Pressure Treated Wood in Contact With Concrete (Analysis)

Undoubtedly, pressure-treated wood is an amazing option for building exterior walls and decks, all thanks to its ruggedness!

It wouldn’t be wrong to call pressure-treated wood the “wood for all seasons”, as It’s highly durable, lasts longer, and has the ability to withstand the test of time.

But what happens to the pressure-treated wood when it comes in contact with concrete or cement?

It starts rotting!

But why does it happen, and how can you stop it from decaying?

Below, in this article, you will find a handful of techniques construction professional structural builders use to ensure the pressure-treated wood doesn’t decay when used with concrete.

Why Does Pressure-treated Wood Rot?

Before I explain to you the techniques, it is essential to understand the science behind the rotten wood due to concrete.

The pressure-treated wood available these days comes with copper, chromium, and arsenic treatment, which acts as a moisture barrier. Still, the wood rots in most cases, and this is due to the moisture present in the concrete.

While pressure treated woods are still the best choice for exterior masonry wall, basement wall, deck, retaining wall if you don’t want to go for non-organic alternatives. However, there’re some cons present to use pressure-treated lumbers with concrete or masonry.

The lumber absorbs the moisture irrespective of the wood preservative treatment and starts swelling up after some time.

So, are these preventive treatments useless? No, the preventive treatments slow down the rotting process, but unfortunately, they don’t stop it completely.

Is there any way to ensure that the wood doesn’t rot and lasts longer? Well, yes! Below-mentioned are some proven techniques that can curtail the effect of concrete’s moisture on pressure-treated lumber.

Techniques to Put Pressure-treated Wood in Concrete to Protect Decay

I’m into the building industry for years and have come across several cases where the wood starts rotting after a few years of installation.

Using the below-mentioned tips will help you enhance the lifespan of pressure-treated wood for up to 40-years.

Don’t forget to use a Gravel Base

All-purpose Gravel

Most people insert the wooden pole after digging a hole in the ground and then add concrete to it. But this is not the right way to do it!

Always install a gravel base after digging a hole. The coarse gravel base will support the wood while wicking away the moisture present in the ground (a decent protection). And as a result, the pressure-treated lumber lasts longer.

Put the Pole First, and Then Add Concrete

Concrete and Pressure-treated Wood

Never pour concrete before putting the wooden pole! Put the wood into the hole, and let it sit on the coarse gravel bed properly.

Now pour concrete around the pole and ensure that there is no concrete under the wooden pole. The concrete floor around the pole will hold it firmly while preventing it from moisture.

Make a Slope

Making a will help you get rid of excess water from the surface. Furthermore, sloping the concrete will also help it settle down properly around the wood.

Sloping even helps in preventing the lumber from absorbing the moisture from the concrete.

Installing a gravel base, pouring concrete, and sloping the concrete can be a daunting task for some.

Is there any other way to install the pressure-treated wood properly?

Yes, here’s how to do it the right way.

Use Steel Brackets

Using steel brackets will eliminate the hassles of installing a gravel bed and sloping the concrete. Furthermore, as steel doesn’t catch corrosion easily, so you can rest assured that the overall setup will last longer.

Whether you are installing a wooden log or want to use bigger pieces of lumber to build a house foundation, you can use pre-painted brackets. These brackets elevate the wood from the concrete, and it prevents their direct contact.

When the wood doesn’t touch the concrete, there are lesser chances of it getting rotten due to moisture.

Installing steel brackets is pretty easy and doesn’t require a lot of work. Here’s how to do it:

One type of bracket

Image Credit: Stack Exchange

Step 1: Insert the Bracket in Concrete

Insert the steel bracket into wet concrete floor so that the lower area settles down completely. The lower bottom of the bracket should touch the concrete bed’s top layer.

Step 2: Install the Wooden Pole

Now let the concrete dry for some time, and then install the pressure-treated wooden pile on it. Use screws to install the wooden pole with the bracket plate for a robust assembly.

Note: It is advised to use pre-painted steel brackets so that they don’t catch rust quickly.

Frequently Asked Questions

Is it essential to coat pressure-treated wood with a wood preservative?

Yes, it is essential to use a wood preservative to ensure the wood lasts longer and preventing it from getting exposed to moisture.

There are multiple types of wood preservatives you can use with pressure-treated wood, these include:

  • Copper-based preservative
  • Arsenic-based preservative

Use any of these preservatives to break down the contact of moisture with the wood. Here’s how you should apply the wood preservative on the pole.

How long does a steel bracket last in concrete?

There’s no certain lifespan of a steel bracket, but it can surely last for decades. Just make sure to buy a durable steel bracket that’s pre-painted.

Which sealant/glue should I use while installing a pressure-treated pole using concrete?

You can go for Loctite 1390595 ADHESIVES_AND_SEALANT. The sealant is strong, provided better coverage, and is safe for the environment.

What to do with the rotten wood?

You can reuse the wood by cutting the rotten part. If the entire lumber has decayed, then dispose of it properly, as you cannot reuse it.

Conclusion

This is what happens to the pressure-treated wood in contact with concrete. Use the aforementioned techniques to ensure that the wood lasts longer and doesn’t decay within a few years of installing it.

The best way to install pressure-treated wood on concrete is using steel brackets, but they are a bit expensive. You can even opt for the gravel bed method to make the wooden pole last longer.

 

 

Leave a Comment