Should the loads on the entire shed construction be recalculated for a green roof?

[Elitost]

We will build a shed (3*4.8 meters) with a sedum roof that we will plant ourselves. This means that the roof weight will increase significantly, and I will base the calculation of the rafters on kn 5.5, according to the approximate value in the Green Roof Handbook. So far, I know how to proceed.

The question is whether I need to calculate further down into the structure's walls, floors, and foundations, or if a proper standard pile foundation and frame (studs 45*95) are sufficient for the downward load.

I have tried to get an idea of approximately how much weight a pile can withstand but haven't succeeded in finding a good reference point.

 

[Ulltand]

We are going to build a shed (3*4.8 meters) with a sedum roof that we will plant ourselves. This means that the roof weight will increase significantly, and I will use kn 5.5 for the calculation of the roof trusses, based on approximate values in the Green Roof Handbook. So far, I know how to proceed.

The question is whether I need to further calculate down through the construction's walls, joists, and footings, or if a footing foundation and a frame in solid standard (studs 45*95) are sufficient for the downward load.

I have tried to get an idea of approximately how much weight a footing can bear, but I can't find any good reference points.

Does that include snow load?

I can't imagine that the wall or foundation construction would need to be reinforced due to the vertical load increase,

45x95 cc 120 supports our roof in tile in Stockholm.

 

[Elitost]

Is that including snow load then?

I can't imagine that the wall or foundation structure would need to be reinforced due to the vertical load increase.

45x95 cc 120 supports our roof in tile in Stockholm.

Yes, in my estimation of the roof's weight, I have taken that into account. I might place myself at an even safer distance considering the margins of error when I make the final construction drawing of the trusses. It involves so little timber that it doesn't hurt to be on the completely safe side.

No, I think that much larger buildings handle greater weights on walls and pillars, without needing to scale up as a result. But as a novice, I don't have much personal experience to draw conclusions from, and there's always the risk that I might do something wrong if I freestyle too much.

 

[Ulltand]

I may be stating the obvious here, but the rafters should meet the wall at the point where there is a vertical stud under the wall plate.

 

[Elitost]

I might be stating the obvious here, but the rafters should meet the wall at the point where there is a vertical stud under the wall plate.

Yes, I'm fully aware of that

What I'm concerned about is that I lack the knowledge of what weights are required to risk breaking a load-bearing wall, or how a reinforced footing with a 19 or 20 diameter handles weights.

 

[witten]

What do you mean by kn 5.5? Do you mean 5.5 kN/m2? In that case, it's quite a lot and not a sedum roof but a grass roof with a thick soil layer.

 

[Elitost]

What do you mean by kn 5.5? Do you mean 5.5 kN/m2? That would be an awful lot and not a sedum roof, but a grass roof with a thick soil layer.

Sedum/herb roof would be around 0.9-2.5 kn/sqm (if it’s not rolled out). Then I thought I could just add 2.5 which is the snow zone. And then I added a bit extra to be completely sure. But if I've got it wrong, I'd only be happy.

 

[Jönas]

What about shear forces/vertical stability when a larger combined roof weight moves dynamically?

 

[justusandersson]

The capacity of the standing rules to support the roof loads primarily depends on how they are braced in the weak direction. With 45x95 directly under each truss attachment, it is suitable to have a row of noggings at half height.

 

[Elitost]

The ability of the standing studs to support the roof loads depends mainly on how they are braced in the weak direction. With 45x95 directly under each roof truss support, it is suitable to have a row of noggings at half the height.

I was planning to frame according to the same principle as in construction descriptions for garages but scale down the length and width. The height of the build is not critical as I live outside the zoning plan.

 

[justusandersson]

Follow that description and it will be good!

 

[Elitost]

If you follow that description, it will be great!

Good to hear!

The major differences are that I'm using a post foundation. Considering whether to use 220*45 on one section (cc60) across the width of 3 m, or to place a load-bearing beam in the middle. But it would be so convenient to avoid that. I will continue to calculate and look at what's sensible in that choice.

And we are going with a 14-degree roof with sedum and other beneficial roof plants.

Here's what the concept image looks like, but it's only a guide for the drawing I'm working on now.

 

[Ulltand]

How does it affect shear forces/vertical stability when a larger cumulative roof weight moves dynamically?

They should reasonably increase but on the other hand, a heavier roof doesn't move as easily due to the law of inertia.