Low level deck extend over multiple concrete

[Zhenny]

Hi everyone,

I am new to the forum and really... new to the DIY community. I am looking to cover my entire backyard with a low level deck. I was contemplating on whether to do it myself or pay a professional to do it. After going through this platform and seeing all the wonderful work that other members have done. I really want to give it a try.

A bit about my backyard:

We currently have a small deck that is sitting on top of a concrete block while the rest of the backyard is covered in loose stones (we dug up all the grass and replaced it by stones as we found the lawn will become really muddy in winter). The current deck roughly sits 110~120mm above the concrete block. And we have a small shed at one corner, which can be easily removed as it is not bolted to the concrete below.

Dimension of existing backyard

There are a couple inspection points for sewage and stormwater etc.

photo

What I am thinking to do:

1. Demolish the existing deck

2. Excavate, lay some drainage stones/membrane and put deck blocks in place (~950mm from block centre to centre)

3. Lay the joists out (90x45) as shown by my drawing. (~450mm centre to centre)

4. Use L brackets to bolt the joist to concrete (~500mm or 600mm gap)

Proposed frame

One thing I have yet to figure out is to how to create some sort of a lift off panel for the two inspection points. Or something that allows easy access to those utilities while still retain the overall rigidity of the deck.

Any tips and advices would be fantastic!!

[MitchellMc]

Welcome to the Bunnings Workshop community @Zhenny. It's fabulous that you've joined us and many thanks for sharing your project.

It sounds like you are on the right track so far. You can create lift-off or hinged panels above the inspection points by adding additional framing to that area. I've added an image below to illustrate. This extra framing allows the surrounding boards to be nailed off at the perimeter of the inspection points. You might like to have a read through Ekodeck composite boards with Quickfix hidden fastening system by @Jfinlay, as they had two trapdoors installed in their deck for access.

Please let me know if you have further question or need assistance.

Mitchell

[Zhenny]

Thanks for the great reply Mitchell,

Just a couple more questions:

1. With the section of joists sitting on concrete, would there be issues when it rains where there might be some water sitting around? Or should I attend lift it slightly with packers?

2. I am thinking of using joist hangers for most connections. I assuming I won't be using those for the end/corner pieces (first and last joist)?

[MitchellMc]

Hi @Zhenny,

You'll definitely need to raise the joists above the concrete as that helps inhibit decay and allows airflow. The more room you can leave, the better. You can either use plastic packers, pedestal feet, or angle brackets.

It depends on how your frame is constructed as to how you attach your first and last joist. They can be nailed directly into the joist perpendicular to them with multigrips or hung with joist hangers. Since the joist hanger will be on the very end of the joist, you can bend one of the attachment wings giving you the ability to nail it on. 

Please let me know if you have further questions.

Mitchell