Hi glottalstop and welcome to The Mattress Underground 
From a local mattress retailer in the Los Angeles area, we found a mattress by Spinal Care Bedding. I’m trying to assess it’s durability. It is a pocket coil mattress with a latex layer. According to the guide latex is a good durable material, but I am wondering if the layer of latex layer is appropriate thickness. We are side sleepers with low BMI looking for an affordable durable mattress with firm feel. Does this sound like a durable mattress? Is the thickness of 1" latex in such a setup normal or less than expected? I cannot find a clear statement on if a certain thickness is considered too low and if the latex is the so-called weakest link.
As you have probably read, any mattress is unique to those sleeping on it, based on their Stats (height, BMI, sleeping position(s) and any underlying health conditions) and their PPP (Posture and alignment, Pressure relief, and Personal preferences).
You are correct that, as per the Mattress Durability Guidelines, latex is one of the most durable mattress materials you can find. And you can see in the Mattress Specifications You Need To Know, that the thickness of a layer is just one data point for you to look at when choosing a mattress.
It is from a manufacturer that is local and listed in the Los Angeles post of this site so that seems positive. The sales guy did not have precise information initially about the layers or coil thickness (admittedly, I did not use the word gauge) but he explained that this is basically a generic mattress that uses the same materials that are found in bigger name brands.
The top is a cotton quilting layer 2-3"
There is a Talalay latex layer which is approximately 1"
There is some thin layer between latex and springs that is wool-like. This may just be a barrier, was not pitched as being related to comfort or support.
Leggett and platt pocket coil system, 850
I took a look at the Spinal Care Beds’ offerings, and while they may be very good beds, there is absolutely no transparency on the thicknesses or components for many of their products. As you can see in the Mattress Shopping Tutorial, this can be a red flag for consumers. I agree 1" of latex is an uncommonly thinner comfort layer than most beds, and if it’s just over a wool pad on top of an innerspring layer it appears it may be lacking in comfort and/or support. How did it feel? There is no ‘proscribed’ thickness for latex, as some consumers enjoy a thicker mattress and others a thinner one, but 1" over an innerspring seems like it would be for very specific back issues or stomach sleepers, and not be comfortable for the majority of consumers. Side Sleepers need more than 1’ thickness. Average BMI side sleepers typically need from 2" -4"
I see some other products on their site, like the Eco Flex 11 lists similar specifications, but they suggest adding a 6" Talalay topper, which makes more sense for a side sleeper. The topper is part of the comfort layer, the Leggett and Platt Coils are for support of the mattress; the layers above support the sleepers and define the comfort options they have chosen. You can read more about Mattress layers in this article. L&P coils are considered very good and a coil count of 850 is suitable for lighter BMI sleepers who like the feel of innersprings.
As side sleepers with lower BMI you have a wide range of mattresses that could be compatible for you both. Many of the Trusted Members of the mattress underground have firm latex and latex hybrid offerings such as Flexus Comfort, Mattress To Go, or Luma for a few examples…If you can provide them with your Stats, PPP and mattress history they can help you choose a comfortable firm mattress which will last for many years. If you have questions on specific mattresses, and include your Stats, we can possibly comment on them.
~ Basilio