Author Topic: 24x32 A-Frame build Northern Sierras  (Read 14333 times)

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Offline black_edelweiss

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24x32 A-Frame build Northern Sierras
« on: August 05, 2016, 07:54:54 AM »
I bought 5 acres on June 15th in a remote part of the northern sierra mtns. Access is via 20min on a dirt road, and property borders state park land on 2 sides. The area gets a lot of snow, so access in winter in only by snow shoes/snow mobile. This will be me and my wife's primary residence year round once completed. We just sold our house which is about 25miles from our new property and have to be out by sept 15th. I am building this house almost entirely by myself. It took me about 1 week to clear out the manzanita so i could actually drive into the property, 2 weeks to dig the footing, and about 2 weeks to mix and pour 450 bags of concrete. All of the material was delivered to my residential house, and i had to load and drive it out the the property as a semi-truck would be unable to deliver it to the property. I currently have 2 out of the 8 pallets of cinder blocks laid out, as my stem wall will be 8ft tall and my A-frame will be built on top of that.













Offline nailit69

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Re: 24x32 A-Frame build Northern Sierras
« Reply #1 on: August 05, 2016, 03:16:10 PM »
Damn... I feel for you.  I just laid 550+ 8x8x16 block and mixed about 350 #80 bags to fill my foundation... glad that part is done.  I just finished up my framing and need to get it roofed and buttoned up before winter hits... my place is 5+hrs. away though so kind of hard to just "run out to the cabin".

Offline black_edelweiss

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Re: 24x32 A-Frame build Northern Sierras
« Reply #2 on: August 05, 2016, 04:15:49 PM »
Yea I'm lucky that i can drive back home to take a shower and eat every night...it would be a lot harder if i had to camp out for days at a time. Do you have a journal on here?

Offline nailit69

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Offline black_edelweiss

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Re: 24x32 A-Frame build Northern Sierras
« Reply #4 on: August 06, 2016, 06:12:26 PM »
I've been laying blocks for about 5 days now...i've never done this before so slowly figuring it out as i go. Ive made a couple mistakes so my wall in a couple places is a bit wavy...hoping to fix that by setting a thicker mortar bed on the next row and leveling them exactly to the string line. I'm almost done with the fourth row which will contain two rows of horizontal rebar the whole way around...going to do this every 4th row. There will be a total of 12 rows of blocks. Anyone have any tips to make this go faster? It seems like I can only get a couple rows done in 7 hrs of work.

A few of the cinder blocks do not have vertical rebar that has been anchored into the concrete footing. Planning on just sticking a section of rebar in them anyway before i fill the cores with concrete.








Offline nailit69

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Re: 24x32 A-Frame build Northern Sierras
« Reply #5 on: August 07, 2016, 01:15:16 AM »
Looking good... plenty of vertical bars too... code (in Wa. and Or.) is @ 4'-0" on center for the verts and 2'-0" for the horizontals I believe.  As long as that top course is on the money it probably doesn't matter how wavy the previous courses are.  Sorry, no tips on going faster.

Offline NathanS

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Re: 24x32 A-Frame build Northern Sierras
« Reply #6 on: August 07, 2016, 12:26:40 PM »
Lookin good. You got line blocks? Build those corners up a few rows perfectly plumb and square then run line blocks with masonry string along the wall. Then you just lay blocks to the line. Double check the blocks for level perpendicular to the wall till you have the hang of it.

You can run mortar down the tops of the blocks ahead of time and just butter the edges of blocks as you go.

In my thread I link to a YouTube video of a pro showing how he does it. I'm on mobile right now though so hard to link it.


Offline nailit69

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Re: 24x32 A-Frame build Northern Sierras
« Reply #7 on: August 07, 2016, 04:54:43 PM »
Lookin good. You got line blocks? Build those corners up a few rows perfectly plumb and square then run line blocks with masonry string along the wall. Then you just lay blocks to the line. Double check the blocks for level perpendicular to the wall till you have the hang of it.

You can run mortar down the tops of the blocks ahead of time and just butter the edges of blocks as you go.

In my thread I link to a YouTube video of a pro showing how he does it. I'm on mobile right now though so hard to link it.

Ya... what he said.

Offline black_edelweiss

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Re: 24x32 A-Frame build Northern Sierras
« Reply #8 on: August 08, 2016, 05:50:13 PM »

Thanks for the info..

Offline black_edelweiss

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Re: 24x32 A-Frame build Northern Sierras
« Reply #9 on: August 08, 2016, 05:51:17 PM »
Ya... what he said.
Looking good... plenty of vertical bars too... code (in Wa. and Or.) is @ 4'-0" on center for the verts and 2'-0" for the horizontals I believe.  As long as that top course is on the money it probably doesn't matter how wavy the previous courses are.  Sorry, no tips on going faster.

Thanks, found the video in your journal, nice wall btw. I have a couple pairs of line blocks, but wasnt using them correctly, so i messed up part of my wall which i fixed today with a perfectly level new row on top. Seems to be going a lot faster now that im getting the hang of it and watched that video which helped.

My vertical rebar attached to the footing got covered in block today, so instead of attaching another length with wire, i decided to just drop a full 8ft long piece in each core before i fill them. The wall is getting too tall for me to be able to get the block over a 5 ft length of rebar, and cant imagine wire holding the rebar together would make much of a difference in strength..? Maybe im wrong. It seems the 3 rows of horizontal rebar will add an enormous amount of strength in case of an earth quake.

The 8ft tall wall will be completely buried in snow all winter, so will need to start thinking about water proofing soon.

Offline nailit69

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Re: 24x32 A-Frame build Northern Sierras
« Reply #10 on: August 08, 2016, 07:21:01 PM »
Might not be the right way but I dropped my vertical bars down full length from the top of finished wall and then filled it with pretty wet cement in one almost continuous pour, we ran 25 or so bags short.  Considering the general nature of the construction of the wall I doubt cold joints would be as big of an issue as it would be on a concrete wall.  Mine is solid as hell and isn't going anywhere anytime soon.

Offline Don_P

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Re: 24x32 A-Frame build Northern Sierras
« Reply #11 on: August 09, 2016, 12:46:55 AM »
The wire is to hold the bars in close proximity which does make it stronger... getting above my grade. If you can bend any kind of "hook", deformation, in the end, before dropping it down the hole it will help quite a bit. Anything you can do to scaffold yourself to a comfortable working height makes the work go faster as well, just be safe. One of our rapid trips to the doc was a bad rebar cut.

Offline flyingvan

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Re: 24x32 A-Frame build Northern Sierras
« Reply #12 on: August 11, 2016, 03:16:17 AM »
I'm very impressed with your willingness to build a solid foundation in a remote location.  Too often a post and pier foundation is planned 'because we can't get a cement truck back there'.  Your effort will pay dividends in the long run
Find what you love and let it kill you.

Offline pmichelsen

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Re: 24x32 A-Frame build Northern Sierras
« Reply #13 on: August 11, 2016, 05:53:54 AM »
I have posted this before...

I've used this in the past when doing foundation work: https://www.whitecap.com/shop/p/basf-corporation-masterseal-hlm-5000-roller-grade-5-gal-51677002 followed by a dimple board.

Here's an image from the web if you're not familiar with dimple board...


Offline black_edelweiss

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Re: 24x32 A-Frame build Northern Sierras
« Reply #14 on: August 11, 2016, 08:44:35 PM »
Thanks for the help and advice.

Only have 3 rows left, decided to do 11 total rows instead of 12 as i can see 11 rows will provide plenty of head space. Still contemplating which way to build the floor that will go over this stem wall...my original plan was to attach joist hangers to the block wall and use 2x8's which would span 12ft and attach via a joist hanger into the 8x8 center beam. This would make it so the weight of my roof and the wind/snow it endures would be directly supported by the stem wall/sill plate.
The other way im thinking about would be to run 2x10x12's so that they are setting on top of the cinder block wall and on top of the 8x8 center beam...i would then attach a rim board to the butt ends of the 2x10's the whole way around. This method would be much easier to install and stronger but the weight of the roof and wind/snow would be supported by the rim board, which i wouldnt think would be as sturdy. My main concern is the steep pitch of my roof and high winds. I'm planning on attaching my roof rafters to the base of the house with hurricane ties...not sure if there is a better way?



Offline ChugiakTinkerer

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Re: 24x32 A-Frame build Northern Sierras
« Reply #15 on: August 11, 2016, 09:08:45 PM »
The weight on the rim board can be mitigated by using a doubled or tripled rim board.  It's common when building log cabins on a platform floor to do that, so that the weight of the logs is borne by a wider rim joist.

Depending on your specific application, blocking between the joists and abutting the rim board could also serve that purpose.
My cabin build thread: Alaskan remote 16x28 1.5 story

Offline NathanS

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Re: 24x32 A-Frame build Northern Sierras
« Reply #16 on: August 12, 2016, 11:48:04 AM »
Man I just nailed about 40 hangers into an LVL. It was brutal. I have nailed close to 150lbs of nails by hand since last fall and I was bending 1 in 3 or 1 in 4 nails into those freaking LVLs through the hangers.

I like Chugiak's suggestions, and also I hadn't heard of needing that much extra support in light frame construction at the sill. Don P could probably answer that a lot better though.

Offline flyingvan

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Re: 24x32 A-Frame build Northern Sierras
« Reply #17 on: August 12, 2016, 01:26:47 PM »
  Best tool ever for nailing ticos
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Offline Don_P

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Re: 24x32 A-Frame build Northern Sierras
« Reply #18 on: August 12, 2016, 06:56:51 PM »
I'm on my third one, they don't work as well for full sized nails in dense wood (Go carefully using "joist hanger nails" in most hangers, check the specs first, ticos usually derate the hanger load) I feel your pain on the nailing, been doing lvl's and old oak :P. A palm nailer into that density usually just folds the nail. An 1/8" drilled pilot hole and hammer was about the only reliable way to get them in. After years of that, holding a pen to sign the check hurts more than banging the nails.  Wood tech note, you can pilot for a dowel type connector 75-90% of fastener root diameter, depending on wood density. (no more than 75% if G<.6, up to 90% if G> .6) Oak is about .7, softwoods run around .35. An 1/8" hole is 84% of a 10 common or 16 sinker diameter, fine for these densities, I'm also going into the last inch or so without pilot.

Generally speaking rafters should be nailed to the sides of the joists to create a tie. sitting the rafter on top of the floor makes it more difficult to reliably tie, or restrain, the spread of the rafter feet. This is much more important at shallow pitches where the horizontal spreading force is high. An A frame has pretty low horizontal force, most of the roof load is directed down vertically. You have high snow loads.

I think best would be to bolt a sill down, roll joists with the roof angle cut on the ends (no rim). Stand rafters alongside of joists resting on sill and nail the rafters to the joists very well. The roof sheathing forms the rim. Fireblock between joists just inboard of the rafters to separate the floor bays from the roof bays. Block between rafters at each floor as well (lack of blocking is the reason they tend to burn so fast, compartment it) Sprayfoam or foam sheet over this type. Running strapping under the sill, wrapped and nailed well and then up onto the rafter would tie the building to the sill well.

If you do build the floor then set the rafters on a plate.. the plate needs to be very well connected to the floor framing. Then I would use joist hangers laying flat on the plate, bob the end of the rafter vertical for 1.5" and slide them into the hangers, there's the thrust restraint IF the plate stays put. It will at this pitch, non code. It is very hard to get enough nails into the plate to make it work for most pitches.

For localized crushing, I can't remember all your particulars but check rafter end reaction, determine bearing area, generally if reaction load/bearing area is below about 300 psi you are good to go. Wow, what a technobabble post this has turned into :D

I was going to suggest going 13 rows when you started, you lose 4" to slab and just about always end up with more stuff dangling down from above than you think. It really depends on the use.

The big ...pine? on the right looks mighty close. Being of the tree hugger persuasion I built tight in the trees. They are now 30 years older and looming big over the house. They have leaned into the hole in the canopy the house created. I call in the pros to drop them which gets expensive. Should have listened harder to she who must be obeyed lo those many years ago.

Offline black_edelweiss

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Re: 24x32 A-Frame build Northern Sierras
« Reply #19 on: August 12, 2016, 10:36:17 PM »
Thanks for the detailed response. The method you describe of bolting the rafters to the joists seems like a solid idea, but what keeps the floor joists locked in to the sill plate? Maybe im missing something, but it seems like it would be hard to brace and stand up the 2x10's 8ft up on a stem wall without a floor to stand on. Definitely would best to bolt the rafters and joists together, but i cant see how i would install that myself.

Since the total 2x10 rafter length will be 24ft long, i know that it would be far too heavy for me to stand the whole thing up on my own. To deal with that, i plan on assembling 16' rafters with the loft floor joists bolting onto the 'A' to hold them together. Once i get a number of these stood up, i will install the loft subfloor which will give me something to stand on while the roof decking will hold the "A"s together.. I can then install the remaining 8' long rafters which will be spliced and bolted on using a 2' length of 2x10 on each side of the rafter.

At this point thinking I will double up the rim board and use the joist hanger method you mention, thanks for that advice.

I would probably go to 13 rows for the additional height but am in a bit of a rush as this project needs to be shelled in by sept 15th...also would need to take a 4 hr long drive to pick up more blocks. Luckily the joists will be sitting on top of the wall instead of flush with it so i will not lose 8" by going the original route...another positive.

Offline Don_P

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Re: 24x32 A-Frame build Northern Sierras
« Reply #20 on: August 13, 2016, 05:11:52 AM »
Nail rather than bolt. Bolts are expensive, few in number, and concentrate stress. Nails are relatively cheap, use large numbers of them to distribute stress broadly over a larger area of a relatively weak material (wood). If you lose one bolt to splitting of the wood or for whatever reason, the remaining bolts take on a serious load. If you have a bunch of nails and lose one, not such a big deal.

With the joists in place and braced from rolling, you can temporarily floor to work from. I scatter sheets or lumber and screw lightly.

Wrapping a strap under the sill and running it up onto the rafter secures the structure to the sill.

another thought, I joists are light and long, would work for floor and rafters and they can provide the design and connection details. If you use spliced lumber I would lap long and nail rather than using splice plates. Outside of my comfort without an injunear.

Offline Don_P

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Re: 24x32 A-Frame build Northern Sierras
« Reply #21 on: August 15, 2016, 05:36:10 PM »
At this point thinking I will double up the rim board and use the joist hanger method you mention, thanks for that advice.

This calc will give the horizontal thrust from each rafter that needs to be resisted by the hanger to floor connection;
http://www.timbertoolbox.com/Calcs/RafterThrust.htm
If I enter 288" bldg. width, 115psf load, 24 pitch rafters spaced 24" on center, I come up with a 690 lb horizontal load. In that scenario a Simpson LUS24 is good for 705lbs. Nailing this directly to the floor deck, through the sheathing into the double rim would work. An LUS26 is good for 915lbs but would need to be nailed to a plate rather than nailed directly to the floor, the nail pattern on it is wider than a double rim. That adds another critical connection, the plate needs to be able to resist that load as well. You need to be connected with at least 350 lbs per lineal foot of plate of shear resistance to keep it from wanting to slide off the floor. Gun nails are good for about 80 lbs each in shear, you need at least 5 per foot of plate connecting plate to rim and joists (I would actually use a plate at least as wide as the rafter end).

To get a sense of how pitch magnifies that horizontal spreading force, keep everything the same on that calc except change the pitch to 4 and notice the thrust.

You are relying on the rim/floor connection here heavily as well, DO NOT end up with a little strip on the rim. You need to buy 7 rows of floor sheathing and start with a 2' wide ripped row. You should then end up with a slightly more than 24" ripped final row. Nail to floor joists and rim well.

Offline black_edelweiss

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Re: 24x32 A-Frame build Northern Sierras
« Reply #22 on: August 17, 2016, 05:06:59 PM »
Thanks for that info, very helpful.

Im done with the wall finally, just need to fill it with concrete which should take 2-4 days (hopefully). Had to take 2 days off to allow home inspectors in to my current residence, fix a hot water heater that wasn't wired to code, and allow my agent to inspect the house. Need to have a roof on in about 4 weeks as thats when we will be out of my residential house. Putting together an order of all the wood which will be delivered to a friends house and i will once again have to load it all and drive it out to the build site, luckily a shorter drive this time around. Also having a small backhoe come in to level the ground in the garage, as it has about a 2.5ft slope. Also arranged to have a 20ft storage container hauled in so we can clean out our house of belongings; will need to do a lot of brush/tree clearing to allow the guy to be able to get back in there, which is why we didnt opt for a 40ft container (narrow roads, not a lot of turn around space).

Bought 5/8" J bolts to tie down the 2x10 sill plate which i will concrete in every 36". For the rafters, thanks to Don-P, i will be doubling up the rim joist, and using the heavier LUS26 joist hangers to secure the rafters into a 2x10 top plate, each 'A' will be spaced 16" for a total of 24. I will also use joist hangers to secure the 2x10 floor joists into the rim board. I think this will tie the two rim boards into the floor joists much better and give the rafters a stronger foundation to tie into versus just nailing the rim board to the joists. I will also secure the 2x10 floor joists to the 6x6 center beam using hurricane ties on each side. The 6x6 posts will be spaced every 8ft and ill use 12"x48" sonotubes reinforced with vertical rebar with a post base concreted in. I will then run a 6x6 over the length of the posts which the floor joists will sit on top. I will use 19/32 OSB floor/roof decking for the whole project.

For the joist hangers, would it be best to use deck screws or nails? It seems screws dont have as much sheer force but are much harder to pull out, and it seems if anything was to fail it would be the rim boards being pushed down and out by the weight of the roof..?




Offline Don_P

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Re: 24x32 A-Frame build Northern Sierras
« Reply #23 on: August 17, 2016, 06:20:27 PM »
If you use a screw it needs to be a structural screw or a ductile screw... might as well say you need a structural screw. Personally, I think you are overthinking that part. If horizontal from the roof gets to the rim you are already done. The floor sheathing is doing more than the hanger will. The hanger is also not rated in that direction. I believe a strap up the rim and onto the floor would do more if you think there is a need, that would complicate the plate nailing.

I think a 6x6 center girder is incorrect... talking through it... 8' post spacing x 12' tributary width on the girder=96 square feet x 50 pounds per square foot floor load (40psf live+10psf dead)= 4800 lbs
Going here;
http://www.timbertoolbox.com/Calcs/beamcalc.htm
inputs
4800 load
96 span
4.5 width
9.25 depth
For #2spf,
Fb 1106
E 1.4
Fv 135 ... I'm passing at a triple 2x10 girder


TABLE R502.5(2) GIRDER SPANS in the codebook is the other (correct) way to check it. 24' is between the table's 20' and 28' columns, you can interpolate. Looks like the same answer there. Do block between joists over the girder.

Just checked a 6x6 girder, about half of the section modulus needed, no go.

The internal piers for the 6x6 posts.
you've got 4800 lbs, a 12" circle is about .75 square feet... probably overloading the soil
They can be 2x8 boxes about 2' square, set diagonally, diamond, to the building footprint. Top of pier at top of slab elevation. Put a post base standoff under the post into the concrete to keep the foot of the post dry. If and when you put a slab in the footing is at floor level and makes for easy sawcuts. At that size footing soil load is about 1200 psf, check. Inside the perimeter you don't need to go down for the footing, not a frost heaving place.

Offline black_edelweiss

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Re: 24x32 A-Frame build Northern Sierras
« Reply #24 on: August 17, 2016, 09:07:10 PM »
Thanks for pointing that out. I figured a 6x6 would be plenty but i guess strength comes from vertical width. It looks like a triple 2x10 would barely not be enough according to the chart. Thats disappointing considering it would fit on a 6x6 post nicely. I guess i'll upgrade to 8x8 posts and use 4 2x10s sistered together as the girder, what do you think?

Also, yes, the 12" sonotube would be too little and i will take your solid advice on the post footing. I've only built a shed and a deck so i greatly appreciate your help with this project.