Warming up
Transactional email API
716 UK construction companies name London on their website and publish an email address, as of September 29, 2026. Microsoft 365 handles email for 9% of them, and EC1 is the busiest postcode district among those that publish one.
Searching is free. You only spend allowance when you export.
373 of the 716 publish a postcode. Among them, EC1 leads with 14. Districts with fewer than five companies are left out.
| EC1 | 14 (4%) |
|---|---|
| W1 | 13 (3%) |
| WC2 | 8 (2%) |
| W4 | 6 (2%) |
| UB6 | 6 (2%) |
| NW10 | 6 (2%) |
| EC2 | 6 (2%) |
| CR0 | 5 (1%) |
| NW2 | 5 (1%) |
Every company here publishes an email address. These are the other routes and signals their websites carry.
A second route for when email goes unanswered.
Growing firms buy more. A useful first filter.
Some sites tell search engines exactly what kind of business they are, in structured data. These are the types they declare most often, which shows the mix inside this category.
| Home and construction business | 341 (48%) |
|---|---|
| General contractor | 83 (12%) |
| Roofing contractor | 49 (7%) |
| House painter | 12 (2%) |
Who hosts their email decides which spam filter reads your message. What their site is built on says what else they already pay for.
| Microsoft 365 | 67 (9%) |
|---|---|
| Google Workspace | 48 (7%) |
| Self-hosted | 33 (5%) |
| IONOS | 11 (2%) |
| Other or unknown | 557 (78%) |
Read from each domain's public MX record. If most of your list is on one provider, warm up a mailbox on that provider first. Filter by provider in the lead finder.
Share of these companies whose homepage loads each technology. Google Analytics is left out because nearly everyone runs it.
156 of them (22%) state a founding year on their site. This is how those split.
| Before 1980 | 9 (6%) |
|---|---|
| 1980 to 1999 | 44 (28%) |
| 2000 to 2009 | 47 (30%) |
| 2010 to 2014 | 25 (16%) |
| 2015 to 2019 | 20 (13%) |
| 2020 or later | 11 (7%) |
What we have learned about emailing construction companies. The numbers above tell you how many there are; this is how to get a reply.
Contractors are practical and short on time at a desk. Keep it to three lines, lead with money or hours on site, and make the next step a phone call rather than a demo link.
Hi [first name], most builders we speak to send plenty of quotes but lose track of the ones that go quiet. We help firms like [company] follow up automatically so more quotes turn into jobs. Worth a quick call this week?
Replace the bracketed parts per company. In a Warmerly campaign they fill from the lead's own fields.
Early morning, 6:30 to 8am, before crews start, or early evening. Midday email is read on a phone on site, if at all.
716 UK construction companies in Warmerly's database name London on their website and publish an email address, counted on September 29, 2026. A company is matched when its site text mentions London, the same way a city search works in the lead finder, so a firm based elsewhere with a London office is included.
Microsoft 365 runs email for 9% of them, followed by Google Workspace at 7%. It is read from each domain's public MX records. It matters for cold email because Google and Microsoft filter differently, so a sending mailbox on the same provider as most of your list is worth warming up first.
By full-text search over each company's own website text, the same match the lead finder uses when you type London into the city filter. It is broader than a registered address: 373 of these companies publish a postcode, which is where the district breakdown on this page comes from.
Yes. Searching the database in Warmerly is free, and you see the same count as this page before spending anything. Exporting or adding companies to a campaign uses your plan's monthly lead allowance. Every result is a business contact route the company publishes itself, and any company that has asked to be removed is excluded. This page shows totals only, never individual companies.
Filter them by size, founding year, technology and hiring, see what each record holds, then send from warmed-up mailboxes in the same tool.
