How to build support piers for small house extension?

[Ext54]

I’m removing an old leanto extension and building a slightly larger enclosed verandah extension using Uni-pier piers. The proposed extension is 3600 by 2700. I will concrete the piers into the ground 450mm, just wondering what dimensions the hole should be?

[Dave-1]

Good morning @Ext54 

Welcome to the Bunnings community page Its a nice place to find a bunch of informnation and ideas.

I have not used Uni-pier piers before but have dug plenty of foundation holes for piers.

I have used a

Square Mouth Shovel as it was the perfect size to get down into the hole and have straight walls with it, I could drive the shovel down into the clay to crack off the next inch or so of soil. I havnt really used a post hole shovel (As in a narrow width shovel) before. The holes I have dug have been between 450mm-600mm. 

Dave

[Ext54]

Thanks for that Dave, that’s about the size I was expecting. I haven’t dug any holes for investigation yet but I think your info is spot on.

[Dave-1]

Good afternoon @Ext54 

Hey just remembered to warn you of stormwater pipes especially near the foundations of the wall. I have run into that issue before. 

Dave

[EricL]

Hello @Ext54 

Allow me to welcome you as well to the Bunnings Workshop community. It's marvellous to have you join us and thank you for sharing your question about Uni-Piers.

It's great that you've received excellent advice from @Dave-1. Just to add to the suggestions made, I recommend calling the BYDA (Before you dig Australia) just to be sure that there are no electrical or plumbing utilities in the area. Since you are building a larger structure with larger piers, I suggest consulting a structural engineer to get an opinion on how large and deep the foundation holes should be. 

The engineer will probably ask you if you have a sketch of your plan and the size of the timbers you'll be planning to use. Any other information you can provide will definitely be helpful. 

Here is a link to the Uni-Pier Brochure: Uni Pier Selection Guide

If you have any other question we can help with, please let us know.

Eric

[Ext54]

Thanks Eric 👍👍👍