Problem with roof fascia

[rgarand]

Hello all,

I am having a problem with my roof fascia and how it appears in the elevation view. I have created my roof with the roof tool and I have added a soffit with my wall tool. I have given the same materials to the appropriate faces of each object so they will blend in elev. My problem is that about 1/3 of the way from the left hand side of the dormer, the bottom part of the fascia is not showing. The part I can not understand is why I see my fascia the 2/3 on the right part of the dormer. Very weird. I have attached an image of the problem. Any help would be appreciated...or any quick fixes for this type of problem.

TIA

[Karl Ottenstein]

I have several ideas...most involving modeling and assigning materials a different way... but to avoid rambling way off base and perhaps help someone else post an answer if I'm not online:

Could you post a small wall section through the elevation that you're showing us ... something to show the soffit and roof in particular, perhaps one on the left where the drip edge line is missing and one on the right where it appears.

Thanks,
Karl

[rgarand]

Karl,

here is a picture showing 2 sections thru the different areas. I do notice that I see the soffit in one...but not the other. If you notice in the plan view...I have selected the soffit, it DOES go the entire length of the eave. This seems to be a display problem maybe.

I am also having trouble on another elev view with 1/2 of my gable wall not showing...yet my windows in the missing half of the gable end are showing.

I am a beginner and I am getting very confused.

BTW, I have drawn the soffits over about 4 times now to try and fix this display problem.

thanks for the reply Karl, you are an asset to this list!

[Djordje]

rgarand wrote:
here is a picture showing 2 sections thru the different areas. I do notice that I see the soffit in one...but not the other. If you notice in the plan view...I have selected the soffit, it DOES go the entire length of the eave. This seems to be a display problem maybe.

Seems to me you have some duplicates (upper section - only the fil lof the roof shows, no outline - a sure duplicate sign!).

Did you try cutting the soffit wall with the roof? Should clean up properly.

Also, be sure that the end nodes match EXACTLY. It is easy to miss a little, and ArchiCAD can be merciless ...

HTH,

[Karl Ottenstein]

Shit. I just spend 45 minutes writing a detailed reply about this problem, and the forum logged me off, and when logged back in the message window was cleared. This sucks.

Too tired to start all over again right now. Perhaps tomorrow if someone else hasn't posted the same thing (keywords: design intent; plate height; truss heel; slab vs wall; objects occupying same space; solid element ops vs trim to roof).

Karl

PS Perfect screen shots for illustrating the problem/situation. Well done.

[Anonymous]

The part I can not understand is why I see my fascia the 2/3 on the right part of the dormer. TIA

Archicad does not take kindly to having two facets in exactly the same plane. I would suggest moving the soffit back 5mm. If you need it to extend the depth of the fascia then trim it to the roof as previously suggested.

[Thomas Holm]

Karl,

[censored]. I just spend 45 minutes writing a detailed reply about this problem, and the forum logged me off, and when logged back in the message window was cleared. This sucks.

A tip especially for those on expensive modem connections: Compose your posts in you favorite text editor, (TextEdit, Notepad, Word, whatever), save now and then just as you would when working, when finished, copy it and paste in the reply text window and Submit.

THis way you won't lose anything, and you save on-line time too!

Thomas

[Karl Ottenstein]

rgarand wrote:
here is a picture showing 2 sections thru the different areas. I do notice that I see the soffit in one...but not the other. If you notice in the plan view...I have selected the soffit, it DOES go the entire length of the eave. This seems to be a display problem maybe.

Hi Robert,

Well, I’m taking Thomas’ suggestion and typing in Word so as not to lose my message again. 😉

Finally a free moment, but you’ve no doubt left this issue in the dust and are on to bigger and better things!

Anyway, since you’re new to AC, let me throw out a whole bunch of things, some of which may help. The problem that is shown in your drawings is the reason you posted, but I think the design intent for the soffit is the place to start.

I can’t tell from the thin roof slab what your structure and intent is. But, assuming that Section 9 is the look you’re after, then there are several things to look at. First, the soffit mass is occupying the same space as the exterior wall. (Section 8 shows that exterior wall as having been trimmed to the roof.)

You generally do not want to have two elements occupy the same space for a bunch of obvious reasons, and some less obvious ones (related to some external rendering applications).

If you want your wall plate height to be at the bottom of the soffit (well, top of soffit sheating) – assuming that the soffit is covering up a truss heel for example, then you need to model your wall that way. If your roof is raftered, then your soffit will not penetrate the exterior wall, but will abut it and you should model that way.

There’s a problem with modeling a soffit with a wall as opposed to a slab. A wall must have its thickness explicitly specified. You have to dimension your plan to figure this out. Let’s not work that hard. By using slab, with rectangular geometry selected, you just drag/draw from (say) the upper left exterior wall corner to the upper right roof drip edge and the width is taken care of for you. (Works in this case anyway since you have a plumb cut drip edge.) If you stretch the roof overhang, then you just stretch the soffit slab…either individually via the pet palette – or stretch both together with the stretch command. If the soffit were a wall and you stretched the overhang, the wall width would stay constant – walls only stretch in length.

Once you think of the soffit as a slab, then you have a choice of it being a mass – as you did with the wall – or of being just the soffit sheathing – setting you up for wall section details. The appearance of the rake at the gable end determines other choices in all of this.

By the way, to trim a slab to a roof, you need to use solid element operations. If you use trim-to-roof, the slab will be plumb cut at the intersection point with the roof – not how you want the soffit to look. With solid ops, subtract the roof from the slab and it will be properly beveled.

I’m guessing that your original problem is related to having used a wall for the soffit. Because the wall does not show in Section 10, I have to guess that you trimmed to roof, but also that your wall edge and the roof drip edge did not coincide, causing the wall to be trimmed as in Section 9 where the wall was inside the drip edge, and causing the wall to disappear entirely in Section 10 where the wall reference line was (minutely) outside the drip edge. A minute difference, as Bruce mentions, is all that has to exist. It is possible the the roof reference line is not precisely at 0 degrees … did you hold the shift key down while drawing it? Ditto soffit wall. Not really sure though. Mystery.

I am also having trouble on another elev view with 1/2 of my gable wall not showing...yet my windows in the missing half of the gable end are showing.

This sounds like a trim-to-roof problem – do you have a lower roof that butts into your gable end wall? Guessing so. Click the gable end wall in plan, ctrl-T properties, and click the button to undo trim to roof. In 3D, click the wall, and the roof that it should be trimmed to – making that be the only roof that will trim the wall. Then right-mouse and trim to roof (top). Better?

HTH,
Karl

[rgarand]

Karl,

I have redrawn the roof fascia's with the slab tool. I am now about ready to do some boolean operations. I am quite familiar with these types of operations, because I come from an AutoCAD background (15+ years) and this is how I draw all of my 3D elements in AutoCAD. My question is this:

To subtract the Roof from the soffit, I will need to copy the roof element and then place this on my "3D-Subtract" layer. Since there is a problem with copies of elements occuping the same space, does this cause a problem?

I will go thru the exercise to experiment, I am just wondering how the program works.

TIA,

[Karl Ottenstein]

rgarand wrote:
My question is this:

To subtract the Roof from the soffit, I will need to copy the roof element and then place this on my "3D-Subtract" layer. Since there is a problem with copies of elements occuping the same space, does this cause a problem?

Ayyyyy! You don't need to copy anything into any special layer to do solid ops. (You may want certain elements to be in layers that can be hidden, but that's something else...where the cutting elements never appear as themselves in any view.)

Glad you've done this before in ACAD, so that it isn't really new!

Do not copy your roof or your soffit. Just select the roof, click the 'Operator' button, select the soffit, click 'Operand' (or whatever it is - AC not open at the moment) ... choose 'Subtract with upwards extrusion' as the operator (probably don't need the extrusion with the low pitch roof in your example, but would with a steeper pitch), 'use own materials' and execute. The operation is now associative. If you change the roof pitch, the subtraction is adjusted automatically...if you raise your soffit ... ditto.

Have fun,
Karl