How to repair rusting flashing?

tiarne.gayton

We’d like to repair/replace the rusting flashing located on the side of our house. I think the 6m long flashing is rusting because it’s bent slightly ‘upwards’ which allows water to pool after a rain event. What’s the best approach to removing the rust and bending the flashing (to prevent water pooling)? Thankyou!

JacobZ

Hi @tiarne.gayton,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

That flashing is often referred to as a weatherboard starter or weatherboard bottom flashing. They are installed at the bottom of a weatherboard wall, and they have a vertical leg that sits behind the weatherboard which attaches to the framing. Behind the weatherboard, there will be a vapour membrane or building wrap which covers the entirety of the wall and then overlaps in front of the vertical leg of this flashing. The idea is that any moisture that finds its way behind the weatherboard hits the building wrap, runs down the wall and is then deposited on to the back edge of that flashing.

You'll notice at the bottom edge of the bottom weatherboard, there is some sealant which coincides with where the rust is.

As the idea is for water to run down the building wrap, hit the flashing and then drain away from the weatherboard and your foundation, having sealant there will block this drainage from occurring. I'd say that the flashing is functioning as intended, but that sealant is stopping it in some areas.

I would throw out the idea of replacing it, as this will involve removing the bottom couple of weatherboards, which is not a simple task. Also, because you appear to have minor surface rust, so it is not likely to be adversely damaged.

I'd suggest you start by cutting away the sealant using a utility knife, ensuring you wear long protective clothing and gloves to reduce the risk of lacerations while doing so.

Once the sealant has been removed, there's a good chance you'll be able to remove the vast majority of the rust with a wire brush or some sandpaper and then give it a good clean and a coat of exterior paint if necessary.

I doubt it will require it, but if the rust is more extensive than it seems, you can use rust converter to convert it into a stable compound before painting over it with an exterior paint.

If water is still pooling on the flashing when the sealant has been removed, which you can test by pouring some water on it and observing where it drains to, then you can look at bending the flashing downwards a bit, but I can't imagine this would be required based on what I can see where there is no sealant.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob