How to fix wall vent to wall?

[Coolaholigah]

Hi and thanks

could you please tell me a good method and materials to fix this wall vent to the masonry brick rendered external wall

https://www.bunnings.com.au/haron-300-x-300mm-silver-aluminium-pressed-wall-vent_p0814362

the ‘hole’ is from the back of an exhaust fan where the plastic cover completely deteriorated. The cut out is 230mm diameter but I can’t seem to find a cover only to buy but I need to cover the ugly hole. 
The fan is above a bbq but we never use the fan as the bbq is outside anyway so I think this vent will be a good way to cover the hole

[AlanM52]

Hi @Coolaholigah,

The usual method is masonry wall plugs but in your case I recommend silicone adhesive.

Run a bead around the vent as shown.

Carefully align and press the vent onto the wall and apply pressure for about one minute.

You could follow-up with the ladder carefully propped against the vent and leave for a while

Cheers

[EricL]

Hello @Coolaholigah 

Thanks for sharing your question about the vent cover. It's great that you've received excellent advice from @AlanM52. I agree with his recommendation of using silicone as it will not damage the structure of the brick. The vent cover can be removed using a craft knife and there would be no need to use heavy tools to remove it.

My best advice would be to use masking tape to hold the vent in place while the silicone cures. I recommend using Parfix 300g Clear All Purpose Silicone to fix the vent in place.

If you need further assistance, please let us know.

Eric

[Coolaholigah]

Hi could I activate this again please?

I'm just wondering why silicon is suggested and not fixing into the masonry. Maybe it’s because of the structure of bricks…could drilling break the bricks somehow?

but I’ve purchased the cover and it is quite light aluminium so I don’t think long screws would be needed. Or would a dynabolt work?

I'm just concerned as the spot is quite exposed and at my age I want to limit the amount of time I spend up a ladder so I’m concerned that the silicone fixing might not last long.

the vent packet says fix with 8 gauge screws

I’m torn because in one way the silicone would be easier but not if I have to redo it too soon.

thank you

your suggestions welcome

[JacobZ]

Hi @Coolaholigah,

They've recommended silicone as opposed to masonry plugs and screws because the bricks have hollow cores, which aren't always suitable for masonry fixings. If you drill through to one of the hollows, there is some potential for blowout and the bricks cracking.

Considering the vent will be light, as long as the distance from the outside of the render to the core of the bricks is less than 25mm, you could try using relatively short fixings such as 25mm Green Wall Plugs with Zenith 8G x 25mm Galvanised Button Head Screws.

If you'd like to give this a try, I would not use the hammer function on your drill; rather, just use the standard drilling function without the percussive hammering action. This will reduce the force applied to the brick and reduce the potential for cracking. I would also suggest putting a piece of painter's tape to act as a depth gauge to prevent over drilling.

If the measurements just don't add up, silicone would be your best option, but I would consider using something a bit stronger, such as Sikaflex 11FC Purform.

Let me know if you have any further questions.

Jacob

[Coolaholigah]

Thank you

yes I thought that structure of the bricks might be the reason. Thank you for clarifying. It’s not worth the risk. I’ll just try the stronger silicon you suggested

thanks again