5"->4" Cover V.s 4"-3"

[JPvZ]

Is the upgrade of an extra inch really worth it for a spa cover (e.g. 4-3" to a 5-4")? I've heard it doesn't make enough of a difference to warrant the extra expense (except in strength, which is not an issue for me), even in a cold climate.

Does anyone have any comments on this?

[Dr. Spa]

Depending on the density of the foam, that extra inch will give you an extra R-3.85 to R-4.35 (this assumes it's a TRUE inch, and not a nominal or averaged measurement).

It sounds like your in an area you consider a "cold climate", and the thicker cover will probably pay for the extra cost in well less than 1/2 it's life.

[mrfixit]

I do live in a cold climate and the extra inch is not substantial in terms of cost savings. You may want to consider the extra weight of the thicker cover, though. If you have lesser strength individuals in your household that may be using the tub alone, it may be too heavy for them to manage on their own.

[JerimiahR]

Pay close attention to the density of the foam. I've seen some covers sold online with 1.2# & 1.5# densities. Most major hot tubs will come standard with 2# density foam cores. The denser the material, the better it will insulate.

[Dr. Spa]

While this is true, it's really quite minimal;

Foam Density R-Value/in. 1.0 3.85 1.25 4.0 1.5 4.17 2.0 4.35

If you do the math, multiply the average thickness of the cover, by the R value, you'll see minumal differences. For instance, on a 4x3 cover, 1.5# foam will give you R-14.6 while 2# is R-15.22.... a big difference of R-0.62. An extra inch of thickness will give you 6 times additional insulation.

Strength is the real difference. 2# foam is about 33% stronger than 1.5# foam.

Pay close attention to the density of the foam. I've seen some covers sold online with 1.2# & 1.5# densities. Most major hot tubs will come standard with 2# density foam cores. The denser the material, the better it will insulate.

[quantumchromodynamics]

I would go for extra slope. The normal slope is usually not enough to allow the water to run off. Over time, water begins to pool on the cover and the cover becomes damaged. A 5--> 3 cover will have improved ability to shed water.

[JPvZ]

I do live in a cold climate and the extra inch is not substantial in terms of cost savings. You may want to consider the extra weight of the thicker cover, though. If you have lesser strength individuals in your household that may be using the tub alone, it may be too heavy for them to manage on their own.

I was thinking that at a certain point, heat loss from the tub itself and the shell-cover interface would begin to dominate and a thicker cover wouldn't necessarily be that benefitial. I'm planning on getting a cover lifter, so weight shouldn't be too much of an issue.

I'm still undecided given that the tub is 12 years old, so I'm not so exciting about putting alot of money into it.

Thanks everyone for commenting! This forum has been incredibly helpful.