Low-level deck for backyard

[siran]

Hi,

I’m building a deck on my alfresco, which is extended few mitres in the lawn area too. The size of the deck is 4.5 x 4.2m. Alfresco area covers the length of 3m and remaining 1.2m is in the lawn area. It’s a low level deck as the max height I can go is around 160mm. I’m using 11x90x45mm joist across 4.5m, with side boards(90x45mm) covers all the edges of the rectangle, these are screwed together using baton screws(75mm). Joist are sitting on the pedestal( Buzon, which can bear more than 1000kg), each joist are sitting on 5 pedestals, 30cm from both side and 3 in the middle spaced evenly. 3 Pedestals are sitting on the concrete Alfresco, 2 pedestals are in lawn area and sitting on the bricks, these bricks are laid on concrete which I freshly did for this project.

I got few questions and need help from the DIY community:

1) At the moment deck is very stable. But do I need to fix few joists in alfresco area to the concrete using L brackets to avoid any movements in deck in future.

2) Do I need to put a post in the lawn area, may be 3, and fix the edge 90x45mm frame using as a bearer to give more support to the joists, these joists are already connected to it using baton screws.

3) any other suggestions 

 

[EricL]

Hi @siran

Welcome to the Bunnings Workshop community. It's amazing to have you join us, and thank you to sharing your question about your low-level deck.

Your timber framework looks excellent. I see you've used adjustable pedestal feet to keep your deck frame nice and level. 

Let me try and answer some of your questions:

• Using "L" brackets is a good option to keep the timber frame from moving. The other option is to drill your frame to the side of the house. On the condition that the mounting point is big enough for a ledger and that the joists are attached with joist hangers.

• With the way that you've laid out your pedestal feet, it's not necessary for you to put a post in the lawn area. If you've used 12g to 14g batten screws these should be sufficient to hold it in place.

• My only other suggestion is to put weedmat and gravel under the deck to help facilitate drainage.

It's a fantastic low-level deck project, we look forward to seeing it assembled and complete.

If you need further assistance, please let us know.

Eric

[siran]

Dear Eric,

thanks for your guidance. I prefer L bracket than attaching the deck to the side wall as I already used batten screws instead of joist hanger. Further, do I need to spray any chemicals to lawn area to prevent weed or lawn growing in the deck area ? if so what product you can recommend? Or laying a weedmat is sufficient.

thanks

[EricL]

Hi @siran

There is no need to spray chemicals, the weedmat and gravel will be enough to kill the turf underneath. 

If you need further assistance, please let us know.

Eric

[siran]

Hi Eric,

Do I need to use joist protector? I cannot see most of the deck work shared in DIY community using joist protector. In my case, only part of the deck will be exposed to wet weather. 

Thanks

[MikeTNZ]

Just a question, if I may, siran?

What are them black coloured supports under the deck bearers?, I've never seen them before, are they commonly available?

I've also never seen a deck with ex.100 x 50 mm bearers either, in the last couple that I've built, they've used ex.150 x 50 mm bearers, however,

given the amount of supports you have under them, I can't see a problem.

I'd love to see this when it's finished, it looks like it's going to be great.

[EricL]

Hi @siran

Any extra protection you can provide your deck is always a plus. So if you can fit it into your budget, I would put the joist protector on. There's no need to put it over the covered area only the exposed part of your decking frame. 

If you need further assistance, please let us know.

Eric

[EricL]

Hi @MikeTNZ

Let me tag @siran to make them aware of your questions. I believe siran used adjustable pedestal feet in combination with bricks and concrete to support the joist. 

Eric

[siran]

@MikeTNZ 

Hi Mike,

I used adjustable pedestal to support the joists. The joists I used are 90x45mm as I got max height of 160mm in alfresco area, so added more footing to support 90x45mm.

thanks

[siran]

Hi Eric,

unfortunately the merbau boards (90mm) I got are not straight, I’m seeing 20-50mm curve in all the boards and I’m using clamp to fix these, sometime I’m cutting the boards to small length. My question is that if I use clamp to fix these, would that be a problem in future that screws will not hold it over time or due to weather changes and timber shrinks and expands etc

thanks