Limited Deflection Foundation paired with 100% natural Latex Mattress

Discussions General Mattresses Questions
1

Hi Phoenix,

I visited three latex mattress retailers in the Austin, TX area this week. I visited Sleepworld, Austin Natural Mattress and Urban Mattress. All of these retailers are knowledgeable on these products and offer a variety of all natural talalay latex mattresses. I also found a variety of price points from 2K to 3K for a latex mattress paired with a foundation.

On my first visit at Sleepworld, I met Bob who appears to be very knowledge on his products. I enjoyed talking with him and learning about his organic latex mattress. I found his 12 inch 100% talalay latex mattress to be the most comfortable. It was plush but firm in support. I did wonder if the mattress would soften too much. He pairs this mattress up with a limited deflection foundation which appears from the sample to be a coil based foundation. My research for all other latex mattress manufacturers seem to recommend a rigid foundation that includes a wood slat based foundation with slats no more than 3" apart. When I inquired with Bob thinks the coil base foundation is superior to the rigid slat based foundation. When I inquired the reason, the response was it is based on his years of experience in the mattress industry. I did find it odd that I can find no other manufacturer who pairs a latex mattress with a traditional coil based foundation. I wondered if the other manufactures simply offer the KD style wood slat based foundation out of simplification and easy of transportation. I am sure it is more cost effective to ship a box of unassembled parts that it is an assembled queen size foundation.

Next I visited Austin Natural Mattress. This retailer carries several different lines of latex mattresses including OMI, Pure Latex Bliss, Savvy Rest, and a private label DIY mattress similar to Savvy Rest. I learned at this retailer that you might want to consider getting a firmer feeling mattress such as the PLB Nature (10" blended talalay) and using a 2" topper (14 or 19 ILD) to make it feel cushier. The advice is that you can always soften up a mattress with a topper but cannot firm up a softer mattress. I thought this was good advice.

My last visit was at Urban Mattress. I settled on their 10" 100% talalay latex mattress as the most comfortable. Again I tested it with and without a topper. I don’t think I would initially add a topper to this model. I questioned the components of their featured foundation which included a cardboard type material directly below the fabric. The foundation seemed rigid but I am thinking I want a foundation with higher quality components. They offered a reduction in the price so I can purchase a different foundation.

So to my question, what are your thoughts on using a limited deflection foundation (coil based) vs. a solid rigid wood slat based foundation? I understand there are different types of limited deflection foundation like the power stack system or but this is not what Bob is pairing with the latex mattress. I’ve read you should use the foundation that is paired with your mattress from the manufacture as it is designed as a sleep system. I get a little concerned when I find different approaches without understanding the reasons.

Let me add that all three of these retailers are good to work with, offer a variety of products in a no pressure environment. They truly try to educate the consumer which makes them stand out among their counterparts. All are knowledgeable on their products which I find refreshing.

Thanks for this forum! I have learned a lot about latex mattresses.

2

As a follow-up to my original question, I now find that Pure Latex Bliss provides the following regarding their foundations (http://www.latexbliss.com/blissipedia-1/foundations-box-springs):

“We use a variety of foundation types around the world. In the United States, most of our beds are shown on either solid surface foundations or adjustable bed foundations. In France, we use a slat foundation. In the United Kingdom, we us a Spring Foundation.”

Any idea why they used different foundation solutions for different locations? May one assume either type of foundation works for a latex mattress? Are they advantages of one system (rigid surface wood slats) vs another system (spring foundation)?

I also found on Leggett and Platt’s website an impact test where 175lbs is dropped on a wood slat foundation and on a steel wire grid foundation. It apparently is a sales video to “simply sell steel”. (http://www.steel-strong.com/) Obviously the wood foundation has a “catastrophic failure” where as the steel foundation had grid deformation but did not have catastrophic failure. Any thoughts on this or do you think it is purely a sales aid to simply sell steel? I would think if the wood slat foundations routinely had “catastrophic failure” the latex mattress retailers would have discontinued their use.

Thanks

3

Hi TR Houston,

You can read a little more about the different types of foundations or box springs and how they are usually paired with different types of mattresses in post #2 here.

It would be helpful to think of a foundation or boxspring as having 4 different properties or benefits and each of these serve a different purpose.

The first of these is flex. The flex of a boxspring (with actual springs) or a “semi flex” or “limited flex” wire grid foundation or a base with various types of flexible slats serves two purposes.

The first is to act as a shock absorber for some types of innerspring mattresses which can be damaged with sudden or more forceful “shocks” because the wires may bend and set in a bent position. Foam isn’t subject to this so it doesn’t require any type of shock absorber underneath it.

The second purpose of these more “active” support systems is to contribute some flex to the mattress which can affect the properties and performance of the mattress and is part of a “sleeping system” that includes the mattress and the box spring. If a foam mattress is too thick (usually beyond about 6" - 8" or so) … then the benefit of the increased give under the mattress would be diminished or even lost completely. In most cases … at least in North America … the layers in a foam mattress are designed to be “stand alone” in terms of how they feel and perform and the foam is designed to do all the work and only needs a firm and evenly supportive surface underneath it. In Europe … thinner mattresses are more common and the bases underneath them are often designed as an integral part of the overall performance of the sleeping system and it’s much more common to see more flexible foundations (often with flexible slats) under a thinner mattress. Even in North America though … you will find some manufacturers that design their mattresses to be used over a flexible boxspring which is an active and important part of the complete sleeping system (although again this is usually with thinner mattresses). There are also cultural differences between mattresses in different areas of the world which leads to some designs being more “familiar” (meaning they would sell more easily) than others.

If you test a mattress with an “active” boxspring that noticeably contributes to the feel or performance of the mattress in terms of PPP (Posture and alignment, Pressure relief, or Personal preferences) in a showroom vs the same mattress on a solid non flexing surface then it’s a good idea to purchase them together because your overall sleeping system will have different properties if you use the mattress on a different type of base with a different amount of flexibility than the one you used to test the mattress.

The second property of a boxspring or foundation is to provide a firm and evenly supportive surface for the mattress so that the mattress doesn’t hammock and sag in the middle and it doesn’t have to sit on the floor. The amount of surface area that physically supports the mattress can be important here because some types of foam (particularly more elastic and flexible foam like latex) will sink into any gaps more easily than foam (like polyfoam) which is stiffer and less elastic. In the case of a latex mattress the suggestions of having gaps that are 3" or less is to prevent the more elastic latex from sinking into the gaps over time. A little wider gaps (up to about 5" or so) would generally be suitable for a polyfoam base layer which is stiffer than latex (although smaller gaps would still be preferable and will be stronger and more evenly supportive). In the case of “wire grid” foundations which are usually called semi-flex or limited flex foundations then the wire grid has much less surface area than wider slats with smaller gaps and can also have some risk of latex sinking into the gaps in the grid (although they would generally be fine for a polyfoam support core). You can read a little more about this in post #10 here.

Third is ventilation under the mattress. The most supportive material under a mattress would be a solid surface (such as a sheet of plywood or MDF) that had no gaps at all but this would also provide no ventilation under the mattress which in combination with other risk factors could increase the risk of mold and mildew and dust mites in the mattress (see post #10 here).

Finally the last reason for a foundation is to add height to the mattress so that the surface of the sleeping system is at a comfortable height to get in and out of bed or that fits the bedframe or headboard or footboard you are using. In some cases a platform bed for example that has strong slats with smaller distances between the slats that are supported in the middle with legs to the floor may not need a foundation or boxspring at all.

In terms of the flexibility of a foundation or box spring … if the one you buy with your mattress has the same flexibility as the one you tested with the mattress the feel and performance of the system will be the same.

In terms of the amount of gaps and the supportive surface area of the foundation then the more “air” there is in between the supportive surfaces the greater the risk that the mattress will compress into the gaps in the longer term. With more flexible foams such as latex then the longer term risk would be greater but this isn’t possible to quantify exactly and the difference may be small depending on the total thickness of the mattress, the firmness of the foam, the type of cover and quilting on the mattress and on the foundation, the type of foam, the ratio of the supportive surface area relative to any gaps, and the weight of the people on the mattress. In other words there is a “range” of potential risk that could range from minimal to much greater.

The same would hold true in terms of the “range of risk” of a less breathable support surface and this would also depend on other risk factors as well (climate, temperature in the room, humidity, the amount of normal perspiration of the sleeper and others). By itself single risk factor may not be as important.

Catastrophic failure would be very rare on any suitable foundation although it may be more common on foundations that weren’t strong enough for the mattress and the people on top of it. I would be more concerned with the ability of a foundation to maintain a flat and evenly supportive surface over time and on any of the other risks that were involved with the type of foundation.

So overall the choice of a “suitable” foundation would depend on which of these functions were most important to the overall sleeping system and the other “risk factors” that were involved in each of them. The “norm” in the mattress industry is that different people will have different thoughts and beliefs about the risks or benefits involved in each choice but I would always want to know the specifics of “why” they believed what they believed.

Hope this helps but if I’ve missed anything let me know :slight_smile:

Phoenix