What does a concrete support pad carry in a house?

An interior support pad carries the posts that hold up the main beam running down the middle of the house. Those posts — usually steel teleposts or columns — concentrate a large point load at each location, and the pad spreads that load over enough soil to bear it safely. Without the pads, the point loads would punch through a standard basement slab.

What size are interior support pads?

Interior pier pads commonly run from about 38 inches by 38 inches up to 46 inches by 46 inches and 12 to 19 inches deep in larger residential jobs. A smaller pad around 24 inches square and 8 to 12 inches deep is common under a single steel telepost. The exact size depends on the post load and the soil, and it should be shown in the plan pad schedule or engineered per site.

What is the difference between a pad, a pier, and a pile cap?

A pad is an isolated footing that spreads a point load over soil at shallow depth. A pier is a vertical concrete column — often formed in a Sonotube — that carries the load down to a footing below the frost line; the pier usually sits on its own pad. A pile cap is a thick concrete block tying together several driven piles in deep foundations, a different application from typical residential pads.

Are concrete pads measured in linear feet?

No. Pads are isolated footings and are always counted as individual units, never measured in linear feet. Footing subcontractors typically bill pads at a flat rate per pad regardless of size — one real convention is $50 per pad. Counting a pad as a few linear feet of footing is a takeoff error that puts the quantity on the wrong basis.

Concrete Pads and Piers: What They Carry and How to Count Them

Everything that isn’t a continuous run on a footing plan is probably a pad. Pads carry the concentrated loads a strip footing can’t handle economically — the posts under the main beam — and they behave differently from wall footings in every way that matters to a takeoff: different shape, different depth logic, different billing, and a different unit of measure entirely.

Here is what interior support pads actually do, how they’re built, how they differ from piers and pile caps, and the one rule that keeps them out of your linear-foot total.

What do interior support pads carry?

Down the center of most houses runs a main beam — steel or built-up wood — carrying the floor joists that would otherwise span too far. That beam is held up at intervals by posts, usually adjustable steel teleposts or fixed columns. Each post lands a large point load on the basement floor.

A standard 4-inch basement slab can’t take that concentrated load; it would crack and settle. So under each post sits a concrete support pad (a pier pad), an isolated footing sized to spread the point load over enough soil to bear it. The pads are the reason the beam line stays put for the life of the house.

These pads are almost always the footing sub’s scope, and they are almost always hand-dug — one at a time, along the beam line, after the slab area is roughed in.

Typical sizes and depths

Interior pier pads are square or rectangular, sized to the post load and the soil below. Common residential ranges:

38” × 38” up to 46” × 46”, 12 to 19 inches deep, on larger or more heavily loaded jobs.
Around 24” × 24”, 8 to 12 inches deep, under a single steel telepost — a 24”×24” pad 8 inches thick is a widely cited adequate size where soil is reasonable.

A key depth distinction: an interior pad inside the heated basement does not have to reach the frost line — it only needs to bear on undisturbed soil capable of the load, because it’s protected from frost. An exterior pad (under a deck post, a porch column, a stair landing) is a different story and must go below the local frost line, the same as any exterior footing.

Under the Ontario Building Code, column pad footings for light-frame houses have minimum areas starting around 0.40 m² for one storey and rising with the number of storeys (Table 9.15.3.4). Whatever the code floor, the plan’s pad schedule or an engineer’s spec sets the actual size — read it, don’t assume.

The hand-digging and forming workflow

Pads are labor, not just concrete, and the labor is what the flat per-pad rate is really paying for. The typical sequence:

Locate each pad off the beam line and the plan’s post spacing.
Hand-dig the hole to size and depth, squaring the sides — often through or beside a roughed slab area, sometimes jackhammering an existing slab on a retrofit.
Form as needed (many interior pads are poured neat against the soil; forms come out for a raised or precise pad).
Set any dowels or post anchors if the spec calls for them.
Pour and screed the pad, and mark it for the post base.

Because each pad is dug and poured individually, the effort per pad is roughly constant across the job — which is exactly why the trade prices them per pad rather than by volume.

New construction and retrofit pads are different amounts of work, and it’s worth knowing which one you’re pricing. On new work the pads go in before the slab is poured, so the digging is in open soil and the pour is straightforward. On a retrofit — adding or replacing a telepost under an existing beam — the crew has to break out a square of existing basement slab with a jackhammer, dig down to undisturbed soil beneath it, pour the new pad, and often temporarily support the beam while they work. That’s meaningfully more labor per pad, and a sub who bills one flat pad rate for both is losing money on the retrofits. Many footing subs carry a separate, higher rate for cut-in pads for exactly this reason, even though the finished pad looks identical on the plan.

Pad vs. Sonotube pier vs. pile cap

These three get confused, and they are not the same element:

Element	What it is	Where it’s used
Pad	Isolated footing spreading a point load on soil at shallow depth	Interior posts under the main beam
Sonotube pier	Vertical concrete column formed in a waxed cardboard tube, carrying load down to a footing below frost	Decks, porches, exterior posts
Pile cap	Thick concrete block tying several driven piles together	Deep foundations, weak/deep soils

A pier is not a footing — a Sonotube is only a forming tube with no structural value on its own; the pier carries load down to a pad or bigfoot base below the frost line, so a proper exterior pier is really a pier plus a pad. A pile cap distributes a building’s load into multiple driven piles and belongs to deep-foundation work — you’ll rarely meet one on a standard residential footing job. For a takeoff, the distinction matters because a pier assembly and a pile cap are counted and priced differently from a plain interior pad.

The takeoff rule: pads are units, never linear feet

This is the rule that keeps a footing takeoff honest: a pad is a count, not a length. Interior pads, pier pads, and isolated spread footings are all discrete units. You tally how many there are — you never convert them into linear feet of footing.

The reason is billing. Continuous footings are billed by the foot; pads are billed by the each. A common footing-sub convention is a flat rate per pad regardless of size — $50 per pad is one real-world figure — because the effort to dig and pour one is roughly constant. Fold a pad into the linear-foot line and you’ve put it on the wrong basis, undercounted the flat labor, and made the invoice impossible to reconcile against the wall company’s own pad count.

Two habits keep pads clean on the takeoff:

Count every pad on the beam line and note its size call-out. If the plan shows posts but no pads drawn, flag it — don’t invent a count.
Keep pads on their own invoice line, separate from the linear-foot total, priced at your flat per-pad rate.

If you want to price a run of pads quickly, the pad calculator at footingcalc.com totals them at your flat rate; the concrete footing takeoff guide shows how the pad count and the linear-foot total sit side by side on the same invoice. An automated pass through FootingTakeoff does the same — it counts the pads as units and keeps them off the linear-foot line automatically, which is exactly where they belong.