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How to Stop a Shed Floor from Rotting (Plus Repair Tips)

How to Stop a Shed Floor from Rotting (Plus Repair Tips)

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Family friends of ours bought a house recently, and we helped them move in. We discovered to our dismay, that their shed floor was in bad condition. It was rotting.

They had a ton of gardening supplies that needed to be stored. A rainstorm damaged the floor, so it had to be replaced. It left me wondering how can you stop a shed floor from rotting?

A shed floor needs to be correctly manufactured, installed, and maintained to stop it from rotting. The leading cause of rot in a shed floor is moisture from the rain, wear and tear from constant use, and overall age. A shed floor should be pressure treated to withstand wood rot, decay, and mold.

After realizing how quickly a shed floor can deteriorate, I had a look at my shed. How could I stop the shed floor from rotting, why was it rotting, how would I know if my shed floor is rotting, and when should it be replaced?

These questions are what I will be addressing in this article.

How to Tell if a Shed Floor Is Rotting

Rotted Out Shed Floor

If you haven’t checked your shed floor in some time, and the threat of floor rot is your main concern, there are ways to help you determine if you have a rotting shed floor.

  1. If you smell old earthy wet socks, that is a clear sign of mold. Mold only grows on surfaces when there is excess moisture.
  1. If you see green or discolored spots in some parts of the floor, this could be water damage or mold growing.
  1. If the wood pieces or boards around the joins are discolored and splintering away, this could be rot setting in.
  1. Look for wet or moist areas on the floor, near the hinges, on the walls, and in the corners.
  1. Look for sagging and sponginess on the floor; if it bounces and gives off wetness when you step on specific areas, the floor is probably rotting.

Why Is My Shed Floor Rotting?

Flooded Shed Floor

All types of timber absorb water. Wood that is constantly wet and can’t dry out properly is the perfect breeding ground for mildew, mold, and fungus.

Wood is a food source for these bacteria and needs to stay dry and protected. Wood rot sets in because the mold, mildew, and fungus eat the moist/wet wood, and it starts to rot.

Usually, after the rotting starts, those parts have to be cut out of the shed floor, or the mold, mildew, and fungus might spread.

After the shed floor does dry out, the fungus and mold might be gone, but the damage will make the wood spongy and crumbly.

Wooden floors that are rotting needs to be repaired or replaced because it is a hazard to walk on; you could fall through the rotten pieces.

How to Stop a Shed Floor from Rotting

When you think about all the items, tools, equipment, and gardening gear in your shed, the thought of the shed floor rotting and destroying your property makes you realize you need to prevent your shed from rotting before it has a chance to ruin your valuable equipment.

Here are a few interesting ways that you can stop your shed floor from rotting:

Pressure Treat Your Wooden Shed

Before your new wooden shed is delivered, request to have it pressure treated. It will be more expensive, but the price is well worth the benefit of not having to replace damaged equipment, gardening gear, or tools.

You can treat the shed at home, but it is better to have it done professionally, as the treatment involves soaking the boards in a vacuum-sealed tank filled with chemical preservatives.

This chemical bath protects against fungal growth and mold even in the tightest corners. If you don’t want to pay extra to have the shed chemically treated before you have it delivered, or you have moved into a house that already has a shed that has not been treated, you do have the DIY option of treating it at home.

The treatment won’t be as effective as the one done professionally, but it will help.

Ensure Your Shed Has the Right Base

Shed On Concrete Pad

Wood and water never mix. A shed needs to have a solid, water-resistant base. The wrong base or placing the shed directly on top of the ground will lead to wood rot.

If you erect the shed directly onto the ground without a base, the wood will start to absorb the moisture in the ground after it rains or if there is early morning dew.

There are bases for sheds that are uniquely designed to prevent the shed floor from touching the soil. They keep the shed raised off the ground and help drain any excess water when it does rain.

These bases are either made of treated wood or eco-friendly plastic that helps to keep the excess moisture at bay.

Your Shed Needs Sunlight to Keep the Floor from Rotting

Place your shed in a place where it will be in direct sunlight from all angles with no trees to block the sun. The sunshine will help the shed dry quicker on rainy days and help prevent the moisture from lingering on the shed floor and walls.

Don’t make the mistake of putting your shed at the bottom of a slope; the rain will gather in the corners, and the sun won’t be enough to keep the shed floor dry.

Even if you have the sun to dry your shed floor, I recommend you check on it now and then and perform the necessary maintenance.

Using Water-Based Sealant to Repel Water from Your Shed

There are some tremendous water-based sealants on the market these days. They will help prevent water and moisture from penetrating into the wood.

You will have to re-apply the sealant every one to two years, but it is worth it as the sealant works to keep the moisture out and helps to keep wood-destroying bugs at bay.

Can You Replace a Rotting Shed Floor?

If your floor is beyond repair, or you want to replace the floor to make maintenance easier, there are many different flooring options to choose from. Here are some options to consider:

Replacing Rotten Shed Floor with Concrete and Epoxy

Epoxy Floor Installation On Concrete

If you take out the old wooden shed floor over a concrete base, cleaning up and patching cracks or dents in the concrete is an excellent way to get the base you need for an Epoxy floor coating.

This solution is relatively inexpensive, and if you buy the non-slip additive, you won’t need to worry about slipping when it does rain. Epoxy protects the concrete and dries to a rock-hard finish.

Epoxy is versatile and comes in various colors and finishes, and little to no maintenance is involved; you will use this floor for years.

Replacing Your Rotting Shed Floor with Cement Sheets

Cement sheets are a great way to help stop the rot. It is a versatile flooring material that can be used on top of almost any subflooring material, from wooden frames and concrete slabs to wooden floors (if they are in good condition).

Cement sheets are water-resistant, durable, and fire-resistant. This flooring material is also impervious to ants, termites, and rot.

The downside to cement sheets is that it is expensive because you need special equipment to cut the sheets, so it’s best to have a contractor install them.

Replacing Your Rotting Shed Floor with New Timber

Taking out the old rotted floor and replacing it with treated timber will be a less expensive option than the cement sheets and easier to do in a DIY project.

The only thing is that timber is still wood and susceptible to moisture retention, mold, mildew, fungus, and rot.

You can treat the flooring every two years, but it doesn’t guarantee that it won’t get any of these problems.

Replacing Your Rotting Shed Floor with Plywood

Osb For Shed Floor

Plywood is usually used as a shed subfloor. If you can’t afford the other options, then this is the one for you. Although plywood is strong, it will need to be treated and sealed to stop it from rotting.

Even if you do seal and treat it, plywood won’t last many years. It is very susceptible to water retention, rot, mold, and mildew.

You need to use plywood only as a temporary flooring solution.

Replacing Your Rotting Shed Floor with Rubber Mats

Rubber On Concrete For Shed Floor

One surefire way of stopping your shed floor from rotting is to use concrete subflooring and put rubber mats over the subfloor. Rubber mats are usually non-slip, waterproof, rot, mold, and mildew resistant.

Good quality mats have the disadvantage of being a bit expensive, but they are comfortable to walk on and easy to clean.

Replacing Your Rotting Shed Floor with Slate Tiles

Tiles are a bit more on the expensive side, but good-quality slate or non-slip tiles will be an excellent choice to replace your rotting shed floor.

Tiles have the advantage of not attracting termites, mold, and fungus and are waterproof and fire-resistant.

You need to have a concrete base to lay the tile on top, or the tile will lift, but you never have to worry about your shed floor rotting again.

Replacing Your Rotting Shed Floor with Diamond/Checkerplate

Diamond and checker plate flooring works well on concrete slabs, poured concrete, or timber subflooring. Diamond and checker plate are mold, mildew, and rot proof. This type of flooring is also water and fireproof.

The drawback to using diamond and checker plate flooring is that it is slippery when wet and relatively expensive to install.

Replacing a Rotting Shed Floor with Self-Leveling Compound

Self Leveling A Shed Floor

For this option, you will need concrete subflooring. You need to remove the rotten floor, clean the concrete subfloor and leave it to dry completely.

Mix the self-leveling compound and spread a thick coat of it on the floor. The self-leveling compound will flow into all the nooks and dings and leave you with a new lever surface.

Make sure to leave the self-leveling compound to dry for at least 24 hours before attempting to walk on it.

Replacing a Shed Floor with Sandpaper

As strange as it may sound, I’ve seen some people use rolls of sandpaper as a temporary flooring material. It’s an inexpensive material and will last until you can afford to fix or replace your shed floor.

Some rolls have adhesive backings that will stick onto a solid subfloor. It won’t work on dirt or loose gravel.

The drawback is that you can get hurt if you fall on this flooring material, and it does curl up if it gets too wet.

Can You Repair a Rotting Shed Floor?

Rotted Shed Floor

If you don’t want to replace the entire shed floor, you can make repairs to it.

Here is how to repair a rotting shed floor:

  • First, remove all the contents of the shed. Test the stability and strength of each board by feeling for rot (crumbly texture) or spongy soft and wet areas.
  • Use a leveler on each board to see if there might be a slope; these boards will require foundation leveling.
  • Using a small ply or claw hammer, take out all the nails to the damaged boards. If you have a solid wood floor, use a jigsaw to cut out rotten pieces in easy-to-replace square sections.
  • Fill the foundation with gravel and dirt and pack it tightly to help give a sturdier foundation.
  • If you have the time and money, installing a concrete foundation would ensure the floor is always level, and it makes a much better subfloor than dirt and gravel.
  • Measure the size of the damaged board you removed and cut the new board (buy pressure-treated wood) to that size.
  • Using galvanized nails, nail the new floor securely to the rest of the floor, ensuring it is level.
  • Apply three coats of wood preserver to the whole floor, allowing each coat to fully dry before applying the next coat. Remember to re-apply the wood preserver at least once a year.

Final Thoughts

A rotting shed floor can be a disaster for the equipment and gear you are storing. The moisture and mold can damage your items, and it could get expensive. Taking preventive measures to stop the shed floor from rotting is a great way to protect your valuables.

If you want to repair or replace your shed floor, you need to find a solution you are happy with and one you are willing to spend the time and money on to maintain.


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Jon Thompson

Thursday 18th of January 2024

I,m installing a "Tuff Shed" in my backyard. I had a concrete pad laid where the shed will be placed. The "Tuff Shed" includes a vented galvanized steel floor frame that will be placed on top of the concrete pad. The shed floor is wood and is placed on top of the galvanized steel floor frame and the shed framing is on top of that. "Tuff Shed" advised "Do not add rubber mats or vinyl flooring inside as they can create a serious moisture and rot issue".

Is moisture and rot a concern even with the concrete pad and ventilated galvanized steel floor frame below the wood shed floor if the wood floor is covered with vinyl flooring?