If you’re thinking about putting Trex decking directly on concrete, it’s generally not recommended. Trex is usually designed to go over a wood frame, not directly on concrete.
One big reason is that concrete can pool water, and the decking needs proper drainage to prevent water damage. It also needs good airflow underneath to prevent problems like mold and mildew.
Also, you’ve got to think about how materials behave. Concrete and Trex decking both expand and contract when the temperature changes. If they’re right on top of each other, that could lead to warping or even buckling of the decking material.
Plus, going against the manufacturer’s guidelines could void your warranty, which you definitely don’t want.
But if you’re set on the idea, there’s a workaround. You could lay down some pressure-treated wood strips, called sleepers, on top of the concrete, and then install the Trex decking on those. The sleepers can help with drainage and airflow.
Before you dive in, make sure to check your local building codes to ensure you’re doing everything up to spec. And maybe give the concrete a good look to make sure it’s in good shape and has a bit of a slope for drainage.
Check the Manufacturer’s Guidelines
If you’re planning on installing Trex decking or any other composite decking, it’s really important to check out what the manufacturer has to say about it.
They usually provide guidelines on how to properly install their products, and you’d want to follow these to keep your warranty intact.
Most often, these guidelines are geared toward installing the decking over a traditional wooden frame rather than directly onto concrete.
Installing decking directly on concrete is typically not advised for several reasons, like poor drainage and lack of airflow beneath the boards. Doing so could void your warranty, which is definitely something you don’t want to happen.
It’s like buying a new smartphone and then jailbreaking it; sure, you can do it, but don’t expect help from the manufacturer if something goes wrong later.
Now, there’s often a workaround, like laying down pressure-treated wood strips called sleepers on top of the concrete, and then attaching the decking to those.
This kind of setup can offer the drainage and ventilation that the decking needs. However, this is also something you’ll want to clarify with the manufacturer.
They may have specific recommendations on how to do this properly so that you’re still covered under the warranty.
What’s the Condition of the Existing Concrete?
The condition of your existing concrete is super important when considering this kind of project. If the concrete isn’t level or has cracks, that could spell trouble.
You see, an uneven surface will make it really hard to get your decking to lay flat, which could lead to all kinds of issues like warping or even tripping hazards.
Cracks in the concrete could also be a concern because they could get worse over time. Imagine putting all this effort and money into your new deck, only to find out that the concrete underneath is shifting or deteriorating.
That could compromise the whole structure, and no one wants that.
If the concrete isn’t draining well, that’s another big deal. Pooled water underneath the decking could lead to water damage or mold. Ideally, the concrete should have a slight slope to help with drainage.
So if you notice your concrete slab has these issues, you’ll want to think about fixing them first. Whether that means leveling it out or filling in cracks, it’s best to start with a good foundation, so to speak.
Is drainage a problem when placing Trex decking directly on concrete?
Drainage is a biggie when it comes to installing anything over concrete, especially something like decking. You see, concrete isn’t particularly forgiving when it comes to water.
If the concrete slab is flat or has low spots, water can pool up, and that’s a no-go for something like Trex decking. Pooled water can lead to all kinds of issues like mold, mildew, and even structural problems with the decking itself over time.
So, how well does your concrete drain? If you notice water tends to gather in puddles when it rains, that’s a clear sign you need to improve drainage before putting down any decking.
You might even consider installing a French drain or another drainage system to channel water away from the area. Some people also opt to re-slope their concrete slightly to guide water runoff away from the house or the center of the slab.
In any case, good drainage is crucial for the longevity of your decking. Even if you’re using sleepers to elevate the decking slightly, poor drainage underneath can still lead to problems down the line.
How to attach sleepers?
If you decide to go that route to elevate the decking above the concrete, securing them well is key. You don’t want them shifting around on you, especially after you’ve got all that decking installed on top.
Typically, you’d use concrete anchors or screws designed for masonry to attach the sleepers to the concrete slab.
First off, you want to make sure the sleepers are made from pressure-treated wood that’s suited for ground contact.
After laying them out in the pattern and spacing recommended for your decking, usually 16 to 24 inches apart, you’d then drill holes into the concrete through the wood.
This is where you’d install the anchors or screws to keep everything in place. And yeah, you’ll need a hammer drill for that; a regular drill won’t cut it with concrete.
Also, you want to make sure you’re not just attaching the sleepers well, but that they’re level and straight. Any unevenness can throw off your whole deck, and let’s be honest, nobody wants a wobbly deck.
Some folks even shim the sleepers a bit to get them just right.
What material for sleepers?
When it comes to choosing wood for sleepers, you’ll want something that can withstand being in close contact with the ground, or in this case, concrete. Pressure-treated lumber is usually the go-to for this.
It’s been treated with chemicals to resist rot, fungi, and insects, which is definitely what you want when you’re laying wood on top of concrete.
You see, concrete can get damp, and dampness can lead to wood rot. Even though the sleepers will be elevated slightly off the concrete by the anchors, it’s still better to be safe with pressure-treated wood.
Some types are specifically labeled for ground contact, which is a good indicator that they’re up to the task.
Cedar and redwood are also known for their natural rot-resistant qualities, but they’re not generally as effective in ground-contact situations as pressure-treated lumber. Plus, they can be more expensive.
So, if you go to the lumber yard and see all these options, you’ll probably want to gravitate toward pressure-treated lumber that’s rated for ground contact.
That’s going to give you the most bang for your buck in terms of durability and peace of mind.
What are the Alternatives if putting decking directly on concrete isn’t advisable?
If laying decking directly on concrete is getting too complicated or just isn’t advisable, you’ve got other paths to explore. One cool option is interlocking deck tiles made from wood or composite materials.
These are designed to snap together easily and can go directly over concrete. They’re pretty user-friendly, and you can even find types that mimic the look of natural wood or stone.
Speaking of stone, pavers are another solid choice. You can lay them right over the concrete to create a patio area that’s both durable and good-looking.
They come in all sorts of styles, so you could go for anything from a rustic cobblestone look to something more modern and sleek. Plus, they’re built to handle outdoor conditions.
Then there’s outdoor porcelain or ceramic tiles, which can be laid directly onto a well-prepared and leveled concrete slab. These tiles can give your outdoor space a really polished look.
Just keep in mind that you’d need to use tiles rated for outdoor use to make sure they can handle the elements.
And don’t forget about outdoor carpeting or rugs as a simpler solution. If you’re not super worried about longevity and just want to make the space more comfortable, outdoor carpeting can be rolled out on top of concrete.
It’s not a permanent fix, but it can make things a lot cozier in the short term.