Decking plans

Hey all

So the time has come to start planning the decking area that will be built outside of my Garden Room office.

We've got a reasonable amount of space to work with, so I'm looking at total dimensions of 5.5m x 4.9m.
I'm planning on building an outdoor kitchen on the deck, and possibly a corner seat, so the entire area won't be one open deck.

One catch is that the garden slopes down to the office, so I'm going to have to do a split level build.
The current plan is to have an approx 1m deep strip across the front of the office in order to allow for the french doors to open out, and then the main deck area will be approx 150mm higher.

The current plan is to use 2x6" C24 pressure treated timber, along with 4x4" posts for the legs.
I'm planning on digging and pouring some concrete footings, and settings in concrete-in post bases, e.g. https://www.toolstation.com/post-base/p82691. That way I shouldn't ever have any issues with posts rotting out.

The design looks like this currently:


I've designed the smaller deck as a single box. The large hole there is where a manhole cover is sited, so I'll be framing around that to allow access via a hatch.
The main deck is split into 2 boxes, with the span being 2.1m.
5 posts to each beam, which I think should give plenty of support.

The joists are going to be hung using metal joist hangers, nailed in place.
I'm also going to be using coach bolts to attach the beams to the posts.

And one more view to give an overview of how the decking fits into the Garden room.


So, anything I've missed? Or any other suggestions?

Thanks in advance.

Gavin

Just be aware you need planning if it ends up being more than 30cm above ground. Also with 2m spans, I’d install some noggins. Id also consider wood stain on the under timbers to improve the life and make sure end cuts are treated.

motorbiking said:

Just be aware you need planning if it ends up being more than 30cm above ground. Also with 2m spans, I’d install some noggins. Id also consider wood stain on the under timbers to improve the life and make sure end cuts are treated.

Click to expand...

Yeh, I was aware of the 30cm restriction. I'm pretty sure we should be able to stay under that.

And Yeh, I should've said that, but I am planning on installing noggins at mid span.
I'm also going to be doing a picture frame border, so there's extra timber to go in round the edges for that.

One other thing I was thinking of doing is installing bitumin tape over the top of the joists before I lay the deck, just to prevent any moisture trapped between boards and timber causing issues. Seems to be how it's done in American.

I'm guessing digging the whole area out to be level is a no go? I'd consider making the lower 1m section wider at say 2m. If you was stepping downward towards the building and happened to trip you'd smash straight into the door/wall. Also it could make for a more cosier seating area under the window????

i like the concrete-in post fixings!

domdee said:

I'm guessing digging the whole area out to be level is a no go? I'd consider making the lower 1m section wider at say 2m. If you was stepping downward towards the building and happened to trip you'd smash straight into the door/wall. Also it could make for a more cosier seating area under the window????

i like the concrete-in post fixings!

Click to expand...

Yeh, I did consider digging down, but I prefer the main deck area being at the same height as the top of the garden.
Making the lower level a bit wider makes sense; cheers for the suggestion.

I've been playing with Sketchup again, and modelled Trex boards at 140mm wide with 6mm gaps:


The un-decked area on the right is where the kitchen and bench seat is going to go... I'll probably wrap the bench seat round the corner aswell, so will be tweaking it a bit further.

Thoughts?