How to Make a DIY Hot Tub Cover: Niel’s Fibreglass and Epoxy Hard Top

Last updated: September 2026

If you’re a regular reader of the blog or subscribe to my YouTube channel (and if you don’t, why not?), you might remember Niel and his DIY hot tub build. He was one of the first customers to really document his journey, so I could write it up and make some videos about it. It was an absolute pleasure to help him. He’s a very talented DIYer, and a very nice chap too.

Well, he’s been at it again. This time he’s made his own hot tub cover, and I think you’ll agree the end result really looks the part. Big thanks to Niel for the commentary, notes and all the pictures. In this post I’ll walk you through the steps he took, what it cost, his top tips, and what to think about if you want to build one yourself.

The challenge: covering a DIY hot tub

One of the big challenges when we build our own hot tubs is getting a cover to fit. An off-the-shelf cover assumes an off-the-shelf tub. Yes, you can have one made to measure, but it isn’t cheap, and the lead times can be long on both sides of the Pond.

And you do need a good one. A cover is one of the biggest savings on your running costs. Air source heat pumps have been a big hit for keeping heating bills down, but a good cover matters just as much. My ultimate guide to hot tub covers covers the types, costs and what to look for in a bought one.

What Niel put together I still wouldn’t call cheap, and I’ll come to the cost later. But it’s a lot more palatable than a custom cover, and a lot quicker.

The hot tub that needed a cover

Here’s Niel’s fantastic DIY hot tub, with him in it. Hi Niel!

Materials Niel used

• Pine timber for the frames of the two halves, with two supports in the middle
• Dense black foam board, the type used for underfloor heating, for the insulating core
• Fibreglass cloth and epoxy resin (slow-curing for the undercoats)
• Olive wood veneer for the top
• 1mm reflective aluminium sheet for the underside
• A UV-resistant epoxy topcoat
• Abrasive paper (120 grit, then wet-and-dry at 400, 800 and 1200 grit) and epoxy polishing compound
• Rubber edging for the bottom edges

How Niel built his DIY hot tub cover

Step 1: Build the frames

Niel started by building a wooden frame for each of the two halves from pine, with two supports in the middle.

Step 2: Fit the foam core

Next, he glued the black foam into the frames. It’s a dense foam used for underfloor heating, which helped Niel keep the cover as thin as possible. There’s no real reason he couldn’t have used EPS foam (which is what’s in most factory-made covers), or even the regular sheets of insulation board you can pick up in a DIY store or home improvement store.

Step 3: The top skin

For the top of the cover, Niel wetted out two layers of fibreglass with epoxy and immediately laid the olive wood veneer on top. He wanted it strong enough to take someone’s weight if they ever climbed on it. Just by the look of it, you can tell it’s strong, and the two layers of fibreglass and epoxy make sure there’s strength there if it’s ever needed.

Step 4: The bottom skin

For the underside, Niel did exactly the same with the fibreglass and epoxy, but instead of the veneer he laid a sheet of 1mm reflective aluminium, to reflect heat back into the water.

Step 5: Topcoats

Once that was in place, Niel applied three layers of epoxy topcoat.

Step 6: Sand, final coat and polish

When the topcoats were dry, he sanded them with 120 grit, then applied the final layer of topcoat epoxy.

For the final stage, Niel wet-sanded it, working up through 400, 800 and 1200 grit, then polished it to a shine with epoxy polishing compound.

Each half weighs about 12kg (26lb), so it’s easy to move. It’s fully waterproof, reflects heat back into the tub from underneath, and looks beautiful on top.

Step 7: Joining the halves and sealing the edges

The two halves slot into each other with a lip, so heat can’t escape through the join. Niel also fitted rubber along the bottom edges to seal against the tub and protect the cover when it’s moved.

What did this DIY hot tub cover cost?

Overall, it cost Niel about £700 ($870).

That might be more than you expected. But a custom-made hard top walk-on cover is going to be three times that and more. So Niel not only did a great job, he saved himself quite a lot by building it himself. For comparison, Angi’s cost guide puts a standard US hot tub cover at around $300 on average, with walk-on covers typically $700–$1,500.

Unfortunately, we can’t give you an insulation rating to compare it against a shop-bought or professionally made cover. My educated guess, from what I know about covers in general, is that it would be up there with them, with little to no difference. It would certainly be a lot better than some of the covers that come with cheaper plastic shell hot tubs. I’ve seen some that are no more than a bit of covered polystyrene.

Niel’s top tips

When I was chatting with Niel about this over WhatsApp, he sent me these points too:

• Use a UV-resistant epoxy topcoat. It may need a polish now and again, but it should be very durable, and he used a UV epoxy so it won’t yellow. This is a really good point. Ordinary epoxy doesn’t like sunlight, so go for a UV-resistant version even if it costs a bit more.
• The epoxy is the hardest part. Niel used slow-curing epoxy for the undercoats (under the aluminium and the veneer), because the surfaces are flat, so there’s no risk of runs.
• Fast-curing topcoats mean working fast. The UV topcoat he wanted only came in a fast-curing version, so he had about 20–30 minutes, tops.
• Mistakes aren’t the end of the world. They can easily be sanded back.
• You don’t have to fibreglass it. Niel used two layers mainly for strength, so it would take someone’s weight if they walked on it.

Thinking of making your own? What to consider

I’m not a fan of the DIY covers you often see online: a sheet of insulation board wrapped in plastic and stuck to a bit of hardboard. They don’t look good and they don’t last. Niel’s shows it can be done properly. If you want to try, here’s what I’d think about:

• Measure the opening, not the water. The cover sits on your coping, so measure where it will rest, and decide whether you want it to overhang the edge or sit flush.
• Keep the foam dry. Factory covers wrap the foam in a sealed vapour barrier, because waterlogged foam is heavy and stops insulating. On a DIY cover, the skins and every edge need to be completely sealed. Don’t leave any foam exposed.
• Think about rain. Factory covers are tapered so rain runs off. A flat top will hold water, so a glossy, waterproof finish like Niel’s matters, and a slight fall helps.
• Protect the epoxy from the sun. WEST SYSTEM says the long-term UV protection of epoxy depends on the finish coat over it, which is why a UV-resistant topcoat (or a UV-stable varnish over the epoxy) is essential outdoors.
• Watch the weight. Two halves of about 12kg each are easy to handle. A one-piece cover for a big tub won’t be.
• Seal the join and the edges. The hinge or join is where a lot of heat escapes on any cover, so a lip or overlap like Niel’s makes a real difference.
• Add handles and straps. You’ll want a good grip, and a way to strap it down in wind.
• Be careful with safety claims. A home-made cover, however strong, hasn’t been tested to a safety standard like ASTM F1346. Keep it secured and don’t let children play on it or under it.

For looking after any cover, see hot tub cover maintenance and how to remove cover stains. To see what a good cover and a heat pump can do together, read how I reduced the running costs of my hot tub by 66%. If you’re designing a tub from scratch, DIY hot tub insulation covers the rest of the heat-loss picture. There’s more on how covers and heating work together in hot tub heating and energy efficiency.

Planning your own build?

If you’re still designing your tub, think about the cover now. A square or rectangular tub near a standard cover size is much easier (and cheaper) to cover than an unusual shape. My DIY hot tub plans come in standard sizes with full CAD drawings, the plumbing layout and a parts list, so you know the finished dimensions before you build.

FAQs

Can you make your own hot tub cover?

Yes, if you do it properly: a rigid frame, a foam core, and a fully sealed waterproof skin. A sheet of insulation in plastic wrap won’t last.

How much does a DIY hot tub cover cost?

Niel’s hard top cost about £700 ($870) in materials. A simpler build would cost less, and a custom-made walk-on cover would typically cost several times more.

What foam should I use for a hot tub cover?

Niel used a dense underfloor heating foam to keep it thin. EPS, which is what most factory covers use, or standard rigid insulation board also work, as long as the foam is completely sealed from moisture.

Can you walk on a DIY hot tub cover?

Niel’s has two layers of fibreglass so it could take someone’s weight, but a home-made cover isn’t tested as a safety cover. Don’t use it as a platform, and don’t let children play on it.

Does epoxy yellow in the sun?

Ordinary epoxy degrades in sunlight, so use a UV-resistant topcoat or a UV-stable varnish over it, and polish it now and again.

Niel, once again, thanks for your insight, pictures and commentary. I think your DIY hot tub cover looks amazing!

Have you built your own cover? Show me in the comments below. I read them all.

Cheers,
Andi

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Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi