Can you use Merbau timber with ProtectorAI aluminium posts?

Question

I have been building some fencing and screens around my garden like the one in the picture below. I have been using posts and screwing the Jack screen channels to them  but I am wondering if I can use these posts for my next project  like this

https://www.bunnings.com.au/protectoral-2400-x-65-x-65mm-black-satin-aluminium-3-way-post_p0989631

Using merbau timber instead of the composite planks that they are designed for. Will the additional weight of real timber be an issue?

MitchellMc · Answer

Hi @nixybrown,

The Merbau will no doubt sag over that distance. At 1.6m between posts, you would need to add a vertical stabiliser between the slats. You could use a

https://www.bunnings.com.au/specrite-42-x-19mm-2-7m-merbau-pre-oiled-solid-screening_p0517078

and then attach it to your horizontal boards. It just helps prevent any sagging in the central area.

Mitchell

nixybrown · Answer

thanks. Yes I checked and the composite boards are 20mm and the merbau is 19mm so should fit no problems. I was going to put a spacer between the boards like the ones in the fence in my picture. As for spacing I was looking at 1.6m between the posts. That is short enough to avoid any problems with the merbau sagging isn’t it?

MitchellMc · Answer

Hi @nixybrown,

Yes, you can use the ProtectorAl aluminium posts with Merbau, but there are a few things to keep in mind.

The posts themselves are quite strong, so the additional weight of Merbau compared to composite infill boards generally isn't the main concern. The more important consideration is whether the Merbau boards will physically fit within the post channels and whether the span between posts is suitable to prevent the timber from bowing over time.

Merbau is a natural timber, so unlike composite boards it will expand and contract with changes in moisture. You'll want to leave a small expansion gap and ensure the boards aren't installed so tightly that they can't move. It's also worth checking the dimensions of your Merbau against the channel width of the ProtectorAl posts before purchasing.

If the screen is going to be exposed to the weather, make sure you use stainless steel fixings, as the tannins in Merbau can react with standard galvanised fasteners and cause staining and corrosion.

Please let me know if you have any questions.

Mitchell