New build questions

[River Runner]

Good Day,

I am getting my material list ready so that I can start framing in 8 weeks. I completed the foundation last summer and it currently sits under 4' of snow. Anyhow, let me preface by stating this is not an engineered structure, it is being constructed under an agricultural permit, but I want it to be done well. Building is 40x64 with 12' walls.

Main use is a shop and shelter for feed and some cows on the backside. I am however trying to make this dual purpose by utilizing attic trusses to create 1,400 sf of space up top for some part time living quarters/storage. The goal is to eventually build a house on the property at a future date.

Due to the insane costs of lumber and sheathing I am trying to reduce where I can. My thoughts are 2x8's on 24" centers with a single top plate and stacked directly under the attic trusses. The attic trusses are big with a 23' opening and webbed bottom chords. 8/12 pitch. My thought is that the 24" oc studs and single top plate will help with reduction in lumber for a building this size. Any issues with the strength on this?
Sheath walls with 5/8 or 1/2"?

I am also toying with the idea of skip sheathing the roof instead of using solid sheathing due to costs. I would then use metal corrugated roofing. But, with a conditioned living space in the attic will I be doing a big disservice by not using decked roof?

Your insights are much appreciated. Thanks.

 

[TractorJeff]

In My Opinion For What Its Worth:
Living Space in the Attic will require a Double Top Plate to support the Weight.
Sorry!

 

[River Runner]

TractorJeff,

I was thinking that too but then I saw some details for advanced framing and it appeared that if you stack the trusses directly on top of the studs the load is transferred down and not between any studs on the top plate. Maybe I'm incorrect in that thinking or detail?

 

[manwithtools]

TractorJeff,

I was thinking that too but then I saw some details for advanced framing and it appeared that if you stack the trusses directly on top of the studs the load is transferred down and not between any studs on the top plate. Maybe I'm incorrect in that thinking or detail?

I think you are correct on that. I'll wait for some more experienced folks to chime in, but 2x8's directly under the truss with single top plate rings true to my recollection.

 

[scofo]

I've worked in auto shops for my adult life. The ones that were just metal with no decking or no insulation were absolutely deafening when it rains.

 

[pmiranda]

IMO, it's never worth saving $10 on a $1000 project, because it will cost you $100 to redo it right later. If I can't afford to do it right, I save until I can. Put off interior finishing if necessary to do the framing right now.

 

[walta]

I think you want a double top plat to keep the wall from bowing at every joint in the top plate.

Walta

 

[CraigStu]

I think you want a double top plat to keep the wall from bowing at every joint in the top plate.

Walta

I had read or heard about the 2x8s at 24"OC and thought it might be one of those, 'wow that is brilliant' thoughts. But walta has a great point. The second top plate is also used for an overlap at the corners. I wonder how these concerns are dealt with.

 

[yeldogt]

You don't try and save money on things that can't and will not be fixable .....

x2 on a building that will be used for an extended time and you may use as living space

Common rookie mistake -- sorry. Do it right .... I agree on the noise close to ceiling if the future plan goes forward

 

[puttinonthekritz]

I just completed something similar to your build. For context mine is a 46x46x14 stick built with 2x8 walls, 24" oc with and 8/12 pitch attic truss. My attic space is a 20x46 area with a 4ft wide stairwell leading up the space.

I purposefully did that spacing as well for load bearing purposes and saved enough money from "traditional" 16"oc to offset switching from 2x6 to the 2x8. I figured I'd keep the strength and allow me to utilize an R30 bat in the wall cavity. I did retain a 5/8 wall sheathing to increase racking strength and mostly because I think 1/2 is barely adequate.

Regarding your questions, I'd recommend the double top plate (that's what I did for strength, especially at 14' wall height). Your 200ft linear of 2x8 will compute to an additional $300-400 at 2021 current fiasco lumber rate. I'd say small details like that aren't where you should be trying skimp, especially since your build doesn't seem to be a cheap build from the start.

The webbed truss are a good call and have higher live loads for storage, exercise equipment, pool tables, or if you are going to create an apartment up there. I had the option of doing my trusses like that. However, due to cost I went with a 'standard' attic truss style with 2x12 bottom cords. In addition, I have 3/4 Advantech flooring. In hindsight I wish I would have done the webbed bottom cords for a little more solid feeling and maybe stepped up to 1 1/8" thick Advantech flooring. But at the end of the day, cost is a give and take and depends how you want to use the space.

 

[dcg9381]

I was thinking that too but then I saw some details for advanced framing and it appeared that if you stack the trusses directly on top of the studs the load is transferred down and not between any studs on the top plate. Maybe I'm incorrect in that thinking or detail?

I've seen construction techniques for using joists, not trusses, below the top plate, attaching them to studs, and blocking below them. This won't save you any wood, at least after blocking below... It does load the studs directly and you're stuck with the spacing of the studs..

I ran into it because I have a height issue (16' ceiling) and need to reduce the height of the floor a bit.

 

[wayout]

If it's 'being constructed under an agricultural permit' and 'due to the insane costs of lumber and sheathing I am trying to reduce where I can', have you considered using ungraded lumber from a local sawmill if available?
'Residential' code requires graded lumber for structural components but, at least where I am, outbuildings can be built with less expensive locally sourced lumber.

 

[River Runner]

Thanks for the thoughts. I have done a fair bit of research on advanced framing with single top plates....it appears that this is a very standard practice for advanced framing techniques. Im not saying it's better or worse, just a direction that framing is going to reduce materials and decrease thermal bridging. It definitely takes more planning as everything has to be stacked and your top plate needs to end splitting the top of a stud with the next top plate, and requires strapping. I think I'll definitely use plywood sheathing on the roof instead of skip sheathing to create a more solid and tight envelope.

In hindsight I would have continued with 8x8x16 block for my walls that I used for the stem walls but I've already grouted the cells and installed the anchor bolts. Its more labor but block is much less than lumber these days, not to mention easy to clean on the inside.

 

[danfromsyr]

never skimp on framing and supportive structure.
always go better than code minimums on span charts and spacings.

even if it takes a little longer..

 

[nadogail]

If you don't have the money to do it right the first time, when will you have the money to do it over?

 

[River Runner]

If you don't have the money to do it right the first time, when will you have the money to do it over?

So are we saying that framing 24" oc with a single top plate is not right?

 

[puttinonthekritz]

24” of framing is fine. Just add the second top plate.

 

[Daniel Dudley]

If you are reading advanced framing techniques, you should try to follow them. Most of us here do things in what was the universal style since not long after WW2. It is a system.

If you are building to a different system, you should have a detailed framing plan with every detail rendered. If there is a building inspector, or if you have any questions about it, you should refer them to an engineer who is at least somewhat familiar with the techniques you are using. Just because it is different, doesn't mean it is wrong.

I am personally very happy with the way I have been building for the last 40 years. When I deviate from that, it is because the details are specified on a set of engineered drawings. If you are building a cat, maybe you put webbed feet on it, or maybe you stick with paws all the way. Most of us would use a double top plate. But is that the detail you have been reading about?

Put it on paper, and discuss it with someone familiar with the style. A lot of the so called new construction is centered around less materials to avoid waste, and to reduce thermal bridging. But there are other ways to get around thermal bridging, and an extra stick or two of wood here or there can solve a lot of problems for a extra 10% in cost.

As long as you are using proven details and not making things up on the fly, you will be fine. I have built a lot of things over the years, but I always have plans, or at least detail sketches, even if they are drawn on a grocery bag. If I don't, things have a tendency to come back and bite me on the ***. It is a proven thing that if you can draw it you can build it. And anyone can look at it and discuss it with you intelligently without using their imagination. And you will often know the sense of it just by looking.

A more minimalist style needs good details, but again, that doesn't make it wrong. You can do it if you are adhering to a proven path. If I tell someone how to do something, there may be many other ways to do it, but you will be able to do it my way, and it will follow all the way from A to Z. Put it down on paper.

 

[tarmy]

Do it once...do it correctly.

This one is 32x56 with living above like you are thinking. Snow country, stick frame and I hate bouncy floors and wanted it strong (earthquake country) and to have a beam hoist downstairs as well. The trusses were designed for all of that. 200Amp panel, heaters the whole deal...but I friggin love it.

I realize that you may need to cut some costs out. Just really think things though and consider what you cut out as something that may bug you later.