What joist support for low level deck?

[Bolton]

Hi, I’m about to start a low level deck with posts and bearers. I have a few questions. 

1. How far apart should the posts be on the external bearers and is it ok to fix with bolts and not notched. 

2. For the joists, do I have an internal bearer of simply support the direct joist with posts ?

Thanks in advance. Im hoping to use 120mm bearers. 

[Bolton]

Sorry just a few more questions as I’m starting the deck today. What should the clearance be on a low level deck ? Is 60mm at the bearers and 90mm at the joists ok and secondly I’m using 90x45 on the concrete patio with adjustable pedestals. No bearers is that ok ?

Again thanks in advance. 

[MitchellMc]

It's best to check with your local council regarding the height requirements for low-level decks @Bolton. They might have a minimum height. However, 60mm clearance to soil is fairly minimal. I'd recommend you prepare the area as best as possible and ensure water can drain away. I recommend you paint the underside of your bearers and possible joists with Gripset Betta 1L Waterproofing Membrane Bitumen Rubber. This will waterproof the bottom of them and assist with preventing the early onset of decay.

The pedestals effectively become the supporting bearer, so they are fine to use without one. Just ensure that you follow the span requirements for the 90 x 45mm. I generally recommend spacing the feet at 1000mm increments.

Please let me know if you have further questions.

Mitchell

[Bolton]

Hi @MitchellMc, the frame and joists are almost done. May I ask your opinion on the great decking tape debate ? Should I cover the frame and joists with decking tape or leave it bare ? Thanks in advance. 

[MitchellMc]

Joists tapes are an effective way of extending the life of your deck frame and preventing the early onset of decay @Bolton. They ensure water sheds of the joists effectively and help prevent a moist environment, which is the enemy of timber, between the joists and decking boards. It's my opinion that it would be worth the additional cost and work to ensure you frame stands the test of time.

Mitchell

[Bolton]

Thank you kindly. 

[Bolton]

I’m about to install the joists right now. The middle bearer I’ll be using batten screw however end bearer I’ll be using joist hangers. I have the nails and hangers from Bunnings 90x45mm. How many nails per joist hanger ? Thanks

[MitchellMc]

You'll be using four Pryda Timber Connector Nails on either side of the bracket into the frame/bearer @Bolton. Once the bracket is in position, mount your joist into it.  Fix your joist in place with two nails into each side and two from underneath.

Mitchell

[Bolton]

I won’t be able to swing a hammer underneath. That’s the nails I’ve bought. 

Would 1 nail each side by ok into the bearer and when the joist goes on 1 nail each side for that too ? I feel 2 nails holding it to the bearer might be far too little. 

[MitchellMc]

Hi @Bolton,

The joist hangers are designed to have a total of 14 nails used with them. Four for each wing holding it to the frame/bearer and then two from each side into the joist. You then have the bottom two, which you can't access. 

I don't think I'm entirely following where one nail each side and two to the bearer would go. Sorry, I think my description has confused you.

Mitchell

[Bolton]

  these are the ones I’ve purchased. So every hole needs a nail to the decking frame here ? I count 6 per side then 3 each side of the joist. Is that enough ?