Now I'm Thinking of Building an A-Frame...

[MountainDon]

Alan looks like you are smack dab in the middle of 10 psf (50 year data) no harm in assuming weather could continue to be more unpredictable and go for 20



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[MountainDon]

Comment on metal roofs and snow.

This winter one of our big storms was preceded by sleet which gave everything a nice pebbly surface. The snow that followed stuck like glue and was wet and heavy to boot. We snow shoed up to the mountains. Our cabin with its 5:12 had snow as I would expect. Our neighbor's 12:12 metal had the same amount of snow stuck to it as well.

So yes, steeper pitched metal roofs often shed snow more readily than shingled roofs or roof with less pitch, but it does not come with a guarantee.

I also noticed that the house roof that has been on a few years now is not as slippery to walk on as it was when new.

[ajbremer]

Don, thanks for all of that information on snow load but what does psf change in a persons build? Am I right in thinking only one thing - the rafter width? Like instead of a 2x6 roof rafter a guy might have to use a 2x8 - or a 2x12 even?

Does a heavy psf require a thicker roof sheathing like instead of 9/16 a guy might be better off with sheets of 5/8 thick on the roof?

Now that I'm starting to think of these things, how about the use of trusses and the design of them, collar-ties, maybe even thicker wall stud width to support the weight of a very heavy snow load?

[Don_P]

Some things that come to mind,

Rafters are the main thing, you can change species, grade, span and spacing but keep following the load down.
Sheathing does have load and span ratings.
Rafter ties are restraining thrust caused by the roof load trying to spread the angled rafters. The prescribed tie connection changes with snowload.
Studs, only if very heavy loads that would require full engineering or if tall.
Decks, a snow load can be higher than the occupancy live load and that would then determine member sizes and connections.
Foundation, the load must be safely transmitted to ground.

Trusses are engineered for snow load, snow and wind, unbalanced snow and wind, then the worst combination is used to design the truss.
It isn't a good idea to think that a roof will always shed snow.
The lowest live load to design for is 20 psf.

[EaglesSJ]

Just ran across this and wanted to comment on the pitch of our roof. We did a 24 pitch roof (every foot over equals 2 ft up) we did this because we wanted straighter walls with more room. The higher the pitch the more room you will have (and the more difficult the build) Many people will post the thread of the failed a frame cabin and why he swapped back to a more common design. IMO building the A's and trying to stand them up is a very poor way of building one of these things. Our method we pretty easy and would be even easier with more man power. After the ridge pole was set in place myself and my friend dan (neither of us over 160 lbs) put in the remaining 50 26' 2x8 rafters. Now had we have built them on the ground and stood them up we would be pushing 400 lbs or more of material so I can see where that would have been dangerous.

Anyways best of luck in whatever you decide. My main reason for building what I did was cost and to be different than everyone else. Ive never liked to follow common practice. Sometimes this comes back to bite me but other times it just makes me smile.

[ajbremer]

Thank you EagleS] for your comment. I still love a-frames and yours most especially! I've read all through your post and now that you've explained your pitch, it makes me want to go back to the decision to build an a-frame.

Now that your a-frame's been up for a little while - is everything ok with it, is there something you would have done differently if you could do it again...as far as maybe the way you did the piers or beams or anything else?

I'm going to go back and read through your build again, I find it really cool...maybe I'll change my mind 'again'. Thank you sir.

[EaglesSJ]

The only thing I would have done differently is put a basement under it. But we didnt have the money last year to do that so I am going to dig it this year under the bottom 1/2 of the house. That will be pretty easy to do since it is so high back there anyways. Other than that there is nothing I would do differently. I am not at all trying to boast or brag but we had to put a gate up at the top of the drive because so many people were stopping in and telling us how much they loved our little cabin and they wish they had of done something like it instead of the one they built. Lindsay and I absolutely love pulling in to the drive and seeing this little thing setting down in the woods. Its just a neat little place. I liked it so much that I built a matching home fore my chickens!

I also like the how strong the place is. There is no other design out there that will give you the strength of an A. Everyone triangulates in between their piers and basically anything that needs bracing. My entire house is a triangle. 

[MountainDon]

Alan, now that we have the snow load question answered there is another. What is the soil like? How much weight can it carry? Is it wet/moist most of the time, etc. The county should have that information available (hopefully). That will determine foundation issues; if piers and footings, how many, what size?

There is a web soil survey available... http://websoilsurvey.nrcs.usda.gov/app/  That may help. Some soils are simply not well suited to piers.

What foundation does your current home use? What is typical in the area (and has not listed or developed other faults?  I believe ScottA said elevated slabs are common in his area od OK. That's a concrete block stem wall a couple courses high and a poured slab within the full perimeter.

[Triathlete]

I have a fondness for A-Frames, at least the uniqueness of them and perhaps the speed of enclosure framing them.  Beyond that I would not build an A-Frame after living in a woodstove heated house with a steep roof.  Climbing up a relatively tall steep roof several times a year to clean a chimney is no picnic, not to mention cleaning it once you are up there.  One slip on that roof and it will be a quick trip to the hospital.  I'm old enough not to court danger.