Method for treatment of wooden materials to improve the flame-retardant properties and also the resistance to rot, fungus, mold and insects of the wooden material, wherein a wooden material is treated with a water-based formulation, characterized in that said method consists of the steps of: a) providing a wooden material; b) providing a water-based formulation which has a shelf life for more than one month in temperatures ranging from 15-35 °C, and containing: - an alkali metal silicate, - water, and - an insolubilizing agent which is selected from an organic acid, an inorganic acid or an inorganic polyvalent ion selected from Al 3+, Mg 2+, Fe 2+, Fe 3+, Ca 2+, Ba 2+, or with counter ions CaCl 2, MgCl 2, FeCl 2 or combinations thereof, added in an amount which is at least 10 weight % lower than the amount of insolubilizing agent needed for the formulation to reach the gelling point; and wherein the weight % of alkali metal silicate compared to the total weight % of the water-based formulation can be from 1 % w/w to 50 % w/w, more preferably from 5 % w/w to 30 % w/w and most preferably from 10 % w/w to 20 % w/w; c) applying the water-based formulation on the wooden material; d) drying the wooden material treated with said water-based formulation at a temperature from 15 °C to 70 °C in order to remove excess of water; and e) curing the dried wooden material at an elevated temperature from 40 °C to 150 °C in order to insolubilize the alkali metal silicate. a) providing a wooden material; b) providing a water-based formulation which has a shelf life for more than one month in temperatures ranging from 15-35 °C, and containing: - an alkali metal silicate, - water, and - an insolubilizing agent which is selected from an organic acid, an inorganic acid or an inorganic polyvalent ion selected from Al 3+, Mg 2+, Fe 2+, Fe 3+, Ca 2+, Ba 2+, or with counter ions CaCl 2, MgCl 2, FeCl 2 or combinations thereof, added in an amount which is at least 10 weight % lower than the amount of insolubilizing agent needed for the formulation to reach the gelling point; and wherein the weight % of alkali metal silicate compared to the total weight % of the water-based formulation can be from 1 % w/w to 50 % w/w, more preferably from 5 % w/w to 30 % w/w and most preferably from 10 % w/w to 20 % w/w; - an alkali metal silicate, - water, and - an insolubilizing agent which is selected from an organic acid, an inorganic acid or an inorganic polyvalent ion selected from Al 3+, Mg 2+, Fe 2+, Fe 3+, Ca 2+, Ba 2+, or with counter ions CaCl 2, MgCl 2, FeCl 2 or combinations thereof, added in an amount which is at least 10 weight % lower than the amount of insolubilizing agent needed for the formulation to reach the gelling point; and wherein the weight % of alkali metal silicate compared to the total weight % of the water-based formulation can be from 1 % w/w to 50 % w/w, more preferably from 5 % w/w to 30 % w/w and most preferably from 10 % w/w to 20 % w/w; c) applying the water-based formulation on the wooden material; d) drying the wooden material treated with said water-based formulation at a temperature from 15 °C to 70 °C in order to remove excess of water; and e) curing the dried wooden material at an elevated temperature from 40 °C to 150 °C in order to insolubilize the alkali metal silicate.