Lean-to Post Bases

[TJP89]

OK, I'm going to attach a lean-to off the side of my barn this spring. The plan calls for 2 sets of 4 by 4 supports. What I need then is bases for 8 load bearing posts. My BIL is a contractor, and he told me to sink concrete piers into the ground to below the frost line. Then embed post anchors in the wet concrete at the top. I followed his advice in making a plan, but I'm unsure about the post anchors. The ones I've ordered are below. Can I just put these in the wet concrete or do I need to bolt them in, or both. Advice on whether I'm on or off the right track here is appreciated.

Link: Simpson Strong-Tie ABA 4x4 ZMAX Galvanized Adjustable Post Base-ABA44Z - The Home Depot

 

[Sysop]

Generally you would use anchor bolts. They're a long, large bolt with no head. In place of the head the shaft is bent into an L shape.

When you pour your concrete, do so above grade and slightly dome the top so water will run off, then stick the anchor bolt into the concrete with only the threads exposed above the concrete. Position it at the exact center point of your post. When it sets up drop your post base from your link above onto the anchor bolt and put a washer and nut on it to hold it into place.

Additionally, when attaching the post to the base, I advise running your nails or screws or whatever you're using at various angles. Running them all straight in allows them to vibrate out easier.

 

[s219]

OK, I'm going to attach a lean-to off the side of my barn this spring. The plan calls for 2 sets of 4 by 4 supports. What I need then is bases for 8 load bearing posts. My BIL is a contractor, and he told me to sink concrete piers into the ground to below the frost line. Then embed post anchors in the wet concrete at the top. I followed his advice in making a plan, but I'm unsure about the post anchors. The ones I've ordered are below. Can I just put these in the wet concrete or do I need to bolt them in, or both. Advice on whether I'm on or off the right track here is appreciated.

Link: Simpson Strong-Tie ABA 4x4 ZMAX Galvanized Adjustable Post Base-ABA44Z - The Home Depot

Those are meant to be bolted or shot (stud driver) down. There is a different type that can be placed in the wet concrete -- will look sort of like those on the top, but have a long "stinger" on the bottom that sticks down into the concrete. They are fairly common, so keep looking, you'll find them.

 

[Coyote machine]

Installing Post Anchors - Deck Building - How to Design & Build a Deck. DIY Advice

Many ways to do post anchors, but do NOT just install any nut and washer when using pressure treated wood. First choice, stainless steel, 2nd choice, hot dipped galvanized. No exceptions! ACQ lumber will eat anything other than the two I referred to.

Also:https://www.google.com/search?q=con...rce=univ&ei=Ak1EVbyQC4LwaPavgMgG&ved=0CDgQsAQ

Note: Simpson Strong Tie has discontinued L bolt type anchors for use in concrete.

 

[redman135]

One little point over looked, tape up the threads so concrete spatter doesn't gum up the threads.

 

[bdog]

Today I was digging the piers for a lean to I am building on to my shop. It is going to be 24' wide and 50' long. It will have six columns supporting the roof made out of 8" I beam. I plan to use weld plates like the attached picture and weld the I beams to them. I am not sure what is best if you are using wood posts.

My question is how big do the piers have to be? Digging the holes with my backhoe they got pretty large in area in order to get what I thought was adequate depth. Thinking of maybe sticking in a sonotube and backfilling with dirt to reduce the size.

 

[LD1]

Note: Simpson Strong Tie has discontinued L bolt type anchors for use in concrete.

I havent heard that.

Any reason as to why? Got a link?

I would think the bolt would break long before it would pull out. Especially looking at all the other types of concrete fasteners out there, I would think an L bolt would be the weakest.

 

[EddieWalker]

OK, I'm going to attach a lean-to off the side of my barn this spring. The plan calls for 2 sets of 4 by 4 supports. What I need then is bases for 8 load bearing posts. My BIL is a contractor, and he told me to sink concrete piers into the ground to below the frost line. Then embed post anchors in the wet concrete at the top. I followed his advice in making a plan, but I'm unsure about the post anchors. The ones I've ordered are below. Can I just put these in the wet concrete or do I need to bolt them in, or both. Advice on whether I'm on or off the right track here is appreciated.

Link: Simpson Strong-Tie ABA 4x4 ZMAX Galvanized Adjustable Post Base-ABA44Z - The Home Depot

First, I wouldn't use 4x4s for anything structural. They are strong enough to support the weight of a properly designed structure, but with the new methods used to create pressure treated wood, they tend to bend and twist really bad. If you buy 8 of them, odds are good that several will bow on you over time. I would be surprised if all of them ended up bowing on you in a few years.

I only use 6x6's. I've seen 4x6's bend, so that's the only option for something that you want to remain straight.

If it was me, I would sink the posts in the ground. This gives you more strength and stiffness. Mounting them to the tops of concrete should work find, it's just more work and a slightly weaker structure. With a solid barn to attach the roof to, you should be OK either way. You can easily attach a regular hex head bolt to that type of Simpson bracket and set it into the wet concrete with good results. That particular bracket is generally used for existing concrete and drilling into the concrete to attach it with an anchor bolt. For maximum strength, you need to give the concrete a few days to a week to set up. A month is when it will have 90 something percent of it's strength, but for building, you're fine after a few days.

How are you going to attach the roof to the barn? Most failures occur because the ledger board was not properly installed. Ideally you want to bolt it into the wood framing of the barn. Here in Texas when I put on roof off of a clients house that's brick, or something that I can't get a proper ledger board attached, I put in posts next to the brick and support it from the posts.

Do not use screws or nails. Be careful on lag bolts because they have to be a certain length and you have to use them in a pattern with a set distance to be effective. If you get it wrong, the roof might fail. To get it right, you have to decide on what you are going to use and then figure out what the proper size and spacing is for them.

How are you going to attach your joists? Will the roof be the joists or are you building rafters or a truss? Resting them on top of the ledger board gives you the most strength, but if that's not feasible, be sure to use the right joist hangers. Gravity isn't the only thing trying to take your building down. Wind comes in every direction, and uplift is just as bad as sideways winds.

Good luck,
Eddie

 

[s219]

Today I was digging the piers for a lean to I am building on to my shop. It is going to be 24' wide and 50' long. It will have six columns supporting the roof made out of 8" I beam. I plan to use weld plates like the attached picture and weld the I beams to them. I am not sure what is best if you are using wood posts.

My question is how big do the piers have to be? Digging the holes with my backhoe they got pretty large in area in order to get what I thought was adequate depth. Thinking of maybe sticking in a sonotube and backfilling with dirt to reduce the size.

What you can do is figure out the maximum dead loads and snow loads the roof supports (will be in psf) then multiply by the roof area, then divide by two and again by six. That is an approximate estimate of the weight each column would need to support if everything was even (you can add a factor of safety based on unknowns, or just do like me and assume slightly higher dead/snow load than is usual). That number will be in pounds. You can again divide by the area of the footing to get psf or psi and see how that compares to the soil bearing capability where you are. Will require knowledge of the soil type and its specs. Another way is to just look at what other people have done in your area and determine if that's good enough.

If it's open to the elements, you will need to consider uplift resistance too, as well as possible side loads from wind. I had to get engineering done for my pole barn footings to satisfy the building inspector, and the biggest issue was not direct uplift, it was sideways loads allowing the poles to push over in their holes, which then led to uplift failure. For that reason, we were unable to backfill around the poles with the spoils from digging the poles, but rather had to use concrete (just dry mix, no water) to backfill the holes all the way up. All along I had though pure uplift was the main concern with pole barns, but the sideways loads were the weak link for my soil type.

For one lean to I saw built in my area, they used a backhoe to dig open the holes, then poured concrete about 12" deep (with rebar) to get a nice big flat footing. Placed the pole on top with an anchor, and then backfilled around the hole. No real need for a sonotube in that scenario.

 

[Ford850]

This is closer to what your BIL was talking about. It embeds into the wet concrete, but there's no room for error on these. You must have them aligned perfect when you set them.
Simpson Strong-Tie PB 4x4 ZMAX Galvanized Post Base-PB44Z - The Home Depot