Waterproofing · Service

Exterior waterproofing — digging up a house you live in

The durable answer, and the one that means machinery in your garden, your deck off, your driveway cut and a trench beside the house for weeks. Worth knowing exactly what you are agreeing to.

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In short

What is exterior waterproofing?

Exterior waterproofing on an existing home means excavating the soil away from the foundation, all the way down to the footing, exposing the outside of the wall so it can be cleaned, treated and drained, and then putting everything back. It is the most durable approach available, because it stops water entering the wall rather than collecting it after it has. It is also a construction project rather than a service call: machinery needs to reach the wall, utilities have to be located, whatever sits in the excavation zone comes out, and the backfill will settle for years afterwards. The interior alternative is cheaper, faster and far less disruptive — and it manages water instead of excluding it. That is the trade, stated plainly.

Triggers

Signs you need exterior waterproofing

Interior drainage has already been installed and water is still arriving through the wall above it
Seepage is coming through the middle of a wall or through a specific crack, not at the floor-wall joint
The basement is finished or you intend to finish it, and you do not want a drain channel around the perimeter
The wall is deteriorating from the outside — block face spalling, mortar joints eroding, coating visibly failed
You need the space to be genuinely dry rather than reliably drained — a wine cellar, an archive, a workshop with tools
The soil against one wall is a known problem: heavy clay, a hillside above you, a neighbour's runoff arriving
You are already digging for another reason — an addition, a new patio, replacing a buried service line
You intend to stay in the house a long time and want to buy the fix once rather than maintain a system

Seeing something not on this list? Browse waterproofing problems by symptom →

The job

How exterior waterproofing actually works

Access is assessed before anything else — including whether it is possible

A machine has to get to the wall and spoil has to go somewhere. A zero-lot-line house, a wall against a neighbour's property, a wall behind an attached garage, or a slope with no route for equipment can make full excavation impractical or impossible on part of the perimeter.

Watch for: A quote for the full perimeter without anyone assessing how equipment reaches the tight side of the house. Hand-digging a section is legitimate and much more expensive; it should be in the number from the start.
Utility locates, private lines and the things no locate service marks

Public utility locating covers the incoming services. What it does not cover is your own buried lines — irrigation, landscape lighting, a gas line to a grill, a septic run, an old oil tank line, the electrical feed to the garage. Those need to be identified by you and the contractor together before a bucket moves.

Watch for: Locates treated as a formality. The trench runs directly along the wall where every service enters the house, so this is the highest-risk digging on any residential property.
Everything in the excavation zone comes out

Shrubs and mature plantings, decks and stairs, patios, walkways, air-conditioning condensers, a section of driveway, fencing. Some can be lifted and reinstated; some are consumed by the job. This is where the difference between quotes usually lives, and it is frequently under-described.

Watch for: Landscaping and hardscape covered by the word "restoration" with no specifics. Get an explicit list of what comes out, what comes back, what is replaced with new, and what is simply gone.
The trench is opened to the footing, safely

Digging a deep trench along a foundation is regulated work with real collapse risk, and the depth is not negotiable — the treatment has to reach the bottom of the wall to be worth doing. Spoil is stockpiled away from the trench edge, and the wall is not left unsupported longer than it should be.

Watch for: A deep, vertical, unsloped trench with spoil piled at the lip and crew working in it. Trench collapse is the serious hazard on this job, and a contractor casual about it is telling you something about the rest of their work.
The wall is cleaned, repaired and treated

Decades of soil come off, old failed coating is removed, cracks and deteriorated mortar are repaired, and then the wall receives its membrane, drainage layer and footing drain. The assembly itself is the same one specified on new construction — that is a different page, and it is worth reading before you choose products.

Watch for: A fresh coating rolled over a dirty or damp wall to save a day. Adhesion is the whole basis of an exterior membrane and there is no second chance once the trench is closed.
Backfill, in lifts, with material chosen deliberately

How the trench is refilled determines two things: whether water drains down to the new footing drain instead of ponding against the wall, and how much your ground drops over the next few years. Free-draining granular fill placed and compacted in layers does both jobs. Dumping the excavated clay back in one go does neither.

Watch for: The trench refilled in a single pass with the spoil pile. It compacts under its own weight for years, leaving a settled trough beside the house that collects surface water and directs it at the wall you just paid to seal.
Settlement, grading and the year after the job

Even well-compacted backfill settles. The finished grade should be built up so that when it does settle it is still running away from the house, and you should expect to add soil once or twice in the following seasons. Hardscape reinstated over fresh backfill can move.

Watch for: A perfectly flat finished grade on day one and no conversation about settlement. Ask who returns to top up the grade, and whether reinstated paving is warranted against movement.
The wall gets documented before it is buried again

Photographs of the cleaned wall, the repairs, the membrane, the drainage layer, the footing drain and its outlet. This is the one and only time anybody will see the outside of your foundation, and you paid a great deal for the view.

Watch for: No photographic record and no walk-around before backfill. Ask to be on site the day the trench is open — it is the only inspection that will ever be available to you.

Money

What does exterior waterproofing cost?

Full exterior excavation is typically the most expensive option in this industry, usually several times an interior system on the same wall, and the spread between quotes is driven less by the waterproofing than by access, depth, and what has to be removed and reinstated above ground.

See the full exterior waterproofing cost guide — by material, size and region →

Straight answer

When exterior waterproofing is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

You need the problem solved this month. This job is measured in weeks once you count locates, weather, the excavation itself, curing and reinstatement. Interior drainage is measured in days. If water is actively damaging things, the timeline matters.
The wall is bowing, cracked horizontally, or otherwise moving. Removing the soil that is currently bracing a compromised wall is not a neutral act. An independent structural engineer — one who sells no repairs — should decide the sequence before an excavator is booked.
The excavation zone contains something you cannot lose. A mature tree beside the foundation, a specimen planting, an established patio. The tree in particular rarely survives having its roots cut on the house side, and the loss is permanent.
Machinery genuinely cannot reach the wet wall. Hand excavation to footing depth on a tight urban lot can push the cost past what the result is worth. That is a real answer, and an interior system exists precisely for these houses.
The water is coming through the floor rather than the wall. Treating the outside of a wall does nothing about hydrostatic pressure lifting water through the slab or up at the joint from below. Establish the entry path before choosing the approach.
You are moving soon. This is a large, invisible, unverifiable-after-the-fact investment. A buyer cannot see it and will not pay a premium proportionate to it. If the horizon is short, the cheaper managed solution is the rational one.

Your options

Types of exterior waterproofing

Interior vs exterior, head to head

The comparison in full — what each approach buys and what it costs you.

Membranes, coatings and drainage board

What actually goes on the wall once the trench is open.

Failed waterproofing and seepage

Diagnosing why the existing treatment stopped working.

Bowing wall repair

If the wall is moving, this comes before the water.

Compare waterproofing options side by side →

Before you sign

What to check when hiring for exterior waterproofing

Walk me around the house and show me where the machine goes and where the spoil sits.

Turns an abstract quote into a physical plan, and immediately surfaces the tight side of the house where the price and the method actually change.
Exactly what is removed, what is reinstated, and what is not coming back?

The biggest source of disputes on this job. You want a written list of plantings, hardscape and structures, not a restoration allowance.
Who calls public locates, and how are my private buried lines identified?

Private irrigation, lighting and gas runs are not covered by public locating and sit exactly where the trench goes. Settle liability before the dig.
What are you backfilling with, and in what lifts?

The single most consequential answer about your yard for the next five years. Granular fill in compacted layers versus the spoil pile is the difference between a stable grade and a settled trough.
How much settlement should I expect, and who comes back to top up the grade?

Settlement is normal and should be planned for. A contractor who volunteers a return visit is one who has done this on occupied homes before.
Can I inspect and photograph the wall before you backfill?

Your one opportunity, ever. A reasonable contractor will schedule it; a reluctant one has told you something useful.
Do you also install interior systems, and why are you recommending this instead?

A firm that offers both and can articulate why yours is the exterior case is giving you a recommendation. A firm that only sells one is giving you a catalogue.

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Local pros

Exterior Waterproofing near you

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Related work

Often done at the same time

Foundation Waterproofing

The wall assembly itself

Interior Drain Tile

The cheaper, faster alternative

Basement Waterproofing

The decision in overview

Foundation Inspection

Before you commit to excavation

All waterproofing services →

FAQ

Exterior Waterproofing — questions people ask

Still have a question? Talk to our team →

Is exterior waterproofing better than an interior system?

It is more permanent, because it addresses water before it enters the wall rather than collecting it afterwards, and it leaves you with no pump to depend on. It is also far more expensive, takes far longer, and does considerable damage to everything growing or built beside the house. On some lots it cannot be done at all. "Better" is really a question about your budget, your timeline, your access and how long you intend to stay.

How long does exterior waterproofing take?

Plan in weeks rather than days once locates, removal of landscaping and hardscape, excavation, wall repair, the treatment itself, backfill and reinstatement are all counted — and weather stops an open trench in a way it does not stop interior work. Ask for a schedule that separates the working days from the total elapsed disruption; they are rarely the same number.

Will my landscaping and driveway survive?

Some of it will not. Anything within the excavation zone comes out, and small plantings can often be lifted and replanted while mature shrubs and trees frequently cannot. Sections of patio, walkway or driveway in the way are cut and replaced. Get the specific items listed in the contract, because "restore to original condition" means very different things to different contractors.

Can exterior waterproofing be done on only one wall?

Yes, and it is common — if seepage is confined to one elevation and the diagnosis supports it, excavating that wall alone is a legitimate and much cheaper scope. Ask the contractor to explain why they are proposing the extent they are proposing. A full perimeter on a house with one wet wall deserves a reason.

What happens to the ground afterwards?

It settles. Freshly placed backfill consolidates over the following seasons even when it is compacted properly, so the grade beside the house tends to drop. That matters, because a trough beside the wall collects surface water and directs it at the foundation. Expect to add soil, and agree in advance who is responsible for re-establishing the slope.

Do I still need a sump pump after exterior waterproofing?

It depends on where the new footing drain outlets. On a sloping lot it may run to daylight and need no pump at all, which is one of the quiet advantages of the exterior approach. On a flat lot the drain still has to be pumped somewhere, so a pit and pump remain part of the system. Ask which applies to your property before you assume the pump goes away.