Galen from Minneapolis Minnesota writes,
Hello Pro,
Our cover did not survive last weekend when the family canine decided to use the skirt and tie down straps from our spa cover as a pull and chew toy! If you assume I can break Poochie from this expensive habit, what cover component do I need to get that will stand up to the weight of snow?
My next email is to the Dog Whisperer!
Best!
Hello Galen,
Snow on spa cover
Simply stated, the thicker the foam the greater the insulation and the more dense the foam, the stronger the cover. This is just another way of saying the thickness = insulation and the foam density = strength. Search this site for additional information on expanded polystyrene, or EPS, to learn more about the material the the foam for covers is made from.
Two kinds of foam are used to make EPS. Some manufacturers use recycled EPS foam beads, and compress and glue them together to make the sheets of EPS. The other type is made from what is called virgin EPS. This is a foam sheet when the beads are first heated and expand all at once to make a much stronger sheet.
The internal cores of hot tub covers are made from expanded polystyrene or EPS. We use virgin EPS only. The density of this foam is measured in pounds per cubic foot, and determines the strength of the spa cover.
Below are some of the statistics and ratings from the EPS manufacturers:
Rough estimates of the limits of static weight loads across the entire spa cover. Do keep in mind static load limits are like a blanket of snow distributed evenly across the entire width of the cover. This is quite different from a person of the same total weight, standing on the cover on one foot. The pounds per square inch are wildly different!
- 4” to 2” taper, 1.0# foam 190 pounds
- 4” to 2” taper, 1.5# foam 270 pounds
- 4” to 2” taper, 2.0# foam 370 pounds
- 6” to 4” taper, 1.5# foam 500 pounds
** Note: All hot tub covers will perform differently due to size differences.
Dog weight on a spa cover is much different than the distributed weight of snow blanketing a cover
Shear – Strength Properties in pounds per square inch by density of foam
- 1.0# 18 – 22 psi
- 1.5# 26 – 32 psi
- 2.0# 33 – 37 psi
Keep in mind too that a thicker cover will be stronger than a thinner cover if they are both made from the same foam density.
Happy Tubbing!
Ethel Elliott
