To Foam Or Not To Foam?

[Stuart A]

Its just that spa manufacturers decide to support spa structures differently.

It can be cheaper to make a spa with full foam, because the costs can and are saved elsewhere mainly on the shell.

[spatech (the unreal one)]

Its just that spa manufacturers decide to support spa structures differently.

It can be cheaper to make a spa with full foam, because the costs can and are saved elsewhere mainly on the shell.

It is not cheap to fill a spa with foam. It is certainly a cost saver for the manufacturer to go with a non-faom filled method yet some of the non-foam manufacturers make it available as an option because in the end they just don't want to lose a sale to a customer who decides he/she wants foam insulation. The dealer will have to pay extra for it and then either pass that cost on the customer or sometimes the agreed upon price has enough margin that the dealer doesn't mind "eating it" to give the customer what they want and avoid risking the sale by asking for more $. I've always thought it contradictory that a manufacturer would make it either way (kind of like a vegetarian restaurant having steak as a special order). To me they should just stick to one story like Arctic who foams the panels-only every time or Hot Springs who foams the entire cavity every time.

[THE SPA GUY]

Spatech,

good points on this...I would agree with you, were some of the manufacturers, will say there spas come full foamed, but lower price models the foam is a n option. on some thermal chamber guys they sell the system but can upgrade to a cold weather insulation(full foam) either way does not make sense. they need to go one direction and stick with, , It is amazing what some salespeople read and now it the best, without not really knowing one way or the other, unless they have experienced it....

[Stuart A]

I did not say it was cheap to fill a spa with foam. What I did say was it could be cheaper overall and by that I meant a manufacturer could use a thinner shell and not back it with fibre glass for support, instead they could use foam to support the shell.

I still think that two or three inches of good quality foam is enough, afterall my hot water cylinder has about this much of sprayed on foam around it and the temperature in this is hotter than a spa.

Overall its just personal preference, a couple of years ago I checked the energy consumption of my spa by direct measurement and I did not find it excessive. In fact the pumps when running will use a lot of energy.

[spatech (the unreal one)]

I did not say it was cheap to fill a spa with foam. What I did say was it could be cheaper overall and by that I meant a manufacturer could use a thinner shell and not back it with fibre glass for support, instead they could use foam to support the shell.

But that's not true. First of all most foam filled spas are fiberglass backed as well and don't use lesser fiberglass backing than the thermo pane type. Second, those that do not use fiberglass backing have to use a much thicker sheet (with ABS backing) which is a more expensive sheet and then have to spray a dense backing (dense foam other method) so its not like they just pocket the $$ not spent on fiber glassing. Finally, foam filling a spa is very expensive. In the end will cost a spa manufacturer more $$ to foam fill a spa than to use a thermopane method.

[Mikey_in_NY]

I did not say it was cheap to fill a spa with foam. What I did say was it could be cheaper overall and by that I meant a manufacturer could use a thinner shell and not back it with fibre glass for support, instead they could use foam to support the shell.

Agree with SpaTech - structurally, full foam has relatively little strength, and plays no part in supporting the tub shell, after all 400 gallons of water weighs around 3,300 lbs. It does play a part in supporting/isolating the plumbing, however we're not talking big $ there.

[Stuart A]

I would of thought that making an acrylic shell then applying fibreglass and hand rolling it would be more expensive, and time consuming, as opposed to making a shell and then spraying foam.

Mikey thats the first time I have heard that full foam plays no part in supporting the shell, could you confirm that if all the foam was removed from these spas the shell would then support the weight of water and people.

I am not involved in the manufacturer of spas like some of you maybe. So I have not got access to the costs for labour and materials.

There are a number of spa manufacturers that have been around for over 30 years now, and even though they do things differently, they must be doing it right to still be in business.

[Mikey_in_NY]

Hi Stuart,

I don't want to get into the thermal pros and cons of FF vs non FF.

In fairness the only tubs I've looked at with full foam are Sundance and HotSprings. From what I can see both of these brands use an independant wood (or more recently ABS) structure to both isolate and support the considerable weight of the tub, water and occupants - they wouldn't be using such a structure if the FF insulation had sufficient strength and integrity on its own. Aside from this - and as a mechanical engineer myself - I struggle to see how such a dimensionally unstable (under load), lightweight material like FF could even begin to contribute structurally as it's going to flex and compress under such large loads, potentially cracking the shell. Applying fiber-glass or some sort of acrylic bonding to the back of the shell will of course offer structural strength, but that's not the same as the insulating foam we're talking about.

All of this being said I'm more than willing to be proven wrong if more knowledgeable members want to step in and comment.

[spatech (the unreal one)]

Mikey thats the first time I have heard that full foam plays no part in supporting the shell, could you confirm that if all the foam was removed from these spas the shell would then support the weight of water and people.

It depends on the brand in question. For those who full foam a spa shell that is fiberglass backed (Jacuzzi, Sundance, Caldera ... and many more), yes if the foam was removed it would make no difference in support as they are fiber glassed backed and the foam is there solely to insulate the spa, not to support the shell. For those who use a co-laminated sheet (acrylic front and ABS back, much more expensive than acrylic only sheet obviously) those do in fact require a rigid backing sprayed on them (rigid foam or otherwise) for support and are then foam filled which provides more support and obviously insulation. I would expect either foam filled method to be more costly than the fiber glassed/thermo pane method (not counting Arctic which is a different kind of thermo pane since they foam the panels as well).

[njmurvin]

Mikey thats the first time I have heard that full foam plays no part in supporting the shell, could you confirm that if all the foam was removed from these spas the shell would then support the weight of water and people.

It depends on the brand in question. For those who full foam a spa shell that is fiberglass backed (Jacuzzi, Sundance, Caldera ... and many more), yes if the foam was removed it would make no difference in support as they are fiber glassed backed and the foam is there solely to insulate the spa, not to support the shell. For those who use a co-laminated sheet (acrylic front and ABS back, much more expensive than acrylic only sheet obviously) those do in fact require a rigid backing sprayed on them (rigid foam or otherwise) for support and are then foam filled which provides more support and obviously insulation. I would expect either foam filled method to be more costly than the fiber glassed/thermo pane method (not counting Arctic which is a different kind of thermo pane since they foam the panels as well).

My Marquis Everyday 660 came standard without full foam. It was a $200 option (that I got them to throw in). I never thought to ask, but I find it hard to believe they would have two different shells based on this option. I'm sure those of us who purchased this option simply had foam sprayed in the cabinet for insulation.

[Stuart A]

Spatech

Thats a good in depth answer, but I suppose we will never know the true answer because we are not going to be shown manufacturing costs. I suppose it does not really matter because it gives people a choice.

njmurvin

Not sure why a spa manufacturer would have two different shells, they would most probably use the same and just fill the cavity, but then I am just guessing at that.