Quite often, "suspicious" developers are interested in what kind of glue for glued laminated timber is used, whether it releases into the air harmful substances how firmly it sticks together, is it not afraid of moisture, etc.
We will focus only on those adhesives that have industrial applications.
- Melamine adhesives. Quite widely used in woodworking enterprises in Europe, in last years become widespread in domestic enterprises. After hardening, they become transparent, have high adhesion, are used during the manufacture of large-span highly loaded structures, and can operate at relative humidity up to 80%.
- resorcinol adhesives. After cooling, they form a dark seam; they are used in America and Japan; they are rarely used in Europe. They have improved bonding qualities, such can be used outdoors.
- EPI adhesives. Type of seam - transparent, universal application, used for the manufacture of glued structures for housing construction. In terms of environmental friendliness, it belongs to the safest group of adhesives.
- polyurethane adhesives. They have a light beige seam, have excellent workability, quickly harden, can be used on high-performance automatic production lines. seam white, specific humidity wood when gluing should not exceed 18%, widely used in production.
According to water resistance, they are divided into several classes: D3 - carpentry, for interior spaces; D4 - can be used outdoors, has increased water resistance and D4 + - increased water resistance, does not lose its original adhesion characteristics at any moisture content of the wood. By environmental safety the international standard establishes three groups: E3, E2 and E1.
As for the notorious "environmental friendliness". You need to know that all modern adhesives have high manufacturability and adhesion, and this is achieved due to the inclusion of synthetic resins in their composition. The latter release formalin, isocyanate, etc. into the air, not very useful compounds. True, their number is scanty, for most people it has no effect. But apart from the majority, there is also a minority. At present, we will not get away from chemical compounds, they are everywhere, this is a kind of payment for progress. About the experience of living in houses from glued laminated timber read .
Comparative table of properties and prices of adhesives for glued beams
To compare some characteristics, it will be interesting to compare three types of adhesives.
There are no special differences in adhesive abilities, the adhesion properties of all three are excellent. In terms of environmental friendliness, emulsion polymer-isocyanate (EPI) glue occupies the first place, and in terms of use it ranks last. Paradoxical? No, everything is very easy to explain. Firstly, such glue reduces the productivity of the equipment - it is very difficult to work in a continuous mode. Secondly, its price is 20% higher than the rest.
Glued laminated timber in Russia is becoming increasingly popular among home developers. The technology of gluing laminated timber wood is being improved from year to year.
Studies show that the reliability and strength of the construction of glued beams largely depends on which adhesive was chosen by the manufacturer. That is why, today, EPI-glue (polymer emulsion with an isocyanate hardener) is used to glue glued laminated timber lamellas together.
Both foreign and domestic producers. Japan is considered to be the birthplace of technology for gluing solid wood parts. It is there that industrial JAS standards for load-bearing and load-bearing timber structures are widely used.
Advantages and scope of EPI-adhesives
EPI-adhesives are capable of gluing not only timber, but also load-bearing beam- they have increased strength characteristics. The seam cannot be unglued even under increased loads. According to the manufacturers of such adhesives, the wood is more likely to collapse under load than the EPI adhesive will fail. Among the general advantages of EPI adhesives are:
- EPI-adhesives do not contain formaldehyde, the environmental friendliness of such products is confirmed by the relevant certificates;
- Wide temperature range during bonding (+5 to +110 °С);
- The pressing time of the glued elements can reach up to 30 minutes;
- Adhesives can glue wood with a moisture content of up to 15%;
- Average consumption during gluing 200–300 g/m2 It should also be noted that when gluing:
- The seam of glue between the lamellas of the timber remains stable under temperature influences;
- It turns out a product resistant to additional loads, due to the absence of internal stress;
- Adhesive connection is waterproof;
- The glued product can be used without further finishing
Thanks to these characteristics, the scope of EPI-adhesives is expanding. Today, these adhesives are also used in the manufacture of furniture, windows and doors. Manufacturers of EPI-adhesives in the world and Russia In Russia, woodworking enterprises mainly use adhesives from foreign companies, such as -Dynea, AkzoNobel Klebchemie M. G. Becker GmbH & Co. KG, Jowat AG. Among Russian manufacturing firms, one can note - Khimtekh NN LLC EPI-glue VIAR-D4.1 EPI, Moscow. Nizhny Novgorod, homakoll EPI HOMA Group LLC, Moscow.
In the production of glued beams, the quality of gluing lamellas is determined by the water resistance of the joint. EPI adhesives for gluing timber in Russia must comply with GOST 27812-2005 "Laminated wooden structures".
Features of gluing timber in production
Rules for storage and transportation of EPI-adhesives
EPI-adhesives should be stored in original factory containers at a temperature not lower than +10 °C. Guarantee period storage 6–12 months. After prolonged storage of the adhesive, it is necessary to bring the composition to optimum temperature gluing.
When working with glue, you need to use respirators and protective gloves. Tools and equipment after working with glue are washed with water. For transportation of glue it is necessary to use plastic containers with a metal frame.
Video - EPI-glue in the production of glued laminated timber
The material was prepared with the help of specialists from the Association of Wooden Housing.
The history of log houses dates back several centuries, they have passed all kinds of tests both by time and by people, and have proven their worth, although they also have some specific properties. Constructions made of glued beams in our country cannot boast of such an impressive experience and, despite their great popularity, are shrouded in a whole set of myths. AT this material we will talk about the most common "horror stories" associated with glue and the technology itself:
- The technology is “young” - will the lamellas disperse.
- How harmful is glue to health.
- How effective is the glue - will the timber not “stick out” in a few years.
Will the lamellas in the timber not disperse
Glued laminated timber is produced by longitudinal gluing of several wooden planks(lamellas), wood is used as a raw material conifers. The characteristics of this material largely depend not only on the adhesive system, but also on the parameters of the lamellae. To prevent the beam from separating into composite parts over time, the lamellas must meet the following criteria.
Permissible humidity– the board after sawing (usually the thickness of the lamella is 50 mm) is dried to acceptable levels - 8-15%, but the humidity of adjacent lamellas should not differ by more than 4%. Exceeding these limits is fraught with cracking of the beam after the assembly of the structure, the house will not fall apart, but the decorative effect and tightness will definitely suffer.
Quality of lamella preparation- after the initial calibration (minus 1-2 mm), before gluing, a final calibration must be performed on a planer, the output geometry must be almost perfect. Allowed error is not more than 0.1 mm per running meter, “waves” or torn fibers are not allowed.
If the equipment is worn out, with blunt knives or sharpened, but at the wrong angle, it will not be possible to process the lamella correctly.
Although when sawing, the tension between the fibers of the wood is removed, which allows the finished timber to avoid deformation, if the processing technology is violated, the quality of the seam may decrease.
This will lead to disastrous consequences for the already built house.
Oberon FORUMHOUSE User
Fine calibration before gluing is done to align the geometric size along the entire length of the board so that the timber is of exact dimensions. This is important both for proper gluing and for the subsequent cutting of glued laminated timber into parts of the house kit. Another 1-3 mm is removed. If non-prongs remain on the board, it should be set aside for re-processing; gluing with non-prostrings is not allowed.
However, our certification of glued beams is voluntary, therefore, tests carried out to prove the conformity of products with the declared characteristics are not practiced in all industries.
In order not to worry about the durability of your house, it makes sense to choose a company that produces timber not according to TU or STO, but according to GOST 20850 - 2014.
It is the most "fresh" and reflects all modern requirements for the material.
In addition, products must undergo regular testing in accordance with GOST 33120-2014 and GOST 33121-2014 or in their own laboratories ( large enterprises), or in outsourcing laboratories (specialized centers). The frequency of tests is up to five times a week, the results are recorded and available for review. That is, high-quality glued laminated timber is produced in compliance with the technology, according to GOST, it is regularly tested, and when buying, you can see all the protocols.
As for the “youth” of the technology, on the contrary, it is already of the “Balzac age”.
Oberon
It is unrealistic to vouch for every house, but the technology itself has existed since the fifties, there are buildings (mainly for industrial and public purposes) of the Soviet era that still exist. In Europe, test houses are located on the territory of one of the institutes, they have been monitored for more than fifty years. While the "flight" is normal. Tellingly, these houses are specially made without antiseptics, since the main idea of the study is to determine the behavior of the glue joints, and not the wood itself.
It is interesting that in Switzerland, to this day, railway stations built from glued beams back in 1910 are in operation, and in the building of the main station in Stockholm (1925) there are load-bearing units made of glued beams, and the lamellas are glued together with casein composition.
Is the glue in the timber harmful?
The production technology itself implies several glue joints in each beam, so potential consumers are most concerned about the environmental friendliness of the material. The beam is produced using various adhesive systems, but most often it is:
- EPI - polymer emulsion with isocyanate hardener;
- MMF - melamine-formaldehyde;
- PUR - polyurethane adhesive;
- PVA - polyvinyl acetate emulsion, is prohibited for gluing house-building structures, as it loses strength under static load.
Glue systems used in the production of glued laminated timber undergo mandatory certification and are environmentally friendly, even if it is MMF. Any glue contains chemistry, but if the glue is of high quality, then all of it polymerizes (converts into a solid) when gluing the timber. The content of free formaldehyde in the timber will comply with domestic and European standards - EN 14080 and GOST 33122-14.
Unfortunately, it is neither tactile nor visually possible to check whether the manufacturer uses the high-quality adhesive declared in the documentation, or saves and dispenses with an uncertified system. Therefore, in addition to domestic SES certificates, the plant must also have a personal certificate of the glue manufacturer. The document will indicate that the particular facility uses their adhesive and that the staff is trained to operate the system. As in everything, when choosing a glued beam, the rule “trust, but verify” works.
Oberon
In order not to worry about the environment in the future, ask the manufacturer for Russian and foreign certificates for the glue used. It is quite easy to check a foreign certificate, it contains the e-mail addresses of the institutions that issued it. Even without knowing the language, during the day it is really possible to find information, online translators to help, and find out if such a certificate was issued.
The remaining doubts can be resolved by asking to arrange a tour of the enterprise, if it is possible geographically - write off the name from the label and check what this glue is.
Will the timber stick out over time?
There are situations when, not even years later, but some time after assembly, the beam delamination is clearly visible on the cuts, as happened with one of the portal users.
Кac77 Member FORUMHOUSE
Friends built big house from glued beams, now, due to the numerous sticking and poor-quality assembly, it is not clear what to do next. The manufacturer of the timber and the developer are one person, whoever produced the timber assembled it. The assembly was done in the fall of 2013, in the winter they assembled it under a roof, glazed it, and did not heat it in winter. During assembly, the box fell under heavy rains, before the roof was assembled. At present (summer 2014) there are numerous stickings, practically on all walls and cuts, along the entire perimeter from the inside and outside.
Quite often, “suspicious” developers are interested in what kind of glue is used for glued laminated timber, whether it releases harmful substances into the air, how firmly it sticks together, whether it is afraid of moisture, etc.
We will focus only on those adhesives that have industrial applications.
- Melamine adhesives. They are quite widely used at woodworking enterprises in Europe, in recent years they have also become widespread at domestic enterprises. After hardening, they become transparent, have high adhesion, are used during the manufacture of large-span highly loaded structures, and can operate at relative humidity up to 80%.
- resorcinol adhesives. After cooling, they form a dark seam; they are used in America and Japan; they are rarely used in Europe. They have improved bonding qualities, such can be used outdoors.
- EPI adhesives. Type of seam - transparent, universal application, used for the manufacture of glued structures for housing construction. In terms of environmental friendliness, it belongs to the safest group of adhesives.
- polyurethane adhesives. They have a light beige seam, have excellent workability, quickly harden, and can be used on high-performance automatic production lines. The seam is white, the specific moisture content of wood during gluing should not exceed 18%, it is widely used in production.
According to water resistance, they are divided into several classes: D3 - carpentry, for interior spaces; D4 - can be used outdoors, has increased water resistance and D4 + - increased water resistance, does not lose its original adhesion characteristics at any moisture content of the wood. For environmental safety, the international standard establishes three groups: E3, E2 and E1.
As for the notorious "environmental friendliness". You need to know that all modern adhesives have high manufacturability and adhesion, and this is achieved due to the inclusion of synthetic resins in their composition. The latter emit formalin, isocyanate, etc., not very useful compounds into the air. True, their number is scanty, for most people it has no effect. But apart from the majority, there is also a minority. At present, we will not get away from chemical compounds, they are everywhere, this is a kind of payment for progress. Read about the experience of living in houses made of glued laminated timber.
Comparative table of properties and prices of adhesives for glued beams
To compare some characteristics, it will be interesting to compare three types of adhesives.
There are no special differences in adhesive abilities, the adhesion properties of all three are excellent. In terms of environmental friendliness, emulsion polymer-isocyanate (EPI) glue occupies the first place, and in terms of use it ranks last. Paradoxical? No, everything is very easy to explain. Firstly, such glue reduces the productivity of the equipment - it is very difficult to work in a continuous mode. Secondly, its price is 20% higher than the rest.
Already from the name of the building material it is clear that special adhesives are used in its production. This leads to some suspicions about the environmental friendliness of glued beams. What glue is used to glue the lamellas, is it safe, how does it affect the characteristics of the material? We will try to talk about all this in the framework of this article.
How to glue glued laminated timber
Most often, lamellas are glued together using one of three types of adhesives:
- polyurethane;
- melamine;
- isoacitate (today they are considered the most environmentally friendly)
European manufacturers mainly use the first two types, but they work with EPI systems mainly in Russia, and even then not all companies. AT total volumes the emphasis is still placed on melamine adhesives, even though they contain the strongest poison - formaldehyde. It should be noted that none of the adhesive compositions has any effect on the “breathing” of the material. negative impact- they are all vapor and gas permeable.
Important! Chemical allergens leading to bronchial asthma include isocyanates and formalin. Just they are used in the production of most adhesive compositions. If you have a predisposition to such diseases, it is better not to take risks - to build a house from an array, for example, ordinary.
Below we examined these three types of adhesives for glued laminated timber according to the main, as it seemed to us, parameters. Interestingly, all of them are certified and approved in a number of countries. It is noteworthy that it takes about 5-7 liters of glue to produce one cube of building materials. If you recalculate the total amount of material that is needed for construction, then you get significant values.
What's better?
In general, it does not make much sense to compare adhesives - they all successfully cope with their tasks. Even in terms of environmental friendliness, the issue is not being resolved chemical composition, but by observing the technology for the production of glued laminated timber: if all the requirements are strictly observed, then there will simply be nothing to complain about. The hardened polymerized composition is safe in terms of environmental friendliness, but how completely the polymerization process went through is already on the conscience of the plant.
About the application of glue
Why is EPI adhesives used by a single number of manufacturers, even though it is considered the most environmentally friendly option? The point is that such compositions this moment do not allow continuous operation. But the situation with melamine and polyurethane compositions is the best in this regard - you can work on a conveyor. They are cheaper than EPI by about 20%, glue waste is minimal. That is why manufacturers are reluctant to switch to the use of emulsion polymer-isocyanate formulations.
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