Tractor Shed - Need Framing Ideas

[EddieWalker]

The spacing for the purlins is based on the metal material that you use. If you use a thicker metal, you can space your purlins out further. I bought my metal roof from Muellers, who advises 4ft centers on the purlins. I forget the thickness of the metal off hand. Sorry.

Here's a picture of my roof with my wife on it when we were installing it. You can see the spacings in the picture and also get an idea of how the trusses and rafters tie in together.

Eddie

 

[RobJ]

The spacing for the purlins is based on the metal material that you use. If you use a thicker metal, you can space your purlins out further. I bought my metal roof from Muellers, who advises 4ft centers on the purlins. I forget the thickness of the metal off hand. Sorry.

Here's a picture of my roof with my wife on it when we were installing it. You can see the spacings in the picture and also get an idea of how the trusses and rafters tie in together.

Eddie

Isn't not worrying about a snow load wonderful!! A few folks around our area have put up metal roofs, seems the in thing to do now is go ahead and deck the whole roof with the radiant ply, then put the metal roof on. Another layer if insulation. FYI, I would not do this on a barn.

 

[cdhd2001]

Isn't not worrying about a snow load wonderful!! A few folks around our area have put up metal roofs, seems the in thing to do now is go ahead and deck the whole roof with the radiant ply, then put the metal roof on. Another layer if insulation. FYI, I would not do this on a barn.

If you build the roof with OSB/PLY decking, lay felt, then install metal roof you accomplish two important things.
1) deaden the dreaded rain on a tin roof sound
2) keep the metal roof from condensating in the building

Most house builders are more comfortable building in a "conventional" method, then choosing the style of roofing (shingles, metal, tile...).

 

[ampsucker]

as just mentioned, condensation on the underside of the metal will be a problem without insulation. we ended up stapling black plastic "under" our lean-to over where the cars are parked to avoid water drippage.

no snow, but probably frost, right? don't forget to get that foundation or footings for your slab below the frostline for your area. up here in kansas, all slab on grade settles unevenly. with large oak tree roots under there? defintely going to be a problem without a good foundation.

ditch the trees. i hate to say it, but trees close to a building a never good. for shade, you want deciduous trees on the south and west with tap root based root systems, not spreading surface roots. for windbreak, evergreens on the north and west. ever cleaned leaves out of your gutters? oak leaves are large enough they really clog things up. plus the root problem plus the falling branch problem. lightning? just not worth it.

don't forget if you go with metal roofing, the fasteners go on top of the ridges, not in the valleys! valley fastening leaks. ridge tops do not.

amp

 

[cdhd2001]

Isn't not worrying about a snow load wonderful!! A few folks around our area have put up metal roofs, seems the in thing to do now is go ahead and deck the whole roof with the radiant ply, then put the metal roof on. Another layer if insulation. FYI, I would not do this on a barn.

I just calculated the wood cost for my design. Interesting results.

Using 24" O.C. 2x4 trusses with 7/16 OSB decking is about $100 cheaper than 2x6 rafters on 48" centers with 2x4 purlins.

The decking should provide better tree limb protection than just metal & purlins.

 

[cdhd2001]

don't forget if you go with metal roofing, the fasteners go on top of the ridges, not in the valleys! valley fastening leaks. ridge tops do not.

amp

Maybe Eddie can confirm this, but I thought with R-panel you screw in the "flats", not the ridges?

 

[dfkrug]

don't forget if you go with metal roofing, the fasteners go on top of the ridges, not in the valleys! valley fastening leaks. ridge tops do not.

The neatest metal roofs have completely hidden fasteners. I have the
Western Metal Standing Seam roof. Clips are screwed to the decking
(or purlins) and the panels snap over the clips. Most of the batten
seam or Ag panel steel roofs have the exposed fasteners you describe.

 

[cdhd2001]

The neatest metal roofs have completely hidden fasteners. I have the
Western Metal Standing Seam roof. Clips are screwed to the decking
(or purlins) and the panels snap over the clips. Most of the batten
seam or Ag panel steel roofs have the exposed fasteners you describe.

Do you have a picture? I do not believe that I have seen one before?

 

[RobJ]

I just calculated the wood cost for my design. Interesting results.

Using 24" O.C. 2x4 trusses with 7/16 OSB decking is about $100 cheaper than 2x6 rafters on 48" centers with 2x4 purlins.

The decking should provide better tree limb protection than just metal & purlins.

Yes I've seen the price of sheet goods come down around here...about $5.50 for a sheet of osb the other day. In 2001 when I did my house is was about $9.00. I don't recall the price of the OSB in the garage in 2004. I think the ply adds a little more strenght to the structure to. I stapled my about every 8".

 

[dfkrug]

Do you have a picture? I do not believe that I have seen one before?

I do not have any good pix (JPGs) of my final installation and a web search
no longer finds my brand. Check out this site for a lot of similar products:

Fabral: Architectural Panels, Concealed Fasteners

 

[cdhd2001]

Yes I've seen the price of sheet goods come down around here...about $5.50 for a sheet of osb the other day. In 2001 when I did my house is was about $9.00. I don't recall the price of the OSB in the garage in 2004. I think the ply adds a little more strenght to the structure to. I stapled my about every 8".

I paid $5.55 per sheet at HD 3 weeks ago. Screwed mine down with 1-5/8" deck screws on 6" centers.

 

[BigE_]

I paid $5.55 per sheet at HD 3 weeks ago. Screwed mine down with 1-5/8" deck screws on 6" centers.

Man, you don't want those going anywhere, do you?

On a small structure, I generally use the 1/2" by 2" staples on OSB. Cheap, quick, easy. Every 6-8" around the edges, and every 12" or so in the field. Note that this is NOT hurricane proof type roofing, but I worry more about a tree falling on the structure vs. a hurricane in my part of the country. (I believe I read that in Florida you aren't even allowed to use OSB on the roof anymore.)

If you are worried about hurricane, use the 2" long ridged nails. I shoot one of those suckers into a piece of OSB / 2x4 combo, and I end up ripping the head off before nail comes out.

 

[mikim]

Cheap, quick, easy.
My Dad's idea of a good job ..... but his jobs never lasted worth a hoot and he was always having to redo them ....which is why I much prefer "doing it RIGHT the first time" over "cheap, quick, easy" which will get you nothing but headaches. ---

 

[EddieWalker]

...don't forget if you go with metal roofing, the fasteners go on top of the ridges, not in the valleys! valley fastening leaks. ridge tops do not.

amp

I've always been told and my dealer recomends fastening metal on the flats. This eliminates any flex in the metal and keeps the roofing material dead solid against the purlins.

I buy from Muellers, which is a pretty big outfit in this part of the country. They manufacture all there own products and have engineers to design what you need. Some companies are actually just salesman who sell metal for a manufacturer. Be careful when dealing with them because the salesman doesn't have anything to do with the actual metal, he's just placing the order and making a commision. These companies have allot of different names, and most of them are advertised pretty heavily. I don't trust salesman who sell other companies products. It's just too hard to get anywhere with them when you have a problem.

There was a thread awhile ago where others mentioned that their suppliers said otherwise and to fasten through the ridges of the metal. I've never seen this before and until I read the links posted to those manufactures, didn't believe it.

Not being an expert on this, it would appear that both ways are correct depending on who you buy your metal from. My roof, and those that I've done for others, are always screwed down through the flat part of the metal.

Airflow is another good way to cut down on condensation on metal roofs. Of course, there will always be some degree of it unless you seal it off from the bottom. I like the idea of the decking with felt, but haven't done that yet. I'm also thinking about trying some of those spray on foam kits that give you an inch of foam over the inside of the metal. I have a problem in one spot of my roof that doesn't get any air flow, so that's an issue I'm working on. I just hate paying $600 for the foam spray.

Eddie

 

[denmansoft]

Out here on the wet coast decking a roof with OSB and then metal can turn ugly. One neighbor did this about 10 years ago. A few leaks around the screws destroyed the osb. The new owner is now faced with ripping it all off and starting again.

 

[Sully2]

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!

I'd swap the corner posts for 4 x 6's ( instead of 4 x 4's) and by all means use trussed....24" O.C.

Dont know about your location...but I can buy pre-made trusses cheaper than I can buy just the material and have to make them myself!

 

[Brad_Blazer]

(For ideas only, the engineering of your building is your responsibility.)

I used power pole posts and mostly lumber I had on hand. The poles are in a 16 x 32' pattern on 8' centers. The diagonal post braces were placed while setting the trusses to account for variations in post size / placement. My posts only go 8' above the ground so the trusses were designed to provide extra clearance. They are full rough cut 2x10. Gussets are glued and nailed. The purlins are 2x8s on joist hangers.
Pics are in reverse order.


















Brad

 

[cdhd2001]

(For ideas only, the engineering of your building is your responsibility.)

I used power pole posts and mostly lumber I had on hand. The poles are in a 16 x 32' pattern on 8' centers. The diagonal post braces were placed while setting the trusses to account for variations in post size / placement. My posts only go 8' above the ground so the trusses were designed to provide extra clearance. They are full rough cut 2x10. Gussets are glued and nailed. The purlins are 2x8s on joist hangers.
Pics are in reverse order.
Brad

Cool! Very informative.

The post size and spacing I took from a University of Tenn. design drawing for a 24'x24' garage.

I was thinking of installing a 10' roll up door and adding an additional set of posts on either side. Extra post on the rear wall also.

 

[RobJ]

Out here on the wet coast decking a roof with OSB and then metal can turn ugly. One neighbor did this about 10 years ago. A few leaks around the screws destroyed the osb. The new owner is now faced with ripping it all off and starting again.

Sounds like they didn't install it correctly. If there is no OSB then there is always something else. Insulation, sheetrock, 50" plasma tv, hardwood floor!!

 

[Sully2]

Sounds like they didn't install it correctly. If there is no OSB then there is always something else. Insulation, sheetrock, 50" plasma tv, hardwood floor!!

I had a scrap piece of OSB laying around here after my home was built..and I propped it up against a tree..outside..no protection and there it stood for a full 5 years. Not one bit of delination on it. I finally tossed it into the burn pile because I got sick of looking at it.