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Construction Documents from a 3D Model - How much information to model?


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21 minutes ago, Tom W. said:

Yes all three walls are on different design layers but that was more to set up their respective elevations so they automatically stack on top of each other correctly when working in Top/Plan.

My workaround is to just group items that need to sit behind other items in top/plan and "send to back" in the drawing order. Not perfect but works. I could put on separate design layers but prefer to not create DL's just for this reason. I also similarly sometimes group some items that I want at the front of the top/plan draw order like dashed lines indicating something to the foreground (or background).

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33 minutes ago, Boh said:

My workaround is to just group items that need to sit behind other items in top/plan and "send to back" in the drawing order. Not perfect but works. I could put on separate design layers but prefer to not create DL's just for this reason. I also similarly sometimes group some items that I want at the front of the top/plan draw order like dashed lines indicating something to the foreground (or background).

I should have phrased it differently. What I meant was the foundations layer has an elevation of -750, the plinth wall layer an elevation of -450 + then the slab layer which the main walls are on is at 0. So when I draw the walls in Top/Plan as long as I draw them on the correct layer they will literally stack on top of each other height-wise in 3D.

 

But what I'm not 100% clear about - and this will come out in the wash - is how to treat the floor finishes. I have a structural slab that the walls - external + internal - sit on + which extends over the whole building. Then I have separate floor finish slabs in different areas of the building which sit on top of the structural slab. What I'm not sure about is how to deal with these floor finish slabs if they are different thicknesses: perhaps 22mm solid wood in some areas + 12mm-worth of tiles in another. I could have a finish floor layer with the same layer elevation as the structural slab but set the datum for the floor finish slabs to the bottom of the components, but then whenever I place objects on those floors I'd have to raise them up by the thickness of the floor...

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9 minutes ago, Tom W. said:

But what I'm not 100% clear about is how to treat the floor finishes.

 

I have 99% a Building wide Structural Slab,

at least when the same Slab runs through the whole Building.

And I fill a second multi-Component Slab into any Room by

Fill Bucket, for the Floor Finishing Package.

 

Normally Structural Slabs runs through ....

but especially in older existing Buildings, Floors and Floor top heights are

different between most Rooms.

The only issue is that you manually have to fill in "Floor Packages" in

the Wall Opening Areas under your Doors too ....

(And that no one was able to explain how to deal with Energos in the

case of 2 Slab Packages ...)

 

And you have to control 2D positions with CMD+F, CMD+B ...

But I have to do that for my Slab anyway, as I draw it after the Walls ...

Edited by zoomer
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^ here too,

 

My Slabs and Floor packages are bound to Story/Levels.

I use Finish Floor top as 0.00 m though,

as current Floors are mostly level, adapted for the needs of disabled.

And it is the level where you want draw relevant things furniture and stuff on.

 

So for me a Finish Floor Package Style of a bath that may be 2 cm lower than

Typical Finish Floor Height (to keep unwanted water inside or such)

Would use Finish Floor 0.00 Level with a 2 cm Offset, or maybe start from

a Top of Structural Level, upwards.

Edited by zoomer
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14 minutes ago, MaltbyDesign said:

If you set top of structural slab at 0.0 then you have to offset door sill, millwork and furniture according to finish floor thickness.

 

Yes.

But mostly I even use a negative Z-Offset for the Doors to go down to

Structural Slab, as I think that is how a Door Frame works in reality (?)

and if applicable I try to assign a "workarounded" crippled Door Threshold (?)

to fill the missing Floor Package under the Door.

But that may require duplicate Door Styles of the same Door, whether the

Door opens in Floor 1, 2 or 3 ... direction ....

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Hmm there's a few different things being said here...

 

I think having the top of the structural floor at 0 is a good idea. And the floor finish on top. Like this from Wes Gardner:

816521410_Screenshot2021-03-11at21_33_10.thumb.png.05681dccb223f3cb9988181e9bf53092.png

But this supposes your finish floor is the same level throughout. Which is what I think Zoomer was saying.

 

What I'm interested in is if you have different thicknesses of floor finish on the same subfloor. I was thinking I'd give the finish floor layer the same 0 elevation as the structural floor but set the datum to the bottom of the floor finish slabs, so they all sit at the correct elevation on top of the sub floor despite being different thicknesses. But then every object (table, chair, person, cat, dog) you place on those finish floors you have to offset the thickness of the floor finish.

 

Or would you have story levels for the tops of the different floor finishes?

 

To be honest, I'm not in the habit of including hundreds of different floor finishes in buildings, I guess I'm mostly interested from an academic point of view. If I had wood boards in one room + floor tiles in the next I'd more than likely give them the same finished floor height rather than worry about a difference of a few mm! But other finishes the height difference might be greater + you'd want that difference in thickness to be represented in sections

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In older houses, here, you normally have a 2cm difference between each floor

to enable the Door's panel to seal at all 4 edges and to prevent water

leaking from the bath (lowest level)

That is is terrible in CAD and BIM terms ....

 

But today we look for all Floors being level, thanks to handicapped people,

which makes real world much more capable to BIM modeling.

Also the Floor Finish is mostly going through in current modern Buildings,

like a Wood or Parquet Floor in Residential or Screed in Commercial Buildings.

The Doors have some Seal at the bottom to do the sealing instead.

That is much more easy to deal with for BIM or limited CAD systems ...

 

Yes, you would not create a Section through a Door Frame but through

the middle of your Door. VW can't reliably calculate Wall Lengths or Volumes

anyway, so in such cases you may be fine with Door Openings starting from

Top of Finish Floors though.

In case you put Floor to Foreground to hide the rest of the Wall at the

Floor "running through" the Door ...

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@Tom W. actually, I think I started including finish floors in my overall floor assembly so that top of finish floor was at 0.0 but quickly changed that and went with what Wes suggested. personally, I would have the bottom of the floor finish sitting on 0.0 and handle the difference in floor finish with floor transition strips just as handled in real life (carpet to wood floor transition strips for example which can be wood or extruded aluminum)

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Two reasons for taking the finished floor level rather than structural floor level as datum:

1) As zoomer says, normally, you are aiming to have the FFL end up as the same everywhere, so that's what you work back from, if you have different build-ups under the finish, in different parts of the building (for me this is typically in extensions to old buildings, where the "structure" for the new bits might be lower than in the old bits, to allow for modern levels of insulation etc)

2) It's what you're worried about when working out stairs. To work out your stairs you want the distance from one FFL to the next, not the SSL.

 

I think @MaltbyDesign's  suggestion to make the datum the underside of the finish layer makes a lot of sense though. Because that's what would happen in construction terms.

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There are different philosophies.

Whatever fits you best.

 

Old School Layer usage, AFAIK is to have at least 2 Layers per Story.

Floor or Slab and the rest of Story.

 

I use to get away with a single Level per each Story as much as possible.

Floor/Slab/Foundation below Finish Floor Height, Walls and everything else

above. That way you can edit visibilities fast and always look into your

Floor Plan in 3D.

and, for complexity sake, I need more than one Layer per Story, it will

unlikely a Slab/Floor Layer but mostly something else ...

Edited by zoomer
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8 minutes ago, MaltbyDesign said:

@zoomer if walls, etc. are above the finished floor elevation, do you offset the bottom of walls to sit on top of the subfloor/slab below?

 

 

Yes, that's the much easier case.

Like Gypsum Walls on a Concrete Floor in an industrial Building.

Then also the Door sits simply on top of the Finish Floor.

But mostly for residential buildings here, the interior Walls sit on

the Structural Slab. Finish Floor Package comes later with

Finishings.

Not sure but currently 70ies Building, here, the wooden Door Frames

look like entering the Finish Floor and may have been installed before

the Screed and Finish Floor was installed (?).

If I am not wrong, I would like to be able to see that in my Sections ...

Edited by zoomer
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For external walls, which in reality continue through several storeys but are usually split up by storey for drawing organisation purposes, there is always the question of where to make the join between storeys. For some reason, for me the join point often seems to be least troublesome if it's around ceiling level (rather than floor level). But I find it's often difficult to be consistent (with buildings with split levels, mixtures of roof types and so on it can quickly get complicated at corners and junctions).

 

And then there's also a whole load of decisions to be made around stairwells and again that can quickly get complicated. For example, if structurally the stairwell walls are sitting on top of the floor slabs, but the wall finish is continuous across the floor levels within the stairwell? Then you can choose between fiddling around a lot with offsets and things, or just cheating and fixing it in annotations.

 

And what about a wall with a staircase against it, where you want a different internal wall finish above the stairs, compared to below the stairs?

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24 minutes ago, line-weight said:

For external walls,

 

I want to be able to see in the plan from above.

 

So the Structural part of the Wall sits on the Structural Slab,

while the insulation Package outside reaches down to bottom

of structural Slab ...

(I use Story + Story Levels generally and in all my PIO Styles)

So basically the Story Top is cut right below the Bottom of Structural

Slab of Story above. This works well for me down to the Foundation ....

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2 minutes ago, zoomer said:

 

I want to be able to see in the plan from above.

 

So the Structural part of the Wall sits on the Structural Slab,

while the insulation Package outside reaches down to bottom

of structural Slab ...

(I use Story + Story Levels generally and in all my PIO Styles)

So basically the Story Top is cut right below the Bottom of Structural

Slab of Story above. This works well for me down to the Foundation ....

 

Yes that makes sense.

 

UK construction is often cavity wall (inner masonry leaf, insulation in cavity wall, outer masonry leaf) and then the floors are timber joists hung on joist-hangers fixed into the inner masonry leaf. So often the entire external wall buildup wants to continue past the floor "edge". A reason for me to make the "join" at ceiling level (instead of bottom of structure) is that then I don't need to offset the inner wall finish at the "top" of each wall, only the "bottom".

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9 hours ago, MaltbyDesign said:

I would have the bottom of the floor finish sitting on 0.0 and handle the difference in floor finish with floor transition strips just as handled in real life (carpet to wood floor transition strips for example which can be wood or extruded aluminum)

8 hours ago, line-weight said:

I think @MaltbyDesign's  suggestion to make the datum the underside of the finish layer makes a lot of sense though. Because that's what would happen in construction terms.

 

These quotes get to the nub of what I'm saying. This is exactly how I was intending arranging my floors where I had different thicknesses of floor coverings. But what I asked in my orig post on this was: if your finish floor layer elevation is the underside of the floor covering, does that not make it a pain when you are placing objects in those rooms? Because they will sit on the subfloor not the finish floor. Then you need to raise them all individually to the correct floor level depending on the thickness of the floor finish in each case. I'm talking about furniture + fixtures, skirting boards etc. If your FFL is the same throughout this isn't an issue

 

Anyway thanks for all the comments all interesting stuff. 

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1 hour ago, zoomer said:

 

Yes, I see it everywhere.

I think that was standard at least until the end of the 80ies ....

 

In Kuwait and throughout the Middle East, it's common in new construction for any wet room to have a 2cm threshold.  One would think this is for ensuring water is directed to the floor drain and prevent a leak from migrating into adjacent rooms.  In fact, its primary purpose is a work generating program for the podiatry sector, as evidenced by my toes 🙂

 

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@Tom W. If the top of your finished floor is 0.0, you then would have to offset the bottoms of your walls to sit on the subfloor/slab. I guess it's a trade off. 

I just had a thought; If you set 0,0 to the top of subfloor/slab and want skirting boards, fixtures and fittings to sit on top of the finished floor could you set up a fixture and fitting layer that is offset from zero by the thickness of the flooring? So when you insert furniture, millwork, etc. it is at the right elevation to allow for the finished floor thickness.

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