Using gravel or crushed stone around deck posts for drainage

[Annahmed]

Hi everyone! Does gravel or crushed stone around deck posts really help with drainage and prevent moisture buildup? Would love to hear any insights!

[Gardenboy]

Hi! Yes, using gravel or crushed stone around deck posts can definitely help with drainage and reduce moisture buildup. It allows water to flow away more easily instead of pooling around the base of the posts, which is especially important if the posts are in contact with or set into the ground. Good drainage helps prevent rot, mold, and even frost heaving in colder climates.

If you’re setting the posts in concrete, adding a few inches of gravel at the bottom of the hole before pouring the concrete can also help with water runoff. And if you’re using gravel alone around the posts, make sure it’s compacted well and slopes slightly away so water doesn’t just sit there.

[Annahmed]

Thanks, Gardenboy! Do you think it’s better to leave a small gap between the post and the concrete or gravel for airflow, or should everything be packed in tightly?

[Gardenboy]

Yeah, leaving a little gap between the post and the concrete or gravel can be a really smart move. It lets air flow around the base, which helps any moisture dry out instead of getting trapped. That’s key to keeping the wood from rotting over time.

If you're setting posts in concrete, it's even better to use a post anchor or bracket so the wood doesn't touch the concrete at all. That way, it's lifted just enough to stay dry and breathe a bit.

With gravel, you can pack it in for support, but it’s fine to leave a slight space, not too tight, so water can drain and air can circulate. Basically, you just don’t want water or damp soil hugging the post.

[Annahmed]

Do you think using a layer of landscape fabric under the gravel would help prevent weeds from growing around the posts, or is it better to skip that step?

[Gardenboy]

Yep, adding a layer of landscape fabric under the gravel is actually a great idea! It helps keep weeds and grass from creeping up around the posts, which means less maintenance and better airflow. Plus, it keeps the gravel from sinking into the soil over time, helping it stay effective for drainage.

Just make sure the fabric is breathable and water permeable (most landscape fabrics are) so water can still pass through easily and drain away from the post base. Secure it with some landscape pins, then layer your gravel on top. Easy and effective!

[Annahmed]

Thanks, Gardenboy. Also, what about treating the bottom of the posts with a sealant or bitumen? Do you think that actually helps in the long run?

[Gardenboy]

Treating the bottom of your deck posts with a sealant or bitumen is actually a really good idea. It adds a layer of protection right where the wood is most likely to absorb moisture, especially if it’s going into the ground or sitting close to damp soil. By sealing that part of the post, you’re helping to prevent rot and keep the wood in better shape over time.

Some people also wrap the bottom of the post with a waterproof material or use a protective sleeve before placing it in gravel or concrete. That helps block out moisture and keeps the wood from staying wet for too long. Just make sure the product you use is safe for pressure-treated wood and let it dry completely before installing the post. Taking that extra step can really help your posts last much longer and stay solid.

[Annahmed]

This sounds like a smart extra layer of protection. Thanks so much for the detailed explanation!

[paultomlin]

Using gravel or crushed stone can help with drainage and reduce moisture around deck posts. It’s a small step that might prevent bigger issues down the line.

[Annahmed]

Using gravel or crushed stone can help with drainage and reduce moisture around deck posts. It’s a small step that might prevent bigger issues down the line.

Thanks, definitely seems like a smart move to help keep moisture issues in check.