Foundation Repair · Service

Crawl space repair, the structural half

Posts, footings and rotted bearing points — the work that actually holds your floor up. The vapour barrier conversation is a different purchase, and confusing the two is how people buy the wrong one.

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In short

What is crawl space repair?

Crawl space repair covers two entirely separate categories of work that share a location. This page is about the structural one: the posts and footings holding your floor up, the wood at the bearing points, and the builder-grade supports that were never adequate. The other category — vapour barriers, sealing, humidity control and encapsulation — is a moisture project, covered by crawl space encapsulation. Knowing which one you need is most of the decision.

Triggers

Signs you need crawl space repair

A support post standing out of plumb, sitting on bare soil, or with its shims fallen out and lying beside it
A stack of concrete blocks serving as a support that has cracked, tilted or partly collapsed
A visible gap between the top of a post and the beam it is supposed to be carrying
The end of a girder or joist that is dark, soft or crumbling where it enters the foundation wall pocket
Sill plate along the perimeter that gives way under a probe rather than resisting it
A floor above that has developed a localised dip or a soft spot over one particular area
Insulation hanging down, obscuring the framing it was installed to insulate — and hiding the condition of everything behind it
A crawl space you have never entered, in a house you have owned for years

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The job

How crawl space repair actually works

Get somebody under there who is not selling a package

The crawl space is the least-inspected part of most houses and the easiest place to be told anything. An assessment from someone who does not sell either encapsulation or underpinning is worth more here than almost anywhere else in the building.

Watch for: An inspection that arrives with a fixed product in mind. If the visit ends in the same proposal regardless of what was found under there, you learned about the company rather than the house.
Deal with access and clearance honestly

Low headroom, standing water, ductwork blocking the route and buried debris all limit what can be reached, and they change what any repair costs. Access is a legitimate line item, not padding.

Watch for: A full assessment claimed for a space with a blocked route or an area nobody could physically reach. Ask directly which parts were inspected and which were not, and get the unreached areas listed.
Examine every support, and what each one stands on

Each post or column gets checked for plumb, for bearing at the top, and for what is underneath it. Builder-grade supports set on thin footings or directly on soil are extremely common and settle predictably over decades.

Watch for: Supports on inadequate footings replaced with new supports on the same inadequate footings. The post gets renewed, the reason it failed does not, and the failure repeats on a schedule.
Probe the bearing points, not the middle of the members

Deterioration concentrates where wood meets masonry and where water has run — beam pockets in the foundation wall, sill plates, the base of posts, and the ends of joists at the rim. The middle of a joist can be perfect while the end sitting in the wall is gone.

Watch for: Wood assessed visually through a layer of fallen insulation. Insulation has to come away for the framing behind it to be judged, and any report that skipped that has judged the insulation.
Identify the water source before rebuilding

Rot means sustained moisture, and the structural crew is not usually the one who fixes it. Ground water, a failing drain, condensation on cold surfaces and surface water entering from outside are different problems with different owners. This page hands that half over deliberately.

Watch for: Two contractors each assuming the other is handling moisture. Name the responsible party in writing, because "we thought they were doing it" is how new timber ends up back in the same conditions.
Replace or reinforce the compromised structure

Failed supports are replaced onto footings capable of carrying them, deteriorated timber is cut back to sound material, and bearing is properly re-established at each point. Temporary support carries the load while that happens.

Watch for: Sistering new material alongside rot without removing the deteriorated wood. It looks like a repair from the access hatch and leaves the decay in place, with the moisture that produced it still available.
Handle mould and air quality as a separate question

Growth on crawl space framing is a moisture consequence and an indoor-air question, and it is a specialist trade with its own protocols. Start at the mould remediation services index rather than treating it as part of the carpentry.

Watch for: Surface treatment sprayed onto framing and presented as remediation, with nothing done about the humidity keeping it alive. That is a cosmetic result on a structural surface.
Document the work and leave the space usable

You want photographs of each repaired location, a note of what was replaced and what was left, and the space left with access maintained rather than sealed off behind whatever was installed last.

Watch for: A vapour barrier laid over new structural work with no photographic record underneath it. The next person who needs to check that repair will be lifting up something you paid for.

Money

What does crawl space repair cost?

Structural crawl space work ranges from replacing a handful of supports onto proper footings, at the low end, to substantial figures once girder ends, sill plates or joist ends need cutting back and replacing. Restricted access and standing water raise every line on the quote.

See the full crawl space repair cost guide — by material, size and region →

Straight answer

When crawl space repair is the wrong call

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

Your actual problem is humidity, odour or condensation. Damp air, musty smells and sweating ductwork are a moisture project. Buying posts will not change any of them — start with encapsulation.
You are being sold encapsulation for a structural failure. The reverse mistake, and the more expensive one. A sealed, conditioned crawl space over a collapsed support is a well-presented problem that is still a problem.
The soft floor is a joist-span issue between supports. Bounce felt in the middle of a room usually points upward to the framing rather than downward to the posts. See floor joist repair.
Nobody has entered the space. A proposal written from the hatch, or from photographs a salesperson took at the opening, is not an assessment of a crawl space. Insist on coverage of the whole footprint or on knowing what was not seen.
The house is on a slab and the "crawl space" is a plumbing void. Small access voids under slab construction are not structural crawl spaces and do not carry the floor. Go to slab foundation repair.
You are replacing wood while the leak is still running. A dripping supply line or a failed drain above the crawl space will destroy new timber as reliably as it destroyed the old. Sequence the plumbing first.

Your options

Types of crawl space repair

Support post and footing replacement

The core structural repair — new supports on footings that can actually carry them.

Bearing-point timber replacement

Girder ends, sill plates and joist ends cut back to sound material.

Crawl space encapsulation

The moisture half of the space, deliberately handled by a different specialist.

Mould and air quality

A separate trade with its own protocols, once the moisture is under control.

Documented crawl space problems

Symptom-level background, including collapse risk.

Compare foundation repair options side by side →

Before you sign

What to check when hiring for crawl space repair

Do you sell encapsulation, structural repair, or both — and which am I being quoted for?

The clearest way to surface the incentive in this specific trade. A company that sells one thing tends to find that thing.
Which areas of my crawl space could you physically reach, and which could you not?

Defines the limits of the assessment. Unreached areas are where the expensive discoveries live, and you want them named before work starts.
What will each new support bear on, and how was that footing sized?

The reason builder-grade supports fail is almost always what is underneath them. A new post on the same footing repeats the history.
Did you remove insulation to inspect the framing behind it?

You cannot assess wood you cannot see. This question quickly separates a thorough inspection from a walk-through with a torch.
Who is responsible for the moisture source, and is it in this contract?

Prevents the gap between two trades where the water problem lives, unresolved, while both invoices get paid.
Will you photograph each repair location before and after?

This work is buried in a space you will never inspect. Photographs are the only realistic verification you will ever have.
Does the warranty cover the wood, the supports, or the floor above staying put?

Three different promises, and crawl space warranties commonly cover only what was installed. Ask specifically whether recurrence of rot in adjacent members is covered or excluded.

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Local pros

Crawl Space Repair near you

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Related work

Often done at the same time

Pier and Beam Repair

The house-carrying pier and girder system

Crawl Space Encapsulation

The moisture half of the same space

Floor Joist Repair

When the framing above is the failure

Beam Replacement

Where a carrying member has to come out

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FAQ

Crawl Space Repair — questions people ask

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Do I need structural repair or encapsulation?

Structural work addresses things that carry load: posts, footings, beams, sill plates and joist ends. Encapsulation addresses air and water: vapour, humidity, ground moisture and the odours that come with them. They frequently occur together, because moisture is what destroys the wood, but they are separate purchases from often separate trades. Establish which failure you actually have before agreeing to either.

Why do builder-installed crawl space supports fail?

Usually not because the post itself was bad, but because of what it was standing on. Supports set on shallow pads or directly on soil settle gradually over the decades, and the load they were carrying redistributes to whatever is next to them. Replacing the visible column without improving the bearing beneath it repeats the same sequence on the same timescale.

How can I tell if crawl space wood is rotten?

Firm pressure with an awl or screwdriver at the bearing points is the standard field check — sound timber resists and splinters, deteriorated timber accepts the point and crumbles. Check where wood meets masonry, where it sits in wall pockets, and at the base of posts. Surface staining alone is not a finding, and clean-looking wood under fallen insulation has not been checked at all.

Is a collapsed support in a crawl space an emergency?

It warrants prompt attention because the load it was carrying has gone somewhere else, and the members now taking it were not chosen for that. Whether it is urgent depends on what has happened above — new deflection, cracking or a floor that has changed noticeably suggests moving quickly. Get someone competent underneath to look before deciding on your own.

Should I have my crawl space inspected if nothing seems wrong?

It is one of the better uses of an inspection, precisely because so little of what happens down there produces symptoms upstairs until it is advanced. Wood decays quietly, supports settle slowly, and the space is out of sight. Periodic access with a light and a probe, or a visit from somebody with no package to sell, catches problems while they are still small.

Will fixing the crawl space stop my floors sloping?

It stops them getting worse from that cause, which is the achievable part. Whether the floor comes back toward its original position is a separate decision about adjustment and lift, with its own consequences for the finishes upstairs — that question is covered on foundation leveling, and it should be answered deliberately rather than assumed to be included.