Mould Removal in London, Ontario: Scope the Job Before You Hire

Mould removal in London costs roughly $500 to $1,500 for a small contained area, $2,000 to $6,000 for a moderate job and $6,000 to $15,000 or more after major water damage. We do not remove mold, and this page will not pretend otherwise. What it does is show you how to get mould removed in London without paying for more job than you have: size it honestly, fix the water that caused it, get the job scoped by someone who is not bidding on it, make every contractor quote against that same scope, and have someone other than the remover confirm it worked.

The size question has an official answer. Health Canada sorts household mould into small, medium and large by area, says most small and medium amounts can be cleaned up safely by following proper procedures, and recommends a qualified professional for large areas. Knowing which one you have is the first thing that protects your money.

Step one: how big is it, honestly?

Before anyone quotes you, measure. One square metre is roughly a 3 foot by 3 foot patch, about 10.8 square feet.

Two cautions sit on top of that table. First, what you can see is not always all of it: growth on the back of drywall, under flooring or inside a wall cavity is common in London basements, and a musty smell with only a small visible patch often means the visible part is the edge of something larger. Second, Health Canada is direct about the cleaning method: do not use bleach. An unscented soap solution is its recommended approach, and porous materials with mould under the paint, like drywall, need to be removed and replaced rather than wiped.

If your patch is small and you know why it is there, you may not need a removal company or a test. Clean it properly, fix the moisture, and watch it. That is the honest answer, and it is the one a company selling removal has no reason to give you.

Step two: find the water, or the removal will not last

Mould is a moisture problem before it is a mould problem. Remove the growth without fixing the source and you are paying to do the same job again next spring. In London the sources repeat:

• Basements that take on water in the spring melt or a heavy summer storm, especially older fieldstone and block foundations in Old North, Old South and Woodfield. See basement mold inspection.
• Attics, where a bathroom fan venting into the roof space or blocked soffits create winter condensation on the sheathing. See attic mold inspection.
• Bathrooms and window frames, the everyday condensation spots.

Step three: get it scoped by someone who is not bidding on it

The reason mould removal quotes in London can range from a few hundred dollars to several thousand for what sounds like the same problem is that each company defines the job itself, usually during a free visit whose purpose is to sell that job. Three quotes written against three different scopes are not comparable, so the cheapest one tells you nothing and the most alarming one tends to win.

An independent scope fixes that. It records where the growth is, how far it extends, what materials are affected, where the moisture is coming from, and what the work should cover. Every contractor then prices the same defined job.

That is what our mold inspection produces: a plain written report with photographs, moisture readings, and lab sampling where sampling genuinely helps, for example to find hidden growth, to document a condition someone else will rely on, or to set a baseline for clearance later. We will not sell you an air test to answer a question a visible patch and a known leak already answer. Health Canada does not recommend routine air testing to predict health effects, and our is black mold dangerous guide explains why symptoms belong with a physician rather than a lab report.

Older London homes: check for asbestos before anyone cuts drywall

This is the step most removal quotes skip, and it matters in a city with as much pre-war and mid-century housing as London.

The Environmental Abatement Council of Ontario's Mould Abatement Guidelines, the abatement industry's own Ontario guideline, cautions that its mould procedures do not address designated substances such as asbestos, and names the materials a mould job commonly disturbs: drywall joint compound, ceiling tiles, pipe and duct insulation, and vinyl flooring. Asbestos on construction and repair work in Ontario falls under O. Reg. 278/05, and the guideline notes that property owners must tell contractors bidding on a project about designated substances that are present. An asbestos survey in London of the materials the mould job will disturb answers that question before anyone quotes.

Mould abatement, remediation, removal and cleanup: what the words mean

London companies use four words for overlapping work, and knowing which one a quote means tells you what you are buying.

• Mould cleanup is the small job: wiping and drying a patch on a hard surface, the kind Health Canada says most households can do themselves with proper procedures. No company is required.
• Mould removal is the everyday term for taking out mouldy material, usually cutting out drywall, lifting flooring or bagging insulation, plus cleaning what stays.
• Mould remediation is removal done to a written procedure: containment sized to the job, removal of affected porous materials, cleaning, waste handling and a clearance check at the end.
• Mould abatement is the term Ontario's industry guideline uses. The Environmental Abatement Council of Ontario's Mould Abatement Guidelines set out the procedures by job size, which is why abatement contractors in London quote against them.

Whatever the word on the quote, ask the same thing: what comes out, how is it contained, and who checks the result. A "remediation" quote that only sprays a surface is a cleanup at a remediation price.

Flood water from a sewer backup or the river is a different job

The same Ontario guideline is explicit that its mould procedures are not written for contamination from sewage, river floods or other heavily contaminated water, and points instead to the IICRC S500 standard for professional water damage restoration. If your basement mould followed a sanitary sewer backup or Thames-area flooding, the first job is water damage restoration with the precautions that category of water needs, and the mould work sits inside it. Make sure the company you hire is quoting that job and not only a mould clean-up.

What a sound removal quote should say

Ask for it in writing, and check it against your independent scope:

• The areas and materials, with approximate square footage, matching the scope rather than a vague "treat basement".
• The moisture fix, or a clear statement of who is responsible for it. A quote that removes growth and ignores the source is a quote for a repeat visit.
• Containment matched to the size of the job. For large areas, the EACO guideline calls for the work to follow a site-specific work plan developed by a qualified health and safety professional.
• Removal, not just treatment, of affected porous materials. The guideline's large-area procedure removes porous materials like drywall and ceiling tile to at least 30 cm beyond the visible contamination in every direction.
• Waste handling and final cleaning of the work area and equipment.
• The designated-substance question, answered before demolition in an older home.
• Who does clearance, and against what standard. The guideline describes clearance as a careful visual inspection plus clearance tests compared against reference or outdoor air, where the work area should not be significantly elevated or show different types of mould.

Choosing between mould removal companies in London

Ontario does not license mould remediation contractors, so anyone can print the business card and the vetting falls to you. Ask which guideline they work to (the EACO guideline or the Canadian Construction Association's Mould Guidelines for the Canadian Construction Industry are the usual answers), ask for a WSIB clearance certificate and proof of liability insurance, ask for references from comparable jobs, and get two or three quotes against the same written scope. Be wary of a company whose inspection is free and whose testing is done in-house on its own work.

When you lay two or three quotes side by side, line them up on the same five items: the square footage being removed, the containment method, the moisture fix, waste disposal, and who does the clearance test. If one quote is far cheaper, it is almost always missing one of those five, not doing the same work for less.

After the work: clear it before the walls close

Do not let the containment come down, the drywall go back up or the final invoice get paid until the area has passed clearance. A remediator grading its own job has an obvious conflict, so have it checked by someone who did not do the work. Our clearance testing page covers how that works and why the outdoor baseline is what makes a pass mean something.

Common questions