Accuracy paradox - a kind of Sketchup cancer

Do not use the polyline width feature in AutoCad. I haven’t used it for years, now that line weight can be controlled either individually, by layer, or with a plot style table. Polyline widths even do not respect your output scale setting.


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You are not alone in your frustration. It’s perhaps unfair to say it’s the fault of sketchup, but it feels like a symptom when it manifests halfway through a project. “Do a better job modeling”, is not practical advise for those of us crunching lots of projects with many collaborators, sometimes you have to work with what you have and forge ahead. Lots of ideas on mitigating the problem in this thread, I thought I would add one more trick that has saved a few lost causes for me. Select the offending batch of “triangulated” lines and use fredoscale to scale them to 0. This forces any batch of lines into a plane, it’s a cumbersome solution for an entire complex model, but perhaps useful from time to time. Good luck.

I have had that happen just in sketchup all by it’s lone some. I was drawing a simple 4/12 roof intersecting a wall the other day and though I used the tape measure tool to lay it out, when I drew over the guide lines with the pencil tool - they would not make cohesive planes.

These sort of things make the program frustrating.

A related question - I want to make an array of rafter tails - they have to be 24" on center but the roof length is not divisible by 24" Can I make an array, then slide it right or left until I find the best looking spacing?


Yes. What do you plan to use for spacing? 24" OC except at each end? There’s no reason you can’t move the components individually or en masse after distributing them.

With plywood (or whatever is going) to cover the rafters and their fixed measures I can’t see why you would want all the rafters to be equally spaced an odd dimension around 24". I would say, make the array with 24" and only move the last one or both at the beginning and end.

p.s. you can create the array by typing /10, then /11 or /9 (and so on) till they fit best, closest to 24". But see the top of my response.

So how do you move them en masse? Do you create a group and drag it back and forth? I love your drawing and would love to learn how to draw that well. Mine look so childish.

Wo3Dan - they are exposed 3 x 6 rafter tails and have to look balanced from the ground looking up. They are spaced at 24" to keep that old school look. They are covered with 1 x 8 ship lap so an odd dimension at the ends won’t matter.

The roof rafters inside the building line are 2 x 6 at 16" o/c so the plywood aligns properly.

I wouldn’t bother with a group. Just select the rafters that need to be moved and move them. Hold Ctrl or Shift while clicking to add rafters to the selection or drag a selection box around the rafters you want to move.

Actually, I drew the first rafter centered on the end of the top plate and then copied it to make the rest on 24 in. centers. After they were done, I moved each of the end ones in 3/4 in.

I’m not sure what’s different. Maybe the style you have selected?

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when I have tried that in the past it drags the wall plate along with it creating a weird shape which I have to delete and redraw. I have yet to figure out how to select an object that is attached to another without selecting the second object.
Perhaps I am not selection properly?

It sounds to me as if you haven’t made components of the parts as you go.

You need to make components of the parts as you go so they don’t stick to each other.

That sounds more like you are not using components correctly. You should model each separate object in the real world as a separate component (or as an instance if they are all the same and need to stay the same even if you edit). So, your rafters should be instances of one component, and the wall plate should be another component.

Components (and groups) are what isolates edges and faces from ones not in the same component. When you don’t use them, everything sticks to everything else.

Edit: as usual, @DaveR replied while I was typing!

Oh. I hardly ever do that. Maybe I should watch more videos abd learn better how. So, how many components are enough? A lot of times I scan a section of plans trace the walls and pull them up. Would I be better off making each wall a component? Or all of the walls one component, windows another etc.

I know it depends on the individual plan, but typically, what do most people do?

Recently I tried making a rafter a component. Then I took the wall line, selected it, divided it, Then copied and dragged the rafters over to the wall and tried to place them at the division points. It took a long time and looked pathetic.

I learn something each time I post here, but I feel like the person who stands at the base of a hill seeing it reach above the clouds, with no idea how high it extends. As I learn more, climbing up the metaphoric hill, I see the hill hasn’t gotten any smaller, but perhaps is actually a mountain.

As many as you need for the project? I would make a component for each discreet board. Of course you can copy components so you only need to draw one rafter tail, make it a component and then copy it.

There’s a better way. Place the first rafter as I said centered over the end of the top plate. Select the rafter and use Move/Copy (hit Ctrl after getting the Move tool) and move the first copy over 24 inches. Type 24 and hit Enter to get the move distance. Then, without doing anything else, type xn and hit Enter. n equals the number of copies you’ll need. Finally, move the end rafters as needed to place them correctly.

yes - that make sense.

I was trying to draw a hip roof - the problem is that each rafter as you go up the hip is longer. How would you deal with that?

Do you drag them in place en masse and use some sort of intersect tool to trim them at the hip? If they are components, if you cut one wouldn’t you end up cutting them all? So you’d have to de-component them?

With a hip roof I like to stack the rafters over the studs. In the case of a “true hip” there is a common or regular rafter centered with the ridge. Therefore the studs and rafters are laid out from the center of the building. In the case below the three blue common rafters would dictate the stud layout below.



In the case of a hip roof, I would do as Shep shows working out from the center in each direction and I would make counterpart pairs unique ( i.e. 1st out from the center, 2nd out from the center, etc.) Then they can be trimmed to hit the hip rafters. There’s actually a handy simple trick for that which I can show you if you want. It would make the trimming much easier. Have to do it later, though. Maybe you want to connect like we’ve done before.

Shep - Oh, I know how to build a hip roof - I have built a bunch of them. Drawing them in sketchup is where my interest lies. On a gable roof, as shown earlier in the thread by making an array seems easy enough. However, on a hip, I was wondering if you would drag the array in place and somehow cut them off at the hip.

What never ceases to amaze me, is when you get down to building a hip roof, is how it always seems the cuts always need tweaking. They never seem to work out according to Hoyle. But, that’s another story for another day.

Dave, yes another day - right now I am swimming in estimates to get out, and am trying to wrap a job where the contractor can’t make up his mind and keeps changing things after they are built. It has dragged the job out terribly.


I hear ya, I’ve been lucky in that I learned to layout rafters with a framing square then moved on to using math and tape. Then came the construction master. But best of all Sketchup.
I think most problems in the field come from lumber that isn’t dimensionally accurate or straight.
You can return anytime for some pointers on hip rafters. You can probably search the forums here and find a few examples.
Think in terms of each stick of wood being a separate group or component.
Good luck with the estimating,


BTW, I love the cutting mat.

Thanks, it’s a nod to some favorite Youtubers.

You might glean an idea or two from this old model…