Why Do Spa Covers Absorb Water?

[TinyBubbles]

Is it just me, or does this make absolutely no sense? Why can't the inside of a spa cover be made of a material that is impervious to water and steam? I'm assuming there is a very logical reason and I'm going to slap my forehead and say "duh" when I hear it. Do higher quality covers absorb less?

[RickJ]

I've wondered that too. I know that most covers are built using expanded polystyrene (white styrofoam). This material absorbs water over time. A higher quality cover will usually have thicker vinyl, and thicker plastic sheeting around the foam core to prevent the water from reaching the core. However, over time, all of these things break down, and allow water to reach the core.

What I would like to know is why can't cover manufacturers use Extruded polystyrene. (pink or blue styrofoam). From what I have read, the extruded polystyrene doesn't absorb water. Wouldn't that material last longer on a cover?

[Dr. Spa]

Wont last any longer. It still soaks up water vapor, just like ExpandedPS foam.

Ceramic insulating, like the tiles on the space shuttle, now there's something that wont absorb water! Anyone willing to pay $50 per square inch for a spa cover? That's really what it all about though, cost. Would you be wiling to pay 4 to 10 times the cost for a cover that will last 3 to 5 times as long?

Oh, the insides of a cover are impervious to water and steam. STOP using bromine, chlorine and ozone and you'll stop degrading it :-)

[biggz]

Ceramic insulating, like the tiles on the space shuttle, now there's something that wont absorb water! Anyone willing to pay $50 per square inch for a spa cover? That's really what it all about though, cost. Would you be wiling to pay 4 to 10 times the cost for a cover that will last 3 to 5 times as long?

Sounds heavy Doc

[Dr. Spa]

My recollection is ceramic insulation is R-50 per inch, and weighs next to nothing.

[deepchillie]

Ceramic insulation is really cool http://www.eaglecoatings.net/ check out the H20 proof stuff, EPOXOTHERM ®

UNDER WATER AND WET SURFACE COATING its kinda interesting.

[biggz]

Ceramic insulation is really cool http://www.eaglecoatings.net/ check out the H20 proof stuff, EPOXOTHERM ®

UNDER WATER AND WET SURFACE COATING its kinda interesting.

Chilly, That stuff is amazing.

[billy sharpstick]

I've wondered that too. I know that most covers are built using expanded polystyrene (white styrofoam). This material absorbs water over time. A higher quality cover will usually have thicker vinyl, and thicker plastic sheeting around the foam core to prevent the water from reaching the core. However, over time, all of these things break down, and allow water to reach the core.

wouldn't it be possible to paint the block with some kind of weatherproof sealer, outdoor latex, thompson's watersealer, . . . ?

bk

[Chas]

I sometimes assume that folks all know the following tips, but there are newbies coming on board all the time, so let me mention a few things which will help a cover last longer:

Vent the fumes: when you add dichlor or powdered bromine, leave the lid open and run the jets. I run mine for at least ten minutes, but longer would really be better.

Don't use a floating feeder for any kind of tablets. Trichlor is very hard on covers and pillows, and bromine tabs have almost half chlorine and are also very hard on things.

MPS shock creates a controversy: I say leave the lid open after adding MPS, but some folks say no. For the greatest safety to your cover, why chance it?

Every year, you should open your cover and look at the vapor barrier. This is what keeps the foam boards from soaking up the water vapor. Pull the zippers back and look to see if the stuff is failing.

[Dr. Spa]

wouldn't it be possible to paint the block with some kind of weatherproof sealer, outdoor latex, thompson's watersealer, . . . ?

bk

The last person to come up with some "new-fangled" idea on something to encapsulte the foam, Seattle Spa Covers, went out of business in about 18 months. I believe he left town, RUNNING fast as fast can be, and left no forwarding address

[billy sharpstick]

wouldn't it be possible to paint the block with some kind of weatherproof sealer, outdoor latex, thompson's watersealer, . . . ?

bk

The last person to come up with some "new-fangled" idea on something to encapsulte the foam, Seattle Spa Covers, went out of business in about 18 months. I believe he left town, RUNNING fast as fast can be, and left no forwarding address

was it because it was a bad idea, a poorly implemented idea, or wa he just a lousy businessman?

bk

[TinyBubbles]

So let me see if I have this right. The material on the inside of spa covers is resistant to water and vapors, but they are degraded over time by chemicals, ozone, etc? I knew there had to be a logical explanation.

[Dr. Spa]

was it because it was a bad idea, a poorly implemented idea, or wa he just a lousy businessman?

bk

Bad idea. It simply didn't work as designed. The warranty claims came pouring in so fast it put him out of business.

[Shaamus]

There are technologies out there that would allow us to build the 10 year cover. The problem is the cost. It is literally cheaper for an end-user to purchase 2-3 standard covers than pay for a cover that would last a long time and they get the same net result without having to front all the cash.

Doc's right. We do install vapor barriers around the foam cores, but the chemicals gassing off your spa break them down over time. Chas's tips are right on about maintenance and chemical use. And when purchasing your next cover, keep these things in mind: 1) Denser foam can't absorb as much water so buy as dense as you can afford and 2) more [multi-wrapped foam cores] and better [look at mil thickness of the plastic] layers delay water absorption.

[Bond]

1) Why are most covers built using expanded polystyrene (white Styrofoam). Why don't cover manufacturers use Extruded polystyrene. (pink or blue Styrofoam). The R value per inch is much higher.

You never use expanded on a residential or commercial project unless you are really trying to cut corners.

[Dr. Spa]

Extruded or expanded, they'll both absorb water vapor at the same rate.

No one extrudes in a tapered style necessary for spa covers.

Even if they did, the cost of a cover would go up significantly.

[Shaamus]

You can get extruded foam tapered. You just have to buy a WHOLE LOT OF IT to get the extruders to do it and no spa cover manufacturer can put together that kind of buying power for an upgraded product. The older design that a certain manufacturer tried was to use a 2in flat XPS under a 2x0 tapered EPS core which yielded the 4x2. What they found is as Doc pointed out: under the conditions that a spa faces (water vapor not water in liquid form) the XPS absorbs water too. Not quite as much, but enough that it sure as hell isn't worth 4x the price. Unfortunately the manufacturer that hung his hat (and his anti-water-absorption warranty) on XPS foam has since gone out of business under the burden of replacing foam cores for free.

We (spa cover manufacturers) use foam as the core of spa covers because it is extremely strong and energy-efficient as an insulator compared to it's weight. I know some of you out there think it's so we can just make a lot more money on repeat business, but think about how much a 4x8 piece of plywood weighs and how much insulation value it brings to the table. The unfortunate fact is that EPS and XPS foam absorbs water. There is no way to get around that fact. You can create a "protective layering system" around the foam core to delay the water absorption, but because we have to put chemicals into the spa to purify the water, that layering system will eventually fail. Sure, there are technologies out these (baked on PVC coating, etc) that will render the core inpervious to water absorption but it will also render your wallet of all its cash. The material is expensive, the equipment is expensive, the process is labor-intensive which is expensive. You get the point.

Bottom line is spa covers that retail up to $600 will get fully-saturated at some point. How long that takes is a function of how many and how good are the layers between the water and the foam. If someone is trying to sell you a cover and they claim to have some new technology to guarantee no water absorption and the price point is $300, they're lying to you plain and simple. 7 year water absorption warranties are designed for people that don't realize that the cost of executing that warranty seven years later is not worth the trouble (warranties on covers hardly ever cover freight). These snake-oil salesman (I have a particular internet seller in mind) have no soul and lie through their teeth about spec and warranty and expected performance and people flock to them because they're cheap, they tell you it's 2# foam when it's really 1# and they offer rediculously long warranties that aren't even spelled out on their website. It's crazy. We've been doing this for 25 years. We wrap our foam cores in a 6mil polyethylene blend and seal it on a $22000 computer-controlled pneumatic impulse sealer that puts a 1/4" weld on all the seams and guess what? It's still eventually going to absorb water.

Sorry this turned into a rant, but the sooner people at least accept the fact that spa covers at the normal price-points are eventually going to get fully saturated, the sooner innocent consumers that don't know any better don't get taken by a long warranty and empty promises of performance. I'd mention the "air cover", but I'm on work/vacation here at the Pool and Spa Show and my wife says I don't have time to stay on my soap box any longer.

[ivieisme]

Since there is a manufacturer here, I have a question. I think I am purchasing a Caldera, with a Caldera cover. I want the lifter that screws into the cover, instead of having a bar over top. My salesman swears that even with a metal plate in the cover, water will still seep into those holes much faster than if I used a regular lifter. Is he full of it?

What lifter is best to preserve the cover?

[Dr. Spa]

They don't absorb water any faster. When installed properly, everything is sandwiched together tight enough to prevent any water intrusion through the screws.

We optionally offer the brackets on the covers we manufacture, and they don't have any effect on the warranty......and trust me, if there was an issue, it would effect the warranty

[Flexfoil]

You can get extruded foam tapered. You just have to buy a WHOLE LOT OF IT to get the extruders to do it and no spa cover manufacturer can put together that kind of buying power for an upgraded product. The older design that a certain manufacturer tried was to use a 2in flat XPS under a 2x0 tapered EPS core which yielded the 4x2. What they found is as Doc pointed out: under the conditions that a spa faces (water vapor not water in liquid form) the XPS absorbs water too. Not quite as much, but enough that it sure as hell isn't worth 4x the price. Unfortunately the manufacturer that hung his hat (and his anti-water-absorption warranty) on XPS foam has since gone out of business under the burden of replacing foam cores for free.

We (spa cover manufacturers) use foam as the core of spa covers because it is extremely strong and energy-efficient as an insulator compared to it's weight. I know some of you out there think it's so we can just make a lot more money on repeat business, but think about how much a 4x8 piece of plywood weighs and how much insulation value it brings to the table. The unfortunate fact is that EPS and XPS foam absorbs water. There is no way to get around that fact. You can create a "protective layering system" around the foam core to delay the water absorption, but because we have to put chemicals into the spa to purify the water, that layering system will eventually fail. Sure, there are technologies out these (baked on PVC coating, etc) that will render the core inpervious to water absorption but it will also render your wallet of all its cash. The material is expensive, the equipment is expensive, the process is labor-intensive which is expensive. You get the point.

Bottom line is spa covers that retail up to $600 will get fully-saturated at some point. How long that takes is a function of how many and how good are the layers between the water and the foam. If someone is trying to sell you a cover and they claim to have some new technology to guarantee no water absorption and the price point is $300, they're lying to you plain and simple. 7 year water absorption warranties are designed for people that don't realize that the cost of executing that warranty seven years later is not worth the trouble (warranties on covers hardly ever cover freight). These snake-oil salesman (I have a particular internet seller in mind) have no soul and lie through their teeth about spec and warranty and expected performance and people flock to them because they're cheap, they tell you it's 2# foam when it's really 1# and they offer rediculously long warranties that aren't even spelled out on their website. It's crazy. We've been doing this for 25 years. We wrap our foam cores in a 6mil polyethylene blend and seal it on a $22000 computer-controlled pneumatic impulse sealer that puts a 1/4" weld on all the seams and guess what? It's still eventually going to absorb water.

Sorry this turned into a rant, but the sooner people at least accept the fact that spa covers at the normal price-points are eventually going to get fully saturated, the sooner innocent consumers that don't know any better don't get taken by a long warranty and empty promises of performance. I'd mention the "air cover", but I'm on work/vacation here at the Pool and Spa Show and my wife says I don't have time to stay on my soap box any longer.

Have you ever seen foil being used both as a radiant barrier and as a vapor barrier in this application?

[Tom]

Have you ever seen foil being used both as a radiant barrier and as a vapor barrier in this application?

Arctic Spas covers use Mylar in that manner.

[Shaamus]

Have you ever seen foil being used both as a radiant barrier and as a vapor barrier in this application?

Arctic is the only one I know of that does this. The reason is cost. As a manufacturer of spa covers, I take my hat off to Arctic for doing what most spa manufacturers don't do: put money into the original cover making it not horrible. In Arctic's case, it's a great cover. Their castcore foam doesn't absorb water and wrapping in Mylar does improve the energy-efficiency. Considering they pay more than double for a China-made product than they could for the low-end-specc'd cover found domestically, Arctic goes the extra mile and provides a nice cover with the spa.