Guelph Excavation Pros digs basement underpinning and installs excavation shoring for homeowners, builders and contractors in Guelph and Waterloo Region. Underpinning extends an existing foundation deeper by placing new footings beneath the old ones, while shoring holds back the walls of an excavation so they cannot collapse.
You need one or both when a basement is being lowered, when a new dig goes below a neighbour's footing, or when a service trench or septic excavation passes 1.2 m (4 ft) deep. As an underpinning contractor, we work strictly to the engineer's pin sequence and to O. Reg. 213/91, Ontario's construction projects regulation.
Our crews bring more than 10 years and over 500 jobs of excavation experience to every deep dig, and each quote is fixed in writing after an on-site assessment. We are licensed, insured and covered by WSIB.
10+ years digging
500+ jobs completed
Licensed and insured
WSIB coveredWe offer four kinds of below-grade support work, from hand-dug underpinning pins inside a basement to engineered shoring walls on commercial sites. Each is designed around the soil, the depth and whatever stands next to the hole.
When an owner wants a deeper basement without losing floor space, we dig short sections, called pins, under the existing footings and pour new concrete footings and walls below them. The house ends up resting on a foundation 600 mm to 1.2 m (2 to 4 ft) deeper than before.
This is the structural half of a basement lowering and dig-out project, and we usually handle both together.
On semi-detached houses, row homes and infill lots, a new basement or lowered floor can end up deeper than the footing next door. Underpinning the shared or adjacent wall keeps the neighbour's foundation fully supported while we dig.
It is the most sensitive job we take on, so it always comes with an engineer's design, crack monitoring and a written agreement with the neighbour.
For water, sewer and storm trenches deeper than 1.2 m, we set steel or aluminium trench boxes or hydraulic shores before anyone climbs in. That includes the trenches dug for our utility, sewer, water and storm line excavation work and deep tank holes for septic system excavation.
Every box is rated for a maximum depth and soil type, and we match the box to both.
Large commercial excavations beside roads, buildings or property lines may need a soldier pile and lagging wall: steel H-piles driven or drilled at intervals, with timber lagging boards slotted between them as the dig goes down.
We carry out the excavation and coordinate with an engineered shoring partner who designs the wall and installs the piles.
Shoring or underpinning is required when a worker must enter an excavation deeper than 1.2 m, when a dig goes below the underside of an adjacent footing, or when the soil is too weak to stand on its own. Any one of these triggers changes how the job is planned and priced.
Under O. Reg. 213/91, the Construction Projects regulation, the walls of an excavation deeper than 1.2 m (4 ft) must be shored, sloped back or protected by a trench box before a worker goes in. The exceptions are narrow: sound and stable rock, an excavation nobody enters, or walls sloped to the angles the regulation sets for each soil type.
This is the "4 foot rule" homeowners ask about, and the province's guidance on excavation hazards explains it in plain language. The regulation also requires a clear strip at least 1 m wide along the top of each wall, kept free of spoil, equipment and materials.
A footing spreads the weight of a wall into the soil beneath it, in a zone that fans out at roughly 45 degrees below its edges. Dig into that zone and the soil can squeeze sideways, so the wall above settles, cracks or leans.
That is why any excavation that goes deeper than a nearby footing, even by a few hundred millimetres, needs an engineer's review and usually underpinning or shoring.
The same risk shows up when an addition's basement drops below the house it joins, a detail we plan for during foundation excavation for additions. It also appears where a new door opening for a basement walkout needs footings deeper than the existing wall.
O. Reg. 213/91 sorts soil into four types, from Type 1 hard, dense soil to Type 4 soft or saturated soil that flows. Dense glacial till common around Guelph usually rates Type 1 or 2, while loose sand, previously dug backfill and anything wet drop to Type 3 or 4.
Sand fails faster than till because nothing binds its grains together, so a vertical face can slough off without warning as it dries or soaks. The weaker the soil type, the flatter the slope or the stronger the support system the regulation demands.
Sloping and benching is cheapest when there is room, trench boxes suit narrow utility and septic trenches, hydraulic shores fit short runs and tight yards, and soldier pile and lagging walls hold deep cuts at property lines. The table compares them side by side.
| System | Typical depth | Space needed | Relative cost | Best use |
|---|---|---|---|---|
| Sloping and benching | Up to about 6 m (20 ft) | The most; in Type 1 or 2 soil a 1:1 slope adds about 1 m of width per side for each metre above the bottom 1.2 m, more in weaker soil | Lowest, but extra digging and backfill | Open lots and foundation digs with room to spare |
| Trench box (shield) | 1.2 m to about 6 m, depending on the box rating | Trench width plus box walls | Low to moderate | Sewer, water and storm lines, septic tanks and pump chambers |
| Hydraulic shores | 1.2 m to about 4.5 m | Very little beyond the trench itself | Low to moderate | Short trenches, service repairs, tight backyards |
| Soldier pile and lagging | 3 m to 10 m or more | Room for a piling rig; piles sit at the property line | Highest; engineered and installed by specialists | Commercial basements and deep cuts beside roads, buildings or neighbours |
Underpinning is the one permanent option: the new concrete becomes part of the foundation, while boxes and shores come out as the backfill rises. Excavations deeper than 6 m, and any support system the regulation's standard tables do not cover, need a design stamped by a professional engineer.
Sequenced underpinning replaces the support under a wall a little at a time, so most of the wall always rests on solid ground. A full perimeter on a typical house is dug in at least three rounds, and each round has to cure before the next opens.
The structural engineer divides each wall into pins, usually 0.9 to 1.2 m (3 to 4 ft) wide, and numbers them 1, 2 and 3. All number 1 pins are dug and poured first, then the 2s, then the 3s, so no two neighbouring pins are ever open at once.
We mark the sequence on the walls before digging and never change it without the engineer's written approval.
Each pin is dug from inside the basement with hand tools, a small breaker and, where it fits, a mini excavator, down to the new footing elevation. The soil under the old footing is trimmed cleanly so the new concrete bears straight against it.
On a typical lowering, a pin reaches 600 to 1,200 mm below the old footing and extends out to the width of the new footing, often 400 to 600 mm.
Before any concrete, the engineer or a City of Guelph building inspector checks the bearing soil, the depth and any rebar or dowels. The pin is then formed and poured with the concrete strength the engineer specifies, commonly 25 to 32 MPa, stopping about 50 to 75 mm short of the old footing.
Once the concrete has set, typically after 24 to 48 hours, that gap is rammed tight by hand with non-shrink grout so the old footing bears fully on the new pin. Only then do the next numbered pins open, and the cycle repeats until the wall is complete.
Every underpinning job needs a structural engineer's design and a City of Guelph building permit before digging starts, and work at a property line usually needs a written agreement with the neighbour. Deep shoring can also need its own engineered design.
The engineer's drawings show pin sizes, sequence, footing depths, rebar and any temporary support for beams or posts inside the house. They go to the City's building division with the permit application, and a set stays on site for every inspection.
Where O. Reg. 213/91 calls for it, such as an excavation over 6 m or a support system outside the regulation's standard tables, the shoring design is stamped by a professional engineer. We install and inspect it exactly as drawn.
If the work touches a shared wall or needs access through the next yard, we recommend a written access agreement covering dates, restoration, insurance and a photo survey of the neighbour's house before work starts. It protects both households and costs far less than a dispute.
Basement underpinning in Guelph typically costs $400 to $700 per linear foot of wall for the pins, concrete and dry-packing. On a 1,000 sq ft (90 m²) house with about 130 linear feet of perimeter, a complete lowering with underpinning, interior drainage and a new slab usually totals $80,000 to $130,000.
Your fixed price is set in writing after a site assessment and a review of the engineer's design.
| Driver | Effect on price |
|---|---|
| Depth below the old footing | Deeper pins mean more digging, more concrete and longer cure times. |
| Wall length | Work is priced per linear foot, so a longer perimeter or extra interior bearing walls raise the total. |
| Access | A basement reached only through a window costs more than one with a walkout or wide door for equipment. |
| Soil | Wet sand or Type 3 and 4 soils need narrower pins, more temporary support and sometimes dewatering. |
| Number of pins | Narrow pins required by weak walls or soil mean more rounds, more forming and a longer schedule. |
| Shared walls | Neighbour agreements, photo surveys and extra monitoring add cost on semis and row houses. |
Trench shoring is priced differently: trench boxes and hydraulic shores are usually included in the price of the utility or septic job, with a daily rate for extra boxes on unusually deep or long runs.
Every deep excavation we open is inspected daily, supervised by a competent person and dug by crews trained in Ontario trench safety. A trench wall can fail in seconds, and a single cubic metre of soil weighs more than a tonne and a half, so we take no shortcuts below grade.
The questions we hear most before a basement underpinning or deep shoring job.
Underpinning is better if you want to keep all of your floor space or gain more than about 600 mm of height; a bench footing is cheaper and quicker when a smaller gain is enough. The two are compared side by side on our basement excavation in Guelph page.
The underpinning itself usually takes 3 to 6 weeks for a full perimeter on a detached house, or 6 to 10 weeks including the floor dig and new slab. Concrete cure times between pin rounds set the pace, not the digging.
Some hairline cracking in plaster, drywall or the old foundation is possible, because the house settles a millimetre or two as its load moves onto the new footings. Following the pin sequence, dry-packing every pin tightly and never opening neighbouring pins together keep movement to a minimum, and we photograph existing cracks before starting.
A professional engineer designs all underpinning and any shoring that O. Reg. 213/91 says must be engineered, such as excavations deeper than 6 m. We build exactly what is drawn, inspect it every day, and call the engineer back if the ground differs from the design.
Sometimes. If a wall is shared, or the only route for equipment and soil runs through the next yard, we need the neighbour's written permission. We suggest raising it early and putting dates, restoration and a photo survey of their house into a short access agreement.
Underpinning is most common where older houses sit close together on small lots, which describes parts of Guelph and each of the Waterloo Region cities we serve.
GuelphIn Guelph, older semis and narrow infill lots in the Ward and around downtown often need shared-wall underpinning when owners lower a basement.
KitchenerAround downtown Kitchener, century homes and closely spaced semis make underpinning beside a neighbour a frequent request.
WaterlooWaterloo owners near Uptown underpin older houses to gain the height a legal basement suite needs.
CambridgeCambridge has many stone and early brick foundations in Galt and Hespeler that call for short, carefully sequenced pins.
Book an assessment and we will check the footings, soil and access, then return a fixed underpinning quote based on your engineer's design. Call 548-918-0387 or email info@guelphexcavation.ca.
Open Monday to Saturday 6:00am to 9:00pm and Sunday 9:00am to 9:00pm.
