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Decking over concrete porch

rhee13
New Contributor

Decking over concrete porch

Hey all!

 

I’m currently in the research and planning stages to makeover my front yard area and wanted to cover the existing concrete porch with decking, extend it out and created a tiered decking to our gate area. 

The new decking area is pretty straight forward, but it’s covering the existing porch that is the issue. It’s almost flush with the front door, about 25mil wiggle room at the moment but we could go another 15mm higher due to inward opening front doors that already has e a gap underneath (want to maintain the original hardwood doors that came with the house). 

Wondering how I would go about attaching a frame to the concrete but also, is it even possible to do and still have room for drainage? We’re in SE Qld so we get our fair share of rain. 

any advice would be appreciated, thanks! 

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Decking over concrete porch

Welcome to the Bunnings Workshop community @rhee13. It's fabulous to have you join us and many thanks for your questions.

 

There is not enough room to create a deck in the traditional sense over the concrete. A deck would have a supporting structure of timber or steel joists and beams. What you would be doing here is cladding the concrete with the decking. There would be no room for drainage or airflow under the decking boards leading to their reduced lifespan. Placing decking directly onto concrete is not recommended. However, I can't find many examples of people doing so and an actual issue arising.

 

I'm hesitant to say that this can't be done, as in this day and age of low-level decks anything seems possible. 15 years ago all these low-level decks we see now would have been considered too low, and that failure of them was an imminent prospect. My primary concern with cladding the concrete would be how quickly the hardwood decking would degrade from trapped moisture on the underside. 

 

Let me mention a few of our helpful members @TedBear, @ProjectPete, @Adam_W and @Brad to get their thoughts.

 

Mitchell

 

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rhee13
New Contributor

Re: Decking over concrete porch

Thanks Mitchell. I really thought this might be the case but was hoping there was some sort of magic fix I hadn’t come across. 

Longevity and sustainability are definitely two elements I want to take in to account so I guess it’s back to the drawing board!

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Brad
Trusted Contributor

Re: Decking over concrete porch

I have roughly 100mm to work with on mine so I am in a slightly better place...

 

My first thought was to use 6mm timber packers where the screws were but my 2nd thought is to use something that won't soak up water like nylon or stainless steel washers. I would think predrill the decking and epoxy the packers on.

 

Bondall Monocel In Ground Wood Protector can be used on the underside of your decking. Feast Watson Timber Primer is another choice but you should also finish the underside with what you are using as a top coat when using this product.

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rhee13
New Contributor

Re: Decking over concrete porch

I was reading a diy blog post from the US with a similar situation to mine where he used PVC spacers under the sleepers but covered the sleepers in flashing tape to reduce damp. He drilled through the sleepers into the concrete through the spacers so there was a small gap for airflow. 

Anyone done similar to this? 

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Decking over concrete porch

@rhee13,

 

US-based projects are where you'll see this type of thing done, traditionally they have far looser construction codes to what we see here. I've seen house walls that are so paper thin that you'd fall through them if you weren't careful.

 

You might find these Macsim plastic shims useful. I'm not sure if you'll find someone who has done similar, as you'd really be paving the way in Australia. Who knows, perhaps in 10 years, we'll all be laying decking directly on concrete.

 

Mitchell

 

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rhee13
New Contributor

Re: Decking over concrete porch

@MitchellMc thanks so much for your advice, I can’t believe how useful this forum is. 

Thankfully the joy of DIY and home

ownership gives me plenty of time to consider other options. I figure there’s a good reason it’s not already being done like that so I’ll save the risk taking for someone else and look at tiling my porch instead!

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