How to build a concrete BBQ benchtop?

[bernieanderson]

Hi, 

I'm looking at constructing the above, and I need advice on the following items.

1. For forming up the underside of the concrete benchtop, I assume some form of cement sheeting could be used and can remain in place (as opposed to using F17 and removing post pour). If cement sheeting was used, acknowledging it is not structural, so appropriate support would be required, what spec would be appropriate? Noting it will remain in place and is outdoor.

2. I have purchased 390*190*140 Besser Blocks for the 4 supporting walls, however, I need to know if they are fire rated or not as two of these four walls will create the side walls of the BBQ cavity. The exact products are noted as  "BESSER BLOCK MASONRY VIC 390 X 190 X 140 B5W010F2".

Cheers, 

[EricL]

Hello @bernieanderson 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about building a concrete benchtop.

I propose taking a different approach to the build, I suggest having a look at this discussion - Concrete tabletop project by @markw. This particular build leaves you with a solid concrete top with no timber support needed. The drawback of leaving timber outdoors is that it will get damaged by the elements, even if it is under the concrete slab. The ones that do have timber support are usually inside the house and not used outside.

As a concrete product, Besser blocks are non-combustible and can withstand high temperatures, making them a good choice for fire safety. The final fire rating is a result of the complete wall assembly, not just the block alone. Factors like core-filling with grout, reinforcement with steel, and adding finishes such as render are critical to achieving a specific fire resistance level. 

Here are some discussions in regards to concrete benchtops:

• Outdoor kitchen with DIY concrete benchtop by @RenovisionAU
   
• D.I.Y. Wood And Concrete Kitchen Island 
   
• Concrete benchtops by @ProjectPete 
   
• How to pour in place concrete benchtop? by @vfrifrcfi 

If you need further assistance, please let us know.

Eric