Foundation Plugin


The foundation of the that goofy donut house:


Some common configurations of concrete columns:


I’ve had a request for adding the option of insulation around a slab on grade, in short a frost protected shallow foundation (FPSF).

This should not be too hard to add in. There are a number of resources online I will study to come up with the most standard configuration as possible.

Are there any particular things anyone would like to see with regards to FPSF insulation.


An FPSF with 2" foam insulation along the wall and vertically. 2.5" foam insulation at the corners with the following horizontal dimensions:

A = 12"
B = 24"
C = 40"

The rectangle foundation is easy, the polygon shaped foundation will be more challenging.

View model here:


An irregular shaped FPSF, note the 135 deg. corners. Once this angle becomes greater than 135 degrees I would probably just treat it the same as a straight wall.

View model here:


Version 1.1.3 - 06.03.2017

  • Added “FPSF” option to rectangular slab-on-grade foundations.
  • Added an insulation layer in the global settings under the “Layers” tab.

  • Added “FPSF” option to rectangular stemwall foundations.


Working on the square/rectangle spread footing tool:

I will start with wood posts as an option with the following sub-options for the wood post:

Post Size: 4x4, 4x6, 6x6, 6x8, 8x8
Post Height (in.)
Post Base: None, ABA, ABU, ABW, CBSQ
Post Cap: None, CCQ, ECCQ
Post Rotation: 0, 90, 180, 270

I also plan on having the option for steel posts with the following sub-options:

Post Size: HSS4x4x1/2, HSS4x4x3/8, HSS 4x4x1/4, HSS3x3x3/8 etc… (round and square tube)
Post Height (in.)
Base Plate Size (in.) - square shape L x L
Base Plate Thickness (in.)
Base Plate Hole Dia. (in.): 1/4, 3/8, 1/2, 5/8 (4 bolts per baseplate)
Vert. Offset (in.) - for non-shrink grout
Post Cap: Not sure what to do with this yet.
Post Rotation: 0, 90, 180, 270

I’ve been contemplating using the Simpson Strong-Tie post caps and bases as provide in the warehouse but I’m worried that the polygon count is too high. I may have to generate my own dumbed down versions.


Added “FPSF” option to polygon slab-on-grade foundations:


An octagon slab on grade (FPSF). Note that the angle of the corners is 225 degrees, any less and the corner treatment would go away.


[quote=“medeek, post:90, topic:27419”]
Note that the angle of the corners is 225 degrees, any less and the corner treatment would go away.
[/quote](bold emphasis added)

So a rectangular foundation, with angle 90 degree angles, would get no corner treatment? :wink:


I am describing the outside angle. You are right in that the inside angles of a rectangular foundation are 90 degrees but the outside angles are 270 degrees. To rephrase any corner with an inside angle larger than 135 degrees will not receive corner treatment.


Added “FPSF” option to polygon stemwall foundations.

Now I’ve thoroughly beaten the FPSF option to death, the only thing I might add in later is a global setting to change the insulation color to pink, blue or white.


Tutorial 1:


I just finished watching your tutorial. It’s fun to see how all the glimpses you’ve given have come together.

One small thing that surprised me though: No preselect of footprint? Say the user has selected a polyline enclosed face (which includes rectangular faces), could you (fairly easily) assume the selected face is the foundation outline - instead of having the user choose rectangular vs polyline and redrawing what they might have already drawn?


Excellent point. Somehow that option fell by the wayside but now that I have the full polygon option it will not be a big deal to add this option in. The next release will allow the user to select a pre-drawn face and eliminate the need to select all of the vertices.


Version 1.1.4 - 06.11.2017

  • Added pre-drawn face outline tool for stemwall and slab-on-grade foundations and slabs.

You can now click on a face (any closed polygon shape) and the plugin will generate the appropriate stemwall, SOG or slab.

A big thank-you to Sjdorst for pointing out this deficiency. If you have your foundation footprint already setup this is a time saver and also will help eliminate errors in manually selecting points.


Version 1.1.5 - 07.18.2017

  • Fixed bug with slab reinforcement for Slab-on-Grade foundations (Polygon, Face).


I’ve been considering adding in a waffle (pod) slab, the type that is common in Australia.

I’ve also been reading quite a few online articles that discuss some of the issue with this type of foundation:

There does seem to be some advantages to this system but also some disadvantages.

Just wondering if anyone has any direct experience good or bad with this type of foundation system that they would be willing to share.


Hi Medeek,

I am a structural engineer in Australia with 17 years experience, specialising in residential foundations. The waffle pod system is a foundation type that we use a lot of. They do generally perform well in most soil types, except for in highly reactive clays, where seasonal differential movement of say up to 75mm is experienced. This becomes more apparent in areas of this country where there are only 2 seasons; wet and dry, and in drought affected areas (90% of the country). Seasonal movements greater than 65-75mm would typically require an alternative footing system, depending on the engineer’s recommendations.

Builders prefer them for their easy, clean setup. They do have their disadvantages though. Drainage around the site is very important. Placement of concrete must be carried out so the concrete does not lift the pods from underneath, reducing the thickness of concrete over the pods (slab thickness: 85mm). There is an instance of someone jacking up a heavy 4WD in their garage and the jack punched through the thin concrete. Lucky the guy wasn’t below the truck at the time.

There are cases where they haven’t performed, for whatever reason, but out of the hundred thousand of homes that have been built in Australia using this system, the concern is probably negligible. Used in the right scenario and installed with the proper method, they can be a good foundation option.

Your plugin is going to be amazing when its all done. I can see myself using it daily. Please keep up the good work.