Why Is My Hot Tub Cover So Heavy?

Have you ever noticed your hot tub cover getting heavier and more difficult to lift? If you have then it’s not because you are getting weaker but it is because almost all hot tub covers inevitably get heavier over time. But what is it that causes this strange problem and is there any way to fix it or to avoid getting a heavy hot tub cover in the first place?

I decided to investigate and this is what I found out.

So, why is my hot tub cover so heavy? Hot tub covers become increasingly heavy over time as their foam cores soak up moisture. The moisture cannot escape and the resulting trapped water is what is so heavy. Good maintenance can help reduce the problem and some foam cores can be dried out if they get too heavy.

What is inside a hot tub cover?

To really understand what causes the problem resulting in a heavy hot tub cover we really need to know what is inside and hot tub cover and how hot tub covers work.

A hot tub cover’s primary function is to keep dirt and debris out of the hot tub but even more importantly to keep heat in. As we all know warm air rises and so all of the heat generated by your hot tub will rise to the top of the water and, without the hot tub cover in place, it will simply escape into the atmosphere.

Obviously this is a problem, and makes running the hot tub more expensive. The water will cool more quickly and we will need to expend more energy just to retain the temperature of the water. With a hot tub cover in place, the heat is kept in and less energy is used. In fact, over the span of it’s lifetime, a good hot tub cover will most probably pay for itself in saved electricity costs.

So, in order to keep the heat in a hot tub cover has to be a good insulator. Traditionally the inner part of the hot tub cover is made from a high-density foam core. The higher the density and thickness of the foam core the better it is at insulating the hot tub and the more energy it will save. Better insulating covers are more expensive but they will over time retain more heat and so, depending upon the amount of use the hot tub gets and the prevailing weather conditions, can potentially pay for themselves in terms of saved energy costs over the course of their lifetime.

There are usually two foam cores in a hot tub cover often with a hinge between them to ais easy removal. They also will have a slope on them so that rainwater will run off them. The cores themselves are tightly surrounded by a waterproof vapor barrier which is intended to prevent moisture from seeping in and the whole thing is then supported in a vinyl outer cover.

Why is my spa cover so heavy?

Problems with hot tub covers start when steam from the hot tub finds a way into the high-density foam core. Whilst it is steam it can find it’s way through the smallest of openings but, as it cools it is unable to escape and condenses into water. Gradually this water fills the air pockets in the foam core. Water is obviously heavy so the hot tub cover gets heavier and heavier the more water collects inside it.

Often the steam gets in through damage to either the vinyl outer covering or through a worn out or damaged vapor barrier. To a certain extent, all hot tub covers will eventually succumb to becoming waterlogged but the whole process can be significantly speeded up if there is an easy way into the foam core for the steam to get in to. In theory better quality hot tub covers should last longer as the quality of the vinyl and vapor barriers is higher and they will withstand the onslaught of steam for longer.

Why is a heavy hot tub cover such a problem?

Your hot tub cover may gradually get heavier and heavier and you may barely notice it until it’s too late. But why is the weight and water issue such a problem?

Less effective insulation – A waterlogged and heavy hot tub cover will be far less effective at insulating your hot tub. The tiny insulating air pockets will be filled with water and so your energy bills are likely to be much higher. Warm air will be escaping from the top of your hot tub and your heater will need to be working much more frequently and much harder to maintain the water temperature.

Risk of injury – A heavy hot tub cover can become very difficult to lift and to move. It is highly possible that you might strain yourself lifting the cover. Often you will be tempted to lean over and to push the cover in an awkward position. The risk of back strain or injury becomes quite high in this sort of situation.

Risk of damage – A heavy hot tub cover core puts additional strain on the vinyl outer covering of the cover and risks damaging it even further. It is also possible that if you are using a hot tub cover lifter that it will strain this and damage it as well.

Reduced use of your hot tub – Finally, if you are struggling to move the cover off your hot tub or you need two people to get it off then you are likely to use your hot tub less. The less you use your hot tub the poorer value for money it becomes and it becomes a wasted resource.

How much should a hot tub cover weigh?

It’s not surprising that a large number of people struggle with their hot tub covers as they slowly get heavier and heavier. A hot tub cover in good condition that hasn’t started to take on water and become saturated should weigh somewhere between 50 and 75lb.

It can be a bit difficult to actually weigh a hot tub cover as it is so large but, as a rule of thumb, an averagely strong and healthy person should be able to lift a hot tub cover on their own fairly easily.

So, if you are struggling to move your hot tub cover or you are requiring help to move it then your hot tub cover may well be taking on water and need either drying out or replacing.

How do you dry out a hot tub cover?

The good news is that, in a lot of cases it’s possible to dry out a waterlogged hot tub cover. It may not dry out completely and it will probably become saturated again but if you can manage to dry it out it will possibly put off the day when you have to buy a new one or replace the foam cores.

So, how do you dry out a hot tub cover? I have a detailed post on this here but here is a quick and easy version:

Choose a sunny day – Your hot tub cover will dry best on a warm sunny day where there is also a bit of a breeze. Bear in mind that it could take a few days to dry out completely so, if you can, have a look at the weather forecast and try to choose a warm and sunny period.

Remove the cover – Take the cover off the hot tub and out of the cover lifter if you are using one. You will probably need two people to do this to do it safely and avoid potentially damaging the hot tub cover. Bear in mind that if the cover is old the vinyl may be weak or damaged so try to remove the cover carefully to avoid damaging it any further.

Remove the foam core – You should be able to unzip the vinyl outer cover and remove the foam cores from inside. Put the outer cover somewhere in the sun to dry out before inspecting it and repairing if needed or possible.

Remove the moisture barrier – The foam core won’t dry out whilst wrapped in the moisture barrier so remove it carefully. You can buy new ones if it becomes damaged or torn.

Leave to dry – Put the cores out in the sun to dry. If you can stand them on bricks or something similar it will allow the air to circulate. Periodically move them around and leave them until they feel lighter and the moisture has had time to evaporate.

Bear in mind that this could take a few days and try to avoid leaving the cores out if it looks like it is going to rain.

Replace the moisture barrier – Once the cores are as dry as you can get them it is vitally important that you replace the moisture barrier. This must be as airtight as possible to prevent moisture from re-entering the cores and the problem repeating itself.

Reassemble and replace – Zip the cores back into the vinyl cover, put the cover back into the cover lifter and replace on the hot tub.

If your cores are beyond help then you can buy replacements as well as replacement moisture barriers. Bear in mind though that it’s false economy to put new cores into a worn and perished outer vinyl cover. The water got into the cores via some damage to the outer cover so it’s important to correct this first before replacing any of the inside parts.

How do you keep a hot tub cover from getting heavy?

All hot tub covers will eventually become saturated with moisture. In theory at least the better quality ones should last longer as they are much more resistant to to the steam. The outer vinyl cover will be tougher and the quality of the vapor barrier will be higher and more resistant to moisture.

However, there are a few things that you can do to try to make your hot tub cover last longer and not get heavy too soon:

Dry the cover regularly – If you take the cover completely off the hot tub each week and leave it out in the sun to completely dry for a few hours this can prevent moisture build-up. It will also help to prevent the build-up of bacteria and mold in the hot tub cover.

This does take a bit of effort and planning as it may well need two people to get the cover off and also relies on good weather. However, if you do this throughout the life of the hot tub cover you should be rewarded with longer service.

Regularly check and adjust your PH levels – Hot tub water that has the incorrect PH level will attack the underside of the vinyl cover and lead to the cover taking on moisture prematurely. You should be checking your PH levels regularly and adjusting as necessary.

Leave off after shocking the hot tub – Leave the cover off the hot tub after you have shocked the tub. This will allow the chemical vapor to dissipate into the air rather than attacking the underneath of your hot tub cover.

Use a cover lifter – Using cover lifter will distribute the stress of moving the cover more evenly and help prevent tears and damage to the vinyl outer cover. A cover lifter will also help make any hinges or moving parts on the cover last longer as well.

Everything you do with your hot tub cover should be with the aim of preserving the vinyl outer cover for as long as possible and preventing any tears or damage that could allow steam to get into the inner core.

How long do hot tub covers last?

Hot tub covers commonly last between 5 and 7 years. The length of time a cover will last will depend on how well it has been looked after and also how high quality it is.

Remember that if your hot tub cover is heavy and full of water it won’t be insulating your hot tub and you will be wasting money on energy. It is false economy to run a hot tub with a worn-out cover so try to either repair the cover or, if you have to invest ina good quality new one.