Basement Lowering Techniques: Underpinning or Benching
Most of the older houses in Toronto were built with basements that were used as storages because extra living space was not needed. Nowadays, the housing price on the market is going up, and most people prefer to extend their livable space turning their basements into a functional room for the family because moving seems to be rather expensive. That is why basement lowering has gained much popularity.
Benefits of Lowering Your Basement:
- Your home will be accessed easily with such a construction.
- You can increase the height of your ceiling and the overall lighting.
- Structural problems of the foundation will be eliminated.
- The project belongs to the least expensive ones.
In addition, you can get extra benefits from underpinning. Your basement may be supplied with heated flooring and large windows. You can also arrange your personal workout zone there!
Steps of Basement Lowering
When homes were purchased many years ago, the basement was never the unique selling point of the house. It was seen as the cold, musty room in the house that was used simply for doing laundry or storing boxes. Now, basements have become an acceptable living space and can be used for a variety of reasons. Underpinning basement walls can allow you to put in a pool table, home theater, TV, and other cool things! In order to accomplish this, underpinning basement walls is generally required. Underpinning your basement allows you to get rid of or hide items such as support column posts, furnaces, and water heaters. Moreover, underpinning is beneficial because you can add luxuries to your basement such as heated flooring, large windows, or even your very own walkout! Basement lowering is usually done in 2 ways:
Step 1. Basement Underpinning in Toronto and GTA
Underpinning of the existing footing of the foundation is used for increasing the basement height. The method is applied under the already existing foundation to maximize the basement space.
There are three stages of this method application done in a certain sequence. There are separate sections that are from 3 to 4 feet wide and 2 to 3 ft deep. Such a variety is caused by the soil conditions. Everything depends on the type of foundation of your house and the aggregate material and its compaction on which the house has been built.
The three-stage approach is necessary because, since the foundation is carrying the load, undermining is allowed only for a small section of the foundation wall at the same time. When the stage sequence is followed, the basement is lowered in a safe and well-controlled way. No shifting or settling in the house structure occurs with such a method.
The underpinning process consists of the following steps:
- First, there is a need to remove the concrete floor and to excavate the soil for proper elevation.
- Dig out the pins in three stages in accordance with the engineer’s drawings.
- If there is a need for new posts, install new footings for them. To start, you will have temporary jacks to support the beam.
- When the first stage has been completed, the 2-inch space between the footings and concrete appears. That is why a 2-inch dry pack grout should be installed.
- After the completion of the three stages, install the new plumbing. There is a need for the sewer injector if the elevations for plumbing do not meet.
- If you want to waterproof your house reliably from the inside, the interior drainage system should be installed.
- Arrange the base by placing a minimum of 3 inches of ¾ gravel on the floor.
- Install the new concrete floor and finish the trowel.
“Basement benching” or “bench-footing” means a concrete bench created over the stable excavation slope. It is used when you need to lower a basement floor but you do not want to extend the footing of the foundation walls to a lower level. So, the existing footings are left without any changes. Instead, you maintain a stable excavation slope that is located below the footings of the foundation wall. The protection ‘bench’ made of concrete is created over the top of the slope. It is made of the combination of rebar and concrete and placed around the inside perimeter of the entire structure.
- Remove the concrete floor.
- Excavate the soil to the proper level of elevations. Pending is needed on the required height to determine how far the concrete will project out from the wall.
- The concrete bench should be 1ft to 1 ½ ft projecting out from the internal wall if you lower the basement 1 ft down.
- The perimeter should be formed after excavating to pour the benching.
- Install the new plumbing. Use a sewer injector if the elevations for plumbing do not meet.
- Install the interior drainage system to waterproof your house.
- Create the base placing a minimum of 3 inches of ¾ gravel on the floor.
- After the new concrete floor has been installed, finish the trowel.
Step 3. Lowering Basement Floor
You can provide your living space with more headroom by lowering the basement floor. According to the building codes established for most communities, every living space should have at least 7 feet of height. In some cities, the requirements are established for 7 ½ or more feet.
Moreover, if the living space is too small, that can evoke the feeling of claustrophobia in some individuals, or people just feel uncomfortable. You can solve these minor issues by lowering the basement floor. It will help maintain the overall comfort of this room.
The main reason why homeowners need to lower the basement floor is to put up its walls and turn the basement into the living area for the family members or renters.
The basic recommendation is that you need to dig 8-10 inches deeper at least than the level at which your planned lowered floor should base. For instance, if there is a need to lower your basement floor 6 inches, dig 14 to 16 inches deep.
Basement Underpinning and Benching Cost
The cost of underpinning is normally established for a linear foot. On average, excavating two feet deep costs between $000 – $050 per linear foot. One foot of bench footing costs between $000 and $000 while 2 feet of bench footing will take $000. To count the price, you need to measure the width and length of your house (each side of it), add the figures, and multiply the sum by the price per a linear foot. As a result, the underpinning of the house that is 50 feet long and 20 feet wide (50 + 50 + 20 + 20 = 140 feet) will cost you 140 feet x $000 = $00,000.
How much does it cost to lower a basement?
Consider that you do not perform basement lowering every day, so there may be some factors that help you affect the cost sufficiently. If you need lowering basement and the basic finish to be performed, the price will be $00 to $000 per square foot.
How Much Does it cost to lower basement floor?
Lowering the basement floor can cost around $00-00,000 for a medium sized basement if you’re doing underpining. For bench footing it would be around $00,000 or more.
How Much Does it cost of lowering concrete floor?
An interior french drain costs $00 to $00 per linear foot or $0,000 to $00,000 on average. An exterior french drain is easier and cheaper to install at $00 to $00 per linear foot or $0,000 to $0,000.
Basement lowering average cost
To calculate the actual cost of the entire amount of work, there is no special formula. You need an experienced estimator who could analyze the square footage and linear footage of your basement which you want to lower. Then, the accessibility for digging outside the house should be considered. Another factor that can influence the cost is the possibility to use the equipment within the existing basement. If all the work should be done manually, the cost will be a bit higher. In Toronto, the average cost of basement underpinning is $00 per square foot. The cost of excavation for basement lowering is about $000 per linear foot.
There is no actual formula for calculating the cost for the entire job. Estimator analyzes square footage as well as linear footage of the basement that needs to be lowered. Than he looks at accessibility to dig outside of the house. Another big cost influencer is if equipment can be taken into the current basement or all work has to be done manually. On average basement underpinning costs $00 per square foot in Toronto. The average cost to excavate for lowering the basement is approximately $000 per linear foot.
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FAQ of basement lowering – underpinning and benching
How long does it normally take to complete this type of project?
The entire project completion for basement lowering takes on average 4 to 6 weeks.
Can you lower a basement floor?
Yes, we can. There are two common methods by which the basement floor of your home can be lowered: 1. Underpinning the foundation walls. 2. Bench-footing.
Can you lower a basement floor?
Sure, we can do it. We use two common methods by which your home basement floor can be lowered: 1. The foundation walls underpinning. 2. Bench-footing.
Can you make your basement bigger?
Though rather expensive, it is obviously possible. To envelope the house, there are two large costly areas – the foundation and the roof. Consider why you need to expand the basement because it can extend the entire house footprint.