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Flashing where siding meets concrete – how to seal it

One of the easiest ways to have your buildings absorb water and sustain damages is by not paying attention to the edges of your building where two different walls meet. For instance, in most cases, the edges of your wall meeting the floor concrete always have some openings which can absorb water if left without flashing.

Flashing, however, allows you to prevent this damage or water absorption if you know how to seal it.This article takes you through how to seal your flashing where your siding meets concrete.

What is flashing and why do you need it

Flashing can be a metal or waterproof material installed in between two different sidings to prevent moist or water from penetrating into the vulnerable areas.

The most vulnerable part of the building is the point on the floor where the siding of the building meets the foundation. Flashing is important because it is the only way to cover up this vulnerable space from water and other elements and channel them to the right drainage paths.

What are the best materials for flashing

There are many materials available for flashing such as flashing tape, rubber, and even nylon materials. However, metal flashing is the best material for flashing. This is because of its durability and functionality. Metal flashing is also very flexible and can be cut to fit into different kinds of shapes in your building. Always remember to use corrosion resistant fasteners on your metal flash before using it for your siding.

One thing to avoid in using metal flashing, however, is using it on wood top of wood siding. Metal flashing, like many other metals, will fall to corrosion when it comes in contact with water or moisture. Therefore, you have to ensure that you cover your wood siding with layers of tar paper or any other water resistant material before using the metal flashing.

What are the types of flashing

How do you seal your clashing

Basically, there are three steps to take in the process of sealing your side flashing.

Area preparations

This stage has to do with getting the area you want to flash cleared and cleaned up to avoid the interference of dirt or other obstacles to the flashing. There is always heat and Sparks from the flashing that you need to prepare your concrete in such a way that it will be able to withstand them.

Flashing installation and sealing

It is always advisable to begin your flashing from the corners so as to prevent the small gaps or protrusion that always comes with indiscriminate flashing. Once you are done with the corners, generously pour the sealant on the flashing and check out for minor gaps.

Decorate the area

Once you are completely done with the second stage, allow it to begin with a touch up of the flashing and sealant. Be aware that some paints may actually react, especially when you don’t allow the sealant to cure very well. Smoothen the edges out and trim the excess parts and your flashing is ready for use.


Flashing is the best thing you can do to save your siding from moist and water absorption, especially where it meets with concrete. Go for metal siding and ensure we stick to the steps on how to seal the flashing to ensure durability and functionality.

Trisha Mae Raymundo
Trisha Mae Raymundo

Senior Writer and Editor of The Home Spot.