Sonotube Removal: Leave It or Pull It Out After Pouring?
Once the concrete cures, the cardboard tube has done its job — what happens to it next is a finishing decision, not a structural one, but it’s worth knowing the trade-offs before you decide.
On this page13 sections
- Leave In vs. Strip Out at a Glance
- Why This Is a Finishing Decision, Not a Structural One
- Related Terms
- When to Strip
- How to Decide for Your Project
- Stripping Method by Tube Condition
- Alternative: Wrapping or Sealing the Above-Grade Tube
- Common Mistakes
- Leave In vs. Strip: Decision Table
- Other Factors to Consider
- Deciding and Executing: Step by Step
- Frequently Asked Questions
- Related Calculators
Whichever you choose, your concrete volume calculation from the concrete pier calculator doesn’t change — the tube’s presence or absence after curing has no effect on the concrete inside it. This guide covers when to strip and when to leave it.
Leave In vs. Strip Out at a Glance
| Leave In Place | Strip Off | |
|---|---|---|
| Below-grade portion | Standard practice, no downside | Rarely done — extra labor with no benefit |
| Above-grade portion | Degrades with weather exposure over time | Cleaner finished appearance, common practice |
| Effect on strength | None | None |
| Labor required | None — just cut off excess above the pour | Cutting and peeling the tube off the cured concrete |
| Timing | N/A | Best done once concrete has set enough to hold shape, before it’s fully cured |
Why This Is a Finishing Decision, Not a Structural One
A sonotube’s job is to hold the concrete in shape while it’s still fluid — once the concrete sets, the tube is no longer doing any structural work. Below grade, the surrounding soil already provides lateral support to the cured pier regardless of whether the cardboard is still wrapped around it, so leaving it in place changes nothing about the footing’s strength. Above grade, the tube is simply cosmetic at that point, and the decision to strip it comes down to appearance and long-term weathering rather than anything structural.
Related Terms
| Term | What It Means |
|---|---|
| Stripping | Removing the cardboard form from cured concrete, typically done by scoring and peeling once the concrete has set. |
| Green concrete | Concrete that has set enough to hold shape but hasn’t reached full cure strength — the ideal window for stripping a form. |
| Above-grade portion | The section of the pier extending above finished ground level, the only part where stripping is commonly considered. |
| Weathering | The gradual breakdown of exposed cardboard from moisture, UV exposure, and temperature cycling over time. |
When to Strip
Strip once the concrete is “green” — firm enough to hold its shape without support, but before full cure — typically 24 to 48 hours after pouring, depending on mix type and weather.
Waiting until full cure (days to weeks) makes the cardboard harder to remove cleanly, since it may have begun degrading and sticking to the surface.
How to Decide for Your Project
- Check how much of the pier sits above grade. If none does, this decision doesn’t really apply — there’s nothing above ground to strip.
- Consider how visible the piers will be in the finished project. A pier tucked under deck skirting matters less aesthetically than one visible in an open crawlspace or exposed foundation area.
- Check your local climate’s humidity and rain exposure. Cardboard left exposed in a consistently wet climate degrades faster and can look worse sooner than in a dry climate.
- Plan your stripping window if you choose to remove it. Mark your calendar for the 24–48 hour window after pouring rather than deciding after the concrete has already fully cured.
Example 1: Fully Below-Grade Pier
- Pier: Entirely below finished grade, no above-grade portion
- Decision: Leave the tube in place — nothing to strip
With no exposed portion, the stripping decision simply doesn’t apply — the entire tube stays buried and does no harm left in place.
Example 2: Above-Grade Pier, Visible Under Deck Skirting
- Pier: Extends 6 in. above grade, will be hidden behind deck skirting once complete
- Decision: Left in place, since it won’t be visible in the finished project anyway
Where the above-grade portion will be concealed by skirting or landscaping, the appearance argument for stripping loses most of its relevance.
Example 3: Above-Grade Pier in an Open, Visible Crawlspace
- Pier: Extends 12 in. above grade in an open, visible crawlspace area
- Decision: Stripped 36 hours after pouring, once the concrete was firm enough to hold shape cleanly
Visible piers benefit most from stripping, both for a cleaner finished look and to avoid a slowly degrading cardboard appearance over the following seasons.
Regardless of your stripping decision, get your concrete volume from the concrete pier calculator before you pour — the tube’s fate afterward doesn’t change how much concrete you need.
Stripping Method by Tube Condition
| Concrete Condition | Stripping Approach |
|---|---|
| 24–48 hours, still “green” | Score the tube vertically with a utility knife, peel away cleanly |
| Several days to a week, partially cured | May require more force to peel; tube can tear rather than come off in one piece |
| Fully cured (weeks later), tube already weathering | Often requires scraping off degraded cardboard remnants rather than a clean peel |
Alternative: Wrapping or Sealing the Above-Grade Tube
Instead of stripping the tube or leaving raw cardboard exposed, some builders wrap or seal the above-grade portion — with a concrete sealant, decorative sleeve, or paint — as a middle option. This preserves the tube as a permanent, sealed cosmetic surface rather than removing it, which can save the stripping labor while still avoiding the weathered look of untreated cardboard over time. It’s a less common approach than either leaving it bare or stripping it, but worth considering if the pier’s appearance matters and stripping cleanly seems impractical for your project.
Common Mistakes
- Waiting too long to strip if that’s the plan. Once concrete fully cures, the cardboard can bond more tightly and become harder to remove cleanly.
- Stripping too early, before the concrete can hold its shape. Removing the form before the concrete is firm enough risks damaging the pier’s surface or shape.
- Assuming leaving the tube in place weakens the pier. It doesn’t — below-grade tube left in place has no effect on structural strength.
- Forgetting to plan for the stripping window in your project schedule. The ideal 24–48 hour window is easy to miss if it’s not planned for in advance.
- Assuming this decision affects concrete volume or curing time. Neither is affected — this is purely a cosmetic and maintenance decision.
Leave In vs. Strip: Decision Table
| Situation | Recommended Approach |
|---|---|
| Entirely below-grade pier | Leave in place — nothing above ground to strip |
| Above-grade portion will be hidden by skirting or landscaping | Leave in place, appearance won’t matter |
| Above-grade portion visible in a finished space | Strip within 24–48 hours of pouring for a clean appearance |
| Stripping window already missed, tube weathering | Leave it, or scrape/clean up degraded cardboard as a later cosmetic fix |
| Prefer a permanent, sealed cosmetic finish without stripping labor | Wrap or seal the above-grade tube instead |
Other Factors to Consider
- Local climate. Humid or rainy climates degrade exposed cardboard faster than dry climates, affecting how quickly an unstripped tube starts looking worn.
- Number of piers with an above-grade portion. Stripping labor adds up across many piers — factor this into your project timeline if choosing to strip.
- Overall project aesthetic. A rustic or utilitarian space may not warrant the extra labor that a more finished, visible area would.
- Long-term maintenance plans. If piers will be painted, sealed, or otherwise finished later, stripping first generally gives a better surface to work with.
- Time available right after the pour. Stripping has a narrow practical window — busy schedules may make leaving the tube in place the more realistic choice.
Deciding and Executing: Step by Step
- Determine whether any part of the pier extends above finished grade.
- Consider whether that portion will be visible in the finished project.
- If stripping, plan for the 24–48 hour window after pouring.
- Score the tube vertically with a utility knife once the concrete is firm enough to hold shape.
- Peel the cardboard away cleanly, working around the full circumference.
- If leaving it in place, simply cut off any excess tube above your intended finish height.
- Address any remaining cosmetic finishing (sealing, painting) once the tube decision is made.
Frequently Asked Questions
Does leaving the sonotube in place weaken the pier?
No — below grade, surrounding soil provides the same lateral support whether or not the cardboard tube remains wrapped around the cured concrete. It’s purely a cosmetic and maintenance choice, not a structural one.
How soon after pouring should I strip a sonotube?
Typically 24–48 hours, once the concrete is firm enough to hold its shape without the form but before it fully cures, which makes the tube harder to remove cleanly.
What happens if I leave an above-grade tube exposed for years?
The cardboard gradually degrades from moisture and weather exposure, eventually flaking or peeling on its own — this doesn’t affect the underlying concrete’s strength but does look increasingly worn over time.
Can I strip a sonotube after it’s fully cured?
It’s possible but more difficult — fully cured cardboard tends to bond more tightly and may tear or require scraping rather than peeling away cleanly, unlike stripping during the still-green window shortly after pouring.
Do I need to strip below-grade sonotube before backfilling?
No — leaving the below-grade tube in place before backfilling is standard practice and doesn’t require any special treatment.
Can I paint or seal an above-grade tube instead of stripping it?
Yes, this is a reasonable middle option if stripping seems impractical — sealing or wrapping the exposed cardboard can slow its weathering while skipping the removal labor.
More deck pier & footing guides
Pouring soon? Use the concrete pier calculator to get your exact volume and bags before deciding what to do with the form afterward.