Separate Below Grade Entrance (Underpinning or Insulating)

3/19/2022 at 1:39:34 PM

For a standard door size 32" not needed but you will need to allow for a concrete pad/drainage and retaining walls depending om how far below grade to be legal. Underpinning would be more important if a large span was being cut out or old type construction from 70 years ago that did not use the kind of foundations we use now. Check with a engineer if really worried but if a modern home don't worry.

3/19/2022 at 4:02:07 PM

Before installing the door, be sure to install a metal lintel above door with a suitable diameter so that the weight of the upper structure is distributed on the concrete!

Note that you have cut the part of the foundation on which the weight of the structure is, so you must divide the weight evenly between the two sides you cut. If you do not do this, you will see cracks over time and the door will also go out of adjustment.

3/19/2022 at 10:52:15 PM

I have witnessed underpinning when a builder built two homes over a fill-site; the footings were resting on unstable ground and the houses shifted significantly over the course of a couple of years. You shouldn't require underpinning provided the footings are resting on stable, undisturbed soil (i.e. clay). The Building Code contains provisions for minimum backfill height, typically 1.2 m (4') for clay soils, less for gravel, rock, etc. If there is less than 4' of backfill (clay or similar soils), the footings may be susceptible to frost movement; however in this case with a small opening for a door it's less likely. I have seen townhouses with garages below where the footings lift during the winter due to being improperly designed/built to accommodate frost action (should have used a pile and grade-beam foundation with void form beneath the grade beam).

Another thing to consider is the allowable openings in a concrete wall which is typically 25% of the length of the wall (window openings) in the case where the concrete wall extends the full height to the underside of the floor system.

Cutting an opening like this can seriously weaken the foundation and it would be wise to first check with your local municipality regarding possible Code issues and then also to have a Professional Engineer assess the situation taking into account all the variables.

4/5/2022 at 10:14:17 PM

Hi Kumar,

That is a great question.

The foundation does need to be underpinned.

The code you are looking for is the Ontario Building Code which stems from the Canadian National Building Code.

A municipality may add additional requirements but cannot remove them.

The purpose of the underpinning (which must be done by a licensed contractor and get a copy of their certificate of insurance and ensure that they are registered and in good standing with the Workplace Safety and Insurance Board (WSIB) prior to commencing work), is to ensure that the foundation is resting on soil below the frost line (approximately 4' in southern Ontario).

If you think of a deck or fence, the foundation (or posts for a fence) must extend down to that depth to avoid frost heave.

Water, unlike most things expands when it freezes instead of contracting. When it expands it displaces whatever is in its path (a deck footing, fence post, or house!). The same is true of your home. The foundation extends down to footings that are located below the frost line. If you had a walk out basement, the foundation and footings would be stepped down to maintain that minimum 4' depth.

In the case of a basement entrance, once the stairwell is excavated the lowest point is now the same as the ground level and cold winter temperatures begin to penetrate the soil beneath to a maximum depth of 4'.

Please note that this work requires a municipal permit and inspections and would require an engineer to provide a stamped drawing detailing the underpinning sequencing. It is not a simple matter of digging a trench below the new doorway and pouring in some concrete. The underpinning will need to be "stepped" up by extending laterally (left and right) of the doorway in increments and be "pinned" with re-bar to the existing footing.

It is not a difficult thing to do but must be done correctly and inspected.

Please do not entertain any contractor that tells you otherwise or that you do not require a permit.

For the safety of your home and its very valuable occupants: 1) Consult an Engineer licensed in the province.

2) Apply for (and receive) a municipal permit for the work.

3) Make certain that your contractor is licensed, insured (for the work being performed), and complies with all applicable requirements.

Not getting a permit may be cheaper and faster in the short run but is illegal and is far costlier to fix after the fact (it will likely far exceed the original basement price to fix).

Again, it is not difficult to do correctly and the municipal inspectors can give you some peace of mind that the work is being done correctly and safely. Do not hesitate to ask questions of the Inspector if you have any concerns or would like clarification.

On a separate note, if this is part of an entire basement remodel, permits are required for that and electrical work is a separate permit with the ESA and it is extremely unlikely that any contractor / handyman is a licensed electrician with a Master rating that is required to take out an electrical permit. They can certainly sub-contract these parts of the work but are not permitted to tackle the entire project themselves.

I hope this helps. Best of luck on your project

10/16/2023 at 2:41:20 PM

Underpinning a basement while making below grade entrance is preferable for a number of reasons. Firstly, it can strengthen your foundation and enhances structural integrity. Secondly it make sure that structure is robust without worrying about weak foundation. Furthermore, properly executed by a contractor, it offers Reliability and durability of your buildings and also helps while compliance with local codes and regulations. So I think, basement underpinning is much better option in a longer run.