the eave side of the building several feet in height can allow for signs for a business or businesses to be placed.

We recently ran across an instance where a client needed to have a tall door in the endwall of his new post frame (pole) building, however his Planning Department had a strict limitation upon the allowable height of building sidewalls.

Enter the thinking caps.
By the creation of a deep fascia overhang, the eave height (read more on how eave height is measured here: https://www.hansenpolebuildings.com/2012/03/eave_height/) was able to be increased by several feet, without the need for longer siding – meeting the strict requirements of the Planning Department!