What end joists for low level deck?

[NilesMerek]

Hi everyone,

I've been lurking around this forum for weeks for my new mini low level floating deck project. I think I got most of my answers covered, but need a bit of help with this one. 

First of all, this is my first time building something this big. Go easy on me with the terminology

The planned deck is in the images below. My total deck height is only 20cm. So, I chose to work with tuffblocks with 140 x 35mm joists all around.  My first question is do you see any faults in this design? Does it seem like I need to change something? Second question is about where two rim joists meet. How can I attach them together? I could not find a joist hanger for that purpose. The only thing I could find which might work is a Boxspan 100mm Galvanised Framing Bracket which seems to be for steel framing, not timber. 

Thanks a lot

[MitchellMc]

Welcome to the Bunnings Workshop community @NilesMerek. It's brilliant to have you join us, and many thanks for your question about constructing a deck.

For joining the two sections of rim joists, you could use Pryda nailing plates on the outside or angular brackets screwed in from the inside. Another simple option is to drive a couple of 150mm bugle landscape screws through the face of one joist into the end of the other; a couple of screws per joint should be enough to secure them adequately. 

Your deck looks well planned, and it’s clear you’ve put a lot of effort into the design. That said, I do have some concerns about the rim joists on the left and right sides, as they appear unsupported. While you have plenty of noggins running down those sections, the tough blocks are inset on the second-last joist, likely because you can't fit them on the exterior joist without them being seen. The issue is that noggins mainly tie the joists together and don’t provide true structural support. To address this, I would suggest adding extra tough blocks directly under the noggins (but still within the footprint of your deck) so they’re supported, which in turn helps support the rim joists. Another option is to use plastic packers or similar supports beneath the rim joists along their length. Without additional support, standing or putting weight along the middle of the exterior rim joists could risk having the noggins detach, so adding these supports will give the deck the rigidity it needs.

Please let me know if you have any questions.

Mitchell
 

[NilesMerek]

Hi Mitchell,

Thank you very much for the guidance. I think I will go with the angular brackets for the corners. 

I was thinking about your advice on the left and right cantilevered boxes. Tuffblocks people recommend such 30cm cantilevered boxes to hide the footings, but you have a point there. Better safe than sorry. I'll just throw a few more of those footings to support the rim joists. 

Thanks for the help. Hope I'll upload the photos of the finished project soon.