Barn raising, sortof

[midlf]

Well I've been off TBN for a bit. Glad to see most of the familiar names are still here. Some time ago we were "acquired" by Chloe, a goffin's cockatoo. Long long story. Anyway she doesn't do well alone and we have limited caretakers sooooo we decided to get a motorhome so she can travel with us. (yeah, I know, we're nuts but what momma wants momma gets). So now we have this and I want to get it into our barn so I can work on this antique 12,000lb hot rod with plumbing. The picture of our "barn". The section to the right (east) is where we want the motor home to go into.

I'm posting a bunch of pictures and drawings to show the problem and to ask for ideas cause I sure need some help here.

 

[midlf]

This is the east end of the barn prior to our raising the door. It was a bit too low.

 

[midlf]

We raised the door header to allow the motorhome to get in. To get the door to work with the new opening we split the original door and had it go both ways. The header is now 124" high, plenty of room.

 

[midlf]

This is the existing roof framing. 30ft clear span. I would like to keep the span clear. Rafters are 2X8 and joists are 2X10. The joist is a collar tie that keeps the rafters from spreading the walls. I need to get additional clearance down the center 10 feet as noted on the drawing. This is the clearance I need for the GMC motorhome and for a two post car hoist. I need more than just the minimum clearance for the motorhome so I can jack it up and work on it indoors in the winter. The barn has heat.

 

[midlf]

This picture is the interior of the barn. The collar ties/joists shown are the problem. I want an additional 36" of clearance down the center 10 feet of the 30 foot span. I'd settle for 30". The height is to allow the motor home to be jacked up for work and for clearance for a two post car hoist. The joist is 111" above the floor. The motorhome is 114" over the storage pod, 111" over the front AC unit, 108" over the rear AC. The barn is 30ft clear span. The rafters are 2X8 and the collar tie/joist is a 30' 2X10.

 

[midlf]

Two more shots of the barn interior. Different angles to show the peak of the roof.

 

[midlf]

Here are two views of the collar ties/joists and rafters where they connect to the walls.

 

[midlf]

This is what the build office at the lumber yard proposed. I could live with the height at the center if it was most of the way across the center 10 feet of the garage. However it starts to get a bit low at the edges of the 10ft wide center area where I need increased clearance. This will be strong enough to bear the load but I'm looking for that little bit of increased clearance. Some extra effort at this time will save a lot of "rats" later.

 

[midlf]

This was one suggested truss configuration. It would give me the height but I don't think it will work. I doubt the 2X8 has enough strength at the connection between the two triangles. It might work with some extensive rework of the rafters with sistering, perhaps with some stiffeners. I know just enough to get myself in real trouble or to be very cautious. I'm going with the cautious as I don't want the barn to collapse.

 

[midlf]

This is another idea for a truss. Make the rafter strong as a truss and use double collar ties. This is shown as a single line drawing. Each line would be some type of 2X. Probably with plywood gusset plates glued and screwed at the joints.

 

[midlf]

I'm open to any suggestions or to a website for ideas or calculators. I have talked to structural engineers but they admittedly are not super familiar with in place wood truss construction and tend to want a steel solution, with columns down the sides of the 10 center section. I would really like to find a wood truss engineer but have been unable to locate one without buying pre-manufactured trusses, which would require completely redoing my barn roof.

Any input would be appreciated (except getting rid of the bird or the spouse, I'm quite attached to both of them.)

 

[Egon]

Would idea 1 be possible using two longitudinal beams with columns at each end? This would only be for the length of the motor home.



Structural firm and specify wood. I'm sure a design can be done.

Will the modifications have to be certified and inspected?

 

[midlf]

Would idea 1 be possible using two longitudinal beams with columns at each end? This would only be for the length of the motor home.



Structural firm and specify wood. I'm sure a design can be done.

Will the modifications have to be certified and inspected?

The structural people that did the modified scissors design looked at a longitudinal beam design but at the peak. In steel it was way more expensive than the modified truss and in laminated it was no better. I may have to go with some form of columns if the modified scissors will just not work.

Not sure yet on the inspected. It's not a domicile and in a rural area and the building is already there with no changes in the sq ft to affect taxes. It is my preference that they would not have to be involved but we're not as easy here as where Eddie Walker is.

 

[EddieWalker]

You have several problems, and each of your truss designs create as many problems as they solve. The sissor truss was my first thought, but it would be expensive, and at 30 ft, beyond my abilities to design. It's just too far of a spread to know what it will take to build it.

Your other designs fail to address the spread of the walls. Tying them together is as important as keeping your pitch.

I think you have three options. The cheapest and easiest is to put in load bearing posts. The ones you have for your horse stalls would be a good location for that side of the building. Replace what you have with some 6x6's that are either in the ground deep enough for your area, or on footings that are strong enough. You'll have to determine that for your area. Put a double header on top of the posts to support your rafters and then tie the tops of the posts on either side of your RV together with a joist. Kind of like your drawing, but with posts to support it.

Your second option is to spend allot of money and put a load bearing beam across the peak of the roof. Either the length of the RV, or the full building. This will be very heavy and pricey, but it will allow you to keep your freespan. If it was me, I wouldn't do this, as it's a very big job. To support the beam, you will have to have another across your door as a header, and have the right amount of support for the load of that beam concentrated at both ends of it. Not my idea of a quick,easy solution.

My best, and probably cheapest in the end, solution is to extend your barn with a roof design for your RV, or just build another barn for it. You can do it Pole Barn style with posts in the ground wide enough to get your RV in there and put trusses over it. 16ft wide won't be that dificult to truss and I'd be you'd be money ahead building from scratch then trying to engineer something that will work in what you already have. Sometimes it's ALLOT easier,faster and safer to start from scratch.

Run the numbers, including labor, and I think you'll be suprised.

Good luck,
Eddie

 

[mikim]

I'm going to go out in left field and throw out another idea ....a bit out of the box.... May not even be doable - but it's a thought. Go in the barn the length of your motorhome and find a spot where your trusses now sit directly on a stud. Take a circler and sawzall saws and cut the barn in half. Now release the bottom plate from the foundation, nail some blocking to the walls, borrow some hydraulic jacks, and jack the entire end of the barn up. Now build some walls to place under the old bottom plate and fill in every where else. ....I said it was from left field ...

 

[hitekcountry]

How long is the barn?
How long is the motor home?
What is the spacing of the ties?

You only need to modify an area long enough for the motor home right?
I have a crazy idea. I just need answers to these questions.

 

[schmism]

Ill run a couple of trusses in the softwere tomarrow when im at work.....

Your only hope is to sister some trusses next to the existing rafters.

YOu could go with some 32" OC ones that you can set next to every other rafter.

YOu can also go with a stronger structrual ridge beam with some LVL that ties into a girder truss 30' in. (so you only have to have one truss) Then you would be able to move the celing ties up and add as second collar tie.

Ill run some calcs tomarrow see what i come up with.

 

[schmism]

you can get 30' 4/2 sissors 32" OC (every other rafter) 2x6 over 2x8 with 25-5-1 loading

hears a hint from the truss profesional..... if you spec out a truss that has like a 2x6 heal height that gives you addtional room to manuver the truss in to place. then you just shim the bearing up tight once its inplace and plumb.

alternativly you can get a fairly simple 2ply girt flat BC truss 30' in to carry the 6750lb point load (30psf total load) at the peak from a new ridge beam. But the ridge beam is going to be something serious.... (multiply large LVL)

but that would allow you to more easly move the existing celing joists up and add collar ties to each rafter at ~ the 1/3 span point.....

 

[midlf]

How long is the barn?
How long is the motor home?
What is the spacing of the ties?

You only need to modify an area long enough for the motor home right?
I have a crazy idea. I just need answers to these questions.

The original barn is 30X70 feet. A 25' garage addition was added on the west end.

Motorhome is a 26' 1974 GMC. I would like to get it into the building by 3 or 4 feet to have some work/walk around room at the back.

Actual length is about 28'. Ties are 48" apart, rafters are on 16" centers.

The "barn" is built on footings with a block wall. It's real construction, not a pole type building.

 

[midlf]

Ill run a couple of trusses in the software tomorrow when I'm at work.....

Your only hope is to sister some trusses next to the existing rafters.

You could go with some 32" OC ones that you can set next to every other rafter.

You can also go with a stronger structural ridge beam with some LVL that ties into a girder truss 30' in. (so you only have to have one truss) Then you would be able to move the ceiling ties up and add as second collar tie.

Ill run some calcs tomorrow see what i come up with.

The scissors truss design in one picture is from the lumber yard building design staff. They are proposing these on 32" centers. They also considered a steel beam along the ridge but passed on that due to cost and weight. No mention was made about using LVL as part of a solution. Their proposing that this truss would be built on site by adding the lower member to the existing rafters.