Gibbo’s Low Ironbark Deck

Hello All,

I’ve been building a deck very slowly over the last couple of months now. I’ve never done any sort of large construction before, so just about all the ideas, inspiration and know-how for my deck have come from this forum and the highly recommended Allen Staines book. I have learned a heap from the WIP threads, experienced deck builders and particularly photos, so I thought I’d throw one together as well, with some pics. A huge thanks to contributors on this forum who have all indirectly and directly helped me – UteMad, Bloss, jba, oohsam, Raff and many others.

Deck Details:
Area: about 3m x 6m
Low level deck with clearance from the ground to bottom of bearers ranging from about 70mm to 240mm
Bearers: 90x90 F7 H4 treated pine bearers bolted straight into Pryda post anchors
Joists: 90x45 MGP10 H3 treated pine
Decking: 85x19 ironbark
Post anchor spacing along bearer: 1300mm
Post anchor spacing between bearers: 1200mm => 3 rows of bearers
Joist spacing: 445mm => 14 joists
Pryda post anchors set into concrete footings

Footings:
First up I needed to dig 15 footing holes which were mostly 300x300x450mm. I hand dug the holes with a shovel and pry bar, and as others have mentioned, solid clay sucks.

Attaching the stirrups to bearers:
I laid the bearers out over the holes, marked the stirrup locations, drilled and bolted them on. (Pic 1)

After free-hand drilling a couple of wayward holes that weren’t exactly at 90 degrees and meant I couldn’t get the bolt through the stirrup and bearer, I drilled a hole in a thick piece of hardwood nice and square at the drill press and then clamped this to the bearer to guide the drill for each hole. No problems after that.

I spent a while agonising over whether to have the bearers sit right down in the base of the stirrup, or to have them elevated with all the weight shear on the bolts. I figured either would probably be fine, but ended up sitting them down in the base with a couple of 3mm packers underneath to let water drain away and avoid the annoying rivet in the base of the Pryda stirrups which stopped it from seating properly.

The 90x90 for the bearers came in 3m lengths so I made the middle hole in each row wider to allow for 2 post anchors to be set in the hole to join the bearers (great idea from elsewhere on the forum). (Pic 2)

I used both 300mm and 450mm Pryda post anchors to make sure I had the minimum 150mm of concrete under the foot of the stirrup and max extension above the concrete of less than 300mm as per the Pyrda tech specs. My max extension from the concrete was 240mm, and I was a little worried about the stirrup post flexing, but it’s quite solid, particularly when the joists tie it all together.

Levelling & bracing the bearers:
Pic 3 shows an idea stolen from jba’s post – using a car jack to level up each bearer section. This method made it very easy to fine tune the height and find enough stuff to pack them up with. Those horseshoe packers are fantastic for fine tuning everything. I used the water level shown in pic2 to get the whole structure level. Getting something this big level was quite daunting at the start, but the water level made it really easy, proved to be super accurate, and best of all was really cheap!
I then braced the bearers with some joists to keep them in place while shovelling concrete into the holes. (Pic 4)

Concrete:
I needed about 0.7 cubic meters of concrete. I first considered getting a minicrete truck delivery to make it easy, but found out they only allow you 20mins to unload and then charge ‘waiting time’. Given that I was doing this solo, I didn’t like my chances of getting all the concrete from the front to the back of the house and properly packed into 15 holes in 20mins. So I got materials delivered, hired a concrete mixer and mixed it all. That was a big day! I’m glad I didn’t get the truck now because it took me quite a while to pack each hole properly – I was being pretty careful compacting it to get the air bubbles out as there’s not a huge foot on the base of those stirrups for load bearing. I read in a few concrete guides that for footings a mix of 5:3:1 was adequate, but because of the small load bearing foot I used the next step up of 4:2.5:1. Overkill or underkill – still don’t’ know.

Drainage:
As the deck is pretty low and at a low point in our back yard, I wanted to make sure there was some reasonable drainage. I dug a drainage channel the length of the deck, sloped the ground around towards it, put down 50mm blue metal, ag line & filled with more blue metal. I have an existing stormwater point at the corner of the house, so will get the ag line connected here. (Pics 5 & 6)

I then threw down some weed mat and covered the whole area with more blue metal.

Joists:
Next I rolled out some of that Protect-a-deck stuff from bunnings on the top of the bearers. The joists were attached with Pyrda triple grips. I checked for any high spots with a spirit level and hit them with an electric planer.

I managed to pick up very cheaply some Joistrip to cover the joists, which is a black rubber flashing similar to the protectadeck stuff, but way better. It’s 2mm thick, has ‘legs’ that fold over the top of the joist, seals itself around the screws and has a line running down the middle to help you keep your screws straight. Normally very expensive though. (Pic 7 & 8)

Step:
A box step is needed off one end of the deck, and I wasn’t sure of the easiest method of building the structure, so I ended up building it like a miniature deck with stirrups, bearers & joists. Probably complete overkill!

Attached Thumbnails http://www.renovateforum.com/attachm...g-holes_sm.jpg http://www.renovateforum.com/attachm...r-level_sm.jpg http://www.renovateforum.com/attachm...bearers_sm.jpg http://www.renovateforum.com/attachm...oncrete_sm.jpg http://www.renovateforum.com/attachm...-trench_sm.jpg

http://www.renovateforum.com/attachm...ag-line_sm.jpg http://www.renovateforum.com/attachm...bearers_sm.jpg http://www.renovateforum.com/attachm...ecking1_sm.jpg



Read the full thread at RenovateForum.com...