Furring Walls

[GilesAlington]

Recently we posted a request to Autodesk to provide a way to allow for the strapping and lining of walls to be removed during demolition and then new strapping and lining (possibly of a different thickness) to be installed.  The response was that furring walls provided this functionality.

We set up the existing concrete wall and furring wall and then added a window.  The outcome is contained in the image file below.  Now clearly a strapped and lined wall with a window needs to have the architraves etc on the face of the strapping and lining not on the face of the original concrete wall.  We through that the issue might be our window family but then tried the revit library window with exactly the same result.

We then investigated if we could some how attach the architrave and window reveal to the window family void as logic would suggest that the void appears to be cutting both wall structures.  This had no impact on the outcome.

Can anyone advise how you can model an existing strapped and lined wall allowing window and door openings to be placed in it with the architraves etc  on the outer most lining material.  Then allow the strapping and lining to be demolished, new strapping and lining installed that may be thicker or thinner while still allowing the window to have architrave on the outermost wall face.? 

Thanks in advance

[ToanDN]

Model the window frame depth controlled by a parameter, not the wall thickness.

Or model the wall as a compound, create parts, and set the furring parts to be demolished.

[GilesAlington]

The problem with using a parameter is that it assumes that the old wall thickness will be the same as the new wall thickness.  Which in our case it isn't. 

The revit model must extend the void through the strapping and lining to create the opening, we assume it doesn't create a separate void hence the assumption if you can attach a sweep to the void thickness is would fix the problem .

Your second solution allow the window to function correctly and demo the strapping and lining but won't allow you to install new strapping and lining while cutting the window openings etc.  Basically you can't merge the parts created in different phases.

[barthbradley]

Why don't you build the Compound Wall Layers a Separates Wall Types (not Parts)  and use Windows that have Opening Cuts - not Void Cuts.  Join each Wall Layers and the Opening will cut through each one.  Then you Phase in and out Wall Layers.  I'm also seeing the Window Trim as separate Components. Maybe even the Window Jamb Extension.   

[GilesAlington]

Ok this is is how we have modelled it and got it to work however its not ideal and hopefully AutoDesk can fix the issue but ensuring that familes recognise voids within joint walls.

We have created a concrete wall in existing and also a strapped and lined wall in existing, joint them and placed a modified window family into the wall.  The modified window family has a parameter to allow the architrave and reveal to be extended beyond the face on the host wall (as per suggested fix in reply above)

We have demolished the strapping in the next phase.

Finally we have created a new strapped and lined wall in new construction phase. Joint it to the original concrete wall thus allow the new strapping and lining to be cut by the window.  Because we are not demolishing the window we have modelled the architrave with a greater depth (to accommodate the additional strapping thickness) which means it shows correctly on the new construction phase.

Barth suggestion below about modelling the reveal and architrave as a separate element would be a solution if we had a depth we couldn't fudge with the thicker architraves.  However it would become a very cumbersome process for the 100's of windows we are dealing with.

Bottom line is that families that cut voids into joint walls should be able to recognise the entire void.  This needs fixing. 

[barthbradley]

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@GilesAlington wrote:

Bottom line is that families that cut voids into joint walls should be able to recognise the entire void.  This needs fixing. 

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What does this sentence mean: "Families that cut voids into joint walls should be able to recognise the entire void"?

BTW: I said to use an Opening Cut and Join the Walls.  If you use a Cut Void, there's an extra step you need to  use. Cut Geometry and select the Walls to cut.  NOTE: "Cuts with Voids when Loaded" needs to be checked in the Family. 

[GilesAlington]

The image we posted with our original massage shows a standard window family in a concrete wall with a furring wall (strapped and lined wall) joined to it.  Clearly Revit recognises the void (opening cut) for the window and creates the appropriate opening in the strapping and lining.  One would make the assumption that Revit has simply extended the window family opening cut through the strapping and lining as a result of the two wall types being joint.  Clearly it doesn't because otherwise the reveal and architrave contained within the window family would then appear on the outside of the combined wall face.

Given that we are not privy to the internal workings of Revit we are simply stating that by whatever means Revit extends the opening cuts within joint walls, the families that contain opening cuts should recognise that the opening cut has increased.  Assume the basic problem is that Revit doesn't recognise a joint wall as a single wall element.

To fix the problem joint walls with the Revit database should be considered a single wall entity and be recognised as such. 

The window family has cuts with voids ticked.  Have attached the window family.  Note the strapping thickness parameter is our workaround set this to 0 and then see if you can make it work. 

[barthbradley]

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@GilesAlington wrote:

The window family has cuts with voids ticked. 

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Doesn't matter. There are no attached or unattached Voids in this family.  

[GilesAlington]

So assume from the lack of comment that there is an issue with the way Revit handles void cuts?

[barthbradley]

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@GilesAlington wrote:
So assume from the lack of comment that there is an issue with the way Revit handles void cuts?

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I don't understand. What do you mean by "lack of comment"? If I was to comment further, I guess I would say that we have no issues with the way Revit "handles void cuts".

P.S. I'm still scratching my head over this statement: 

"Families that cut voids into joint walls should be able to recognise the entire void"?

What does it mean?

[GilesAlington]

Ok so in your opinion it perfectly satisfactory for a window to be placed in a wall, furring added to the wall, but the window reveal and architrave stay buried in the wall. Do you not understand the issue?
To reiterate the problem. We have an original historic building that is constructed from 150mm reinforced concrete. The interior walls are strapped and lined. We want to remove the strapping and lining, retaining the windows. In order to do this it is suggested that we create a concrete wall and a furring wall and join them. This works well except that the reveal and architrave of the window (which are referenced to the interior face of a generic wall within the family) don't move to the exterior of the furring wall (existing phase)
We then want to reline the interior walls with a thicker furring wall and again the window architrave and reveal remain attached to the original concrete wall.
If joining the two wall types is supposed to create a single wall element then the window should behave in the correct manner.
Yes we understand that we can make a number of work arounds including creating separate families for existing and new window reveals and architraves but the fact still remains that windows aren't cutting joint walls correctly.
If you believe that Revit is performing correctly then please provide us with a solution as how we can model the following without deleting the concrete wall structure and retaining the windows with architraves on the inside face of the furring:
Existing - concrete walls (150mm) with furring to the interior (approx. 35mm thick)
Demo - Delete furring
New construct new furring (approx. 75mm thick)

[barthbradley]

Did you read Message #4 where I spoke of using an Opening -- not a Void -- in the Window Family? 

...maybe I don't understand. Post some pictures.  

[GilesAlington]

It is our understanding that the window family file we provided to you has an opening (not a void), believe you confirmed this also? That family produces the outcome we posted as a jpg at the start of this communication which isn't acceptable.

[barthbradley]

I would like additional information from you. I want to understand the construction and how you are going about modeling it.

BTW: Did you make the changes to the Window Family that @ToanDN suggested in Message #2?

[GilesAlington]

This is how we are proposing to model the building:
Existing 150mm insitu concrete walls, modelled in existing phase. These remain unaltered during the course of the works
Add strapping and lining (furring walls) and join, modelled in existing phase ( created as joint wall to allow strapping and lining to be demolished)
Demo existing strapping and lining, modelled in demo phase
Construct new furring walls (insulation, strapping and lining) and join to concrete walls, modelled in new phase
The outcome is that we have remove the existing strapping and lining from within the building but retained the concrete base structure to which the new insulation and lining is then applied.
We can get the above working correctly if you ignore any windows and doors.
If you place a window into the joint existing wall construction (concrete and furring) the outcome is that the architrave and reveal only extend to the internal face of the concrete wall, not to the internal face of the furring wall. This is what we believe to be a bug in Revit.
Yes you can modify the window family so that you set a parameter that pushes the reveal and architrave to the outside face as suggested in an earlier post but that is just hiding the fact that the window family doesn't recognize the joint wall type.
It would also be great if when the new furring was applied to the wall the window reveal and architrave adjusted however we understand that this is not real world modelling and could live with having to demo the windows and reinsert them in the new wall structure provided they behaved within the joint (concrete /new furring) wall correctly.

[barthbradley]

Isn't a jamb/extension and interior trim part of the New Construction?  If so, why don't you model it that way?  That's the other thing I was alluding to in Message #4.   

[GilesAlington]

Happy to sort out modelling the jamb extension in new construction but this still doesn't fix the original problem that the existing window doesn't behave correctly in the joint wall.
The first image titled window in furring wall is what Revit generates when placing a window in a joint wall. The second image is how it should look.

[barthbradley]

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@GilesAlington wrote:
The second image is how it should look.

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Where's this second image? I only see one image and one rfa.  

[GilesAlington]

Clearly you can't attach images when responding via Outlook. Hopefully you can see the embedded ones.
Below is how the window behaves when inserted into a joint wall. Note the architrave is embedded in the furring
[cid:image001.png@01D65452.2C35E7B0]
The image below is how the wall should appear

[cid:image002.png@01D65452.2C35E7B0]

[barthbradley]

No luck.