Tractor Shed - Need Framing Ideas

   / Tractor Shed - Need Framing Ideas #1  

cdhd2001

Silver Member
Joined
Mar 31, 2007
Messages
161
Location
texas
I am trying to get my final design together for my tractor shed. Would love to have some ideas, advice, help, etc.

Dimensions:

Pole barn style construction.
16' wide by 24' long. 8-10 ft. height.

4x4 treated posts on 8 ft. centers.
double 2x8 top girts

Roof will be 3:12 pitch with 26 ga. R-panel.

The roof layout is my biggest point of indecision. I am trying to design for 30 psf roof load, no snow (Texas). Should I do trusses or rafters? 24" O.C. with 1/2" OSB decking or XX" O.C. with purlins? I am leaning towards purlins but am unsure what to use for rafter/trusses and what spacing.

Thanks!:)
 
   / Tractor Shed - Need Framing Ideas #2  
That's a small shed .... how did you plan on finishing it out? For a small shed like that I wouldn't bother with roof decking - set 2x8 rafters with 2x4 purlins and fasten your metal to that. You can buy trusses if you like - save yourself some work then run the purlins on them. If you have a local McCoy's and a trailer you can order the trusses from them and haul 'em yourself.
 
   / Tractor Shed - Need Framing Ideas #3  
CDHD:

I did my workshop with a standing seam steel roof, Kynar coated. A
look at the R-panel website shows me that product is a "batten seam"
or "Ag panel" style. I am considering the building of a carport style
shelter with no sides and I have been looking at a similar roof panel.
The R-panel site indicates these panels are only 8-feet long...is that
right? If your bldg is 16' wide and it is gable style, you will need panels
about 10+' long for a 4:12 pitch. I also do not find any roof peak finish
panel in the details. What's up with that?

Finally, consider that a perlin style of installation will easily dent if you
have to stand on the roof. Continuous roof sheathing is stronger. I
like simple rafters versus trusses in than you have more overhead clearance
inside the structure.

My $.02. Good luck.
 
   / Tractor Shed - Need Framing Ideas
  • Thread Starter
#4  
dfkrug said:
CDHD:

I did my workshop with a standing seam steel roof, Kynar coated. A
look at the R-panel website shows me that product is a "batten seam"
or "Ag panel" style. I am considering the building of a carport style
shelter with no sides and I have been looking at a similar roof panel.
The R-panel site indicates these panels are only 8-feet long...is that
right? If your bldg is 16' wide and it is gable style, you will need panels
about 10+' long for a 4:12 pitch. I also do not find any roof peak finish
panel in the details. What's up with that?

Finally, consider that a perlin style of installation will easily dent if you
have to stand on the roof. Continuous roof sheathing is stronger. I
like simple rafters versus trusses in than you have more overhead clearance
inside the structure.

My $.02. Good luck.

Our local metal building supplier (DDM Pipe) can make any length of R-panel in house. Same with the flashing and trim. I just finished my back porch and used rafters with 7/16" OSB and R-panel. Turned out great in my opinion.

As for the "simple" rafters. I am going to build the shed with the gable at the 16 ft wide section. I was under the impression that to use rafters in this configuration that I had to include the bottom chord and create a "king" truss?

With purlins, what kind of rafter spacing? 24", 32" 48", 96" ?

I have downloaded many different pole building design plans and some use rafters/trusses 24" O.C. and some go 8-12 ft. spacing on the trusses and run purlins at 24" O.C.?

Questions, questions...:eek:
 
   / Tractor Shed - Need Framing Ideas #5  
cdhd2001 said:
Our local metal building supplier (DDM Pipe) can make any length of R-panel in house. Same with the flashing and trim. I just finished my back porch and used rafters with 7/16" OSB and R-panel. Turned out great in my opinion.

That is good. You do not want horizontal seams betw panels. I do not
see the ridge cap piece in any of the details. Curious.

cdhd2001 said:
As for the "simple" rafters. I am going to build the shed with the gable at the 16 ft wide section. I was under the impression that to use rafters in this configuration that I had to include the bottom chord and create a "king" truss?
A true "simple rafter" roof has no trusses at all. A ridge beam provides
support for the rafters in the middle. Clearly this would require a good
load path to the foundation, which requires a stronger lintel over the
door. A truss could involve one or multiple ties between the top chords,
depending on the design. These are usually pre-engineered for your load
and span. You should be shooting for a total load of at least 30psf (LL +
DL), even if you get no snow.

cdhd2001 said:
With purlins, what kind of rafter spacing? 24", 32" 48", 96" ?

I have downloaded many different pole building design plans and some use rafters/trusses 24" O.C. and some go 8-12 ft. spacing on the trusses and run purlins at 24" O.C.?

Questions, questions...:eek:

It looks like the R-panel web site gives purlin and rafter (truss) spacing
for the 2 diff guages of steel offered. Purlins not needed if you go with
roof sheathing.
 
   / Tractor Shed - Need Framing Ideas #6  
The difference between a truss and rafter design is the truss will span a distance with the exterior walls supporting the load. Your walls will be 16 feet apart, so your span is 16 feet. You can make the trusses wider to include an overhang, but that 16 foot width is what counts in truss design.

Rafters rely on a load bearing wall in the middle of your span. Sometimes on really wide buildings, you can have multiple load bearing walls. You don't have this in a small shed like yours.

For a short span, the truss is pretty simple. You can order them from a supplier and have them certified for that span, or you can just build your own. Again, for such a short span, it's pretty hard to get it wrong.

Why those dimensions? Is that all the space that you have?

For your purlins, use 16 foot lengths and overlap the seams. Use 4x6's for your entry door posts. I like my trusses to be 4 feet apart with 2x4's on the flat for my purlins. If you go 6 feet on center, then you need to put your purlins on edge. The wider you go, the bigger the lumber that you will need.

How close are you to Muellers? I like them for my metal siding and roofing. Good people with a quality product. Don't buy your metal from the Home Stores. It's thin and the finish isn't very good.

The secret to fastening down a metal roof is to tighten the screws just sung enough to bulge the washers. If you tighten them too much, you will ruin the rubber gasket and it will leak.

If you live in an area with high humidity, you should insulate the ceiling. Otherwise, it will create condensation. This will give you the affect of rain inside the building on certain days. If money is tight, you can avoid this, but don't be suprised to see water on your floor or what's in there on perfectly dry days.

Make the door as big as possible. Mine is 10ft by 10ft, which I consider just about right. It's a roll up door, which I also really like. No wind issues, it's water proof and opens real easy without taking up allot of ceiling space that I can use for my ceiling lights.

Try to pour concrete for the floor as soon as possible. If you put it off, it might never get done. Once you start filling up the building, it gets harder to pour concrete and easier to keep putting it off.

Eddie
 
   / Tractor Shed - Need Framing Ideas #7  
Not a lot of weight in this one..to keep it reasonable...

2x6 rafters on 24" centers.
1x4 purlin on 16" centers (probably cheaper, easier to put up than ply, you are probably not on the roof that much).
2x6 or 2x8 joist every 3 or 4 feet just to help keep the walls in.

At 3-12 and 16' wide there isn't going to be much storage room in the attic. Maybe some lumber.

Post some pics!!
 
   / Tractor Shed - Need Framing Ideas #8  
If you go with trusses you could make the building a bit wider. Trusses on 4’ centers and purlins on 2’ centers would most likely be cheaper than decking the roof. Sixteen feet becomes pretty narrow after you start putting things in it or have to get to that equipment in the back corner. A small 2 car garage is 20x20.

MarkV
 
   / Tractor Shed - Need Framing Ideas #9  
   / Tractor Shed - Need Framing Ideas
  • Thread Starter
#10  
EddieWalker said:
Why those dimensions? Is that all the space that you have?

Eddie

I am building in between 4 large oak trees. 16 ft wide gives me about 6 ft. clearance on either side between the trees. I was originally going to go 20 ft. long, but decided to go 24 ft so that it is divisible by 8 ft. (post spacing).

I think I have decided to go trusses on 4 ft. centers with 2x4 purlins on 2 ft. centers.

I will build the trusses myself. I have looked in my framing book and decided on the fink (W) truss design. The book shows two choices in framing the trusses. One is to use 2x4's and use double 2x4's for the top chord. The other choice is to use 2x6's for the top chord. Both would use a 2x4 bottom chord.

Any thoughts?


On Edit (to muddy this further :) )

My rafter table on 30 psf and 24" O.C. (No. 2 pine) shows:

2x4 = 7'-10"
2x6 = 9'-9"

So either would work on 16 ft. as rafters...??

So many different ways to skin this cat.... :)
 
Last edited:
 
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