22 insulation contractors ranked by CR ScoreUpdated 0 paid placements in this rankingHow we rank →
Best overall in St. Thomas: Great Northern Insulation, CR Score 57/100; 4.7★ from 368 Google reviews.
Best for emergencies (open 24/7): Koala Insulation of London, posts 24/7 hours; ranked #5 of 22.
Most-reviewed: Hometown Heating and Cooling, 827 Google reviews at 4.9★, the most of 22 ranked; ranked #13.
Rankings can't be bought. Contractors can't pay to change their rank or score. How we rank
22 St. Thomas insulation contractors are ranked here by CR Score, from ten published factors. 2 are open 24/7, 7 open Saturdays and 5 open Sundays, based on posted hours. The median Google rating is 4.7★ across 22 rated businesses.
| Rank | Business | CR Score | Google rating | Based in | Hours | Best for |
|---|---|---|---|---|---|---|
| 1 | Great Northern Insulation | 57 | 4.7★ (368) | London, 21 km away | — | Overall |
| 2 | Advanced Basement Systems | 57 | 4.9★ (172) | London, 18 km away | — | — |
| 3 | Net Zero Insulation | 57 | 4.9★ (142) | London, 30 km away | Sat · Evenings | — |
| 4 | Canadian Spray Foam Systems Ltd. | 56 | 4.7★ (15) | London, 10 km away | Sat · Sun · Evenings | — |
| 5 | Koala Insulation of London | 56 | 5.0★ (21) | London, 29 km away | 24/7 | Emergencies |
| 6 | Ritchie's Insulation & General Contracting | 55 | 4.5★ (26) | St. Thomas | — | — |
| 7 | Home Choice Insulation | 53 | 5.0★ (5) | London, 24 km away | Sat · Sun | — |
| 8 | Eco Insulation | 53 | 4.6★ (57) | London, 25 km away | — | — |
| 9 | Sprayco Insulation Inc. | 52 | 4.7★ (15) | Aylmer, 29 km away | Sat · Evenings | — |
| 10 | Belform Insulation | 52 | 4.8★ (4) | London, 17 km away | — | — |
Ordered by CR Score, a 0–100 score from ten published factors. Paid placement never changes the order.
Ranked #1 because of its Google rating and trade focus: 4.7★ from 368 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 18 km away
Ranked #2 because of its Google rating and trade focus: 4.9★ from 172 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 30 km away
Ranked #3 because of its Google rating and trade focus: 4.9★ from 142 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 10 km away
Ranked #4 because of its Google rating and trade focus: 4.7★ from 15 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 29 km away
Ranked #5 because of its Google rating and trade focus: 5.0★ from 21 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in St. Thomas
Ranked #6 because of its Google rating and trade focus: 4.5★ from 26 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 24 km away
Ranked #7 because of its Google rating and trade focus: 5.0★ from 5 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 25 km away
Ranked #8 because of its Google rating and trade focus: 4.6★ from 57 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in Aylmer, 29 km away
Ranked #9 because of its Google rating and trade focus: 4.7★ from 15 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 17 km away
Ranked #10 because of its Google rating and trade focus: 4.8★ from 4 Google reviews, listed on Google as “Insulation contractor”.
Based on 7 of 10 factors; credentials, recency and availability not yet collected.
Based in London, 18 km away
Ranked #11 because of its Google rating and trade focus: 4.2★ from 15 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 24 km away
Ranked #12 because of its Google rating and trade focus: 2.7★ from 27 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in Ingersoll, 38 km away
Ranked #13 because of its Google rating and review volume: 4.9★ from 827 Google reviews, the most in St. Thomas.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 22 km away
Ranked #14 because of its Google rating and trade focus: 4.7★ from 10 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 19 km away
Ranked #15 because of its Google rating and trade focus: 4.7★ from 7 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 29 km away
Ranked #16 because of its Google rating and trade focus: 3.6★ from 5 Google reviews, listed on Google as “Insulation contractor”.
Based on 7 of 10 factors; credentials, recency and availability not yet collected.
Based in London, 26 km away
Ranked #17 because of its Google rating and trade focus: 4.2★ from 12 Google reviews, listed on Google as “Insulation contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 17 km away
Ranked #18 because of its Google rating and review volume: 4.0★ from 254 Google reviews.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 30 km away
Ranked #19 because of its Google rating and availability: 4.3★ from 6 Google reviews, open 24/7.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 28 km away
Ranked #20 because of its Google rating and review volume: 5.0★ from 34 Google reviews.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in Lambton Shores, 16 km away
Ranked #21 because of its Google rating and trade focus: 5.0★ from 14 Google reviews, listed on Google as “Siding contractor”.
Based on 8 of 10 factors; credentials and recency not yet collected.
Based in London, 24 km away
Ranked #22 because of its Google rating and review volume: 4.5★ from 42 Google reviews.
Based on 8 of 10 factors; credentials and recency not yet collected.
12 more insulation contractors within 40 km that we can't rank yet: too few reviews, or a trade we couldn't confirm. Listed A to Z.
| Business | Google rating | Distance |
|---|---|---|
| 1,2 Seal Insulation Inc. | 35 km | |
| 4Point Home Solutions | 5.0★ (1) | In St. Thomas |
| Attic Loose Fill Solutions | 5.0★ (1) | 19 km |
| Dicola (Drywall) Interiors Limited | 28 km | |
| Forest City Foam Insulation | 22 km | |
| HotRockPanels | 5.0★ (2) | 27 km |
| Insulation Contractors London | 5.0★ (1) | 20 km |
| Insulation Ingersoll | 38 km | |
| London Spray Foam | 5.0★ (2) | 23 km |
| Net Zero Insulation | 23 km | |
| Paulray insulation | 16 km | |
| Tornado Insulation | 17 km |
US national ranges converted to CAD, not adjusted for St. Thomas. Each row names its basis and the month we checked it.
| Job | Low | Typical | High | Basis | Checked |
|---|---|---|---|---|---|
| Attic insulation | CA$2,390 | CA$2,950 | CA$3,510 | Per attic: typical range of customer-reported jobs (about $1 to $3 per sq ft). US national range converted at 1.4054 CAD per USD (Bank of Canada, October 20, 2026) | October 2026 |
We scored 22 St. Thomas insulation contractors on ten factors, weighted as shown. A business is ranked when its trade is confirmed and it has 3 or more Google reviews or a claimed profile. A business with no Google reviews scores zero on rating, review volume and recency. Other unknown factors are left out, not counted as zero. Scores last refreshed October 22, 2026.
Paid placement never changes a rank or score. Featured businesses are paid, labelled, limited to 3 and shown above the ranking, outside it.
| Factor | Weight | Computed from | In St. Thomas data |
|---|---|---|---|
| Reputation | 25% | Google star rating, adjusted for how many reviews back it | Measured |
| Credentials | 15% | Active state license, bond and workers’ comp on file | Not yet collected |
| Review volume | 10% | Number of Google reviews, compared with the most-reviewed business on the list | Measured |
| Recency | 5% | Share of reviews from the last 12 months | Not yet collected |
| Availability | 5% | Weekly open hours, Saturday, Sunday, 24/7 or same-day | Measured |
| Trade focus | 10% | How clearly the business does this trade (its Google category and name) | Measured |
| Proximity | 5% | Based in the city scores highest, less the farther away it is | Measured |
| Claimed profile | 10% | The business has claimed its ContractorsRanked profile (free or paid earn the same) | Measured |
| Partnered | 5% | The business links to ContractorsRanked from its own website with our badge, checked periodically | Measured |
| ContractorsRanked reviews | 10% | Verified customer reviews collected by ContractorsRanked: their rating and how many there are | Measured |