Modelling walls to be stripped to studs

[Anonymous]

I'm working on a renovation to a summer house that will now be a year-round residence in Nova Scotia (ie cold-weather climate). The house was built in the 1970s so the existing insulation is the pits.

As near as I can tell (we haven't done any investigative work yet), I believe the exterior walls are:

- 2x4 wood studs with insulation in the cavity

- sheathing

- weather barrier

- wood shingles

In order to improve the building's thermal performance, the client wants to strip off the shingles and weather and add continuous insulation before re-installing new shingling over top. I'm preparing a demo and proposed floor plan but I'm not sure what the best way to model it is. I've considered the following:

- Leave the existing walls in place and create a new wall type that is basically continuous insulation + new shingles and wrap that wall type around the existing. I suspect this will create all sorts of problems when it comes to modelling around the window openings. It doesn't allow me to get rid of the existing shingles in the demo plan or proposed plan without doing linework overrides. Yuck.

- Set the existing walls as demo'ed in the demo plan and then in the proposed plan put in new walls that are essentially the same except with the continuous insulation. This is probably the most straightforward in terms of modelling but I'm concerned it will be very misleading to the contractor to show the whole wall assembly as demolished.

Is there a way to show just one wall component to be removed and then add new components in a new phase or is there at least some more straightforward workaround?

What's the best way to model this for both a demolition plan and proposed floor plan? I want the existing building components

[barthbradley]

I prefer to model the wall layers as separate walls (not compound-layered walls) in this type of work.  But, I 've also used Parts (a little more involved) and also done what you are thinking aloud about -- demoed and replaced the entire compound-layered walls.  All approaches have their pluses and minuses. 

I'm curious to know what you mean by "it doesn't allow me to get rid of the existing shingles in the demo plan or proposed plan without doing linework overrides."  

[Anonymous]

Thanks, bb. I guess I'll have to experiment and see what the best solution for this purpose is.
Regarding what I meant in my comment about the linework - In the existing wall there is a material thickness for the existing shingles (modeled at +/-1/2"). If I simply leave the existing wall in place and model a new wall over it, the inside face of the new continuous insulation will need to meet the outside face of the existing sheathing and will therefore overlap the thickness of the shingles.
To work around this, I could:

- in the demo plan - do a linework override to make the outside line of the shingles appear as a 'demolished' line.
- in the proposed plan - make the outside line of the shingles invisible so you don't see the continuous insulation overlapping the shingle thickness (of course I would still get a message about the two walls overlapping but that's not a big deal).
Hope that clarifies. Thanks for your input!

[georgehobel]

I know this is sort of a different topic bb, but are you saying you would build a 2 x 4 wall in separate pieces... 2 x 4, then sheathing, then siding... all separate walls...then drywall??   I can see where that might be helpful in some cases.... but can you place all of them together as a unit, or do you need to place them individually?? 

[barthbradley]

I'm not quite following you still. Sorry. But after re-reading your initial post, it sounds like the only change between the new and existing walls is the insulation, which wouldn’t change the walls’ dimensions. The only change I read, is the insulation between the studs. If the existing walls are 2x4 studs, the core remains 3 ½” after insulation. If this is the case, I don’t see a need to demo and replace those modeled walls -- in whole, or in part -- unless you want to phase/schedule the rehab work. That’s not really what Revit is about though.

[barthbradley]

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@georgehobel wrote:

I know this is sort of a different topic bb, but are you saying you would build a 2 x 4 wall in separate pieces... 2 x 4, then sheathing, then siding... all separate walls...then drywall??   I can see where that might be helpful in some cases.... but can you place all of them together as a unit, or do you need to place them individually?? 

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Yes, that's what I'm talking about. Modeling wall layers as "separate pieces". And no, I don't mean breaking a compound-layered wall into parts via "Create Parts" in Revit.  But essentially, that's what it is.  Parts without the headaches of working with Revit "Parts".  I'm actually comfortable with it, but it's a modeling method that took some "grooming".  It has its pluses and minuses.        

[Anonymous]

Sorry, no. The wall thickness will change, even though the studs remain in place. The shingles are being removed from the exterior face so that the sheathing beneath will be exposed. Then a 3" layer of continuous foam board insulation will be applied over top the sheathing and a new layer of shingles will be installed over that. The wall thickness will increase by 3" total even though the studs and batt insulation are remaining in place.

So the question it comes down to is - what is the best way to show the removal of the shingles and the addition of new continuous insulation and shingles on the exterior face of the wall even though the core components of the wall are remaining in place?

[ToanDN]

I would model the existing layers to remain, the existing layers to be removed, and the new layers to be installed as separate walls. Using parts may work in theory but you will spend much more time into it.