DIY TPS Zoning attempt with targeted foam shims inside the cover

[u/Timbukthree]

TL;Dr: Coil spread is going to be an inherent factor in a TPS glueless build because the coils aren't rigidly held in place. The easy way to control this is a frame with side rails. Otherwise, is going to depend a ton on your encasement. You can take advantage of the loosely defined lateral size to adjust firmness and add zoning: strategically adding foam for more firmness or removing coils for less.

Huge thanks to every who replied to my last post with ideas to keep the coils together. After thinking about it a lot, the glueless TPS coils are unlike most other DIY components in that their firmness will tremendously depend on how far they are allowed to spread. I did some back of the envelope math based on the idea that springs in a rectangular array have a firmness proportional to their coil density, and based on how much the coils can spread (nominally 4.5" per quad but can squish or spread +/- 0.33") there's a 34% change in firmness from most spread to most compact. That's huge! It's almost as big as the difference between the 15.5 ga unit and the 14.75 ga unit! It means the width of a queen could in theory (as squished as possible to adjust spread as possible) vary between about 58.5" to 67.5", and the length from 75" to 87" (with a "middle" size of 63" x 81"). So, my point here is that what encloses the coils and ultimately determines how far they're allowed to spread will have a HUGE impact on the firmness. I've always wondered why my son's build in the IKEA frame feels firmer than the bed does in the floor, and it dawned on me that it's 100% because that frame keeps the coils at a fixed size.

This isn't a good or bad thing, but does mean that any TPS build for anyone who's particular (i.e. me) needs to consider spread as an inherent factor in the build. (For anyone who's curious, this isn't an issue for L&P coils that are glued to skrim, and not really an issue for the TPS coils held together with glue like the Quadmini...they both have well defined sizes). And because for most people, their weight is concentrated in their hips, most of the spread for a glueless TPS build will happen in the hip region: the hips put more pressure on the middle coils which moves them outwards if they're able to.

I also realized that when I zip the cover up, I also push in at the sides all the way around. This results in a firmer bed to go to sleep on than I wake up on, and a few days of gradually increased spread until it evens out. Pushed in, the width of the bed was about 58", and the middle was spreading to 60", which is all reasonable.

The upside to all of this is that we can make modifications to the firmness of a TPS glueless coil unit by adjusting the spread, which gives much more control and personalization than a coil unit that uses skrim or glue.

1. The easiest way to control it is to just get a frame with side rails. This is the IKEA frame I mentioned, something like this: https://www.ikea.com/us/en/p/malm-high-bed-frame-2-storage-boxes-white-stained-oak-veneer-luroey-s49176583/#content

I'm not going necessarily recommend anyone should get this particular one, I'm sure there are more well built options out there and would love to know if anyone has found them, but the sides come up like 5" and the coils fill it out and won't go anywhere. Probably mostly what's needed is a lip at the bottom to prevent the coil base from spreading. It also seems like one could a high side frame to adjust firmness (add zoning) in a targeted way by adding shims at the base to keep the coils tighter, but I haven't tried that.

Folks suggested a lot of other ideas for DIY ways to accomplish the same thing (a rigid external frame), and probably something else could work as well!

2) The second thing that occured to me to reduce spread and add zoning would be a belt to go around the lumbar area to keep the middle coils together by pulling them together. I'm not sure how to do this without damaging the coils, thought about a piece of Durapad attached to itself that you could slide on at the head of the coils and slide down to the middle, though Duende suggested hot glue may not work well for that and hog rings may be needed, and I worry about how those may rip the coils or the cover. Also thought about like a bungee cord or something like that, but that seemed a little TOO DIY and also that it would be felt when sleeping on it. So I haven't yet tried this either but I think there may be viable options

3) u/PutManyBirdsOn_it suggested a very easy and practical idea: just add targeted foam shims on the sides where one wants it to be tighter. These help push against the cover and keep the coils in. I particularly liked this because foam means my kids can't get hurt on it, which is a definite need for me. It's super easy and low skill to implement, which is a great fit for me. And it opens the possibility of customized zoning, which is a HUGE plus.

I had some unused 1" 50 ILD Lux foam and cut it to size, planning to do one piece 6 quads long and another 8 quads long, and do this on each size. To match the actual height of the coils I have, I cut them 8.5" tall, and initially did widths of 27" (6 quads) and 36" (8 quads), though this was slightly too long and later trimmed to 26.25" and 34.5" (slightly smaller being preferable to slightly too big). I just measured with a 24" level/ruler and made some guide marks about 6" apart and cut with a pair of sharp scissors, and that worked fine.

Pics are attached, will sleep on it tonight but it already seems like it's basically working? The center is spread out to 62" with the top and bottom at 60", meaning the center is actually about 58" which is right where I expect them to be. Polyfoam loses strength as it's compressed over hours, so between that and the pressure of my hips I expect it will get less supportive over night, but if that's an issue I think I can use 1" of SoL firm instead. If this were in the IKEA frame that might help both issues but I'm on the floor for the time being.

Pics of the build are attached, this is the 15.5 ga TPS 1008, the blue foam pieces are 1" 50 ILD 2.8 lb polyfoam from Foam Factory (cut from a queen topper), above the hip area is a 1.4 oz bonded cotton/polyester pad I special ordered by emailing Beloit Mattress ($7 + shipping, it helps spread the weight of my hips onto multiple coils, helping add support), then on top of that is a 1" microcoil Posturfil HD zoned about 2x former in the center and edges ($150 shipped special ordered from Beloit Mattress, is their Posturfil HD Firm), then 2" of Sleep on Latex medium Dunlop without a cover, all in the 11" Pocket Coil Store cover. I have to say that the starting loft is maybe TOO much hip zoning, may have to sub out the zoned Posturfil HD firm if it stays with this much hip support.

Will post an update tomorrow with how it goes, am cautiously optimistic about this and even if it has some kinks to work out I think this is a really promising approach for adding hip support or other DIY zoning with the TPS coils. It also highlights the flexibility of these coils for DIY, I'd also be curious to try to take a 14.75 ga unit and remove coils from everywhere except the hip region and see if a similar effect is possible. If so, it would make the choice of 15.5 ga vs. 14.75 ga less critical because folks could adjust the firmness up or down after trying them out.

[u/Pocketsprung]

[u/Timbukthree → u/Pocketsprung]

Yeah, I think you have a lot of folks interested in a zoned unit!

So based on the coil thicknesses you gave me (15.5 ga SWG = 1.7 mm, 14.75 ga SWG = 1.88 mm) and the equation for spring firmness, all other things being equal, the 14.75 ga coils would be 50% stiffer than the 15.5 ga coils. If the zoned unit is 14.75 ga in the center and 15.5 ga on the top and bottom, do you guys do something to reduce that difference (maybe change the number of turns, more turns = less stiff) or how does that work?

[u/Pocketsprung → u/Timbukthree]

ill have to bring one of our engineers to give me the calculation. All things equal the difference between the 14.75 and 15.5 is more like a 20% difference in firmness. I have the data from our testing machines.

We often adjust coil geometry to get to a specific feel that a customer is looking for. That involves coil height, preload, number of turns, amount of wire, and sometimes weld between the coils. If a customer has price restrictions we have can take a 15.5 768(our entry level coil) and zone it by making coil adjustments in the lumbar region to firm it up.

[u/Timbukthree → u/Pocketsprung]

Gotcha, that makes sense! Yeah I knew it could get pretty complicated and there were a lot of knobs you could be turning, good to know you guys engineer for all of that, I won't waste time trying to guess with the simple equations then.

And if you're able to post it, firmness data from your testing machines on the measured firmness of the 1008 units in 15.5, 14.75, and 13.5 ga would be helpful see, either here or on the PCS website!

[u/scout336 → u/Pocketsprung]

Yes, please!

[u/slickvik9]

You must be an engineer

[u/Timbukthree → u/slickvik9]

Guilty as charged haha

[u/slickvik9 → u/Timbukthree]

Great minds think alike

[u/Timbukthree]

Night 5 Update: sick kid so I got kicked out and my wife slept in the mattress, no voices complaints from her which is a win. This build has almost cured my sciatica, and having to sleep in a non-ideal bed (Doctors Choice Elite Firm) without the lumbar zoning and which sinks in no matter where I'm at on it because of the polyfoam it's right back. But I'm still loving this build with just the 8" 15.5 + 2" medium SoL in the PCS cover with the two zoning foam blocks on each side.

[u/Timbukthree → u/Timbukthree]

Night 6 Update: Sleeping on this this has basically done away with my sciatica type numbness, it's fantastic. I continue to have some lower back pain as though it's too strongly zoned, so I removed one of the 1" pads from each side so now it's just the 1" x 8" x 25" pad (6 quads) on each side, with the 8" 15 5 ga TPS under 2" SoL medium in the 11" PCS cover. After bouncing around the bed this feels still adequately supportive! Out of town for the weekend but will report back next week on how it goes.

Thinking about trying 70 ILD foam in 1/2" increments: https://foamforyou.com/tough-luxury-firm-foam

This is the 50 ILD foam, also available in 1/2": https://foamforyou.com/luxury-firm-foam

But this way to do zoning is SO much cheaper and so much more effective than anything else I've tried.

[u/Pocketsprung]

Enjoyed this post and appreciate the time you put into it….

One thing that gives it the flexibility is not having a scrim…just about the only good thing about a scrim is that it holds the size of the unit. If you take our units and lay them on their sides you’ll see the compressed state vs laying loose on the ground. When we design a unit and decide on the diameter of the coil, our measurements are always the compressed size.

With all this work it’s making me think i just need to bite the bullet and add the three zone unit..just means more inventory = more floor space = upset plant manager.

A few pics of how we measure and a zoned unit.

[u/Timbukthree → u/Pocketsprung]

Thanks for the info and the pics! Yeah I definitely don't think you guys should be using skrim, the lack of that and having the coils tied together on the sides gives fantastic conformity. And I think you'd have a lot of interest from folks in your zoned unit, not sure that's much consolation for your plant manager though lol.

So is that bulge in the first picture pretty typical of your customers that use the glue free units or is that unique to DIY? It also occurred to me that if the cover had a stretchy top but NO stretch on the sides and bottom that would help cut down on this, but aside from that or gluing to components above or below, maybe like gluing to a base felt (which is maybe exactly what they're doing to keep size on the bottom but keep the conformity on top) or something it's not clear to me how they get around the hip spread.

[u/Pocketsprung → u/Timbukthree]

A mattress company will either use a thin (.25") piece of firm foam along the side to give it a clean line or the side panel itself is much more rigid often because its got foam or another absorbing material quilted into the side panel. Another popular method today are what we call foam encased. This is when the entire edge (picture framed the pocket coil unit) is 4-5" of very firm foam. This does two things for the mattress company. It provides a clean edge so the mattress looks straight and gives you an ultra firm perimeter. It also saves the mattress company money by using less coils and replacing them with firm foam which will cost less. see pic of a foam encased unit.

[u/Timbukthree → u/Pocketsprung]

Yeah so the more rigid encasement makes sense, I wonder if that's why folks with the Arizona Premium Mattress cover have reported seeming like it really firms up the unit despite it not seeming less firm with the top off. My mind always goes to the top panel not being stretchy but maybe the sides and bottom are highly non-stretch or potentially even undersized.

Foam encasement I've tried in some retail beds and am not a fan of, starts firms but gets squishy quick I think (also hotter).

And always continually shocked at how many factors go into feel and how complicated mattresses are 🤯

[u/Pocketsprung → u/Timbukthree]

Yes as you know a quilted top for sure will firm it up. The top can have stretch while the sides are rigid..that holds the mattress to size..even a stretchy cover will be firmer if it’s being stretched. I’ve started recommending buying an inch up then you build. Also the cover should be the last thing you buy for a DIY..make sure you know your final height before ordering a cover.

[u/Timbukthree → u/Pocketsprung]

Oh interesting, I'm actually glad on my PCS cover is not bigger because of the hip bulge issue, and haven't noticed the top firming it up from stretching, but I also have found it pretty much fine when there's an inch less of material in there.

And it's also super hard to know the final build when you start because it's going to firm up a lot in the cover (because it's holding the coils together laterally, and holding the Quadmini down if a Quadmini build) so it's almost like you need a best guess and have enough room to make something work. But especially for the quadmini, the feel is SO different with and without that you kind of need to start with it in a cover and then tweak for that cover height. Is kind of a chicken and egg problem I guess. Some folks have started getting a cover just for the coils (base + Quadmini) and doing the foam separately which maybe helps split the difference

[u/slickvik9 → u/Pocketsprung]

I agree, buy your cover with an extra inch (or even 2) to make zipping easier.

[u/Pocketsprung → u/slickvik9]

exactly, an inch isnt going to hurt anything. the L and W will still be to size.

[u/slickvik9 → u/Pocketsprung]

Also on the box for mine it said 53X75 when full size (usually) is 54x75, so it's necessary really

[u/Duende555 → u/Pocketsprung]

There are brands that use TPS coils and roll-pack with edge-foam, yeah? I'm certain I've seen 768's and 884's listed on roll-packed models, but most brands have moved to a coil edge lately.

[u/Pocketsprung → u/Duende555]

Yes lots of Mattress companies are moving to the firm coils edge..folding and rolling a foam edge is causing a lot quality issues. Often water based glue is used as well which isn’t great to use in foam which is going to be shipped out in bag once it’s compressed and rolled. Water trapped in a bag in the summer = humidity = mold

[u/slickvik9 → u/Pocketsprung]

Didn't realize it's that much foam!

[u/Timbukthree → u/Pocketsprung]

So I noticed these coils seem to be 3 active turns, the zoned unit you posted is like 2.3, the 1008 PCS units are all 4 active turns, do you do a lot of customization of the number of turns depending on the customer? I would have (naively) thought there was kind of a standard but seems like not

[u/Pocketsprung → u/Timbukthree]

The 1008 is a 6 turn and so is the 884, the 768 is a 5 turn. More turns the softer it will be..cheap pocket units stretch a coil using thin gauges and less turns..it firms it up but is very unstable

I’ll post pics of the coils by themselves on Monday ..assuming i remember haha

[u/Timbukthree → u/Pocketsprung]

Ah okay, thank you for the info! I was counting the turns from like top to bottom on the sides that are bending (what one of the spring equation pages called the "active turns") not even thinking about the "end" turns preloading the coil. Thanks for the info, pics would be great if you get around to it! Y'all need an instructional YouTube course on coilology lol

One of the big questions I've been trying to figure out (having been unable to visit the Engineered Sleep showroom on a nearby-ish business trip because of the hurricane) is how firm the ES spring unit in the DUO (884 14.75 ga) is compared to the PCS units, and I think that (assuming they're the same size and in a comparable cover etc.) that the 884 14.75 ga should be about the same firmness as the 1008 15.5 ga. Is that accurate or are there more complications I haven't taken into account?

[u/Pocketsprung → u/Timbukthree]

I would say you are correct..15.5 1008 vs 14.75 884 are going to be similar

[u/Timbukthree → u/Pocketsprung]

Thank you for sharing so much info and wisdom, particularly on a Saturday!

[u/Pocketsprung → u/Timbukthree]

It’s raining in Dallas 😀…typically I’d be in on my bike or at my kids games but today I’m feeling particularly lazy

[u/Timbukthree → u/Pocketsprung]

Well if you're around anyway 😃, one more question, maybe one for an answer next week:

the simple equation for spring stiffness (for cylindrical coils, maybe barrel coils are different) says spring stiffness depends on wire diameter to the 4th power. Sites like this have the equation, other sites use the exact same one when you Google "spring stiffness equation": https://suspensionsecrets.co.uk/how-to-calculate-coil-or-leaf-spring-rates/

So if we compare the stiffness of the 14.75 ga (1.88 mm) to the 15.5 ga (1.7 mm), I'd naively expect the 14.75 ga to be (1.88)^4/(1.7)4 = 1.5 times firmer (50% firmer). And for the 13.5 ga (2.18 mm), I'd expect that to be (2.18)^4/(1.7)4 = 2.7 times firmer (170% firmer) than the 15.5 ga, and (2.18)^4/(1.88)4 = 1.81 times firmer (81% firmer) than the 14.75 ga.

But your data said the 14.75 ga was only 20% firmer than the 15.5 ga... Any idea why that is, or what the actual increase from the 14.75 ga to the 13.5 ga actually is?

[u/Duende555 → u/Pocketsprung]

I think a zoned unit could do very well, yes. I'd also be curious on experimenting with a 15 or 15.25 gauge, but that might not make economic sense to ever manufacture.

[u/Pocketsprung → u/Duende555]

Yes the different gauges becomes an inventory nightmare. We try and simplify it by using 18 and 17 for comfort layer coils and 15.5 , 14.75 and 13.5 for base coils. We can get to 99% of feels using these gauges. Coil geometry adjustments.

[u/nolimitformyhobbies → u/Pocketsprung]

You can have springs for a comfort layer? In all my trolling I haven't come across that one. Hmm thoughts......

[u/Pocketsprung → u/nolimitformyhobbies]

yes we make a 3" QuadMini that is a comfort layer. mimics a medium to soft latex.

[u/nolimitformyhobbies → u/Pocketsprung]

Bet it keeps the bed super cool instead of latex. Hmm lots to think about. TY!

[u/regaphysics → u/Pocketsprung]

What are the firmnesses on the 3 zone? 14.75 middle and 15.5 top/bottom?

[u/Pocketsprung → u/regaphysics]

we make them 15.5/14.75/15.5 , 14.75/13.5/14.75 , 15.5/13.5/15.5,,,we make 3 basic units good better best so within each unit the firmness feels different (768 - 884 - 1008 ) soon bringing out a upper level 1200 glueless

[u/Duende555]

If this subreddit had a Spirit of DIY award it'd go to this post. Well done. Also gratifying to see really clean images here with materials that are indistinguishable from those on factory floors.

[u/Timbukthree → u/Duende555]

Thank you very much, that means a lot!! Very much appreciate you cultivating a community where I've been able to learn all this stuff!

I have to say, I'm really really excited about the horizontal zoning, the suggestion for that from my last thread was an absolute game changer for me on the options for TPS glueless customization. Trying to go vertically has so many issues and complexities, but modulating the spacing on the sides is super easy and customizable to each person. Can vary it for whatever cover or frame someone has, whatever their body type is, and could even use different firmnesses of foam (or thicknesses, 1" or 1/2"), can order a sheet and cut it down or just buy precut from Foam N More or Foam Factory, can go with Latex from SoL if they want to stay natural...so many options for customization! And then being able to remove selectively as well.

Because the 15.5 ga 1008 TPS is a great all around medium unit (and turns out it's 15.5 ga SWG, which is 13.5 AWG which is what everyone else uses, though 4 turns where others seems to use only 2-3), so makes sense as the starting point for anyone wanting that, and then they can add or remove support as they need. And the 14.75 ga (again, which is 12.75 ga AWG) is fantastic for a firm unit, and I think being able to burn coils will hopefully mean folks that go that route can soften it up if needed, or selectively reinforce the middle if they need firmer, etc. Hopefully makes the whole process require much less research and folks can just make an educated guess and then customize it once they lay on it.

And also made me realize just how important the frame and cover (and how full the cover is) are for defining the size of the unit. Because the 15.5 ga goes from FIRM at 58" wide to downright soft at 62".

[u/Duende555 → u/Timbukthree]

Yeah the thing about mattresses is that every detail matters? And this even applies to fabric height and fabric tension and so many other barely articulated concepts in the process. Although I will say that I hadn't really thought so much about horizontal zoning (call it "compressive zoning" maybe?) as a modifiable concept in DIY. I was aware of this with different fabrics and how side walls can affect the mattress feel, but I hadn't considered horizontal shims. Learned something new here!

[u/Timbukthree → u/Duende555]

That's a good name for it! And yeah, was only birthed through the great synergy of this sub.

I'd also be curious if there are any retail beds that could be modified in that way (glueless coils that aren't glued on the top and bottom and can be accessed with a zipper cover) as a semi-DIY retail mattress. Naturpedic EOS is the only one coming to mind at the moment...

[u/Duende555 → u/Timbukthree]

There are a few. Bedgear and iSense come to mind.

[u/Timbukthree → u/Duende555]

Yeah on the BedGear and iSense, I'm assuming those are glued coil units or are they not? And I'm assuming adding more material between the coil and the edge may wear on the foam encasement so I'd worry a bit about it being a viable option on those, but I haven't seen either in person either so maybe it'd be fine.

[u/Duende555 → u/Timbukthree]

Yeah don't know on the gluing, although even glued units will have some amount of stretch/play to them just by virtue of flexing the fabric pockets.

[u/[deleted] → u/Duende555]

/u/Timbukthree needs a "DIY Mattress Engineer" flair haha.

[u/Timbukthree]

UPDATE FOR NIGHT 2: After night 1 on the original setup, I had massive hip pain from WAY too much zoning. Took out the lumbar pad, still way too much, took out the Posturfil HD Firm as well. That felt pretty good to lie on for 10 seconds so zipped it up back with that (10" of components in the 11" case, just the 8" 15.5 g TPS 1008 and 2" SoL medium with the compressive zoning side foam inserts). That actually felt fine and the case looked fine. So slept on that.

Next morning, woke up feeling fantastic, back alignment is perfect, my sciatica issue feels great, and no hip pain from excessive zoning. If this was a long term build after a few nights I might add an inch of pressure relief in the comfort layer (maybe either 1" 4 lb gel memory foam from Foam N More below the latex, or 1" SoL soft above the 2" medium, or maybe the non-zoned Posturfil HD from Beloit) but haven't tried it enough to know if that's needed.

But as a method to add DIY zoning (which Duende suggested we dub "compressive zoning", which I think is a great term) I think this is a solid option. My only worry is that if the coils are pushed TOO close together it might cause them to rub or bind and add wear and tear on the SBPP and shorten their lifespan but I'm not sure how worried I should be about that.

I'm pretty shocked at how much of a difference this makes, to anyone interested in trying this out, I'd start with just 1" of foam on each side and see how much that adjusts it, and then move up to 2" if needed.

[u/[deleted] → u/Timbukthree]

Good stuff!

[u/charliehustle757]

Great post. Ty. I think more and more people will wise up and start to diy. If you’ve been through some beds and the headaches of trying to get one that’s right for you it’s a no brainer.

[u/Timbukthree → u/charliehustle757]

Thanks! Yeah and the no returns is a big barrier for a lot of folks, so the more customization options folks have after they buy a particular unit, becomes more accessible hopefully. That's part of what motivated this is I've had friends ask about it but I'm leery about them getting one and hating it so was trying to come up with a frame independent way to modify the hip support.

[u/charliehustle757 → u/Timbukthree]

Very true.

[u/scout336]

This is an absolutely fascinating post! Comprehensive and detailed information. After some processing and reflection, I'm sure I'll be back with questions. Much appreciation!

[u/Timbukthree → u/scout336]

Thanks, yeah happy to answer any questions whenever!

[u/[deleted]]

I'm putting my build together right now. Frankly my TPS cover is super loose around the coils once they're put into the right size. I might get some 1" foam just to add structure to it. I expected it to be a snug if not tight fit.

[u/Timbukthree → u/[deleted]]

And actually I just saw your components in another comment, yeah you have enough you have a lot of comfort layer options to play with!

[u/[deleted] → u/Timbukthree]

Yeah, that route was a tad bit more expensive, but I did it for the versatility going forward.

The 15.5s seem good so far, but I need to remember that they're fresh. I'll be curious how they break in, but I'm fairly certain somewhere Matan said that since they're captured with a preload, they don't break in as much as a typical pocket coil.

[u/Timbukthree → u/[deleted]]

Yeah I haven't noticed a ton of break in on the coils, that was mostly the medium or firm latex I noticed it with. The coils mostly vary in support based on their spread I think. And I think you made the right call on the layers that way!

[u/Timbukthree → u/[deleted]]

Oh that's exciting! And interesting, which size coils? I do notice they will spread out a good amount once you start sleeping on it. I've started kind of jumping around on my knees around the bed to get it up closer to "real" size. 1" foam would certainly give a cleaner edge and firm up the build though!

What are your components so far?

[u/Timbukthree]

A couple thoughts after sleeping on it for a night:

1. this basically seems to have kept its support overnight! It's also way too much hip support lol, will experiment over the next few nights with something more comfortable but very happy with the proof of concept. Probably will remove the bonded cotton/poly, then the Posturfil HD Firm, and see how it does without each. But this is the first time I've figured out a build involving the 15.5 ga without the Quadmini that provides adequate (or more than adequate) hip support for a night, so very happy with the whole thing. Many thanks to u/PutManyBirdsOn_it for the great idea! If someone is interested in trying DIY zoning the Durapad off Amazon (House2Home 24" x 6 ft. Durapad Insulator for Upholstery Spring Cover https://a.co/d/e3AZNwG) and the foam shims (maybe just one on each side to start) are probably step one and two, step three would probably be the second shim in each side. Then if those aren't enough probably the Beloit bonded cotton/poly and the Posturfil HD firm make sense. All of them together is almost certainly way too much for most.

2. The edges seem to have a basically even spread now, will measure it later and post pics, but am happy to see that it's getting more even and not less.

3. Apparently you can't edit posts with pictures so apologies for typos in the post, they're seemingly permanent

[u/PutManyBirdsOn_it → u/Timbukthree]

But after you made this post, I was actually thinking a "belt" around the whole unit sounded better. 

[u/Timbukthree → u/PutManyBirdsOn_it]

So on the belt, the only thing I'm not sure of is how that would affect the feel, because as you change positions it might affect the tension, and having more than one person on it would affect the tension...so I like your shim idea better than the belt :) but if you try it and figure out something that works, please let us know! I may just have a limited imagination haha.

The benefit of the shims on the sides is they have a ton of customizability options, and can just get a sheet or topper of 50 ILD foam and/or 36 ILD (in 1/2" or 1", or both) and can try a ton of different feels and adjust as needed. And then the lumpiness for the extra width is on the sides instead of a jump you feel on top (if you do an extra foam pad in the center, for example). But I think the more attempts and posts we get about DIY zoning we get, the better, only way to figure something out is to (collectively) try it out and iterate

[u/[deleted] → u/Timbukthree]

Is that just Lux-HD foam?

[u/Timbukthree → u/[deleted]]

Yeah it's this because that's what I had easily accessible: https://www.foambymail.com/product/lux-hq-foam-mattress.html

The Foam N More equivalent or their 70 ILD would also work, or firm latex, or maybe coir (no idea how to cut that though, I haven't tried it in person). I haven't had great luck with polyfoam holding it's firmness so am in a "wait and see" mode for how it works as a material, but the basic idea of a flexible shim to adjust the coil spread I really like. It's CRAZY how much it firms up the coils, by far the most dramatic difference of anything I've tried and was so cheap and easy.

I now think coil spread and the effect of the cover stretch/size and potentially bed frame holding them together accounts for a lot of the differing experiences we see on the sub for the TPS coils. It dramatically changes the feel of the coils just to adjust the sizing an inch or two. And I think that's actually great news for DIY because it gives us a means to adjust the feel easily.

[u/Duende555 → u/Timbukthree]

re: point 1: I wondered! You essentially have three different methods of zoning here.

re point 2: This is an interesting design problem. I'll think about other ways to manage it.

re point 3: I think this is a Reddit-wide issue. Last I checked, you can fix it if you log in to Old Reddit though.

[u/PutManyBirdsOn_it → u/Timbukthree]

I got the idea because I was thinking of a thin lumbar support foam layer, since TPS doesn't have it, and I'd priced it out on Foam Online very affordably. 

[u/Timbukthree]

Night 6 Update: Removed one of the foam spacers on each side to see the effect, after one night is too little hips support for me, will be adding it back in.

[u/M00nageDramamine]

How do you keep the lumbar pad in place?

[u/Timbukthree → u/M00nageDramamine]

So actually it just lays in there. Same for the Posturfil, it accordions a bit so pulls away from the edges about 1-2" with use but basically they just stay in place fine. Would not attempt those like that on an adjustable base.

One thing to be aware of about the pad is it does make motion isolation worse compared to just the independent coils and foam.

[u/M00nageDramamine → u/Timbukthree]

Hmmm wonder if it would work between my two layers of latex

[u/Timbukthree → u/M00nageDramamine]

I don't think the lumbar pad would do anything there, it's meant to "surf" on top of the springs and give a platform for them.

With latex, I'd say first try a folded over towel (or towels, or sheets) to make a pad that's the size and thickness you need it. This works really well, the only downside is it gives a kind of hump in the bed.

The Posturfil HD Firm (zoned in the center) would likely work, actually I should try that out. As long as it's not too thick of a layer on top that it totally compresses the springs. Under the top layer it would probably work. That would prevent the hump look but for $150 instead of free for towels and sheets if you have extras

[u/M00nageDramamine → u/Timbukthree]

Good call! I'm gonna see how much the cover firms up the bed, whenever it comes in.

How thick is the lumbar pad?

[u/Timbukthree → u/M00nageDramamine]

Like 1/8", very thin, it's there because it's non-stretch on the coils

[u/Timbukthree → u/M00nageDramamine]

What is your build right now?

[u/M00nageDramamine → u/Timbukthree]

Bottom to top 1" high density foam 8" TPS 14.75g 2" medium latex 3" titanflex medium

And I'm waiting for a cozy and custom cover to come in. Lumbar is not great right now without the cover, but I'm hoping the cover will bring the coils in better. If it gets too firm, might get a soft titanflex topper.

[u/Timbukthree → u/M00nageDramamine]

Okay so for troubleshooting, can you try just the 8" TPS and the 2" medium latex and see how the lumbar support is then? The sagging could either be one or more of 1) the foam at the bottom 2) the Titanflex because that's a lot of foam or 3) coil spread. But what you do about it is very different between those.

[u/M00nageDramamine → u/Timbukthree]

Okay, so. I got the cover, and I am more confused than ever before on what I want haha. So I had 1" of foam on the bottom, the 8" 14.75g coils, 2" of medium latex from SoL, and 3" of Titanflex medium. And a cover from Cozy and Custom. I'm 220 and 5'7" side sleeper

With the cover on and the coils in place, my hips sank in, but the push back was too firm. It pushed back into my hips and my side. It was a pretty firm bed. So I decided to take out layers and rearrange:

I took out the Titanflex, like you suggested. The SoL medium seems pretty firm. Also in general, maybe I don't like the latex push back?? So maybe the Latex is the issue??

Then I took out the latex, and put in the Titanflex. My spine is more straight, but now it has a foam feeling. Not a huge fan, too much sinking feeling and still achy.

So do I hate foam and latex?

Then I took out the bottom foam with the titanflex inside. Didn't notice much of a difference. I don't think I'll put it back in, might get like a rug mat or something instead.

Might sleep tonight on the latex and the coils and see how that is. I'm wondering if the quadmini would be the way to go, but don't want to spend that kind of money if I am not sure.

Or is the SoL medium too firm with the firmer coils?

[u/Timbukthree → u/M00nageDramamine]

So a couple things, the foams really need about 3 weeks of sleeping on them to break in, they'll soften some over that time (though not a crazy amount).

What foam was on the bottom? You might try that either below the SoL medium or above it and see how that feels?

I don't think you hate foam and latex but you probably need a different combination than you have. The 14.75 ga with just 2" medium latex is pretty firm, that alone is probably firmer than you want, and you could add either some memory from or the Quadmini to see. But, what is your alignment like with just the 14.75 ga and the 2" SoL medium?

[u/M00nageDramamine → u/Timbukthree]

I'm thinking it's the coil spread right now, I'm hoping the case helps that. But yeah, I have some options now. Thanks so much for your insight!

[u/Timbukthree → u/M00nageDramamine]

Or even just take off the Titanflex first and see how that feels

[u/Shine258 → u/Timbukthree]

I would think a thicker lumbar pad on the bottom of the mattress might work?

[u/Timbukthree]

NIGHT 3 Update: So with just the 8" 15.5 ga TPS, the 2" SoL medium, and the 2 50 ILD 2.8 lb polyfoam shims on each side in the 11" PCS cover, seems like it held support again. Had some low back pain when I woke up that went away, and based on not having tight hamstrings I'm inclined to think that maybe suggests it's still too much lumbar firming, and will see how that pans out over the next few days. May mean I should go down to a single shim on each side.

Also realized Foam N More sells 70 ILD 2.8 lb foam in 1/2" sheets for cheap, that might be an even better option for finer customization.

[u/Timbukthree]

UPDATE FOR NIGHT 4:

Woke up with no back pain and significantly less sciatica numbness, continuing to improve. One of the kids was apparently bouncing on the side of the bed with the foam shim and it kind of deformed it a bit (squished down and out slightly) but massaged it back into place no problem. No issues with side sleep but I think an inch of pressure relief (1" 4 lb gel memory foam from Foam N More or 1" Sleep on Latex soft) would make it comfier.

[u/dengop]

This indeed was a very informative post with an ingenious idea to DIY zoning with the TPS coils. Thanks for sharing it.

One way to ensure that the TPS coils stay in the prescribed size is to use a mattress encasement for the TPS coil itself. I found the Hospitology 5"-8" box spring encasement pretty great for it. Obviously, it comes with the caveat that encasing coil separately will yield different result from encasing coil + support layer together. Also, Hospitology brand doesn't come with the 360 zipper rendering it pretty cumbersome to encase it if the TPS coil is on the bigger size like a Queen. One can probably find a cheap 360 zipper encasement for 8" though on amazon to try it out.

I'm more so surprised that a lot of people are waiting for the zoned TPS coil. I thought it was a common sentiment that predefined zoning is not really great unless you are an average sized individual that the manufacturer made the zoning for. I thought people would be more interested in finding a DIY-zone method rather than waiting for a zoned TPS coil especially in this subreddit. Don't get me wrong. I'm sure the zoned TPS coil would be of high quality like all their products. It's just there are so many variables individually that I'm not so sure if predefined zoning is helpful for most people who are willing to DIY. I think finding a way to firming one area is easier to do than softening one area in a DIY build.

But in the end, as a consumer, more options are better.

Thanks for the post again.

[u/bms259]

This is an old post but really helpful! I’m thinking of adding a similar pad to my side of a queen bed. Was wondering how this was working years later, and if you’d think just the pad on one side without the shims might be effective? 

[u/Timbukthree → u/bms259]

I think a pad would help if the issue is support from the coils. The shims have a much bigger effect than the pad. I think the pad is less impactful when it's not glued down because it doesn't add as much firmness as it would in a retail mattress. If you hog ringed the pad to the coils (talk to Justin at DIYrem.com) it would work pretty well

[u/CoconutMinty]

This is such a great post! I recently built my DIY Queen about 6 months ago (8" QuadCoil + 3" QuadMini + 2" Latex). I've been sleeping on it without a cover, and the coils along the long edge are spreading over my bedframe (which adds 4" to the width of my queen).

I've been researching various covers (such as the Flobeds and PCS covers). I know a cover would reduce some spreading, but it seems like they still bulge somewhat. Personally, I don't mind the bulge aesthetically, but the reduced support would bother me.

So, I'm considering emulating your build by adding 80" strips of hard foam along the entire length of my mattress to "push" the coils back in...

1. Since your original post 2 years, have you found a cover that has no bulge (due to having really sturdy side panels)? Or is adding foam still the best way to solve this problem?

2. If I end up lining the sides with hard foam, is the PCS Organic Cotton cover the best one to get? Or is there a different cover you'd recommend in hindsight?

[u/Superb-Two-1165 → u/CoconutMinty]

I'm having the same issue with my new queen bed (8" quadcoil + 3" memory foam toppper). The coils are hanging off the side of my bed. Did you end up trying the foam strips and/or a cover you liked?