ᐅ Attaching a House Number to a Wood Fiber Insulation Facade

Hello everyone!
Question for you: What is the best way to attach a metal house number to a facade made of wood fiber insulation boards?

The house number is about 30cm (12 inches) high and has 4 holes/pins on the back for mounting.
The plastered facade consists of 120mm (4.7 inches) wood fiber insulation boards on the outside. Using anchors is not ideal. For example, the mailbox was attached with Spax 8x120 screws.

Should I drill holes, insert anchors, and press in the fine-threaded pins?
Or drill holes, apply mounting adhesive, and then push in the pins along with the number?

How about removing the pins and applying adhesive over the entire surface?

RobsonMKK schrieb:
How about removing the pins and using mounting adhesive across the entire surface?

That doesn’t look like it was just slapped on.

As you already mentioned: drill holes, insert anchors, press in threaded rods. That works perfectly fine with the right combination of threaded rods and anchors.

Knallkörper schrieb:
This works perfectly with the right combination of threaded anchor.

How would that look? The threads have a 4mm (0.16 inch) external diameter. Do you have any specific anchors in mind?

I also have 4 mm threads, but unfortunately, I can’t remember whether I used size 6 or size 8 wall plugs. I tend to think it was size 6 because the pins hold quite firmly. You can try that beforehand. You don’t need any special wall plugs for this.

Okay, I was concerned because the facade feels somewhat "soft." However, the mailbox and other fixtures are holding up well...