This tool scores an interior and an exterior weeping tile system against your answers: the problem, how much of the house, the basement finish, access outside, whether there is a sump, the wall’s condition and what matters most. Each answer adds or removes published points. It shows the better fit, the pros and cons behind it, and a planning range built only from this site’s cost-page rates.
- A gap of three points or more between the two scores marks one route as the better fit; closer than that, both are workable.
- Water coming through the wall, a single wall, a finished basement and a priority on keeping the concrete dry favour exterior work.
- An unfinished basement, a whole perimeter, a wall built over outside, and a priority on cost favour interior work.
- Costs are your length multiplied by $150–$300 per metre inside or $250–$500 outside, plus sump, obstacles and finish adjustments.
- Tile tied to the sewer is sent to a different answer: disconnect and add a sump first.
Interior vs Exterior Weeping Tile
01 /What does this tool compare?
Two ways of giving a basement a working foundation drain. An exterior system is dug from the yard: the trench goes down to the footing, a membrane goes on the wall, and new tile is laid beside the footing in clean stone. An interior system is installed from inside: a strip of floor along the wall is cut out, new tile goes in beside the footing under it, a membrane on the wall guides seepage down, and a sump pumps the water out.
Neither is right for every house. The tool makes the trade-offs explicit: every answer adds or subtracts points for one route or the other, and the reason for each point is printed in the result as a plus or a minus. Because every rule is on this page, you can see exactly why it leaned one way.
02 /What do I enter?
| Input | Options |
|---|---|
| What is the problem? | Water at the wall–floor joint; water through the wall; water up through the floor; old tile clogged, crushed or collapsed; tile tied to the sanitary sewer; no weeping tile and the basement gets wet |
| How much of the house? | One wall or corner; two walls; the whole perimeter |
| Basement finish along those walls | Unfinished; partly finished; finished walls and flooring |
| Outside, along those walls | Open yard; a deck, steps, patio or AC unit in the way; driveway, walkway or neighbour close by; attached garage, addition or sunroom on that side |
| Is there a working sump pit now? | Yes; no |
| Condition of the wall | Sound; cracks that leak; bowing, leaning or moving |
| What matters most? | Lowest cost now; keeping water out of the wall itself; least disruption inside; least disruption to the yard |
| Length of wall to treat | 3 to 150 m (default 12) |
| Obstacle sides outside | 0 to 6 (default 0) |
03 /How are the two routes scored?
Both scores start at zero. Each answer applies the rule below. The result compares the two totals.
| Answer | Interior | Exterior | Reason printed |
|---|---|---|---|
| Problem: water at the joint | +2 | +1 | Interior collects where water shows; exterior stops it before the joint |
| Problem: water through the wall | +1 (with a minus noted) | +3 | Only exterior puts a membrane on the outside face; interior leaves the wall wet |
| Problem: water up through the floor | +2 | 0 (with a minus noted) | Interior relieves water under the slab; exterior does not reach it |
| Problem: old tile failed | +2 | +2 | Both replace it; a camera and repair check is advised first |
| Problem: no weeping tile | +1 | +1 | Grading and roof drainage first, per Calgary’s lot drainage guide |
| Problem: tied to the sanitary sewer | 0 | 0 | Verdict becomes "Disconnect and add a sump first" |
| Extent: one wall | 0 | +2 | One wall is where digging outside is most competitive |
| Extent: whole perimeter | +1 | 0 (minus noted) | Inside avoids digging every side |
| Finish: unfinished | +2 | 0 | Nothing to remove before cutting the slab |
| Finish: partly finished | 0 | +1 | Leaves the finished part alone |
| Finish: finished | −1 | +2 | Finishes come off and go back inside; 15% to 30% is added to interior cost |
| Access: open yard | 0 | +1 | Room for the trench and spoil |
| Access: obstacles | 0 | −1 | Each obstacle side adds cost |
| Access: tight | 0 | −2 | Deep trench beside a driveway or neighbour is harder |
| Access: garage or addition | +2 | −4 | The wall cannot be reached from outside |
| Wall: cracks that leak | 0 | +1 | The trench exposes cracks for repair |
| Wall: moving | 0 | 0 | An engineer’s assessment is placed first in the notes |
| Priority: lowest cost | +2 | 0 | Lower cost per metre inside |
| Priority: keep the wall dry | 0 | +3 | Keeps water out of the concrete |
| Priority: least disruption inside | 0 | +2 | Nothing happens inside except at the outlet |
| Priority: least disruption outside | +2 | 0 | The yard stays as it is |
| No working sump | 0 (minus noted) | 0 | A pit and pump is added to both cost ranges |
Two answers change the result without points. "Tile tied to the sanitary sewer" always gives the verdict "Disconnect and add a sump first", because disconnection normally reuses the existing tile. "Bowing, leaning or moving" puts an engineer’s assessment at the top of the notes, because drainage work beside a moving wall can make it worse.
04 /How is the verdict chosen?
- If the problem is tile tied to the sanitary sewer: "Disconnect and add a sump first".
- Otherwise, if the wall is built over outside (garage, addition, sunroom) and the exterior score is lower: "Interior system".
- Otherwise, if the interior score is at least 3 higher: "Interior system"; if the exterior score is at least 3 higher: "Exterior system".
- Otherwise: "Either can work: compare quotes". If the problem is old tile on one wall, that becomes "Camera first, then repair or replace".
Each card carries a badge. A route whose score is 3 or more above the other is a "Better fit", 3 or more below is a "Weaker fit", and anything closer is "Workable". The bar under each heading is a visual of that difference, not a percentage.
05 /How are the costs calculated?
Only from the ranges on the cost page, multiplied by your inputs. Nothing else is added.
- Interior: length × $150 to $300, plus $1,500 to $3,500 if there is no working sump. In a finished basement the low end is multiplied by 1.15 and the high end by 1.30.
- Exterior: length × $250 to $500, plus $1,500 to $4,000 for each obstacle side, plus $1,500 to $3,500 if there is no working sump or approved outlet.
- Repair what is there (shown when the problem is failed tile or water at the joint): a camera run at $250 to $450, or $400 to $1,200 with flushing from the sump.
- Disconnect and add a sump (shown for a sewer tie-in): a sump pit and pump at $1,500 to $3,500 and a backwater valve at $1,800 to $4,500; severing and capping is quoted on site.
| Inputs | Scores (interior / exterior) | Verdict | Interior range | Exterior range |
|---|---|---|---|---|
| Joint, one wall, unfinished, open yard, has a sump, sound wall, lowest cost, 12 m | 6 / 4 | Either can work: compare quotes | $1,800–$3,600 | $3,000–$6,000 |
| Through the wall, one wall, finished, obstacles, no sump, sound, keep wall dry, 11 m, 1 obstacle side | 0 / 9 | Exterior system | $3,600–$8,850 | $5,750–$13,000 |
| Joint, one wall, unfinished, garage on that side, has a sump, sound, lowest cost, 8 m | 8 / −1 | Interior system | $1,200–$2,400 | $2,000–$4,000 |
06 /What should I do with the result?
Use it to ask better questions, not to choose a contractor. If the result is "Either can work", get one quote for each route and compare them on scope as well as price: trench depth relative to the footing, the pipe and stone, the membrane, the sump and pump, the discharge, restoration and warranty. If the result leans strongly one way, ask a contractor who offers both why they would or would not agree.
Before any new system, make sure the problem really is the drain. The Weeping Tile Problem Finder checks the pump, the outlet, surface water and inside sources first. The two routes are explained in detail in exterior weeping tile replacement and interior weeping tile systems, and a single broken section may only need a spot repair. When you are ready, request quotes through HAUSE.
07 /What does the tool leave out?
Depth, soil type, groundwater level and the state of the old tile all affect price and suitability, and none of them can be judged from a form. The tool does not assess structure; a moving wall needs an engineer. It does not know your city’s permit rules or subsidies; see Across Canada for the programs checked this month. And it treats both routes as done well: an interior system laid on top of the footing, or an exterior system backfilled with clay against the membrane, will not perform like the ones described here.
FAQQuestions people ask
Why does the tool favour interior drainage for an attached garage wall?
Because that wall usually cannot be dug from outside without major demolition. The access answer takes 4 points from exterior and adds 2 to interior.
Why is exterior favoured when water comes through the wall?
Only exterior work puts a membrane on the outside face of the wall, where the water enters the concrete. Interior drainage manages the water after it has come through.
Does the tool include the cost of a sump?
Yes, when you answer that there is no working sump. It adds $1,500 to $3,500 to both routes, since exterior tile also needs an outlet.
Can I trust the dollar figures as a budget?
Use them as planning ranges. They are this site’s CAD 2026 per-metre rates multiplied by your length and vary by city, access and contractor.
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