Can you anchor a Simpson Strong-Tie (900x900) directly on top of tile?

[Nathan_21]

Hi all,

I am looking to build a pergola and I would like to know if I can fasten the Pryda 90mm M10 Bolt Down Post Anchor directly on top of the outdoor tile. The tile thickness is around 20mm, concrete thickness under the tile is around 170mm.

I can only see online people fixing posts directly to concrete, I cant find anyone going directly onto the tile. I would also like to know if the Pryda product is good for this project or should I spend more and go for the Simpson Strong-Tie 90 x 90mm?

Any help would be greatly appreciated.

Regards,

Nathan

[JacobZ]

Hi @Nathan_21,

A warm welcome to the Bunnings Workshop community and thank you for your question about mounting post anchors to a tiled surface.

When building a structure like a pergola, it is always best to check with your local council about your legal requirements in terms of building approval. Smaller structures often don't require building approval, but it is worth checking to be sure. If they require the submission of engineering plans, then the anchoring method for your pergola is something that will need to be discussed with an engineer or suitably licenced person.

Anchoring things to concrete that is beneath tiles is certainly possible, but there is some potential to crack the tile in the process. This risk can be minimised by drilling through the tile with a suitably sized tile bit, before using a masonry bit to drill into the concrete beneath.

You will then have to use masonry anchors such as Dynabolts or threaded rods that are chemically anchored with Chemset. Either of these methods will ensure the physical anchoring happens deep in the concrete as opposed to near the surface where it could potentially crack the tile. The anchors should be tightened, but not over-tightened as the downward pressure could also crack the tile. 

Assuming they fit within any anchoring requirements your local council has, either the Pryda or Simpson Strong-Tie products are made for this purpose, so the choice is entirely up to you and will likely come down to personal preference or aesthetics. 

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

Jacob