Patio Construction: Sizing Issues

[Nanorch]

Now it's time for the deck building.

Since the patio door is very low and the area around the house is filled quite high, there isn’t room for a solid support beam + floor joists + decking, it simply builds too much in height.

My planned solution is that instead of a support beam closest to the house, I prop up with slabs, and unfortunately, I’ll need to do this on each floor joist.

At the front, the ground is a bit lower, so I can fit a support beam without it falling below ground level.

For the front support beam, the dimension will be 45 x 145 mm, and for the floor joists 45 x 170 mm. The decking will be 28 x 120 mm.

According to the sizing table I found, this should be okay, but I would be very grateful if someone could double-check or provide additional input. I am well aware that this is not the classic method

 

[pellepite]

Isn't there room to screw a support beam and then attach the floor joists with joist hangers? It should be much easier and sturdier than propping up each joist with a bunch of plates.

// Per

 

[Nanorch]

Isn't there room to screw in a ledger board and then attach the floor joists with joist hangers? It should be much simpler and more stable than supporting each joist with a bunch of slabs.

// Per

I assume you mean that I should screw a ledger board into the house facade, but there's no space for that. Moreover, the span would be too long, and I'd end up with a span of 3400 mm, which means I'd need three ledger boards, resulting in more work than this solution entails. However, such a solution would be ultra-stable =)

Now I'm hoping that my solution will be stable too ;-)

 

[titanium]

How stable it becomes depends quite a lot on how "stable" the ground is under the tiles.
Well-drained = no problem.
But if you can fit 45x170 joists, how come you can't fit a ledger board on the façade? The ledger board can be at the same level as the floor joists.

 

[Nanorch]

How stable it becomes largely depends on how "stable" the ground is under the slabs. Well-drained = no problem. But if you have room for 45x170 joists, how come you don't have room for a support beam on the facade? The support beam can sit at the same level as the floor joists.

The ground under the slabs is gravel and stone, which feels like a good condition.

The 45x170 joists will mostly end up under the facade; an alternative would be to lower them even more and fasten them to the concrete slab, but I'm not entirely comfortable with pounding away with a hammer drill there; the edge element might crack, or I might damage the waterborne floor heating. However, the biggest disadvantage of that solution is that I would have to dig out even more at the front edge of the deck.

It's so low that with my current solution, the front support beam will still partially be below ground level. Now I hope it is well-drained enough so that water won't settle in the trench I plan to dig for the support beam.