Foundation Plugin

Here is a typical section through a wall/floor junction in the UK, using either shallow strip or deep strip foundations.

Basically, we start by digging a foundation trench. Then we fill with unreinforced concrete to the desired depth (deep fill is more common nowadays than shallow strip). Then we build the base of our walls, usually up to damp proof course. The walls are used as formwork for pouring the ground bearing concrete floor or for supporting beam and block flooring. Only after that stage is complete do we start raising walls above dpc.

This is for the vast majority of foundations in good ground. In poor ground, we might use a raft foundation or, more usually, some kind of piling.

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Everything Simon said above. These are the two ubiquitous methods for domestic foundations in the UK covering ~90% of situations. The only thing I’d add is that with the traditional version (on the left) the below ground masonry is now often a “trench block” which measure 440mm (w) x 215mm (H) (+10mm joint) x 300mm (D) (average cavity width) and used as they’re much less labour intensive.

UK trench blocks

Hummm No rebar. Do you have seismic forces?

Er, no. Nor do we have to deal with hurricanes or volcanic activity. It’s real peaceful round here.


Lucky you! Lateral bracing seems be my #1 Continuing Education credits subject.

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90% of the English buildings are built on deep wet clay that rarely dries out…

any of the relatively minor activity is simply absorbed…

it makes the news, in London, when a window gets broken in Oxford…


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According to this article, we do have seismic activity, albeit too faint to be felt most of the time.

One of the most extreme tremors this century occurred in Sandwich in Kent with a quake registering 4.2 on the Richter scale. That was as recent as 2015. My parents live in Sandwich and I don’t remember them mentioning it. Those that did feel it probably thought it was the quality of their lovemaking at the time.


Version 1.2.2 - 02.25.2019

  • Fixed a bug in the display of the toolbars (Mac and Windows).
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Version 1.2.3 - 03.15.2019

  • Updated toolbar icons to be compatible with 4k (UHD) resolution monitors.

First look at the new edit menu for slab on grade foundations:

Version 1.2.4 - 06.26.2019

  • Enabled the “Edit SOG Assembly” function/menu for rectangular slab-on-grade foundations.

Version 1.2.4b - 06.27.2019

  • Corrected the code for raising and logging exceptions.

Version 1.2.5 - 06.29.2019

  • Enabled the “Edit SOG Assembly” function/menu for polygon slab-on-grade foundations.
  • Enabled the “Edit SOG Outline” function for polygon slab-on-grade foundations.

The ability to edit the outline of polygon shaped foundation is fairly important not only for this plugin but also for the complex roof module of the Truss plugin. I will be moving back to the Truss plugin this next week to continue my work on the complex roof module.

P.S. I think now would be a good time to put out another tutorial video on how to use these new editing features.

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Tutorial 2: Editing Slab-on-Grade Foundations

Version 1.2.5b - 07.01.2019

  • Enabled the “Edit Slab Assembly” function/menu for rectangular slab foundations.
  • Enabled the “Edit Slab Assembly” function/menu for polygon slab foundations.
  • Enabled the “Edit Slab Outline” function for polygon slab foundations.

Version 1.2.6 - 07.03.2019

  • Enabled the “Edit Stemwall Assembly” function/menu for rectangular stemwall foundations.
  • Enabled the “Edit Stemwall Assembly” function/menu for polygon stemwall foundations.
  • Enabled the “Edit Stemwall Outline” function for polygon stemwall foundations.

All of the current features of the foundation plugin are now fully parametric. However, I do need to introduce a new system for handling stepped foundations and internal strip footings for both slab-on-grade and stemwall foundations.

The absence of a interior footing module for the slab-on-grade type foundation is very frustrating for me and I am sure for a lot of other users as well.

With that being said I’ve decided to put my thinking cap on again and give this issue some further thought. Based on what I have so far for foundations and looking at some other foundation examples I think the following parameters should be sufficient to fully define an interior (thickened slab footing):

Basic Options:

Footing Width
Footing Depth
Slope Angle
Slope Start: Yes/No
Slope End: Yes/No
Vertical Drop: default is zero
Reinforcement: Yes/No
Anchor Bolts: Yes/No

Reinf. Options:

Ftg. Bar Dia:
Ftg. Bar Qty: 1,2,3,4,6

Anchor Bolt Options:

Anchor Bolt Length: 10,12,14 (in.)
Anchor Bolt Dia.: 1/2 or 5/8"
Washer 2X2, 3X3
Bolt O/C Spacing
Sill Plate Thickness:
End Distance:

The vertical drop option is the 6" dimension in the image below:

The interior footing module will be quite similar to the window and door module in the Wall plugin. It will allow the user to add, delete, move or edit any interior footing within the SOG. Unlike the current system (only one interior footing possible), the user will be able to create as many footing as they like, criss-crossing the slab in any direction at any angle. Once this feature is in place the slab-on-grade foundation will be much more versatile and hopefully much more capable of modeling real life (complex) foundations.

Please let me know if there are any other parameters or options that I might be missing from this list.

First look at the interior footing toolbar:

This toolbar will allow the user to add, delete, edit or modify interior footings within stemwall, slab-on-grade or slab foundations.

I will also be adding in a toolbar for working with brick ledges on slab-on-grade and stemwall foundations.

This will enable the user to add a brick ledge to any edge of a foundation, and also edit or delete the brick ledges. Currently brick ledges are only available with stemwall foundations and if enabled applies the brick ledge to the entire foundation outline.

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Version 1.2.7 - 07.05.2019

  • Added the Interior Footings toolbar and icons.
  • Added the Brick Ledges toolbar and icons.
  • Enabled a resync function in the License tab of the Global Settings for license renewals.

Within the License tab if you click on the license exp. date the plugin will then resync with the server and update your license exp. date accordingly. This is a resolution to the issue some users have recently had when renewing their license.

Previously the user had to remove their serial number and then re-enter it in order for the plugin to update itself with the new license expiration date.