Plywood Under Mattress

Furniture changes with time; not just the style of the furniture, but the technology represented in how that furniture is made and how it functions as well. At one time, wealthy Mayan people in southern Mexico and Central America used nothing more than a platform made out of stones as their bed. This was somehow considered to be better than what the common people had, but nowhere near as comfortable as the beds we enjoy today.

Perhaps there was something spread across that stone platform to make it smaller; but if so, there is no archeological evidence to prove it. Even so, it is hard to believe that people slept on those platforms without at least spreading plant stems or animal skins over them for padding.

Moving forward in history, we find a variety of kinds of mattresses being used. Early mattresses were nothing more than a big cloth bag, stuffed with something to provide padding. From straw to feathers, a wide variety of materials were used. In places where animals with heavy fur coats were available, those furs were used both as mattresses and blankets.

In modern times, mattress technology has become quite complex, with most mattresses combining springs, foam and other padding materials in a multi-layered pad, designed with the idea of providing consistent support across the body, taking into account the curves in the body, as well as the difference in weight between the body itself and the limbs.

A few decades ago, accomplishing that required both a mattress and a box springs. The box springs provided support to the mattress, acting as a foundational intermediary between the frame and the mattress, as the frame didn’t usually provide support across the entire length and breadth of the mattress. At the same time, the surface of the box springs was designed to keep the mattress from sliding off the bed.

But even that has changed, with mattresses today no longer requiring the use of a box springs. In fact, some mattress manufacturers specifically state that their products should not be used on top of box springs. Those manufacturers tell their customers to put plywood or a Bunkie board on top of the box springs, if one is used.

Even in cases where manufacturers sell mattress and box springs combinations, what is sold in place of box springs today is just a fabric coated box, usually with some quilt batting to make the surface feel softer. But there are no springs inside. The springs inside the mattress are sufficient for the task.

Mattresses of this type are designed for use on a platform bed, without any box springs. The platform beds themselves come made with two distinct types of construction, although the style can vary considerably. The two styles of construction are slats and a solid flat surface, much like plywood.

Care must be taken when making a bed platform with slats, as mattresses are designed to be used with no more than four inches of space between the slats. More space can result in damage to the mattress, making it less comfortable to sleep on and shortening its life. The mattress needs a solid foundation all the way across its length and breadth and slats don’t always provide it.

Plywood, on the other hand, provides consistent support across the entire dimension of the mattress, which is ideal. The only question then, is what sort of plywood to use, so that the right support is provided.

plywood mattress support
Plywood mattress support, SK

Using Plywood to Support a Mattress

In making one’s own support for a mattress, the type of plywood used is important. A minimum of ¾” thick plywood is needed to provide the proper stiffness. While thinner plywood may be considered strong enough to support the weight of the mattress and the people sleeping on it, it does not have the stiffness needed for the span. Typically, the span between supports is greater than that of floor joists in a home.

The type of plywood is not as important as the surface. While the particleboard is not strong enough to support the weight, OSB should work fine. But it is best to use normal AB or BC softwood plywood.

A smooth surface finish and rounded edges are critical to prevent snagging and damaging the mattress cover. All corners should be rounded with at least a one inch radius and edges should be rounded over with a ½” or larger router bit. The surface needs to be sanded fine and should be sealed with paint or varnish to prevent splintering.

A better option exists, than just finishing the wood. That is to cover it with a layer of batting and then upholstery fabric. In order to do this, a spray adhesive should be used to adhere the batting to the surface of the plywood, wrapping it over the edge and onto the back side. Then the fabric can be stretched across this and stapled on the back, making sure that it overlaps the edges of the batting.

Most upholstery fabrics do not require hemmed edges, but to make a more finished foundation for the plywood, another smaller piece of upholstery fabric can be tacked or stapled on the bottom side of the plywood, with the edges folded under, so as to not leave any exposed edges. This will add life to the plywood support board, especially if the bed gets moved around from place to place a lot.

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