Paving slabs, typically made from concrete due to their durability, strength, and reliability, are a very popular modern flooring option for outdoor spaces.
If you currently have a concrete patio and are interested in building a deck, you may be curious if you can lay decking on top of the paving slab. Or you may want to cover up your old concrete patio because it is no longer being used and has turned into an eyesore over the years.
Can You Lay Decking On Paving Slabs?
Yes! In fact, a hard concrete paving slab is an ideal surface to install decking on. Even if you have an unsightly and/or damaged paving slab (which may be unable to be repaired), it is possible to build a deck on top of the concrete surface. This is an easier, faster, and less costly job than simply tearing out the patio and rebuilding it or building decking from scratch.
During the planning of the installation, make sure to take into account material expansion and contraction, as well as water drainage.
This means the building of a substructure. Sleepers, which are boards that go under the deck, are recommended to help with this, as well as small spaces between the concrete and the sleepers.
If you opt for composite decking, you may not need sleepers. Your manufacturer’s installation guide should let you know whether sleepers are recommended. If you donโt use sleepers, you will want to ensure the patio remains level, as the deck will sink if the paving slab sinks in the future.
If sleepers are used, they should be no more than 12 inches apart in order to provide the proper support.
Generally, concrete bolts and plastic anchors are used when attaching things to the concrete. Keep in mind that standard screws and nails will not work with the concrete.
When Should Decking Not Be Put on Top of Paving?
While you can generally always lay decking on top of a paved slab, there are instances when this process does not come highly recommended (or at the very least you will need to take other factors into consideration before doing so).
- Severe Damage โ While a deck can be put on top of a cracked concrete slab if the cracking is severe or the slab tends to sink into the ground noticeably, keep in mind that the decking will end up sinking and losing some of its structural stability. Eventually, concrete will stop sinking, so you should put the decking project off until the concrete has finished settling.
- Increased Height โ When you add decking to an existing paving slab, you have to consider that the patio will be increased in height. The amount of this increase will vary depending on the deckingโs thickness and the presence (or lack thereof) of spacers. Therefore, if a door threshold adjoins the patio, it will need to be that much higher. If you live in a cold climate and experience frequent frost, an extra half inch should be allowed so the threshold isnโt damaged when the slab rises.
- Stairs โ If you have stairs that connect to the concrete patio, the building of a deck can be a bit complicated. To keep from having to remove the steps, the treads will need to be raised the same distance that the patio is raised, which will help keep the height of the steps equal.
Should Wood or Composite Decking Be Used on Top of Concrete Paving Slabs?
Wood and composite decking boards are the two go-to options when building a deck, but you need to decide which one is best for your situation.
Wood Decking
Using wood for your deck is a traditional approach. While it is still a popular option, it is not nearly as popular as in previous years. Wood decking offers a rustic and natural beauty to your outdoor space.
Unfortunately, wood is vulnerable to drying, rotting, and fading over time, and it requires regular maintenance in order to maintain its appearance. However, in terms of pricing, wood decking is more affordable than its composite counterpart.
Composite Decking
Composite decking has grown considerably in recent years, and this is due to the numerous benefits this type of material offers. Recycled plastic and wood fibres are used to create composite decking, which means the composite boards are not prone to drying, swelling, warping, splitting, or splintering like wood decking boards.
Furthermore, composite decking tends to last longer and requires less maintenance than wood. However, it is generally more expensive than wood decking.
How Is Decking Attached to Paving Slabs?
As mentioned above, a substructure is needed on top of the paving slab before the decking can be placed.
The presence of this substructure will allow for air circulation and proper water drainage. The substructure is designed to provide structural stability, which ensures the deck is able to safely hold the weight of furniture, people, and other elements.
Without the substructure, the decking would be vulnerable to moisture damage, warping, and rotting. This will lead to the need for repair or replacement of the decking and will also reduce the structureโs lifespan.
Final Thoughts
A wood or composite deck is a good way to cover up your old patio. The process of laying decking over an existing paving slab is easy and can often be completed without the need for a professional.
However, if you feel that the project is beyond the extent of your abilities, we can help ensure that the patio is sufficient at holding up the deck while building a deck that will last for many years. Get in touch today for all your decking needs.
