What is the approx cost of building a deck yourself?

[Patto]

👋 Hi everyone, just wonder if there is an estimate or guide someone could share (per mtr I guess) of Merbaui 120mm decking onto H3 timbers which will be over existing concrete slab.

I'm just wanting to get rough numbers to see if I proceed to next step and cost the whole project.

My wife has got a quote to build it for around $10k so it's a big enough job but if there is some savings to be made by DIY I'd consider it.

Cheers Patto

Community manager's note: Check out How to build a low-level deck for expert advice.

[MitchellMc]

Welcome to the Bunnings Workshop community @Patto. It's great to have you join us and many thanks for your question.

Rough square meter numbers are really quite variable when building a deck. There can be a dramatic difference in cost depending on wastage, dimensions of bearers and joists, lengths of timber available and the fixings you'll use.

I've worked out a basic per square meter cost of materials below:

• Timber for a one square meter section of the deck- 140-x-19mm KD Select Grade Merbau Decking, Treated Pine Outdoor Timber Framing 90 x 45mm and Treated Pine Outdoor Timber Framing 190 x 45mm. Cost $125.35

• Fixings to mount the bearers to the concrete slab- four Carinya 100 x 100 x 50 x 4.5mm Hot Dipped Galvanised Angle Bracket, eight Ramset 8 x 40mm Dynabolt Plus Hex Nut Bolt and eight Zenith M6 x 40mm Hot Dipped Galvanised Coach Screws. Cost $33.52

• Fixings to hang joists- eight Pryda Joist Hanger Suits 45 x 90mm and quarter packet Paslode 40 x 2.5mm 500g Griplock Galvanised Nails 260 Pack. Cost $16.75 (Please note this bracket is the incorrect orientation for your joists. I'll follow up with our Merchandise team about the availability of the correct product)

• Screws to fix decking boards- Half packet Buildex 10-8 x 65mm Climacoat Treated Pine And Hardwood Decking Screws 100 Pack. Cost $8.12

As a very rough approximation, I come to $183.74 per square meter for materials cost. After checking some other approximations online that appears to be on the lower end of costs for building a deck. I would use this only as an example and base it as your bare minimum in a perfect build situation.

Please let me know if you require further information or had any questions.

Mitchell

[Patto]

@MitchellMc  Thank you very much. More detail than I was expecting. This is very helpful. 👍

[DoSimpleBetter]

Hi Mitchell, 

I found the above post very helpful - thankyou! 

Did you have an outcome on this? 

(Please note this bracket is the incorrect orientation for your joists. I'll follow up with our Merchandise team about the availability of the correct product)

I'm hoping to order these brackets online for 70x45mm joists. What is the correct recommended product to place in each 'corner' join?

[MitchellMc]

Hi @DoSimpleBetter,

These brackets for joist hanging work with bearers and joists being stood on the thinner edge with the 45mm facing vertically. In your instance, you are laying the joist and bearers flat on their 70mm side. There is no Pryda hanger that can mount timber 70mm wide in the 45mm thickness you have available. 

The best solution I can think of would be to screw through the bearers into the end of the joists and use Pryda Nailplate Knuckle 67 x 127mm to add support from the underside. In your deck, for the corners, you could use a Pryda Corner Plate 110 x 60 x 30mm for added support underneath once you have screwed the timber together.

As we were discussing before the method of construction for your extreme low-level deck is slightly unconventional and it limits the connection fixings available to you.

Please let me know if you need further advice or had any questions.

Mitchell

[Cass1]

Hi,

Great info  

I have a verandah which extends the length of my house out the front and back. It is quite old and uneven - am I able to lay decking on top easily or can you think of an option to make it look better without redoing the whole thing. 

The wood is in ok except where the deck meets the edge of the house, then there is wood rotation creeping in  

[MitchellMc]

Welcome to the Bunnings Workshop community @Cass1. It's terrific to have you join us and many thanks for your question.

Would it be possible to see some images of the rotted area illustrating how badly it has decayed? A product like Earl's Wood Hardener might stop the wood rot from getting any worse. That would then allow you to fill the damaged areas and sand the whole deck down to remove the un-evenness.

You should find this step-by-step tutorial helpful: How to sand a deck. The very knowledgeable @Adam_W has put an article together on How to renovate a timber deck which I trust you'll also find useful.

I wouldn't advise laying new decking straight on top of the old decking as moisture would build up between the two boards. This would lead to the new timber decaying faster than it should.

We look forward to seeing some images of the deck and offering some great solutions.

Mitchell