The Do It Yourself guide to a better spa cover.

How to build a better spa cover To build a better spa cover we need to define the purpose for having one. The first thing a spa cover is designed to do is keep debris out of your spa. With no cover on your spa you would quickly find it full of all kinds of stuff that would make your soaking time less pleasant. The next thing a good spa cover should do is help keep the spa water warm. Again this may seem like a “no-brainer” but considering what is considered the standard of the industry it bears careful consideration. Step one then is understanding the nature of heat or in this case heat loss. Anyone who has lit a candle could relate where heat goes. Watch the candle flame. It points to where the heat goes. Yes, if you get close the the side of the flame, you get warm. But if you got above the flame you got burned. Ever wonder why Fireman cut a hole in the roof of a burning building? It gives the heat a place to go rather than just building up inside the burning building. If they allow the heat a place to escape they have a better chance of controlling the fire. So if the opposite is true on your spa, you don’t want the heat to escape up. So having a cover that really keeps the heat in would be the absolute best. Lets take a look at the industry standard and see if it does what we are looking for. The typical spa cover is a two piece rigid foam cover that is covered with some vinyl. The vinyl forms a hinge in the center to allow the cover to be folded back. The rigid foam cover is designed to rest on the top of the acrylic of the spa, several inches above the spa water surface. Since the object of having the cover is to keep the water warm you might think it would be better to put it right on the water. You’d be right except that in the foam the thing that does the insulating is the air it holds in it. The beads of foam that form the rigid board actually have little air spaces that make up the insulation value. If you placed the foam directly on the water, those little air spaces would quickly fill with water. Once the air spaces are replaced with water two things happen, the cover gets heavy and filled with water, whatever insulation value it did have would be gone. So having the foam rest on top of the spa, far above the water slows the saturation down. Anyone who has owned their spa for a few years can tell you that eventually the foam gets heavy even though it doesn’t come in contact with the water. The reason is that when the spa water is heated, it evaporates into steam. Steam rises. With no cover on the spa that steam would just go off into the atmosphere and you would be constantly refilling your spa because of the water lost. But with a foam cover sitting over it, the steam has something to condense on. Some of the steam will condense inside the foam, slowly replacing the little air spaces. Some the steam will just hit the bottom of the cover, which is cooler, condense and fall back into the warm water below, cooling it. It never ceases to amaze me how many smart people are fooled into thinking their foam cover is insulating the spa water because snow will sit on top of it in the winter. Lets think about nature for a minute. Being warm blooded a seal needs to stay warm even in cold water. An important part of the seals arsenal against the cold is it fur. The fur traps a layer of air close to the seal insulating it from the cold. If you take away the furs ability to trap the air (remember the devastation caused by an oil spill) and the seal quickly dies of hypothermia. The same is true for birds. If their feathers are dirty or coated with oil they can’t trap the air next to their bodies that insulates them from the cold. That being said, if your foam cover is filled with moisture it has the insulation value of a wet piece of plywood. If snow falls on a wet piece of plywood what happens? The moisture in the plywood freezes. Would snow melt off a frozen piece of plywood? Does that mean frozen plywood insulates? Here's a little tip. If plywood insulated you wouldn’t need insulation in your attic to keep your house heated. Remember when you were little and your mom was trying to get you to think. She would ask you why you had done something and your answer to her was, “Everybody else was doing it.” The next words out of her mouth were usually something to this effect, “If everyone was jumping off a cliff would you have done that too!” My question is, “Just because that’s what everybody does, is it the right thing to do?” Let’s take a minute to discuss the nature of insulation. We put fiberglass insulation in our walls and attics. Why? Somebody discovered that fibers of glass spun like cotton candy, hold air still. Holding the air still is what creates the insulation. If you took the same fiberglass insulation and smashed it flat (squishing out all the air) it would not insulate. If it did your spa would not need insulation around the inside of the cabinet. Your spa probably has a layer of fiberglass (woven into a fabric) coated with resin to give it strength and reinforce the acrylic shell. Fiberglass layered like this is very strong but it has no insulation value because it is not holding any air. Get the insulation in your walls or attic wet (replacing the air with water) and it looses all it insulation value. When your cold at night and you pull a blanket over you, you are using air trapped next to you to insulate you from the cold. Would it work if the blanket was wet? So fiberglass, feather, blankets and fur insulate because they hold air. If you replace the air with water there is no insulation. To build a better cover for our hot tub then we need to come up with something that will trap the air, next to the water and not get saturated. Lets start with putting something right on the water to act as a barrier between the moisture of the water or steam and our layer of air. Go to the hardware store and get a big roll of the heavy duty plastic, as many mils thick as you can find, wide enough to go over your whole spa. Lay it right over the whole tub, from the outside of the cabinet on one side to the outside on the other. You don’t want any of the water inside the spa to get on top of the layer of plastic so it needs to be held in place outside the spa. Be careful during this stage because you don’t want the plastic down it the water because in order for your spa to work the water needs to flow unhindered through the filter, pump and heater. Allowing the plastic to hang down in the water would restrict that flow and cause problems. Now you could take a piece of two inch thick foam insulation (again available at the local hardware store) and lay it right on top of this. Or you could put a layer of fiberglass insulation on top of the layer of plastic. Lets look at these options. First the foam board. Being rigid you will need to cut it to the form of the inside of your spa in order for it to sit right down on the water. This is going to be messy but done carefully it can be done. Also not that the foam is not available in eight foot by eight foot pieces so you are going to have to get at least two to cover the entire water surface. It is important to note that the closer you get the foam to fit in here the better it is going to work. If you choose to use the fiberglass ti will be easier to get to fit down on the water surface since it is far more flexible. However it usually doesn’t come in pieces eight feet by eight feet so again you’ll have to use several pieces to make a layer to cover the entire surface. Fiberglass is nasty stuff to handle so wear eye protection and gloves every time you go near it. For all its soft appearance the glass fibers are actually extremely sharp and one little fiber of it in the eye can cause serious damage. Which ever you choose you should know that eventually the layer of plastic will fail and allow moisture to seep into the area of you insulation. Watch for this and replace the plastic at the first sign of failure or the foam will become heavy with water and difficult to move. The same would be true for the fiberglass. Once it gets soaked it becomes a real pain to move. If you live in a place that never rains, snows or blows I suppose this much of a cover would be sufficient. Since I don’t know of anyplace like that I’m going to go on. We will need to cover our cover with something to avoid ending up with a pool of water trapped on top of our cover the first time it rains. Or a pile of debris next time the wind blows. So I think another layer of plastic right over the whole thing again to keep the garbage and moisture out of the spa. Now unless your foam or fiberglass is extremely thick, it still is going to be below the outside edge of the acrylic of the spa so you can either add more layers of fiberglass, foam and plastic until it is higher than the outside of the spa or you can get an inner tube from the local tire store to lay on top of the plastic to form a little bit of a peak to help the rain to run off. You might need to layer the inner tubes and plastic until you get enough to do the job. Remember to secure the layers of plastic to the outside edge of the spa so that the rain and debris have no place to sit on top of the cover. How ever many layers you end up with you will want the top outer layer to be something weather resistant. Plastic is okay but not very stable when exposed to the elements, eventually it will get brittle and fall apart. So let’s go back to what is used on the industry standard, vinyl. You could go to the local fabric store and get several yards of the best marine vinyl you can find. Again this material is not available in pieces eight feet square so you will need to sew it together to form a piece big enough. A word of caution here do not attempt to sew this on your wife's home sewing machine. This fabric will need to be sewn with heavier thread that a household machine can handle and the weight of the fabric will severely strain any machine not built specifically for upholstery fabrics. But before you go to all that trouble consider this... ALL Vinyl's are rated by hours outdoors. That means no matter how much you spend on it, eventually it will get brittle, crack and fall apart. So since you are going to this much trouble you might want to consider something better than the industry standard. The best outdoor fabric for this job is Sunbrella. Sunbrella is a name brand fabric made by Glen Raven Mills. It is an acrylic fiber woven into a canvas like fabric. It is extremely UV stable and is rated by YEARS outdoors rather than hours. It will never crack and fall apart like vinyl and it will not rot like canvas. The local fabric store might carry this in widths of sixty inches typically used for awnings and such. It will need to be sewn together to make a piece big enough to cover your whole spa but you might be able to sew it on your wife's machine. Now the stripes are going to make the new cover look like a circus tent and you’ll need to hold it securely to the sides of the spa. You could put some grommets in the edge of the fabric and bungee straps to secure it to the spa. Maybe get a bunch of eye screws to put into the side of the spa or into the deck beside the spa and then hook the bung straps from the cover to the eye screws. Depending on how much wind and rain your particular area gets you may need more but I think if you have at least two straps per side and one in each corner that should do the job. Now step back and admire your new cover. It won’t be easy getting into the spa so you’ll want to give yourself a little more time. Unfastening will be easier because you can just go around once and undue every strap. Hooking the bungees on the cover though you will have to go back and forth like you would tightening the lug nuts on your cars wheels. If you try to just do it as you go around I think you’ll find it off center or flopped over. You will want to give yourself time to inspect each layer as you take it off and replace it. Any worn or perforated layers should be removed. No matter how careful you are the foam will eventually saturate so keep enough on hand to rotate it off the spa. You can reuse it if you stand it up in the garage long enough for the moisture to drain back out. You should plan on having enough on hand to always have some dry and ready. You can also experiment with other materials to increase efficiency. One I have had great success with is Reflectix. Available at your local hardware store, reflectix uses aluminum as a radiant reflector like a space blanket bouncing radiant heat back into your spa water. Be careful with this though since aluminum and chlorine have an undesirable reaction changing to aluminum(III) Chloride. However if you are careful to keep the Reflectix layer away from the spa water it does add effective insulation. You can also try different materials instead of the plastic. We use a poly vinyl coated (PVC) fabric like used on truck tarps. It is heavy duty polyester fabric coated on both sides with a nice even layer of vinyl. The vinyl is much more stable than just plastic and with the poly base fabric it is very strong. If it gets punctured it can be patched which is another plus. The challenge is it only comes in widths of sixty inches and sewing it together doesn’t make it water proof. You could get two pieces and glue them together (it glues nicely) but be careful because the glue is both highly flammable (used in Hollywood to make those big fiery explosions we all have come to know) and toxic (the fumes will cause brain damage). We use a radio frequency heat sealer to weld the pieces together. This welds the vinyl by melting it forming a nice water proof seal. If you can find the material (not available at the fabric store) and find someone with a RF sealer these tarps would make a better layer than plastic. The benefit for you is that your spa water will stay warmer while using a lot less power than you needed with your old rigid foam cover. A recent study by the Davis Energy Group found that the spa is nearly always the biggest single user of electrical power in the home. Saving power heating the water should result in some significant savings. Since we know heat rises having the best insulating cover should be a priority. One thing I like to mention here is that if you have your spa set up to run when the thermostat determines the water has cooled, your going to need to change it to run on a timer. With the old rigid foam cover this worked fine because the spa did need to circulate often and long to constantly reheat the water. During these long and frequent cycles the water in your spa had sufficient time to circulate through the filters and chemicals to stay nice and clear. With your new, improved cover, the water will stay warm and the pump won’t circulate it enough to stay clear. If you switch the pump to run on timed cycles, two to three times per day for two to three hours each time, the water will cycle enough to stay clear and the heater will only be on when it needs to heat the water so you will still save money. The purpose of this article is to educate and inform spa owners that there is a better way to cover their spa and save money on their energy bills. But after years of being a spa owner I have found one more crucial truth about spa use. If it is a struggle to get into, only the most determined and hearty will be using their spas. Since as I watch the world at large and the older I get the more I think everyone should have and use their spa I want to discuss this for a minute. If you have your spa shoved into a corner on your deck or built into a corner of your house or put one of those nifty tea house type things on it, no cover especially one like I have described above will be easy to use. Since I don’t want you to quit using your spa I want you to consider either changing the way your spa is or set aside money to replace your cover on a regular basis. If you buy a rigid foam spa cover you should expect to replace it at least every two years because it will have lost all the little insulation value it might have had long before you notice it get heavy. If you have limited access to the spa pushing a rigid cover over it will be easier than our do it yourself cover and if you always have one drying (draining) in the garage you might be able to get a little more time out of each of them before they crack and fall apart (because of the vinyl this is unavoidable eventually). If on the other hand you have easy access to all the sides of your spa the Do It Yourself one will work. However it will not be easy to get off and on. Again my goal is to get you to keep using your spa until you are old and gray like me. Since I know our human nature is to get what we want with as little effort as possible, I need to say there is an easier way. If you don’t want go go through the do it yourself, layers on, stacked neatly, carefully secured, repeat. If you don’t want to run all over looking for the ingredients to build and maintain your cover... If you don’t want the hassle but just want to get into your spa there is a better cover out there. It is not the typical industry standard rigid foam cover. It does insulate right from the water eliminating evaporation and condensation. It is Custom made for your spa and sewn and sealed together so it is a lot easier to use and secure than tarps or plastic. If you do go to the trouble of building your own and getting the best materials you can, putting them together right, the Sunbrella fabric professionally sewn and finished alone will probably cost more than just buying one. SpaCap.com makes a great cover built custom for your spa in a wide range of colors. I urge you to at least check it out before you quit using your spa. Yes, quit using your spa. Years of experience has taught me that people eventually quit using their spa once they can’t remember the last time they used it. This happens slowly over time. You begin to use it less because it is such a hassle to get the cover off and on. Eventually it gets to the point your wife can’t or won’t use it herself. You might buy another rigid foam cover and get back to using it for a while but that one will eventually end up heavy or broken or it will blow away. Eventually you will forget when the last time you were in it. It will just be the place you stack stuff outside, kind of large expensive picnic table that you can’t sit around. Then some winter the local power company will raise it rates and you’ll get a bill that shocks you. You will run around the house trying to think of things to turn off. You’ll look outside at the spa. If you bought it new, you paid thousands of dollars for it and now you can’t remember the last time you were in it. You look at the bill a realize you’re paying to heat water you’re never in. You turn it off and drain it. “In the spring,” you promise yourself. But when spring comes your wife wants to reclaim that section of her yard. You sell it cheap just to get it out of the yard. In order to sell it you take the old crappy looking cover off it because the spa itself still looks pretty good. If you bought your spa used for a great price this is where you came in and why it didn’t have a cover. It is also why you balk at spending ANY money it. Most spas are built to last for years. With the new composite sides who knows how long they’ll last. Yes you may need to spend a little on maintenance but the spa will last. It’s a pity then that we would waste so much money heating water because of a cover that doesn’t insulate. Or that we eventually quit using something that makes us feel so good just because of a cover that is too difficult to use?