Foundation Plugin


There are quite a few options to play with, rebar size and quantity. Notice in this example I’ve used #3 bar for the slab reinforcement rather than the mesh and I’ve doubled up bars on top and bottom of the footing:


Version 1.0.5 - 12.01.2016

  • Enabled reinforcement for stemwall foundations.

View model here:


I’ve been thinking about adding in a retaining wall feature that auto sizes the rebar and qty. based on my typical retaining wall details:

For stemwall foundations I typically check the footing width (bearing pressure) and min. rebar for shrink (ACI 318-11), see engineering calcs per this PDF:

I could easily incorporate this type of engineering calculations into the plugin, however I’m still trying to figure out how to have the plugin output PDF reports, or Excel spreadsheets, which would be necessary if engineering reports become part of this plugin.

Same sort of thing with square or rectangular footings can be done:

With stemwalls or pony walls (not necessarily retaining walls) that exceed 24" in height (but not in excess of 48") I like to add #4 bars cont. horizontal at 18" o/c. Logic could be incorporated that adds in additional stemwall and foundation wall rebar per a number of prescriptive criteria, IRC tables etc…

Currently it is entirely up to the users to specify rebar size and qty. with both stemwall and slab on grade foundations.

Stemwall foundations allow you to place rebar at the top of the wall (5" below top, qty. 1,2, or 3 bars) and rebar at the bottom of the wall (3" above bottom, qty, 1,2, or 3 bars). It also allows placement of bar in perimeter footing and interior footings (qty 1,2 or 3 bars). Bar sizes range from #3 to #8 and similar sized metric equivalents for the metric templates, I can always add more sizes if requested.


Version 1.0.6 - 12.03.2016

  • Added a “Layers” tab within the global settings.
  • Enabled custom layers for both stemwall and slab on grade foundations.


I’ve been working on the polygon slab-on-grade this weekend and by extension the polygon stemwall foundation as well. The interactive “tool” portion has been difficult mostly because I don’t understand a lot of that portion of the code (blackbox to me), but I’m almost there with it.

I would like to be able to create a foundation with any shape or size simply by drawing a polygon, point by point.

A simple example would be something like this:

Note, the interior floor beams at 12’ on center. Using an Web dialog I should be able to allow the user to easily add in as many floor beams or bearing walls as required.

Once I have the foundation working correctly then I need to extend the floor truss/ floor joist module so that it can also handle polygon shaped structures within the Truss Plugin, then we will have a full package.


Has anyone ever seen a stemwall framed liked this?


Or like this?

These two methods seem to be fairly popular in Oregon, I’ve never seen a floor/stemwall constructed this way any where else.


I’ve never seen anything like them in the East but I’m sure it could have been tried. Seems like it only serves to lower lumber to finished grade. But like most things it’s likely just to increase P/M.


At our parts putting wood in the foundations or inside concrete is considered a no-no. There is also a substantial cold bridge there.



The argument for this construction method is the sheathing height is decreased because the rim board is eliminated. However, in my mind the cons outweigh the pros:

1.) As mentioned there is a thermal bridge through the stemwall at the corner where the floor meets the wall.
2.) Stemwall construction would become more complicated and time consuming.
3.) Proximity of the I-Joist to the concrete could be problematic, requiring additional measures and more time and effort.
4.) The crawspace height is reduced making it harder for other subs to install and work in and moisture from the ground is more likely to be an issue.
5.) Nut and Washer of anchor bolts protrudes into floor sheathing and bottom wall plate, requiring additional notching.
6.) If you want to run plumbing or electrical down through the wall bottom plate and into the floor, this is nearly impossible with this configuration.


Any thoughts on an advanced option that auto-inserts anchor bolts?

Options would be:

Size: 10", 12", 14"
Dia.: 1/2", 5/8"
Washer: 3"x3" Square, 2"x2" Square, Round
O/C Spacing (ft.): 6’
Sill Plate Thickness (in.): 1.5"
Distance from Corners (in.): 12"


Then there’s these things. I’ve seen a lot of them.


I’m trying to determine if its easier to write a module that draws the anchor bolts or just bring in the component (pre-drawn). I’ve never brought in a component before so something I need to explore further. The other thing I feel is key is to make sure any of these minor components are modeled in such as way as to remain fairly lightweight within the model. No one is going to want to use a feature that bogs down their overall model. That is my one big gripe with using the 3D Warehouse models, the polygon count on most models is usually outrageous.


If you have a number of components that do not need to change in size you can easily access them and bring them into your plugin.

For example my cabmaker plugin brings in door / drawer handles. In my case the key is saving various handles centered.

def get_handle_def(handle_name)
  model = Sketchup.active_model()
  definitions = model.definitions

  definitions.each{ |my_def| return my_def if ( == handle_name && my_def.valid?)} if (definitions)

  filename = File.join(@cfgs.library_root, STORE, 'handles', "#{handle_name}.skp")
  filename = File.join(@cfgs.library_root, 'handles', "#{handle_name}.skp") if (!File.exist?(filename))



I’m assuming that this will drop them at the origin. Is the insertion point point of the component the origin of the file inserted?


Yes - I use y = 0 and x = 0 and z = 0. Also I want the handles vertical. When they are for drawers I simply rotate them. Essentially I have a routine for parts placement and the various parameters allow me to scale x, y and z and origin for rotation including rotate x, y and z and provide an origin for transformations and an optional move which occurs after rotation.

Email me if you are interested in more details.


I need some input from the foundation and truss plugin users. I’ve decided to pre-model certain things like Bolts, Nuts, Washers etc… With Nuts and Bolts I’m planning on using a cosmetic thread so that the polygon count is minimal. As I’ve been experimenting with the bolts and nuts I’m wondering if I should eliminate the 30 deg. bevel on the head of the bolt and nut, it looks nice but adds quite a bit of complexity and polygons to the model. Any thoughts on this?

You would sacrifice some realism for a smaller model…


Seems like you could make a very simple component for an anchor. Even as little as a L shape with a tee across the top. The user could then replace these with as “heavy” a component as they wish. I’m thinking the insertion point would be the top of the mudsill for example.




How many sides do the cylinder of the anchors have? SU does a good job of rendering a smooth cylinder with just six sides in my drawings, as long as SU considers it a circle or otherwise smoothed. They look OK rendered, though they don’t 3D print well in general, since that follows the actual polygons drawn. Don’t know if this helps…

All the best,
Charles Sloane


For now I will eliminate the beveling of bolt heads and nuts, the added number of polygons is too hard to justify and the bevel doesn’t really add much when your zoomed out at building scale anyways (in other words you really can’t see the bevel).

There is always an option to turn the anchor bolts on or off, that is a given. Some users may want this function others may have absolutely no use for it. It will be there if you need and want it.
For now I am going to go with 1/2" and 5/8" anchor bolts, I can always add more sizes later by request. The standard sizes of anchor bolts are per a specification I pulled from Fastenal (major manufacturer of fasteners in the US). I will start with 10", 12" and 14" lengths.

For the square washers I will give an option between 2"x2" and 3"x3", with the 3x3 being the more typical I would think with the latest 2012 and 2015 cycle of ICC codes. The exact dimensions of the square washers are per Simpson Strong-Tie’s offering in there wood fastener manual.

The hex nuts are per the Machinery Handbook 27th Edition.

If anyone has a metric spec. for anchor bolts (L-bolts) please send it my way and I can add in the metric equivalents.

I think the intent with providing the anchor bolts is partly a graphical representation and also for estimating. Ultimately the exact layout of the sill plates will drive the number and location of the anchor bolts as well as any requirements from an engineer for tightening up the spacing due to lateral loads and shearwalls.

Per the code (IRC/IBC) you are required to have at least two (2) anchor bolts per sill plate segment and the bolts must be within 12" of the end of the segment and no closer than 7 bolt diameters (3.5" for a 1/2" DIA bolt). Max. spacing is 6’ o/c with 7" min. embedded.

So even if I lay out my bolts starting 12" from the edge of the foundation and space them at 6’ o/c there will probably still be some additional bolts required since there will be sill plate splices (for buildings larger than 16’x16’).

I’ve always wondered if the builders actually give this much thought as they are placing their anchor bolts.

Another question I have is one would not want the anchor bolts to clash with the Floor Joists or Trusses. Do the contractors typically layout the location of the anchor bolts to ensure that this does not happen.

Your right there are a lot of constraints on the location of the anchor bolts, hence it actually might be useful to a designer to have them in the model to see potential issues as those raised above.