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Merbau decking over concrete slab

Neo19
Making a Splash

Merbau decking over concrete slab

IMG_20191207_141119.jpg

 

Hi Everyone 

 

I have been going through these discussion boards for a while and finally mustered to courage to post a question here :smile:

 

This would be my first deck. Have done some landscaping for myself in the past including a raised garden bed, however nothing major. As far as tools, I've a drill kit including hammer drill, a cordked circular saw and a random orbital sander. 

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My proposed deck would be 350 x 370 with height from the slab between 17 - 18 cm so it stays flush with the brick and same level as my internal floor. 

 

I've been advised that i could use H3 structural timber (140 x 45) as joists and lay decking boards on top that. 

 

My questions, 

 

1. How do I attach joists to the concrete? Use galvanized angle brackets like this?

 

2. How can I adjust the height so the finished decking board stays flush? If i used 140 board + .5 bracket + 19 mm board = it would be around 165 cm height. Which is around 1.5 cm lower than bricks. Can I use plastic wedges / window packers to compensate for around 1.5 to 2 cm? 

 

3. This deck would be under alfresco cover and under eaves. In terms for water drainage, what would be helpful. Would the packers / wedges mentioned in Q. 2 help with the same?   

 

IMG_20190916_143835.jpgAlfrescoAlfrescoRough plan showing pillarRough plan showing pillar

On the last image, pillar is on the corner of the alfresco slab and the decking to the south of it would be on top of soil (this would 370 x 45 cm). Not much height difference from alfresco slab. What do I need to provide here under joist for support? Not enough height for a stirrup. 

 

Thank you very much for reading through. 

Brendon_B
Getting Established

Re: Merbau Decking over concrete slab

Hi @Neo19 

They are just 140  x 19mm Merbau

So far no stain/oil

Most have that rich colour, but they do fade a little after the tannins leach out.

Will be coating with a wet look deck oil.

Cheers

Brendon

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Merbau Decking over concrete slab

Welcome to the Bunnings Workshop community @babakr.

 

I see you have already received a helpful reply from @Brendon_B about their project. It would be great to hear more about your own decking project and we'd encourage you to let us know if you need any assistance or if you'd like to share it with the community. I trust you'll find loads of inspiration for your decking project, just like this one, from within our community as our amazing members are contributing their projects here all the time.

 

Mitchell

 

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Re: Merbau Decking over concrete slab

hi @babakr I've got 90x19 mm merbau boards from bunnings. the stain I've used is Feast Watson Traditional Timber Classic Timber finish here 

Re: Merbau Decking over concrete slab

sorry @babakr , although that was the timber finish i've used what you see in the pic is just untreated deck after a wash. Glossy effect due to water on it :smile:

babakr
Getting Established

Re: Merbau Decking over concrete slab

Hi @Neo19 

Sounds great but I am wondering how it looks reddish while Merbau is brown. I actually wonder what timber can give me a reddish look (or what stain/oil). I found Kerri probably is a good choice for red/pink colouring but I looked at them in Bunnings and they look different from what I see in the finished deck projects.

babakr
Getting Established

Re: Merbau Decking over concrete slab

@MitchellMc 

Hi Mitchell,

I am at the end of joist installation on my veranda concrete floor for a 14 x 1.7 m deck. I haven't used brackets as the concrete was too uneven and I had to use window packers and sometimes other supports to level all joists across the floor. I screwed down the joists by 125 mm batten screws directly into the concrete using 10 mm wall plugs and it looks firm and strong. The next step is choosing deck boards which I am after a reddish look finish like what I saw in @Neo19 job. Here is the photos and appreciate any comments.

https://photos.app.goo.gl/JXtBCzDK26fJYtDV9

 

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Merbau Decking over concrete slab

Hi @babakr,

 

You'll find most decking timbers don't show their true colours until they receive a coating on them, so what you see on the shelf in stores might not reflect the final appearance. In the case of Neo19's deck, their decking boards have a vivid red due to the water which is sitting on them. Perhaps @Neo19 could update us on what the deck looks like with the Feast Watson oiled applied to it instead.

 

You might like to have a look at Jarrah as an option as it tends to have some dramatic red colours. Depending on your location Jarrah decking boards can be a special ordered item into our stores.

 

Mitchell

 

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Re: Merbau Decking over concrete slab

Visitors to this very popular project might be interested in a comprehensive new guide by D.I.Y. expert @Adam_W - How to build a low-level deck.

 

Please let us know if we can assist with your own decking project. We're here to help.

 

Jason

 

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babakr
Getting Established

Re: Merbau Decking over concrete slab

Hi everyone,

I am in the process of choosing right decking screws. I searched in the building documents and everyone recommends 8-10 G/ 65 mm length (2 1/2") to fasten 90/19 mm decking boards (I am using Stringybark boards) but I saw in Bunnings (as well as other hardware stores) most screws being sold are 50 mm in length and it appears most people are using this range for common 90/19 mm decking boards. Can anyone please shed a light on this and what size (both diameter and length) is recommended for this application? Thank you in advance.

Re: Merbau Decking over concrete slab

@babakr sorry I haven't got any pictures of the deck soon after applying the oil. It's currently looking like it's time for another oiling with a little jaded and dusty at the moment. However from what I could remember it was reddish and closer to the wet look. I think I have applied 2 - 3 coats.

 

I have used 10g 50 mm square drive ss screws. I agree it's only been less than a year, however still feels solid.

 

I have also used https://www.bunnings.com.au/starborn-no-10-smart-bit-flat-head-countersink-drill-bit_p6360119

 

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