Pre-fab trusses for shed style shop?

N80 · Dec 22, 2021

I am in the process of planning a shop for down on my property. I have no idea if this will become a reality as it is still early in the planning stage. What I want/need is a 30x40 3 bay shop.

I have had a site prep guy out and he says location is fine and won't need too much earth moving at all.

I will be milling my own lumber. I will be doing most of the work myself. It will be on a concrete slab (concrete contractor). It will be stick built. Probably on a low cinder block knee wall. 5v crimp metal roof. Looking for about 12' of height clearance inside.

When I built my log cabin kit 20 years ago it came with prefab wooden scissor trusses for a single peak roof. They were no problem to install.

However, I would prefer that my shop have a shed roof that slopes to the back (where drainage is best.) I would prefer to have a clear internal space with no posts/columns.

My question is this: Can pre-fab shed type trusses be purchased? Any guesses on cost? Is it feasible to make your own? Any ideas much appreciated.

duffer · Dec 22, 2021

N80 said:
My question is this: Can pre-fab shed type trusses be purchased? Any guesses on cost? Is it feasible to make your own? Any ideas much appreciated.

Sure. Any truss company can make shed roof trusses. Easy peazy. I just got done quoting a shed roof design for a 4 car garage/shed my neighbor wants to build. Depending on the slope you want (1½:12, 2:12, etc) cost will vary, along with the length you're wanting. I planned on 2' OC spacing, and using 5/8" sheathing for the roof, or better yet, use the zip system for the roof, then add shingles or metal.

Quoted 24 common trusses, and 2 end trusses, 32' long, with 2x4 chords top & bottom, was $3350

tfuller · Dec 22, 2021

Here is a place in Augusta, GA that should be able to help you out Armour Metals

3Ts · Dec 22, 2021

My question is this: Can pre-fab shed type trusses be purchased? Any guesses on cost? Is it feasible to make your own? Any ideas much appreciated.

1) Yes, 30' is not that big of a span for engineered trusses.
2) No, I did mine over 10 years ago so what I paid won't reflect todays prices with all the increases over the years.
3) Yes, BUT! It is feasible to make your own but I found that the truss company could do the load analysis, make them and deliver them on site and certify the drawings for the inspector, for a little less than I could buy the lumber (from a big box store).

N80 · Dec 22, 2021

@duffer Excellent info. Looks like my costs would be similar to your quote and that's really not bad and seems low enough that making my own would not be worth the time and effort (or the inferior product if I make them).

@tfuller Thanks for the link. Had not thought about metal but it seems worth looking into it.

@3Ts Agree. Looks like making my own would not be worth it.

As usual, great info from TBN members.

PILOON · Dec 22, 2021

I have built a few sheds using prefab trusses.
The specs for sheds/barns/garages are less than for homes and much more affordable.

In fact I cost compared DIY vs prefabbed and simply could not justify DIY based on materials alone since they use up all those bits and pieces that we'd otherwise simply trash.
Also they make them on a huge jig table and hydraulically ram the plates in better than we could do manually.
Plus each one is an exact copy of the first.
Another bonus is they only use KD #1 wood therefor much lighter.

In my area most yards stock a range of prefab shed/garage trusses.
The last one we did was for a 24 x 36 building.

jthibodeau89 · Dec 23, 2021

tfuller said:
Here is a place in Augusta, GA that should be able to help you out Armour Metals

The metal shed sttle trusses are not shown in 30' span. Perhaps they can build custom. The steel trusses are usually placed on 10-12' column spacing with 2x6 purlins for pole barns. Not the same structure as wooden trusses, but can be adapted to stick frame walls on a slab. Would need 5 steel trusses for a 40' wide building

buckeyefarmer · Dec 23, 2021

When I needed floor trusses to span my garage I just went to the manufacturer and they designed them for me. Same with roof trusses.

Egon · Dec 23, 2021

Go to a few suppliers and get Quotes. They will be able to design and build the trusses for you.

Prefabbed is the way to go. Building them you’re self involves setting up jigs and lots of angled cuts. The cost will probably end up the same as self built or even lower.
At thirty feet you may need equipment to place the joists. Again an area that may be easier/quicker done by an experienced crew. A slightly crooked roof can be real fun when the roofing material is applied.

buckeyefarmer · Dec 23, 2021

I put 30 ft trusses up with my tractor FEL.

Egon · Dec 23, 2021

buckeyefarmer said:
View attachment 726152
I put 30 ft trusses up with my tractor FEL.

Ive put up 28 foot trusses with a ladder and myself.

John0829 · Dec 23, 2021

Egon said:
Ive put up 28 foot trusses with a ladder and myself.

Yeah, BTDT and won't do it again!

N80 · Dec 23, 2021

When we built our cabin we started putting the trusses up by hand using ladders and scaffolding. It was not hard per se but it was slow. Then a neighbor was able to get his old boom truck running and that made things super easy. Then the truck broke down again and sat there for weeks but I didn't care.

That old boom truck is now rotting in a field somewhere so this time I will have to come up with something else. I like the rig @buckeyefarmer showed but my tractor has a fixed bucket so not sure how I would put that together. Will have to get creative.

3Ts · Dec 23, 2021

Similar to Buckeye's post but I had to reach over an 8' porch to set 24' trusses at 10' up. The trusses were only about 150# so not that heavy, but awkward and pretty high up. It's a 20' H beam attached to a set of forks.

Another bonus is they only use KD #1 wood therefor much lighter.

That's not been my experience, I found a grade stamp on one of the web members stamped as grade #3. But, I'm ok with that since they are all engineered with load calculations for each member of the truss.

sunandsand · Dec 24, 2021

I'd use light gauge steel trusses instead of wood. Stronger, lighter, fireproof, termite proof, about the only thing you can't do is hang a block and tackle on it to lift something, you will bend it (but of course you can also break a wooden truss that way).

Price of lumber has come down a little, and you no longer need a police escort to take the scraps to the dump (boy scouts will do nowadays), but steel is better and competitive anyway (YMMV).

Lots of fasteners for steel to wood, wood to steel, the biggest problem in building with steel is people are unfamiliar with it. Personally, I'll never go back to wood. (Wood is for hippies, steel is forever!)

Pix below is a 24 by 36 structure, scissors trusses. Don't know the price of just the trusses, it was part of a package of a panelized home. Went up FAST, too. The trusses have to be lifted from the TOP, lifting from the bottom bends the bottom chord. Lifting from the top also makes it much easier to set the trusses into position and fasten them to the top plate with LOTSA strong screws. 140 mph wind load rated.

Tony H · Dec 24, 2021

N80 said:
I am in the process of planning a shop for down on my property. I have no idea if this will become a reality as it is still early in the planning stage. What I want/need is a 30x40 3 bay shop.

I have had a site prep guy out and he says location is fine and won't need too much earth moving at all.

I will be milling my own lumber. I will be doing most of the work myself. It will be on a concrete slab (concrete contractor). It will be stick built. Probably on a low cinder block knee wall. 5v crimp metal roof. Looking for about 12' of height clearance inside.

When I built my log cabin kit 20 years ago it came with prefab wooden scissor trusses for a single peak roof. They were no problem to install.

However, I would prefer that my shop have a shed roof that slopes to the back (where drainage is best.) I would prefer to have a clear internal space with no posts/columns.

My question is this: Can pre-fab shed type trusses be purchased? Any guesses on cost? Is it feasible to make your own? Any ideas much appreciated.

Most lumber yards can farm out your truss desires to a truss company. These companies calculate snow loads for what you need.
When you use trusses, they go up relatively fast. They are accurate with the other ones so you get a nice roof if you set them accurately. Some issues include; No Attic Space... they are 2x4's so any idea of storing things in the rafters needs to be dismissed. Not mention the trussing deletes open attic space. Because trusses are 2x4's, the roof collapses very early on IF you have a fire. Many counties require a sign outside of structure showing the truss construction. The sign is for firefighters to not enter. Fight from outside. How do you plan on lifting?

LouNY · Dec 24, 2021

Something I don't hear anyone mentioning is the elimination of bird roosting places unless you want bird droppings on every thing.
Trusses and C channels are open invitations for them.

mgstevens · Dec 24, 2021

If you are able to mill your own structural lumber and are asking about DIY trusses, one then guesses there are no building codes or enforcement of same in your area. Here in BC, to use self-milled lumber for structure, you need it graded, or an engineer needs to stamp the plans, and carry the liability, which usually means the lumber will be triple-sized.

In any case, as many have noted, go pre-fab. Their engineer will design them, any building authority will approve them, and your ease and speed of assembly will increase dramatically. Properly designed, 30' span should be no problem at a reasonable cost. It's an unfortunate time in human history to be requiring building materials of almost any sort. I've delayed building anything until we see an easing of these tight-market prices.

But unless you have no restrictions from a local authority, and can feel confident you are designed for the local snow load and all attachments can withstand wind loading, you'd be better off paying for pre-fab, in my opinion. Building is a lot of work, a lot of cost, and to have something fail down the road is not worth the additional up-front cost.

jthibodeau89 · Dec 25, 2021

The 25 yr old 2x6 King trusses on my pole barn were sagging and carpenter bee infested. Replaced with built in place CFS Howe truss. I would have preferred a bar joist truss, but that required removing and replacing the entire roof. These should last the remainder of my lifetime. I am in TN, so no appreciable snow load, we occassionally get ice, though. Jacked the ridge beam up about 3" and inserted truss members. Welding next to the hay bales was interesting.

Rustyiron · Dec 25, 2021

You need to consider what you'd like for overhangs before you order them. They'll probably just extend the top chord out to your desired (soffit) dimension but this will be much easier than you building them up in the air.
I'm a firm believer in a healthy overhang to "move" rainwater out away from the walls and foundation-slab. 16" is nice and greatly contributes to the design and appearance as well.
Also keep in mind that the "tall side" will be 5' (@ 2/12 pitch) higher than the wall with a mono pitch truss. That might not be what you've envisioned.
While it's a simple building, do yourself a favor, go to Staples and buy as big a they have pad of 1/4" squares graph paper. Sketch it out using a 1/4" scale. That's would be each block on the pad would equal a foot. It's very easy to make it any scale that you want, just make each square equal to whatever you like for more or less detail.
Doing this will reveal some things that you didn't consider previously and will be a huge help overall including estimating your materials.