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New tool for modelling cavity barriers


Christiaan

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Ever since the Greenfell Tower tragedy, which killed 72 people, the installation of cavity barriers (used to inhibit the spread of smoke and fire in concealed spaces) has come under the microscope in the UK.

 

Partly in response to this we've started modelling cavity barriers. This makes them a more prominent part of the design process and has helped me to put earlier thought into their arrangement. Instead of applying them as 2D objects latter in the process. It also provides the possibility of displaying them in 3D, in a 3D view or even on an elevation, with the outer wall components turned off.

 

The problem is I've only been adding horizontal cavity barriers to the model, using the Slab object. At the moment I'm still relying on 2D for vertical cavity barriers. Because there's no suitable tool that comes to my mind that can conveniently model vertical cavity barriers and insert them into walls. And the Slab object is not particularly ideal for the horizontal barriers either, as it would be useful to be able to insert these into walls also.

 

So I'd like a tool designed for this purpose.

 

See also: 

https://forum.vectorworks.net/index.php?/topic/98035-wall-closures-support-for-cavity-closers/

 

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Any reason not to use simple vertical extrudes? Or is the problem then how they interact with wall objects when seen in section?

 

How do you use slabs for the horizontal ones - do you somehow wrap certain wall components around them?

 

If a tool were to be developed for this I'd suggest considering a general-purpose "elevation embelishment" tool that could deal with different kinds of linear elements within/on an elevation, so that it could also be used for things like edging trims, or maybe even rainwater goods.

 

(Really I'd prefer all the other tools to be fixed before developing an inevitably half-completed and ten abandoned new one though)

Edited by line-weight
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16 hours ago, line-weight said:

Any reason not to use simple vertical extrudes? Or is the problem then how they interact with wall objects when seen in section?

If I model them in next project I think that's what I'll use. What would be better of course is a tool that inserts them into the wall and binds them to a top and bottom Level.

 

16 hours ago, line-weight said:

How do you use slabs for the horizontal ones - do you somehow wrap certain wall components around them?

No, just by manually drawing the shape. The advantage of the Slab object is that I can set it to a Level.

 

16 hours ago, line-weight said:

If a tool were to be developed for this I'd suggest considering a general-purpose "elevation embelishment" tool that could deal with different kinds of linear elements within/on an elevation, so that it could also be used for things like edging trims, or maybe even rainwater goods.

Yeh good idea. 

Edited by Christiaan
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This is a cavity closer as a hybrid symbol with wall hole component inserted in a wall:

866234118_Screenshot2022-07-02at17_47_18.thumb.png.5d1521b15bc9b773a05d0acc4d2309a3.png

234171517_Screenshot2022-07-02at17_47_27.thumb.png.1fbaac3ca9708b58928a6c2585f7391a.png

 

So far so good. But what I haven't been able to do particularly successfully is insert a window as well + get the wall closures working as they should. The best I could achieve was when I ran Command-K on the window + turned that into a hybrid symbol too but even then the wall closures aren't showing in Top/Plan:

 

1017883186_Screenshot2022-07-02at17_49_31.thumb.png.0a72c2c1adef975e6fb44a7b393ba215.png

 

127889577_Screenshot2022-07-02at17_49_41.thumb.png.721dfdb0469614b01c91379e5d130fd0.png

I feel like wall closures are a massive step in the right direction for allowing us to create the kinds of details we want but the feature's still in its infancy + needs developing further, which I'm sure is happening... (have been improvements already since first release). I'm sure my custom cavity closer symbol could be made parametric using Marionette if I had the patience + brain power to pursue it. Otherwise if using standard door/window sizes it's just a matter of spending 20mins knocking off a few different-sized versions. I'd be quite happy inserting the wall closer + the window as two separate objects (+ moving/adjusting them separately). The main stumbling block I think is in the wrapping controls. And the horrible window sill of course...

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13 hours ago, Tom W. said:

Oh yes good point!

You're right that ideally it would be dealt with as part of wall closures (along with window or door insertions) though.

 

But are cavity closers a bit of a UK peculiarity - because masonry cavity walls are very common in the UK (& some other NW european countries?) but not elsewhere?

 

In which case we might not see much time invested in such a feature by a north american software company.

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1 hour ago, line-weight said:

But are cavity closers a bit of a UK peculiarity - because masonry cavity walls are very common in the UK (& some other NW european countries?) but not elsewhere?

 

In which case we might not see much time invested in such a feature by a north american software company.


I’m pretty sure these are covered in the IBC for fire protection, but perhaps called something else.  Also, Cavity barriers have a lot in common with thermal breaks in Passive House, at least in terms of how one might want to include such detail in a BIM model and energy analysis.

 

I would think such features would be handled in 2D detailing rather than BIM modeling though.  Regardless, my point is Vectorworks users all over likely have a use case for needing this functionality for a variety of reasons if a tool were developed.  One would hope it could approach the excellence found in stairs, doors, GIS importing, and looped mainlines for irrigation this software is lauded for 😉

 

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On 7/2/2022 at 10:05 PM, line-weight said:

A cavity closer is a different thing to a cavity barrier of course.

Technically speaking, at least in the UK, a Cavity Closer changes name to Cavity Barrier if it provides resistance to fire. Bit weird really. I think they'd be better off referred to as Fire-Rated Cavity Closers! A Cavity Closer for me is something that closes off the cavity around an opening in a wall, whereas a Cavity Barrier closes of any length off cavity. But as far as the building regs are concerned, a Cavity Barrier is any barrier or cavity closer than resists fire.

 

Of course, either way, I have a wish for them too 😁

https://forum.vectorworks.net/index.php?/topic/98035-wall-closures-support-for-cavity-closers/

 

Edited by Christiaan
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3 hours ago, jeff prince said:

I would think such features would be handled in 2D detailing rather than BIM modeling though.

I agree with this principle, but I want to show them on 1:50 plans and sections. That's the threshold for me. If I want to show an object at 1:50 then I want to model it.

 

And if you're not showing cavity barriers on 1:50 plans and sections then your drawing is probably wrong (unless it very clearly states that barriers are shown on details only), because it's indicating the continuation of cavity and insulation instead.

 

3 hours ago, jeff prince said:

Also, Cavity barriers have a lot in common with thermal breaks in Passive House, at least in terms of how one might want to include such detail in a BIM model and energy analysis.

Yes they do. For instance an insulated balcony connector—used, say, to thermally isolate a concrete balcony slab from the main internal slab—can be fire-rated rated or not fire rated. If it's fire-rated then it's also a Cavity Barrier.

Edited by Christiaan
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11 hours ago, line-weight said:

There's not only the confusion between cavity closer & cavity barrier, but between cavity barrier and fire stop (and I often have to look it up to remind myself which way around they are).

Ha, yes, I've had to do the same there. The time between having to detail these things is often enough for the need to jog the memory.

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On 7/2/2022 at 6:09 PM, Tom W. said:

So far so good. But what I haven't been able to do particularly successfully is insert a window as well + get the wall closures working as they should. The best I could achieve was when I ran Command-K on the window + turned that into a hybrid symbol too but even then the wall closures aren't showing in Top/Plan:

I've run into the same problem with my separately modelled window sills.

 

On 7/2/2022 at 6:09 PM, Tom W. said:

I feel like wall closures are a massive step in the right direction for allowing us to create the kinds of details we want but the feature's still in its infancy + needs developing further, which I'm sure is happening... (have been improvements already since first release).

It is for sure. Apparently wall closures in 3D is no easy task, but I think the main leg work has been done by upgrading the wall object itself. (they may even be able to extend wall projections to corners now too, finishing off a tool that was half-baked: https://forum.vectorworks.net/index.php?/topic/94062-create-wall-feature-projection-at-intersecting-walls/#comment-425348 )

 

 

On 7/2/2022 at 6:09 PM, Tom W. said:

I'd be quite happy inserting the wall closer + the window as two separate objects (+ moving/adjusting them separately).

Yes, me too. If it's installed separately in real life then it's probably better off being a separate object in the model as well. If you try to combine things into one tool just because they're attached to each other you end up with unrealistic limitations. The railing combined with the stair tool is the best example of this I think. We need instead more/better ways for objects to attach themselves to other objects.

 

I was chatting to Matt P about cavity closers and cavity barriers and he was saying they are having similar discussions about what constitutes part of a window, what constitutes part of the wall, what should be separate objects etc. 

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I do not really get the cavity closers around the Windows idea.

 

Say you have a high rise building like from the disaster with the

facade burning.

 

You wont a cavity over the whole building height (?) to allow air flow

for a dry insulation.

That means if it starts burning you will get a strong chimney effect and

good oxygen supply. If you have an inflammable insulation it will burn

like nothing and fast over the whole building.

 

So are the cavity closers around Windows mainly to avoid, or at least

slowing down, that the insulations starts burning when one of the

Apartments is burning ?

And at the same time give some more time for the Apartments above

that they don't catcht fire.

 

I think it will not take that long, when an Apartment is on fire until the

Window bursts and the heat will float around the cavity closer and

set insulation above on fire anyway (?)

 

 

Are there also cavity closers planned between a certain amount of Stories (?)

Or should not all buildings above a certain Story amount just have strict

non inflammable insulation or facade ?

 

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1 minute ago, zoomer said:

I do not really get the cavity closers around the Windows idea.

 

Say you have a high rise building like from the disaster with the

facade burning.

 

You wont a cavity over the whole building height (?) to allow air flow

for a dry insulation.

That means if it starts burning you will get a strong chimney effect and

good oxygen supply. If you have an inflammable insulation it will burn

like nothing and fast over the whole building.

 

So are the cavity closers around Windows mainly to avoid, or at least

slowing down, that the insulations starts burning when one of the

Apartments is burning ?

And at the same time give some more time for the Apartments above

that they don't catcht fire.

 

I think it will not take that long, when an Apartment is on fire until the

Window bursts and the heat will float around the cavity closer and

set insulation above on fire anyway (?)

 

 

Are there also cavity closers planned between a certain amount of Stories (?)

Or should not all buildings above a certain Story amount just have strict

non inflammable insulation or facade ?

 

 

This was my fault for focussing on cavity closers rather than cavity barriers as per the original post! Cavity closers are just to seal penetrations in the cavity wall from damp/condensation/heat loss

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20 minutes ago, zoomer said:

So are the cavity closers around Windows mainly to avoid, or at least

slowing down, that the insulations starts burning when one of the

Apartments is burning ?

And at the same time give some more time for the Apartments above

that they don't catcht fire.

As Tom pointed out, cavity closers are designed to deal with damp/condensation/heat loss, however they can also be fire-rated**, in which case they're also designed to stop fire and smoke inside one dwelling/space making it's way into the cavity in the wall and travelling to another dwelling/space.

 

**  To complicate things, in the UK, they actually change terminology at this point and get called cavity barriers too

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@Christiaan presumably your horizontal cavity barriers extend around the whole perimeter of the building i.e. across multiple Wall objects? And the same with vertical barriers: they need to extend the whole height of the building across however many floors you have? It feels like in these cases - as opposed to my cavity closers example where it's a standalone object which is easily inserted as a symbol into a wall - you need the ability to incorporate elements within a Wall's existing components, in the same way that has been discussed elsewhere I think with regard to including repeating structural elements as part of Walls/Slabs/Roof components.

 

Rather than attempting to insert multiple barriers as separate objects into each individual wall it would be good to have it part of the wall style somehow + give it an offset to determine its position. A bit like the way you insert posts in the Railing/Fence tool + can set the distance between them them edit the individual positions afterwards if required. Or the Curtain Wall Tool for that matter + the frame positions.

 

As regards Jeff's earlier comment about whether there's a need to model elements such as these I imagine it would be very useful in a large building to use Data Viz to highlight in 3D where the cavity barriers occur + easily check that continuity/integrity has been achieved throughout the building.

 

Wall closures probably don't come into it

 

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44 minutes ago, Tom W. said:

@Christiaan presumably your horizontal cavity barriers extend around the whole perimeter of the building i.e. across multiple Wall objects? And the same with vertical barriers: they need to extend the whole height of the building across however many floors you have? It feels like in these cases - as opposed to my cavity closers example where it's a standalone object which is easily inserted as a symbol into a wall - you need the ability to incorporate elements within a Wall's existing components, in the same way that has been discussed elsewhere I think with regard to including repeating structural elements as part of Walls/Slabs/Roof components.

 

Rather than attempting to insert multiple barriers as separate objects into each individual wall it would be good to have it part of the wall style somehow + give it an offset to determine its position. A bit like the way you insert posts in the Railing/Fence tool + can set the distance between them them edit the individual positions afterwards if required. Or the Curtain Wall Tool for that matter + the frame positions.

Agreed. 

 

44 minutes ago, Tom W. said:

As regards Jeff's earlier comment about whether there's a need to model elements such as these I imagine it would be very useful in a large building to use Data Viz to highlight in 3D where the cavity barriers occur + easily check that continuity/integrity has been achieved throughout the building.

 

Wall closures probably don't come into it

They do if they're fire-rated. If they're intended to resist fire then they're even more important than general cavity barriers as they're the first line of defence, and their positioning is paramount. On Grenfell Tower, for instance, they were located too high above the head of the window, allowing fire to escape out of the flat, into the cavity, and ignite the cladding. This was a design issue rather than the builder putting it in the wrong location, but it's conceivable that modelling them might have helped identify the problem earlier. And they need to be displayed as having equal importance to the general wall cavity barriers.

Edited by Christiaan
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2 hours ago, zoomer said:

I do not really get the cavity closers around the Windows idea.

 

Say you have a high rise building like from the disaster with the

facade burning.

 

You wont a cavity over the whole building height (?) to allow air flow

for a dry insulation.

That means if it starts burning you will get a strong chimney effect and

good oxygen supply. If you have an inflammable insulation it will burn

like nothing and fast over the whole building.

 

So are the cavity closers around Windows mainly to avoid, or at least

slowing down, that the insulations starts burning when one of the

Apartments is burning ?

And at the same time give some more time for the Apartments above

that they don't catcht fire.

 

I think it will not take that long, when an Apartment is on fire until the

Window bursts and the heat will float around the cavity closer and

set insulation above on fire anyway (?)

 

 

Are there also cavity closers planned between a certain amount of Stories (?)

Or should not all buildings above a certain Story amount just have strict

non inflammable insulation or facade ?

 

 

When you want a cavity over the whole building height (for air flow as you say) you use cavity barriers that have an intumescent treatment, so that in normal use they let air pass, but if there's a fire they expand to fully block the cavity.

 

On your last question about whether buildings over a certain height should have a strict non flammable facade, this really is the big issue raised by the Grenfell disaster here in the UK. I think most people would agree that the answer is "yes". The question of how the Grenfell tower ended up with the entire facade burning has been the subject of the long and detailed enquiry that is just about concluded now. It came about because of multiple failures... at almost every stage of the process including the certification and testing of products, the wording of building regulations, the specification process, the design process, the construction process, the building regulations inspection process, the risk assessment process, the building management & evacuation strategy and the emergency services response. It really is a horror show.

 

I agree with what Christiaan says, that including fire barriers in a 3D model would make it easier to visualise what's proposed and therefore more easily spot mistakes and problems. It might not have prevented Grenfell because there were so many other things that went wrong - but perhaps it could have reduced the scale of what happened.

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