7

We are designing a courtyard with a knee wall that would be run between lawn and brick patio. The idea is to define the space and to provide a comfortable place to sit.

This is an old house on an odd lot, and there are virtually no right angles in sight. So I thought we might embrace the irregularities and use a crinkle crankle wall (serpentine wall) to dispel any notion of square. My concern is that it might not be strong enough to handle a bunch of people sitting on it.

I've seen the ones at UVa but they were all too high for sitting on as far as I recall.

So, can these walls bear the weight of a few humans?

UVa walls

  • How many bricks thick? – Graham Chiu Oct 13 '17 at 19:02
  • @GrahamChiu They are typically a single brick thick. The curves give them the strength to stand on their own without buttressing. – That Idiot Oct 13 '17 at 21:43
  • By your words discussing design principles; to go with a home with no angles or rationale, I thought I'd assist your design thinking as well and ask for details on what that wall would be holding up other than people on a thin edge. Like surcharge and drainage (which I was going to bring up later). Just to help you save money with professional advice. Anyhoo, grins, sorry my work didn't help you. – stormy Oct 15 '17 at 4:02
5

A linear brick wall is strong in compression but resists lateral forces poorly. The serpentine wall attempts to overcome that with its curvature so that it provides as much strength as a linear two brick wall but uses far fewer bricks to build.

However that strength comes at a cost in that the convex portions of the wall are strong, but the concave portions are weaker in resisting lateral forces.

So it's likely to support several people at a time, but they should mount and dismount from a convex surface.

There's another practical issue in that it's much harder to construct than a linear wall since you're not following a string line.

http://www.m-a.org.uk/pdf/equals_18_1.pdf

| improve this answer | |
  • Every concave surface of this type of wall is convex from the other side. – Ecnerwal Oct 17 '17 at 18:18
  • Exactly, so you approach from the closer, and convex side of the wall. – Graham Chiu Oct 17 '17 at 19:07
3

I'm not a mason, but my general inclination is that a single row of bricks without some reinforcement (rebar through brick at regular intervals) wouldn't be strong enough. I realize they are curved which does give the wall a certain type of structure (I forget what it's called), but I think there's also load issue (perhaps thinking of it as torque helps). In any case, if it can support one human, it can support many humans.

Also, I worry that sitting on a ledge that thin isn't going to be comfortable for very long.

| improve this answer | |
3

Yes, a Crinkle Crankle Serpentine wall that has no other job to do such as hold back soil and is only 15-18" high, has a decent foundation of compacted gravel and a foot deep concrete foundation and the units are mortared together will be able to support human weight...you won't need to double it at all unless you actually want people to be comfortable, have a place to set their plates of food and drinks. The difference in price for a crinkle crankle serpentine double wall and cap and a cmu garden wall not including the labor to construct a serpentine wall is huge. I'll go check out the difference but I'd still need more information; drainage, surcharge, how to get a 'cap' on a small serpentine wall only doubled (or spaced with fill inbetween). I am guessing a small serpentine wall with custom caps, doubled walls will infill will be at least 3X more expensive. You could hope for a 1' wide wall. Concrete masonry unit (CMU) is 2' by 2" by 2' in length each.

The simple answer is yes, that wall as long as it is mortared can be used for human butts and weight. Good luck anyone would chose to sit on that wall without a cap.

And even a serpentine wall done well will enact a straight line. Otherwise, you could go nuts with erratic radii, a curved line of build that is also erratic. Just do the foundation correctly, allow no surcharge or build up of soil on one side making this a free standing nonsensical crazy wall to go with your free form home.

I did a Dr. Suess landscape once. You know, Dr. Suess and the cartoons? We had huge cranes to fit huge weird trees into the landscape and built a kid's playhouse that looked like a hobbit home, and serpentine walls made of ledger stone. Very short walls, that came off the hobbit home. Lots and lots of money in Seattle.

| improve this answer | |
  • Some of the CMU wall stones are actually designed for doing radii. I've frequently used a product call Roman Stackj Stone (expocrete.com/residential/stackstone.php). The units are 8" wide one side and 6" wide on the other. The depth is 8" and the height 4". The radius is about 2.5 ft to outside edge or curve, and with a little skill both sides can look very good. – Ben Oct 16 '17 at 22:50
1

I don't know if it would support the weight of a number of people, or even one, (though I suspect not) but it's unlikely to be an issue, because anyone perching on it won't stay there long, it'd be far too uncomfortable. Most dual purpose low walls are built wide enough to take a 9 inch flat paving slab on top (though they can be wider than that), on top of which the owner rests cushions for when visitors are there. There's no reason why it can't be a curved wall, although it won't be so easy to slab the top, but the crinkle crankle design wouldn't work for that.

| improve this answer | |
  • good point. maybe double crinkle crankle with slab/paver at top - but that kind of defeats the purpose of the single brick thickness. – That Idiot Oct 15 '17 at 20:00
  • You may have to choose between a crinkle crankle wall or a wall you can sit on.... – Bamboo Oct 15 '17 at 21:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.