How to laminate double bearers?

[Scottydont85]

Hi there,

I'm seeking some building expertise on how to properly laminate two 140 x 45 MGP10 bearers.

I'm currently building a low-level back deck and have worked out all my spans. I need to install three double bearers, which will be made by laminating two 140 x 45 sections to form a 90 x 140 bearer.

However, I haven’t been able to find information on the correct method for laminating them together.

I've attached a mock-up drawing showing how the bearers will be joined over the stumps (note: the drawing is not to scale), as well as a photo of the stumps I'm using.

My current plan is to use Liquid Nails and 75mm galvanised nails at 250mm centres. Would this be an appropriate method?

Any advice would be greatly appreciated.

Thanks in advance!

 

[JacobZ]

Hi @Scottydont85,

I would skip using the liquid nails as it can trap water between the bearers that will eventually rot the timber.

I was taught to put two nails at each end of the bearer, roughly 30mm in from the end. These nails should be shot through both sides of the laminated bearer so that they cross over each other in the middle.

You would then nail along two distinct rows that are around 30mm in from the top and bottom. On the bottom row, fire a nail 150mm in from the nails at each end, then every 300mm along that row. On the top row, fire a nail 150mm to the right or left of the nail in the bottom row so that they are offset by 150mm then every 300mm along that row

You would then do the mirror on the other side of the bearer so that there is a nail every 150mm entering the bearers from opposite sides.

It's a bit hard to explain in writing so I have created a render showing what I mean.

Let me know if you don't follow so I can try to explain further.

Jacob

[Scottydont85]

Legend!

Thanks for explaining that.

I had only put nails in one side, so I will hammer some nails in the opposite side.

Your drawing makes absolute sense.

Thanks again