Our products are mainly to be used to construct foundations, supporting walls and partition walls. Therefore they need to be extremely strong and durable.

To give you the certainty you deserve we give out certificates with all our products, which are issued by highly respectable institutes and admission authorities, both domestically and abroad.


KOMO is an independent institute, situated in Gouda (the Netherlands) and is striving to bring more clarity in the construction -and plumbing industries and has been doing so since 1962. By giving out the KOMO-certificates and having the KOMO quality mark, the institute serves as an independent supervisory body, inspecting and guaranteeing the quality of construction materials.

KOMO delivers several services in the field of product -and process investigation and certification and gives out the following certificates: KOMO product certificate – KOMO attestation – KOMO process certificate – KOMO management certificate.

KOMO also has a KOMO-attestation with a product certificate, which combines the benefits of a KOMO product certificate with a KOMO product certificate and a KOMO-attestation. An increasing amount of actors in the construction -and plumbing industries recognize the value KOMO adds to quality control. That is why the amount of products with a KOMO-attestation with product certificate is increases daily. Products which are supplied with KOMO-attestation with product certificate should at the least display the KOMO-label and the certificate number.

If you are going for an attestation with product certificate, you are choosing certainty about the product specifications of said product. This certainty is guaranteed by means of an external expert who is constantly checking if the construction product, building element or construction system complies with relevant regulations and legislation. However, a requirement is that the (eventual) processing instructions and the application of those, comply with the conditions of the attestation.

KOMO is also checking the specifications according to the systematics specified in the assessment guidelines. Thanks to the methodology applied by KOMO to inspect the quality of construction products -and processes, the client, prescriber, contractor and eventually the user himself are all enjoying the certainty that the product used correspondents with the technical (product) specification of the quality statement.

The only stacking block currently on the market today with a valid KOMO-product certificate is Masterbloc. Both the block itself as the wall build with Masterbloc stacking blocks are KOMO-certified.
KOMO-certificaat-Masterbloc (pdf)

“Allgemeine Bauaufsichtliche Zulassung”

The  „allgemeine bauaufsichtliche Zulassung“ can be translated into English as “general technical admission”.

The ABZ is an admission certificate meant for innovative and non-regulated technical products and construction methods. In Germany it can only be issued by the Deutsches Institut für Bautechnik (DIBt)“. The DIBt is the admission authority of the German Regional Governments (Länder) and inspects, among other thigs, if products are in accordance with the Building Code of the various German States.

All important aspect of a product will be checked to see if they comply with the pertinent regulations and legislation, with a special interest in safety regarding features and influences, before an „allgemeine bauaufsichtliche Zulassung“ is issued.

Among which: Stability – protection against harmful influences – Health protection – The protection against fire, heat, sound and sudden shocks – Traffic and logistic safety.

Masterbloc has received a “Zulassung” by the DIBt (with nr. Z-17.1.-1146) for both the individual blocks as well as a wall constructed with Masterbloc-elements. With the “Zulassung”, the Masterbloc-system is also approved to serve as a firewall.
Allgemeine_Bauaufsichtliche_Zulassung_Masterbloc (pdf)


Kiwa is an independent certification organization situated in Belgium and the Netherlands and has the aim to guarantee the quality of products and processes. KIWA does this though inspections, examinations and performing tests, which combined are the basis on which certificates are issued. Kiwa is also serving as a technical hub for information gathering, research and training. Kiwa is not only focused on the construction industry, as it performs technical surveys for clients in numerous industries, including the government, utilities market and the industry.

The aim of Kiwa is to build trust in the quality of the products and processes by making them transparent and guaranteeing them, by means of focused application of the in-house technical knowledge. By persistently doing this, Kiwa has built a solid reputation for themselves over the years as a trustworthy certification authority who are delivering solid results.

The best known example of the work Kiwa does, is their Kiwa quality mark, which often can be found on the bottom of products. This quality mark (and corresponding certificate) immediately shows the inherent quality and trustworthiness of your product.

Masterbloc has received a certificate (with nr K23375/01), acknowledged by both the Dutch Ministry of Transport, Public Works and Water Management as well as the Ministry of Housing, Spatial Planning and the Environment, declaring the Masterbloc-system complies with the Building materials resolution.

The NLBSB-certificate specifically guarantees that the used concrete products are made of pure granulates, which can be traced back to the source, as well as that the water/cement ratio is being respected (which determines the frost resistance among others), to the end user. The independent and accredited certification authority KIWA checks whether the producer is producing concrete according to legal regulations, several times a year.

KIWA-Certificate (pdf)


CE is an abbreviation and stands for Conformité Européenne, meaning as much as in accordance with European legislation. Practically speaking, the CE is not a European quality mark, but rather an indication that said product complies with all pertinent European legislation and is in accordance with the applicable guidelines set by the European Union. By showing the CE-logo on its products, the producer acknowledges publicly that it meets the high European quality threshold and furthermore makes him legally responsible for the quality of his product. In this way the CE-logo guarantees that our final products are being produced according to European legislation, regarding quality, performance and conformity.

Most construction products are obliged to have both a CE-mark as well as to prepare an additional conformity/ performance declaration, before it is even possible to launch them onto the internal European market.

We have decided to take it even a step further, by putting a CE 2+ marking on our products, thereby declaring that all steps in the production process, in our production facilities are being checked by an external agency (KIWA)

The CE 2+ quality mark has come about to overarch the national quality marks (for example BENOR in Belgium, KOMO in the Netherlands), because the demand for quality stretches across borders. In short CE 2+ is an improved method for internal quality guarantee on a European level.

The independent inspection service Kiwa has issued a conformity certificate (with nr. 0620-CPR-90475/01) to Masterbloc for the production process. Furthermore Gubbels Masterbloc Concrete Group Ltd has received a certificate from Kiwa (with nr. 0620-CPD-41438) for the conformity of our production process.


WTCB stands for the “Scientific and Technical Centre for Construction Companies”. It is a private Belgian research facility with the main aim to conduct scientific and technical research to the benefit of the Belgian construction sector as well as to technically assist, to advice and to educate and finally to encourage innovation in the construction sector. As part its services the WTCB also conducts technical approvals, normalizations and  certifications.

Whenever we launch a new product we use the amassed knowledge of the WTCB to check our product thoroughly, on all engineering properties applied. We are doing this voluntarily and at our own expense, without being forced legally, because we have established a tradition of quality and a mission to provide our customers with only the best construction materials.