has anyone heard of "framing trusses"?

[sirswank]

as i lurk and research my future garage plans, i've come across an interesting roof truss design and cannot seem to find any more information about it.

it's called the frame truss, and looks similar to an attic truss, except that the legs are used to raise the wall height, thereby giving more space to the second floor.

this website, where i found the pic, is date stamped 2006 and claims these have been used in Denmark, so i'd imagine they'd be suitable for a sizable snow load.

http://adm.aau.dk/fak-tekn/phd/diss0102/ellegaard.htm

i've seen all the images Google can pull up of all the various truss designs, but this is never shown. i've also browsed the truss threads and found nothing. i'm curious if anyone has seen these, has any experience with them, and can provide any arguement for or against trying to proceed with a roof truss design like this.

thanks

 

[reverand2000]

Search for information on scissor truss. I think that might be what you want/need. One use is to raise ceiling so a lift can be installed.

 

[Falcon67]

I'm not seeing anything special about a "frame truss" on top of an 8' wall vs a 10' wall with sistered studs to support joists at 8'. I suppose if you are taking the roof off already on an existing structure it would be some labor/material savings.

 

[KPSquared]

I just added 2' to the heel of my attic trusses. . . Gave my 8'1" in the centre and 6'1" on the sides. 14' of my 30' wide shop. It was only an extra grand.

Here's a couple pics:

 

[boiler7904]

I've seen roofs stick built the way the OP showed but not trusses.

Curious how this design would hold up in a coastal environment with hurricane wind load requirements for construction which I think most if not all of RI is subject to.

 

[Herb67SS]

Just as a point of reference, I used "attic trusses" on a 28' deep and 36 wide building with an 8/12 pitch roof. This resulted in a clear center area 12ft wide the length of the building ( had i not used scissor trusses the last 16 ft for a lift bay) with a sloped ceiling from a 4 ft knee wall to over 8 ft at the peak. That's a bunch of attic space. The joists are 2x10s.

 

[Nostraquedeo]

Looking at the Frame Truss, makes me think one could build a small knee wall on the upper-level, then install regular rafters with a cross member at the top. Might take more time, but probably cheaper. In that drawing you posted, there appears to be a center post or structure of some sort, so your attic floor would really only be spanning half the distance of the structure. That's basically my construction, minus the knee wall, which I thought of doing. My center structure is a steel I-beam, over-sized to hang 2000lbs from. The beam runs perpendicular to the garage door, so the garage door header is another steel I beam.

 

[tomroblee]

I've seen something similar used for building relatively small sheds, and I've seen something somewhat similar for timber framed buildings.

I would worry about using such a truss as a replacement for an attic truss if the building was very wide. This is because there isn't any triange bracing except above the "attic" ceiling, and the bottom cord would have to be extremely large to span the width of the entire building.

 

[Justanoldguy]

I see NO problem with that type of truss design.
Reason being. It IS A TRUSS and WILL be engineer
designed to suit it's purpose.
People find fault with it either don't understand the
term "Engineer designed" or think they are more
qualified to make judgement.
I suggest the OP taks to his Engineer and makes
it happen if he want the extra height.

 

[willymakeit]

At one time 30 or more years ago,we were doing truss assemblies with floor joist,wall stud and rafter combined for small structures.
With the correct ties and raising your exterior sheathing there shouldnt be any issues with wind ect.

 

[The Boss]

I don't see how that frame truss will work. The horizontal tie needs to be no more than 1/3 or the way up from the bottom of the rafter for that to even hope to work.

I used attic trusses on mine - 8 pitch roof, 36' span gave me a room 14' wide with an 8' ceiling.

 

[yousesteers]

Looks like what my barn built in 1941 has in it but the loft floor has a center support and looks more like loft and rafters to me than a truss

 

[glazier]

I see NO problem with that type of truss design.
Reason being. It IS A TRUSS and WILL be engineer
designed to suit it's purpose.
People find fault with it either don't understand the
term "Engineer designed" or think they are more
qualified to make judgement.
I suggest the OP taks to his Engineer and makes
it happen if he want the extra height.

What you said makes a ton of sense, that math stuff works every time in the right hands.

 

[LutzTD]

looks weaker to me, maybe its just me. But think of a load straight down on the peak of both of those trusses. the second one is triangulated at the base but the first is not. What keeps the load from just pushing those short walls outward when the triangle tries to grow at the bottom?

 

[Nowater]

Look at the angled 2 by going from the floor joist out and up to the roof truss at the point you said-where the triangle will try to grow at the bottom. Also look at the other 2 by members going from the top chord (like the roof rafter) down to the bottom chord (the floor joist if you will). All of those pieces are triangulated. Those short walls really aren't walls at all, but a picture at a different angle would make it easier to see. Still, I too, wonder if it could take Florida hurricane winds, and to what speed.

 

[rsa]

Take a look at hockey88fan's garage. Click on the pic for his build thread...

 

[theoldwizard1]

First I would not call that a "truss" in true sense of the definition. Trusses are designed to distribute the load to top and bottom members. Technically, the top member is called a collar tie.

I like the design, because it gives a lot of attic space. I would be very concerned about how the knee walls are connected to the first floor top plate and how it is connect to the rafters.

Roofs try to push the walls out and I don't think simply nailing the studs in the knee wall would hold them perfectly vertical, although the collar tie does help limit the outward deflection.

 

[theoldwizard1]

I see NO problem with that type of truss design.
Reason being. It IS A TRUSS and WILL be engineer
designed to suit it's purpose.
People find fault with it either don't understand the
term "Engineer designed" or think they are more
qualified to make judgement.
I suggest the OP taks to his Engineer and makes
it happen if he want the extra height.

+1 !

The span and height of the knee walls are an important part of the equation. I suspect if the span is large (>20' ?) that you may have to go to a design more like KPSquared.

 

[Nick Ferry]

I just added 2' to the heel of my attic trusses. . . Gave my 8'1" in the centre and 6'1" on the sides. 14' of my 30' wide shop. It was only an extra grand.

Here's a couple pics:

What are some of your dimensions? I am looking at building a 20' long by either 16' or 20' wide shed/garage. What is your length,width,side wall height, head room in the attic, width of the attic?

Thanks in advance