Nils Ludvig Lagerstedt and Anton Leonard Krantz established the company Lagerstedt & Krantz, the 6th of July 1910. Lagerstedt & Krantz begins as an agency and iron manufacturing company with sales to Swedish ironmongers and country shops of articles such as lanterns and mosquito nets. The offices were located in Jakobsgatan in the Klara district of Stockholm. The staff consisted of a clerk and a secretary in addition to the two partners who looked after sales.

Lagerstedt, from Västergotland and a bit of a roaming peddler, sells in rural areas in western Sweden, while Krantz from Stockholm makes use of the phone and makes sales successfully all over the country. Krantz left the company in 1912 while Krantz continued until his death in 1926.

Operations were taken over by Lars Schuberth and Albrecht Behm. This allows the registration of the limited liability company Lagerstedt & Krantz AB. Eventually the range of products graduated to water and waste-water products as well as heating and plumbing products. Contacts were established with leading European manufacturers of such items as lock gates and steel tubes in large dimensions on the water and waste-water side and for tanks, taps, sanitation products and bathtubs on the heating and tapwater side. Difficulties in obtaining licences for water-pipes and increased domestic competition led to the abandonment of the water range and the company concentrated on heating and plumbing products.

As general agents the company now had great success with several well-known brand names; KWC’s “spakblandar” programme for public spaces; sewerage systems and cisterns in plastic from Geberit; sanitation products from the Dutch company Sphinx and bathtubs from the Italian manufacturer Zoppas. Swedish housing production was increasing at a rapid pace, but the public housing corporation wanted to see products from the cooperative’s own company. This disadvantaged the private sector and LK was not welcome in all projects.

One of the most important events in the company's history took place in 1970 when the company was made general agent for Conex fittings for HVAC installations. The agency for these fittings that save on installation time came about because of the demand by heating and plumbing wholesalers and sales took off. Conex become the cornerstone of LK’s continued growth and profitability that was used to create a nationwide distribution network of installers and heating and plumbing wholesalers. The sales force continued to have access to new time-saving heating and plumbing products and systems to launch in the Swedish construction market.

With these successes the company grew in size. The old industrial building in Bromma was purchased in 1977 and an office and warehouse was built in Malmo, Helsingborg and Oslo in 1980, 1987 and 1990 respectively. In addition to the property in Oslo, Lagerstedt & Krantz Fastigheter AB markets, owns and manages other business sector properties in the company.

From the 1980s onwards the company gradually transformed from trading in other companies’ products to the development and production of its own technically more advanced products and services.

The company’s first location outside Sweden is established in Oslo.

The partnership between Schuberth and Behm that had lasted for 50 years finally comes to an end when Schuberth sell his share in the company to the Behm family and Stikkan Andersson's company Music Sweden AB. The latter's shares are transferred in 1987 to Skrinet AB and then on to G&L Beijer AB, and finally taken over in 1995 by the Behm family who then basically become the sole owner of the whole group of companies.

The subsidiary LK Armatur AB was now established in Helsingborg and took over the parent company’s rights to sell Thermotron’s valve products intended for hot water heaters and boilers. Today, LK Armatur AB is a successful company that produces its own valves, components and system solutions for the OEM market for heating products and hospital equipment.

After selling a German under floor heating system for five years, Lagerstedt & Krantz now introduced their own proprietary under floor heating system tailored to Swedish building standards. Today, LK is a strong brand within floor heating, radiator heating and ground heating as well as tap water systems. 

For the further development of LK’s heat and tap water systems polyethylene pipes took on a central and strategically important role. With the task of developing and manufacturing this kind of pipe the company LK Pex AB was set up in Ulricehamn. Today, from its own factory, the company supplies not only its sister companies LK Systems and LK Armatur, but also retailers in Europe, the USA and the Middle East with its proprietary quality pipes. 

When LK Norway bought A-H Andersson AS’ heating and plumbing operations in 1990, this was also the beginning of the Marine Valve Business Sector. The range also includes brass valves for installation in ships, and counts the Norwegian Navy among its customers. Sales of these valves grew and soon the product range was given its own company, LK Valves AS. Today the business sector consists of two companies, LK Valves AB in Helsingborg, with operations in Sweden and Norway, and also Changzhou LK Valves Co. Ltd.. (2006) with production in China.

Since the early 1990s prefabrication of heating and plumbing installations was part of the activities of the Heating & Plumbing Business Sector. Now prefabrication has its own company, LK Prefab AB, with manufacturing facilities in Gävle. In 2013 the operation moved to larger premises to meet the ever increasing demand for this type of service.

LK inaugurated a modern pipe factory of 10,000 m2 in Ulricehamn.