Hanging indoors: concrete-specific questions

Howdy, y'all. Long time, no talk! My kiddos keep me too busy for much hammock camping these days. Hopefully as they get older, I can get them to hang in the woods, too.

Getting to my questions . . .

My wife and I want to replace our bed with a small couch for daytime use and hammocks for nighttime.

Outside wall is a sandwich of 4" concrete--2” polystyrene--4" concrete. The wythes of concrete are tied to the insulation layer by special, plastic form-ties.
The opposite wall is 17 ft. away. It is an interior wall that is 6" concrete.

I weigh 260#, but let's figure 300# for each hammock to build in a lot of extra safety margin. I plan to fabricate the anchors from steel plate, with 4 bolts in each (1 per corner). Unless someone has a better idea or thinks this is overkill. But how large should each base plate be? And what size bolts? Wedge anchors or something else?

For the two hammocks, how far apart should the anchors be on each wall to allow for slight rocking without bumping into one another?

Any other thoughts? I know there are a bunch of clever folks here..:D

Sounds like an interesting project!!! Wish I knew more about this style of construction and what type of lateral strength it has. Is there any type of rebar in either of the walls? I'm also wondering why this vs a stand?

Just to be clear, are the interior and exterior walls poured concrete, or concrete blocks?

Is the interior wall bearing or non-bearing (carrying a load or just a divider)?

Wedge or expansion anchors should have the pull out strengths labeled.

that house must be hurricane proof

I did a quick search and found this website that has LOTS of info on all the different anchor types: http://www.confast.com/concrete-fasteners.aspx This is a vendor, but they certainly believe in educating their buyers. Personally I'd probably go with wedge anchors. Spacing is a function of anchor diameter.

I would like to avoid stands because I want the floor space clear when we're not sleeping.

The walls are poured concrete. Each wythe has an embedded rebar grid.
As for the load-bearing: each wall has z-purlins that run across the tops of the walls, holding the metal roof panels.

I lean towards the wedge anchors, too (probably just cuz I've used them before). But according to the hammock hang calculator, I could get away with tapcons. Perhaps it would be sufficient to do a vertical, rectangular plate with just two wedge anchors.

My spacing question was more about hammock spacing. I've always hung solo. So I'm not sure how far apart I should put the two hammocks to avoid bumping into each other.

That's an educational site. I'm no engineer but I have two thoughts. First, if you wanted to go with the plate idea a 14 in plate with 3/8 in wedge anchors 3 in deep would over 3000 lb per bolt, not sure if you get to multiply by 4 or not. Second, it would look like you could go with something like a 3/4 in wedge anchor at 8 in to tap into the second layer of concrete on one side and 5 in on the other. That would give you about 10,000 lb and then thread an eye nut like this on the end, providing the threading is compatible.

On second thought that's probably way to over engineered. If my amsteel suspension is good at 1600 lb anchors in that neighborhood should be good too. 1/2 x 4 in wedge anchors with the lifting eye nut would be limited to the 2150 lb strength of the eye nut. That would give you an almost 10:1 safety ratio.

I've been using 4"x4" plates with tapcon screws in each corner for the past year+ and my 230ish hasn't had any ill effects, either on the wall or my butt. I don't usually sleep in it but I'm probably in it at least an hour a day.

I used something like this but after the cheap weld on the ring split I replaced the ring with a quicklink.

A 1/2" wedge anchor with a 1/2" I bolt would hold you with no problem if set properly. I think a 4" plate with four 3/8" anchors (shells) would be your safest bet. You never know what you hit or being your first time, how well you set them. I also am not sure of the concrete. Make sure you don't drill too deep that the anchor get hammered into the center void. They do sell "shallow" anchors at Home Depot that could be used in this situation. I would definitely not use tapcons. They can strip out or even loosen up.
As for distances apart, not really sure. Give yourself enough height so you can adjust tensions and foot rise without being too high or too low. That could be the tougher part.

When hanging tandem, I use 26" spreader bars on the hammocks. It's enough to keep both rigs under one tarp, but occassional contact happens. 36" might be better for a permanent setup. You could each take turns in a hammock and measure the max space (width) you occupy while lying in various positions. The spacing would be the largest measurement + a few inches. If wall space allows, instead of hanging exactly parallel, you could position the head ends a little closer together to allow for good morning kisses form the hammock :boggle::lol:.

A particular anchor may spec out at needing just one or two anchors, but what will give you peace of mind each night in the long term? None of these fasteners/plates are very expensive. If you've got a proper hammer drill (bits with SDS Plus shanks) setting anchors is easy.

Another option instead of a plate and ring is to mount a piece of slotted angle to the wall vertically. This will allow you to adjust the hang angle/hammock height more easily. Attached is a pic of what I did in my daughter's room.

RAW
Welcome back.
Why not just attach to the purlins? They would be my choice.

IMO, avoid attaching to those walls.

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Originally Posted by gargoyle

RAW
Welcome back.
Why not just attach to the purlins? They would be my choice.

IMO, avoid attaching to those walls.

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agree 100%

I wouldn't use a wedge anchor if there's a 2" poly void in there. Look into epoxy systems that are used for both hollow and solid concrete... Hilti makes one called HY-70.

(I work for Hilti.)

Here's my set up I have personally tested this to a little over 600 pounds(3 people) and am using 3/16" diameter tapcon screws into the concrete block. And these tiedown rings can be bought at tractor suply for about. $3.50 each and are rated to 5000 pounds and the tapcons are rated at 1750 pounds each as long as they are in the concrete at least 1.25 inches and over 2 inches apart And these brackets holes are spaced right at 3 inches my other side is attached to double 2X6 studs next to my closet with 3.5 inch deck screws also I thee in a picture of ho tight the weave of a Mayan hammock is that's my thumb at the top of the pic for a size refrence. Also the washers that I used are nickles that I drilled holes in ( who says coins are useless LOL)

+1 on the purlins, must agree with gargoyle and surreal trip.

With a 17 foot span you might appreciate that height as well.

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Originally Posted by busan321

...using 3/16" diameter tapcon screws into the concrete block....and the tapcons are rated at 1750 pounds each as long as they are in the concrete at least 1.25 inches and over 2 inches apart...

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I'm glad it is working for you, but this rating is incorrect. According to the following Tapcon chart...Attachment 44830 , a 3/16" Tapcon in CMU (concrete masonry unit) under ideal conditions has a pull out value of 540 lbs.

A pull out value of 1730 lbs. is achieved with 1-3/4" embedment in 5000 psi poured concrete which is a stronger mix design then normally used in housing construction.

Gargoyle,
Why are you against anchoring to the walls?
My concern about the purlins was that the bottom lip would twist/bend.

No matter the scenario, I will have to fabricate custom brackets because we have drywall over thin metal studs in front of the concrete and a similar system installed just under the purlins.

Wedge anchors are going to make big holes, I would second what Keg said and use Tapcons with Hex heads on a plate or 2x4 mounted on the wall. They have exact specs for drill size to make the holes but you aren't going to pull them out and you can't break them without a 5 foot crowbar. The holes will be much easier to patch someday.

Quote:

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Originally Posted by gmcttr

I'm glad it is working for you, but this rating is incorrect. According to the following Tapcon chart...Attachment 44830 , a 3/16" Tapcon in CMU (concrete masonry unit) under ideal conditions has a pull out value of 540 lbs.

A pull out value of 1730 lbs. is achieved with 1-3/4" embedment in 5000 psi poured concrete which is a stronger mix design then normally used in housing construction.

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I stand corrected. I went back and looked at the package that the tapcons came in and they are the 1/4 " thickness not the 3/16" and I don't know what Psi concrete was used to fill the blockwall when my great grandfather built the house in 1952 but the walls were poured solid after the block was put up and the walls were framed with 2x6 instead of the regular 2x4 so I'm guessing that also has something to do with the strength of my hammock setup either way I have had 3 people n the hammock and we didn't end up on the ground