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I need help validating my clothesline design. It'll be on our deck for convenience (I don't want to lug a heavy basket of wet laundry down to the backyard). I want it to be collapsible so we can hide it if we ever have guests again. And, if we have to sell the house to someone who doesn't appreciate clotheslines, we'll just unscrew the hinges and take the whole thing down with minimal damage to the railings.

The idea is, the clothesline posts will be attached to the top of the deck railings with hinges. When in use, the bottom ends of the posts will simply sit on the deck railings. When we need to hide them, we'll simply fold them back so they hang upside down behind the railings.

enter image description here

My questions are specifically about the stability of this design. I'm only expecting less than 15 lbs of load, consisting of 2 king-size sheets and up to 2 bath towels, so maybe I'm overthinking this, but better safe than sorry. By which I mean, better to ask now and look like the beginner that I am, than spend 5 hours putting it together and have it sag or bend or fall apart

In my mind, these are the Bad Things™ that can happen:

  • The hinges may be pulled out by heavy wet laundry pulling on the top of the posts. I read that screws can withstand shear forces of 600 lbs so I don't think this is likely.

  • The hinge itself may pull itself out of shape, or even come apart, from bearing the weight of the posts when the posts are stowed. That would actually be dangerous, since the posts can then fall on someone under the deck. And obviously hinges are not meant to be used like this - not as part of a set, and bearing forces that pull them apart. But then I think the posts will only weigh 40 lbs or less, and in any case, I think I can work around this by simply nailing some blocks of wood to the railings under the posts when they're stowed, to bear the weight of the posts instead of the hinges.

  • The posts may lean inward when there's laundry on the lines, since they're just sitting on the railings with no fasteners. Is this a risk with the center post being a 4x4 (so there's a decent amount of surface for it to sit on)? I can also add shims underneath to counter any leaning.

So, what do you think? Are there other glaring design flaws I'm not thinking of?

Thanks all in advance!

EDIT Aug 2, 2020: Some people have suggested some intriguing ideas, including a prop in the middle of the line and a telescoping post. I am interested in all those ideas, but could you please include some details on the materials and hardware I need to implement them? I am a DIY beginner, and this project is apparently far more demanding, engineering-wise, than I'd estimated. Who knew hanging 13 lbs of sheets to dry would be this complicated?

Also, the 13 lbs estimate is from Googling the weights of the sheets and towels, cotton absorbency and washer spin cycle water extraction rates. I am aware that wet laundry weighs more than dry laundry.

Bad Request
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    A foldaway clothesline frame looks like a good idea in general, but the design as you have drawn it will rip the cap rails right off. You need a design with deeper bracing against the deck railings. – A. I. Breveleri Aug 01 '20 at 01:19
  • @A.I.Breveleri Thanks. JRaef's answer brought that up too, and I'm definitely going to address that. I'm thinking of sistering the thick railing with an extra post and toenailing its ends to the cap railing and floorboard. Would that work? – Bad Request Aug 01 '20 at 01:30
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    those clotheslines are too low ... clothes will touch the deck ... wind will make the clothes wipe the BBQ ... also, no access to barby when clothes are up – jsotola Aug 01 '20 at 01:36
  • 50 lb of wet clothes will produce about a 300 lb tension on the cable due to gravity ... add wind to that – jsotola Aug 01 '20 at 01:49
  • @jsotola. I already thought through all those variables. My question is specifically about stability. And if you're going to criticize the design, please also suggest fixes. – Bad Request Aug 01 '20 at 02:10
  • not criticizing ... just voicing my observations ... there is no fix required if you are aware of the variables – jsotola Aug 01 '20 at 02:22
  • Not to be snarky, but the end goal is for me to have a working clothesline, and telling me what's wrong with my design without telling me how to fix it doesn't get me closer to that goal. It goes without saying that I don't have the skills to come up with the fixes myself, or I'd've done that already. So far I've made the effort to research and propose solutions to people's raised issues, with what little knowledge I have, but nobody is telling me if those solutions are good enough. – Bad Request Aug 01 '20 at 02:24
  • Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/111290/discussion-between-bad-request-and-jsotola). – Bad Request Aug 01 '20 at 02:27
  • Are you stuck on wood as a material? Or would you consider a steel post/pole on either side, either hinged as per other designs, or simply socketted into some wooden battens? – Criggie Aug 01 '20 at 12:45
  • Wet clothes, even when centrifugally dried, weigh more than dry. Place heavy clothes near the posts. Consider the idea of using no hinges but poles as high as the distance from the floor to the lines, sliding into and outside of tubes **solidly** connected to the floor. – gboffi Aug 01 '20 at 17:36
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    A prop in the middle would considerably reduce the tension and raise the textiles. It stands alone due to friction at the (rubber) foot, and under the lines. – Paul_Pedant Aug 01 '20 at 18:42
  • @Paul_Pedant is this prop a product one can buy? – Bad Request Aug 02 '20 at 16:06
  • Nevermind - just learned that clothesline props are indeed a product! – Bad Request Aug 02 '20 at 16:17
  • Might not be a bad idea to wash a load and then weigh a basket containing everything you plan to hang. Old school method of getting Google out of the way... :,) – zedmelon Aug 02 '20 at 16:43
  • Believe it or not, the idea has occurred to me too. I just didn't have a load of wet sheets handy because, surprisingly, I was waiting to have a clothesline before washing my sheets! – Bad Request Aug 02 '20 at 17:14
  • I'm in the UK, but a search in Amazon "retractable clothes prop" threw 128 results. As you seem to have multiple lines, a simple wooden T-piece would be more in keeping. Same height as the end poles (or slightly higher), and with grooves in the top surface spaced the same as the lines. Lateral stability is from the tension lines, and longitudinal from friction. – Paul_Pedant Aug 02 '20 at 17:36
  • Would long clothesline in U-shape around the deck be a valid alternative? I'm thinking the mediterranean-style balcony clotheslines like e.g. https://en.wikipedia.org/wiki/Clothes_line#/media/File:Tripoli.JPG That would have the advantage that you do not need to remove the lines. Also the leverage arm is shorter and thus far more favorable. Or of course a rack (one per sheet). – cbeleites unhappy with SX Aug 03 '20 at 18:17
  • @cbeleitesunhappywithSX The thought has occurred to me! GMTA :) I was a little concerned about how far out I'd have to reach, whether the sheets touch the railings, etc, but it does have a lot of advantages otherwise. I wonder how those levers are attached in that photo? – Bad Request Aug 03 '20 at 20:31
  • I'd guess the levers in the photo were welded on when they welded the rest of the steel railings. But I've also seen screwed steel angles or T-bars. I added a rough outline to my answer. – cbeleites unhappy with SX Aug 04 '20 at 09:06

4 Answers4

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Suggested construction:

deck folding clothesline

This spreads the torsional load over the entire banister railing instead of stressing only the cap or top rail.

If there's any bending at the hinge, or other distortion, it will be confined to the added pieces and will leave your existing railing unaffected.

A. I. Breveleri
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  • Wonderful, thanks! This is exactly what I need. – Bad Request Aug 01 '20 at 02:41
  • And thanks for editing the diagram to be clearer! Just one question: by "strap hinge" do you mean this skinny triangular kind (https://p1.cdn.hardwareandtools.net/is/image/HardwareandTools/400x350/045734643604.jpg?vkey=7%2FlAqsBmUeUDdsoTMvCtfkAH%2F37fbHvjuKYA9BUVs%2BY%3D)? I thought a 4" wide hinge with 4 screws in a row (like this: https://mobileimages.lowes.com/product/converted/704780/704780181170.jpg?size=pdhi) would be best since the pull is spread out more widely. – Bad Request Aug 01 '20 at 03:02
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    Use the largest hinge that you can fit onto the wood. If you can, use through bolts with nuts and washers instead of wood screws. As @Jasen has pointed out, the stresses at this location will be tremendous. – A. I. Breveleri Aug 01 '20 at 03:05
  • Thanks. This is making me think I should abandon the foldaway idea and just use a long board and try to make it less ugly haha. – Bad Request Aug 01 '20 at 03:09
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    A pair of totem poles would look good! https://i.pinimg.com/736x/71/32/1c/71321cb1896d090923d4faabd827c202.jpg – chasly - supports Monica Aug 01 '20 at 10:38
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    A problem with trying to spread the load over the bannister railing is that in the absence of some form of safety breakaway, someone who hangs on the rope could break the entire railing. – supercat Aug 02 '20 at 03:41
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Just one detail: the horizontal force does not need to be tremendous and you can in fact adjust/limit it.

The force the clothesline transmits to the post is in direction of the angle the clothesline has directly at the post, α. We can decompose it into a vertical component Fv that adds up (for both posts) to the gravitational force of the combined mass of clothesline and clothes. So, say, 100 N for 10 kg of clothes, clothesline and some water. If you hang your clothes "symmetrically" (i.e. the center of mass is in the middle of the clothesline), Fv = 50 N on each side.

The horizontal force Fh is Fv ⋅ tan α. E.g. if α = 45°, the horizontal force will be equal to the vertical force. If α is larger than 45° (the line is sagging less), the horizontal force is larger than the vertical force e.g about twice as large at α ≈ 60°, 3 times as large at α = 70°.

Of course, you "pay" for this low horizontal force by needing a higher pole (which also means more leverage).

As a back-of-the-envelope estimation (image below) I put 1 m of railing plus 1 m post at a distance of 5.7 m, accepting the clothesline to sag 1 m, i.e. down to the railing. That would put the "working height" between 1 m (like a standing clothesline) to 2 m which should be doable. The resulting maximum angle for "symmetric load" would result in a 70° angle which gives us Fh ≈ 3 Fv with the clothesline length being 1.06 ⋅ the distance between the posts (so an additional 35 cm ≈ 14"), the momentum at the joint between lower/upper part of the railing would be 150 Nm (i.e. the vertical equvalent of hanging 15 kg at a lever of 1 m length) - which should be well within the capabilities of many hinges. And a railing should certainly be able to withold this horizontal leverage - though the torsion on the cap rail may still be too high in your initial design.

Hanging clothes throughout the full length of the clothesline would ease the inward force since it causes a smaller α right at the post and a more flat clothesline in the middle.

sagging clothesline

Final thoughts:

  • If OTOH you insist on the clothesline almost not sagging, the horizontal force will increase tremendously.
  • A post in the middle (tie to sunshade stand?) would help a lot, in a similar back-of-the-envelope calculation halving the sag and at the same time also halving the horizontal force (since it would take half of the total vertical force.
  • I'd have estimated 7 kg of clothes (dry weight) to need 1 or maybe 2 lengths of your clothesline, but certainly less than 4 lengths. But I may be quite off here.
    The comment about the sheets makes a whole lot of sense - though I find hanging sheets in double (i.e over one line) works fine here (Germany) - already a little bit of wind and more distance than on a clothes stand make drying a whole lot faster anyways.
  • With a sagging line, clothespins are your friend.
  • Since you'll anyways remove the clothesline you can go for a braided cord rather than the smooth-coated variety (which is easy to clean if the clothesline stays outdoors). Braided cord may be far less slippery (I usually use "Reepschnur" [don't know in English, it's the kind of nylon cord one uses e.g. for Prusiks] since I have anyways have suitable lengths of that around).

Alternative: Clothesline outside the railings

You could also consider putting a permanent clothesline (blue) outside the railings (black):

clothesline outside railings

Such a construction with the lines anchored to railing posts easily allows a whole lot of tension (so not much sagging) since the horizontal forces are quite nicely countered.

  • The ones I've seen (e.g. outside my window when I was living in Italy) were usually steel constructions - but you could also use wood to be consistent with your railing.

  • Sheets touching the railing: depending on the wind, this may happen. However, I'd say one could have the outermost line maybe 50 - 60 cm outside the inner end of the railing (will be tedious, but/and train your arms and back...). The further out, the less risk of the sheet touching. Also depends on what is below: it may be better or worse to hang the sheet single or doubled up.
    It may be a vialble compromise to hose/wipe down the parts of the railing that may be touched, say, once a year or so. You'd certainly want to wipe the top of the railing where the wet clothes may touch

cbeleites unhappy with SX
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    Yes!! Your calculations match both my intuition, and the tension physics I read up on last night. Very nicely laid out too, thanks! Now I can use this model to minimum acceptable sag (I do want as little sag as possible since I’m drying sheets, which would slide into a pile toward the center with too much sag). – Bad Request Aug 01 '20 at 15:07
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    The 4 lengths are so I can dry one sheet on each pair and have air circulation underneath them :) – Bad Request Aug 01 '20 at 15:08
  • For the sheet calculation, I'd assume the weight evenly distributed along the length and then maybe even use a parabola instead of the catenate. Happy computing - I have to run now. – cbeleites unhappy with SX Aug 01 '20 at 15:24
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    If one wants to have a horizontal hanging rope, the way to do that is with a double suspended rope design, such as used by electric railways. – supercat Aug 02 '20 at 03:42
  • @supercat generally correct, but that doesn’t work for a variable load applied to the lower rope. The railways’ work because there is no load applied to the wires (if anything, they are lifted slightly by the pantograph). – Tim Aug 02 '20 at 09:06
  • @Tim: That approach won't keep the wire perfectly horizontal under all loading conditions, but it will allow the line to stay much closer to horizontal for a given level of lateral stress than would otherwise be possible. – supercat Aug 02 '20 at 21:50
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    @supercat: it's a valid alternative to "intermediate posts" that may result in better "horizontalness", but care is needed or it will be even more cumbersome for hanging sheets than posts. – cbeleites unhappy with SX Aug 03 '20 at 12:11
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    @cbeleitesunhappywithSX: Care is needed with the design, but I was suggesting it as an alternative that might (or might not) be useful. One of my concerns is to limit horizontal loading even under unexpected-stress conditions. If horizontal forces can be reasonably limited, it may be practical to use a counterweight and pulley to hold the lines, so that if someone trips and grabs the clothes, the counterweight could help slow their fall without putting undue stress on the railing. – supercat Aug 03 '20 at 15:22
  • @supercat: it would in any case be super cool to look at. But experience in pegging sheep fences suggests to me that such a net-like is probably better suited for permanent installations than as something you'd care to put up and down again for a single load of laundry. – cbeleites unhappy with SX Aug 03 '20 at 18:08
  • Thanks again @cbeleitesunhappywithSX! Your answers are always so thoughtful and thorough. They are my favorite :) – Bad Request Aug 04 '20 at 19:02
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the clothes-line with 6 inches of droop over 10 feet of span multiplies the weight of the clothes by about 20 to get the tension in the rope.

The 4 feet tall 4 inch wide folding arm multiplies by another factor of twelve

Your hinges need to withstand 50x20x12 pounds in tension 12000 pounds, without using steel and posts with welded hinges that's not going to happen.

I'd go with telescoping instead of folding, enter image description here

the triangle is to hold the post up in its high position. the circle stops the post from tipping inwards (the rope will stop it from tipping outwardsm, or to could add another bracket)

The circle could also be a wheel could have a rope around it to the bottom of the post for a counterweight to make the post easier to lift.

Jasen
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  • Couple questions. 1. Could you please explain where the numbers 40 and 12 come from? 2. Isn't 6" a rather excessive sag estimate? That's about 45º right? I'll have tensioners so I hope not to have that much sag. 3. How does it change the calculations if the load is spread over 4 lines instead of 1 (as shown in my drawing, though admittedly not clearly)? – Bad Request Aug 01 '20 at 03:13
  • 4 feet of 4" pole is 12 time longer than it is wide. less sag means more tension, 6" is about the max acceptable 1 line or 4 makes no difference all the forces add up the same. 40 is wrong should be 20 as the sag is in the middle still massive forces. – Jasen Aug 01 '20 at 03:17
  • OK thanks. Some more questions if you don’t mind: 1. What hardware do I need to build a telescoping post? 2. In your drawing, those 12000 lbs of tension will be borne by the triangle wedge, right? How should that wedge be attached and how do we know it can withstand more force than the hinge? – Bad Request Aug 01 '20 at 03:22
  • One more :) 50 lbs is actually a very conservative estimate. The actual load is a king-size sheet set and up to 2 bath towels, all spun dry. I just Googled their weights, cotton absorbency and washer spin cycle water extraction rates. Apparently the realistic load is about 12 lbs. That makes the tension 3000 lbs. Still too much for the hinge? – Bad Request Aug 01 '20 at 03:33
  • the hinge might work for that... you'll need to use screws that add up to 3000 punds on each half of the hinge. – Jasen Aug 01 '20 at 04:10
  • with the solif post the 12000 (or 3000) pound force is internal to the post. the. 50x20 (or 12x20) side force acts on the top of the post as the post is about half above and half below the rail twice that force acts on the rail and at the bottom the opposite force acts on the "wheel" (or bar or whatever is behind the post.) – Jasen Aug 01 '20 at 04:13
  • also remember, if it rains your wahsing will get heavier. – Jasen Aug 01 '20 at 04:44
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    @BadRequest 50lb is only "conservative" until somebody slips or trips (e.g. by stepping backwards into a laundry basket on the deck!), instinctively grabs the line to stop themselves falling, applies a 250lb load to it. and ends up on the ground underneath a pile of broken wood. – alephzero Aug 01 '20 at 12:56
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What are you going to use as an upright member on the posts? I would do it with a 4x4 because it would add some stability when resting on top of the rail while in use. Your laundry is going to want to pull the posts in toward each other. That will put a lot of strain on the hinges, which themselves are probably fine, but will be pulling on the screws and the rails very hard. In fact, the rails may twist on you so I would also put another vertical post under the rail on the near side one and use a "strap hinge" that would go down into both posts. enter image description here

JRaef
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  • By "upright member" do you mean the center of the post that sits on the railing? If so then yeah, it'll be a 4x4 as described in my drawing. The hinges will be the 4" wide outdoor type, so the pulling will be distributed over 4" and 4 screws. Does that seem OK to you? Twisting railings are a real concern, especially with our deck being so old as you can see, so thanks for bringing that up! – Bad Request Aug 01 '20 at 00:53
  • Also, if I understand you correctly, are you suggesting a strap hinge because it's long enough to reach both the clothesline post, the top railing, and the extra vertical post? That'd be at the expense of it being skinnier than the rectangular hinge I was considering though. Perhaps I can just join the top railing to the extra post with a toenailed screw? – Bad Request Aug 01 '20 at 01:15
  • the strap hinge is good because the wood is weaker near the cut end and the strap hingr has two screws that are not near the weak part. however if the screws are good for 600 pounds shear force it still might not be strong enough, – Jasen Aug 01 '20 at 09:54