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After a month delay due to snow, I am preparing to build my 10x16 lean-to shop.

It will have 3 4x4x10s across the 16ft length in the front, and 3 4x4x8s in the back.

I plan to be open air, with the two long sides covered by half walls and one short side by a full wall of metal sheet. The roof will be sheet metal corrugated roofing.

 

I am building it on an existing 25x35 slab, with 4" thick concrete.

Regarding anchoring the posts into the concrete, I have researched the premade concrete anchors that sleeve the 4x4 and have bolts set into the concrete.

 

I want to make sure that my building does not catch wind and pull those out.

Other options I have is to pour concrete footers around some of the posts, with bolts running through the wood and two bolts stuck into the existing concrete to grab the new concrete in two places.

 

If anyone has some wisdom. They can impart regarding my thought process, I would greatly appreciate it.

My main concern, as always, is that with a lean to, I do not want to create an airplane wing and rip the anchors out.

Cheers, 

Ridgeway Forge Studio 

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Since you already have a nice, assuming level slab, I would go with standard 2x4.  4x4's are expensive and better if you are digging a hole and cementing in the ground.  You could attach 4x4's to simpson bracket with titan concrete bolt and make it work fine, but.  I would use treated 2x4 for base plate and then drill and bolt into concrete.  Use torque screws, assemble wall, fold up wall, plumb wall, bolt into concrete and repeat.  Double plate top of wall and make rafters with overhang  to keep rain off of wall.  Metal roofs are fun.   Make sure you allow clearance on lean to roof rafters for forge pipe.  Best luck on project.

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Upright 4x4s on 8'centers seem a little underbuilt for me.For the back and sides I would just do a stick framed 2x4 wall, maybe go on a 24" spacing. Bolt down as Will said above. For the open front, maybe some short 2' wing walls on either side with some diagonal bracing then run a double 2x10 or 2x12 across the  opening. If you want the full 16' opening in the front, go with the doubled header with a 4x4 post in the center, set on  and screwed to a post anchor bolted to the concrete.

Steve

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Simpson strong tie 4 x 4 anchor (whatever it's called) and ram set it into the concrete. My preference is a frame wall construction as described above. Both those boys appear to have framed a structure or two. I've done it but am FAR from an accomplished framer. If you're in a high wind area I recommend you screw the roof down and finish as you like. I'm a fan of steel myself and increasing the screw count goes a long way in high wind areas. 

We doubled the screw count ad halved the interval on our steel roof but have enjoyed gusts in the 140mph range a few times in the last 23 years. Rare but it happens, 70mph isn't uncommon. 

I own a copy of, "Carpentry for Dummies." It's worth it. 

Frosty The Lucky.

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My concern would be the shear strength....please bare with me through this analogy lol!

Think of your structure like an empty pop can, with good balance you can pretty much put all of your weight on it. But...with the slightest lateral pressure, it folds. So when you put the weight of the roof on, it's kind of the same principle. The 1/2 walls would help if sheathed (I believe you are using metal?) and fastened securely, but coming in 2'-3' on each corner and sheathing from top to bottom would greatly increase the shear strength. Also if you run purlins across your rafters to fasten the metal to would help stiffen the roof system adding lateral bracing. Just my 2 cents, not sure if it helps...I might be brand new to smithing, but I've spanked a few nails lol!

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This has given me a lot to think about- 

I will be using purlins between each rafter, as well as 45 degree bracing on the corners and tied to the center posts. The walls will not really be framed, just 2x4x8s with metal roofing screwed to them, so only coming up 4ft off the ground. 

Regarding the wind, we get a prevailing wind towards where I have planned the high end of the lean to. Would it be better for structure to swap it so the prevailing wind rides the angle of the roof instead of being against it?

My main concern isn't the roof weight, as I have done this style several times to great success..

Mostly concerned about wind pulling at the 4x4s and trying to pull it off the slab...

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Simpson strong tie makes a huge variety of metal ties sold at every hardware store.  Use a hammer drill, drill into concrete, use concrete expanding bolt with Simpson tie or drill through treated wood base plate and use concrete expanding bolt.  Some hardware stores have display with different types of concrete expanding bolts also only use drilll bit specific for concrete.  

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15 hours ago, Ridgeway Forge Studio said:

This has given me a lot to think about- 

I think you're on the right path, glad to hear you'll be using purlins and angle bracing. I think the strong ties would work fine, prior to their existence we just toe-anchored posts & didn't have issues so they're an upgrade. Also, I would recommend using the ones that have a raised base plate that keeps the post about 1" off the surface, helping alleviate any heaving from freezing underneath. If you want added upward pull insurance, you could always get some "L" brackets for the sides of post to slab (or if you know any blacksmiths they could make them :) lol!). 

Edited by Mod30
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I used these simpson titan bolts to attach rafter hangers in my concrete shell monolithic dome home to suspend the entire loft.  Hammer drill and screw in.  You could forge the  L brackets like bending lawnmower blade.  Even twist a railroad tie for anchor.  I broke many heads off of cheap anchors, very frustrating after drilling a hole in concrete.  Titan bolts are $1 per but will not break, worth the money.  

3/8 x 3" Simpson Titen HD Wedge Bolts 316 Stainless Steel ...
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I have never had much luck twisting RR *ties* perhaps a RR *spike*?

Maryland gets snow and rain, I'd think a lot about putting in sliding barn doors so you can open the shop up for use; but protect it from storms.

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40 minutes ago, Will-I-am said:

I used these simpson titan bolts to attach rafter hangers in my concrete shell monolithic dome home to suspend the entire loft. 

I've had good experience with these also. Another consideration would be if the components (base, bracket, fastener/anchors) react to each other. Metalurgically (?) speaking lol

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If you buy name brand concrete anchors, brackets, ground or concrete contact lumber folks in a lab with hundreds of years experience have taken dissimilar material  reactivity issues into account and solved them. There are extreme situations but I doubt you have any. 

I certainly wouldn't face the OPEN high side INTO the wind:o unless I had a reason to funnel it for maximum effect. 

Asking that makes me think you might want to hire a professional to design and build your shop. At least you'd have someone who's licensed, bonded and insured  to cover any mistakes.

Frosty The Lucky.

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when I built my closed sided shop, I did  2x4 walls and used 3.5 inch Tap-Cons to hold the bottom plate to the slab I also used gasket  between the slab and wood, of Aluminum sheeting and roofing material for vapor barrier

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53 minutes ago, Frosty said:

If you buy name brand concrete anchors, brackets, ground or concrete contact lumber folks in a lab with hundreds of years experience have taken dissimilar material  reactivity issues into account and solved them.

I completely agree. Any manufacturer of anchoring systems has done the research/testing and following their recommendation would be a good thing to do. 

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Compliance is huge, hate to get it all set up & end getting fined or worse yet forced to demolish. Not to insult your intelligence, but if you intend to install any permanent electrical that might require a permit. Sounds like you're doing your research though and top of it. Look forward to seeing your new shop!

Edited by Mod30
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Frosty, setting the ridge into the wind was not really my intention, more my consideration as to aesthetics, at the request of my grandparents (whose property it is! :)

however, I just wanted to be sure that I would not be making a suction system by angling it the other way- had a problem in one if my old shops built the same way. 

As far as i was able to check, legality will jot be an issue.

I will not be running electricity into the shop, and if needed there is an exterior plug on the adjacent carriage house that I have run my bandsaw off of.

some of the design elements of the shop are fairly dictated by the powers that be (wife), as my budget was about 800, and it looks like I will come in around 750 for the whole thing.

Picking up my brother's hammer drill, and will review the plans with him as well. He's a contractor and woodworker in Harrisburg PA.

I'm very grateful for all of the input, I wanted to check with people far more knowledgeable than myself before I set something in stone (pun intended!)

-patrick

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One more item you might consider to ease your concerns about uplift are hurricane clips. Quite simply its a piece of flat metal with a 90* twist in it allowing 1/2 to fasten to the side of the rafter/truss and the other 1/2 to the fasten of the top plate of your wall/header. I know Simpson makes them and only around $1/ea so are pretty cheap insurance.

PS, sorry MODS for incorrectly using a quote

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  • 2 weeks later...

I'm late to the party but it shouldn't matter in the event you like my suggestion with regard to "aesthetics, at the request of my grandparents (whose property it is "   People who live on small acreage estates often want large animals and must satisfy their HOA with animal shelters.  A very popular feature added to shed roof is a short roof overhang/bill/cover on high point of shed.  Imagine a short sloping roof( 2'-3' ) cantilevered off the high end of your shed roof.  It improve's appearance plus break's wind lift.  

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