Al and Robins 20x30 1 1/2 near Lake Eufaula, OK

[Don_P]

The first "truss" was actually a "frame" where this is an assemblage of stable triangles, a truss. The "legs" are tied better, not best, better. A scissor is tied but it deflects and produces thrust, much less, but it is there.

The tech used higher loading than the previous guy I think. In the 12/12 he has 1/2" horizontal deflection at 158 lbs of thrust at each truss under full load. Think about that as you tie the trusses to the kneewalls and as you connect the floor joists to the studs. Under full load there is a college linebacker pushing out on each truss foot as hard as he can without losing traction. There is 133 lbs of uplift. I'd ask about using a framing angle flat on the top of the top plate and into the truss.

Actually regular #2 southern pine 2x4's straight from Lowe's is adequate for the <5' spans of the chords, stud grade is adequate for the webs. If you can sit down with the tech try higher grade for the top and bottom chords and then plug in 2x6. Every smidgen you can drop the interior pitch will improve those numbers. I agree with MD, include raised heels in this if possible. Watch the horizontal deflection, reaction and cost while doing this.

Take field measurements of the 2nd floor deck to kneewall height. Using that as your baseline draw all of this to scale and make sure it works inside and out. I would think about another 12/12 truss to nail against the pitch transition framed gable wall. The other gables will be framed, I would drop them 3-1/2" and pass lookouts over them to support the gable overhangs.

You are not out of options, take your time, ask questions.

[UK4X4]

heheheheee call that a truss ! this is a truss.............I can see where my higher costs are comming from
these are the gable ends

[duncanshannon]

Holy cow... whats the deal with those?

[MountainDon]

White stuff called snow most likely. And lots of it. Plus it's a gable end and must handle more wind load across the end, I think. Wider span too most likely.

[ajbremer]

Wow UK4X4, those are some massive trusses.

I called the truss builder and told him that I would like the raised 8 to 10" heel like MD says. I also told him that
I would like it stronger so he said he would change the top and bottom chords to 2x6's. I'll have the quote before
the day's out and I'll put it here as usual. It will be interesting to see how the math changes.

All of the online trusses tended to be flat roofed when I googled raised heel trusses.

Thank you again Don_P and MD...al

[UK4X4]

Yep lots of snow 90lbs added support required for the outriggers
The inner trusses just have the basic diagonalsand linking verticals

[MountainDon]

Link to...  Document with simple illustration of conventional vs raised heel truss detail

I wish they had been used back in '85 when our present house was built. 

[Alan Gage]

Just something to throw out there regarding heels and local lingo.

I told my building supplier I wanted raised heels. He said, "oh, an energy heel."

I, not know anything said, "ummm, yeah."

Anyway after we talked a while we both became more confused about what the other was saying. Sketches ensued and we figured out the discrepancy. Around here an energy heel means the bottom cord isn't cut at a taper where it joins the top cord, gaining you a couple inches. That's what they were familiar with locally. I was thinking of a raised heel, like Don linked to above. Must not be too common around here as they thought it an odd request but were happy to oblige. I'm sure the truss company does it all the time though.

I ended up going with an 8" raised heel, which in addition to my 2x6 top and bottom cords gives me 19 inches. I think it was an extra $500-800, but I could be wrong, I don't remember for sure. This was for a hip roof so lots more pieces that needed to be "raised" in comparison to a gable.

Alan

[ajbremer]

Friday Morning - March 2nd, 2012 Mid-Oklahoma

The truss man must have gotten busy yesterday, I'm awaiting my 2nd truss quote today.

Here's some shots of raised-heel trusses that I've found and put together:



More progress:

[ajbremer]

Friday Night - March 2nd, 2012 Mid-Oklahoma

Ok, I got my new 'revised' truss quote. I spent a little while talking to the truss builder before
he did the quote. I told him about the suggestions I got - about adding another 12:12 truss to
nail against my pitch transition framed gable wall and dropping the gable end trusses 3 1/2" so
I can pass lookouts over them to support the gable overhangs. I also told him I wanted raised
heels.

I mentioned that I wanted to lessen the 158 lb thrust against the walls caused by the 12:12
trusses and for him to see what 2x6's would do. He tried the 2x6's and said that it actually
caused more thrust so we stayed with the 2x4's. He also had me change from 24" o/c to
16" o/c and said that it would lessen the thrust against the wall going from 24 to 16.

The weirdest thing that I noticed is that in my new quote, the dropped 12:12 gable has
no overhangs. I emailed the truss builder and asked him why.

I took a couple of screen shots of the 6:12 truss, the old one and the newer revised 'raised heel' one.
On a side note, I thought the raised heel would happen by way of a vertical member but he used
the members under the top chords.

Here's something I put together comparing the old and newer quote:



Now, here is my actual quote in 5 pics. Please let me know what you think
and I appreciate all of the help:

[Don_P]

I'm suprised the deeper members made things worse

I had really intended that the gables would be stick framed, simply dropped 3-1/2". The gable trusses introduce another hinge in the wall. It is laterally supported by the ceiling, do follow all the footnotes and google the BCSI pamphlet to study that bracing. Do put bracing on the top side of the bottom chords to hold things until the ceilings are installed, it'll be tender until they are in.

We are catching wind tonight that reminds me of why it is good to build stout.

That is a typical raised heel for me.

Delete truss 20 3-1212g. I was trying to be lazy and get the wall backing by using an extra truss... the price of that will be too dear.

If these are on 16" centers then it should be easy to look at the wall studs and confirm their quantities. It would be good if the first bay between a dropped gable and the first regular truss is ~24".

Overhangs are field framed by you, they are not included. You will need material for fly (or barge, or verge) rafters (those are different names for the gable end outboard overhang rafters). You'll also need 2x4 lookouts that pass perpendicular, from the last common truss, over the dropped gable truss and out to support the fly (this is why it is good to have a wide gap in the first truss bay, it improves the backspan on the cantilevered lookout. The first common truss will land over the window stud in the front room, skip the little bay). You'll need 2x subfascia along the lower edge, there will also be a ledger along the wall and soffit framing underneath.  There is alot of detail framing done in the field.

On the floor framing, in the front room, fill the I joist web zone between the joist and stud and nail that all together well. This is the restraint of that last bit of thrust. Don't forget to lower the walls before sitting the joists on top of them for the 2 story half of the house. Save the cutoff stud ends, that is good blocking, soffit nailer, etc. There needs to be an LVL "joist" supporting each end of the catwalk.

Edit: Ahh I now see what you mean by

The weirdest thing that I noticed is that in my new quote, the dropped 12:12 gable has
no overhangs.

When you lower the top chord of a common truss the dimension of a 2x4... the overhang disappears
But the lookout framing will replace it 

[astidham]

Al,
you should get a Quote from Pryor truss, at least to gt your more local truss company to match...

[astidham]

also I meant to mention, I bought my gable end trusses, and would stick frame my own like Don_p said, if I had it to do all over again.

[new land owner]

Al

     I went with the xtra truss and nailed to the wall for the tranistion.  When your project is 5 hrs away from home speed is important.

[MushCreek]

I just had the 'raised/energy heel' truss conversation with my contractor. At this point, we are thinking of going ICF all the way to the eaves, and he said that you don't need raised heels, because the extra wall thickness of the ICF gains enough height. Well, if the wall is 12" thick, and the trusses are 5:12 pitch, you gain 5". Coupled with the 3-1/2" bottom chord, that =not enough. He thought 8-9" of blown-in was more than enough in the SC climate. In that case- why would I consider ICF? Do these guys think about what they say?

[Don_P]

Nah, you just have to nurse us around until it's our idea, and then let the idea be ours, diplomacy in action... that door swings both ways before the project is through, don't worry  .

Excellent pic NLO. Notice that an extra common truss has been nailed to the sheathed transition wall. It could be just a 2x4 nailed along that wall to support the roof sheathing and another level of 2x4's along the wall to support the ceiling plane. Slapping another regular truss against the wall is fast and easy, but is more expensive... judgement call.

[Redoverfarm]

Al I realize that you are overwelmed at this point but have you ever considered an "attic truss".  It would render you more usable space.  I put these on an addition at the house.  The truss manufacturer gave me an option of 12' or 15' room with either 5' or 3' knee wall with 10/12 pitch. Yes they are a little more expensive but in the long run the benefit outweighs the cost.  That reminds me I still have this room to finish.  12' X 44' over a 26'X44' garage. Just thought I would give you some idea of other options.

[Don_P]

I was going to remind Al to lower the gable walls and pass the floor over them, then start the upper rake walls from the floor. If you use attic trusses this would complete the job by lowering all the walls to 8'. If you look at Redover's trusses the rafters "launch" from above the walls. If the bottom chord extends on out to the fascia the rafters can launch from there... this would effectively raise the roof elevation back up to where it was before removing the kneewall. With TJI's stocked up there I think Al has already passed that intersection.

This is a 2x12 stick framed roof with 2x6 lookouts passing over a stick framed 5-1/2" dropped gable wall. My parts are wider but the framing is the same as what I've been envisioning;


It is nice to block between rafters or trusses. It strengthens the assembly and helps resist lateral loads. If this is a vented roof notice that the blocks are dropped about 1-1/2" below the rafter top edge. This allows ventilation intake air to pass up over the insulation rather than trying to blow through it at the lower edge. If it's a sprayfoam unventilated roof the blocking runs up tight and forms the backstop for the foam so you don't fill the soffit. You can see the top plane of the overhang framing at the far end;

[ajbremer]

Saturday Afternoon - March 3rd, 2012 Mid-Oklahoma

Thank you all for so much information, it can get pretty overwhelming for a guy who 8 months ago
didn't know the difference between a joist and a rafter. I'm not saying that I'm so overwhelmed
that I don't think I could ever build my roof with different pitches but I have changed my mind once
again. I'm going to go with the original plans that John has created and stick with the 10' walls and
the 12:12 pitch roof using the site built trusses.

I do love the way a loft looks when you add the shed dormer / pitch change look but due to time
constraints, money, and a dried-in time limit put on me by my home owners association - I think
that it's best to make things simpler and faster.

So my plan now is to complete the sheathing on the outside all the way around and then to
finish the rest of the interior walls which is very minimal. After that, I plan to sister stud the
I-joists into the wall cavities and insert backing in the i joist making sure that their connection
to the walls is very good. Then will come the loft sub-floor, I plan to use 5/8 OSB there.

Me and my wife have apparently decided to not use a catwalk between the main loft and the
nook loft. That nook loft is going to be 8'8" out from the gable wall and it'll use 5 i-joist 24"
between each. The main loft will be done the same way, same height, but at 16" oc.

When the loft floor is complete, I will then begin to build the site built trusses according to
plan. I wish I knew what the horizontal thrust was for those site built trusses just like I knew
about the thrust of those truss quotes that I've gotten. I think Don_P mentioned that there
was thrust with the site built 12:12 trusses but I've seen a lot of builds here that use them
with no problems.

Many people have given me much information for me to do the pitch change and all the
work that it contains and I am very grateful and have learned a lot. Some of the things
that Don_P says to me are hard for me to understand at first read but I take it slow, think
about what's been said, google the subjects, ask a few more questions, read it 10 or 20
more times and before ya know it - I 'almost' totally understand it. To me, it's like talking
to a rocket scientist when I'm still trying to figure out how to fold a paper airplane! Not
eally but you know what I mean.

So, my wife just told me to stop talking here and get out there and put up another sheet
before it gets dark...she's right. Oh, by the way, my wife understands just about as much
as me and more sometimes. She reads all of this stuff and helps me out a lot to. I am so
thankful for her help.

[MountainDon]

...using the site built trusses.

Keep in mind they are not real trusses and if the county or local authority having jurisdiction was enforcing things according to the IRC, they would not be permitted without an engineers pedigree. John's plans mentions this eventuality/possibility. Not saying they are bad; just saying there are better choices that are tougher and provide lower horizontal side loads on the wall tops....

...wish I knew what the horizontal thrust was for those site built trusses...   

My guess is that is going to be greater than the number for the first truss design you got; more properly called a frame according to Don_P, if you recall. I guess that because the materials are lighter than those in the first quote you received. Just a guess.

[Don_P]

I can assure you, NASA hasn't called  I'm glad you read elsewhere to check on us and to fill out your understanding. Like any profession there is alot of jargon unique to it.

The "correct" way to proceed, if that matters, would be to use trusses similar to the first quote, or a ridgebeam (this leaves the most options, eliminates thrust) or site built trusses with an engineer's blessing.

The joists need to be securely attached to each stud using web fillers in the connection. This is part of the thrust restraint for the roof. I believe this dictates that the joists are on 16" centers.

A 10' section of missing floor tie, 10' tall walls with unknown site built trusses on top... that doesn't make me real comfortable.

This is the original truss spec sheet. Look at the reactions section, there is 101 lbs max horizontal, the max horizontal deflection is ~5/8" (.62"). On the 10' tall unfloored section the walls have nothing to resist that thrust, the wall will bow out 5/8" under full load.

[ajbremer]

Sunday Morning - March 4th, 2012 Mid-Oklahoma

Well, I got up early thinking about thrust so I studied the subject once again for about 2 hours. I found
an older post where Don_P had the thrust formula so I plugged in some of my own numbers and played
around with them a bit.

As other people have said here before, the Nash cabin was my main inspiration for deciding to get the
20 x 30 with 1 1/2 loft plans. The loft up there looking down on the great-room below is very spacious
and gives it a country look to me that can't be beat. If I use trusses then some of that height will
disappear. I think the best way to go is with a ridge beam supported at both gable ends and one
place near the middle.

At first I wanted to go with those site-built trusses in the plans but I want to totally get away from
the wall thrust situation and the ridge beam method looks like it does that job better than anything
else. I would think that at a 12:12 pitch, with rafters sitting on the beam, the walls will actually be
taking some inward thrust from the weight of the roof pushing down on the wall at a 45 degree
angle. But I perceive that to not be a problem because of the loft joist and the couple of rafter
ties that I'll use across the building in the non-loft area.

Now I just have to decide what to use for a beam. I read somewhere here where a guy had a
30' beam and it weighed 800 lbs!? Aren't there any beams much lighter than that that will do
the job?

[Don_P]

Where is the support post location? Follow that in a straight path from a pier below, a direct load path from ground to ridge. This will give us the span lengths to figure from. From there we can size the ridgebeam and see what it is. After something weighs over about 200 lbs it really doesn't matter if it weighs 1,000, you're going to have to outsmart an inanimate object that has gravity issues  . If the ridge does not move there is no thrust, in or out. If the ridge drops there is outward thrust. If the ridge rises there is inward thrust. If the ridge rises... shoot down the UFO to break the tractor beam.

[Bob S.]

Is it possible to build a beam up? Would it be feasible to build it up in place? Maybe you could buy another long board like the one you alredy bought. Don might be able to give you some insight.

[Don_P]

It will probably be at least 2 members thick, it can break over the support post if we have to. Let's get the span lengths first and see what we are working with.

How are you accessing both lofts with no catwalk?