Low density oriented strand board

1. A method of forming a low density OSB having a homogenous vertical density profile comprising the steps of:

a) combining wood strands with thermosetting resin to produce a wood strands resin mixture;

b) forming a mat including a core layer and two outer face surfaces, wherein the core layer has a moisture content about equal to or higher than the moisture content of the outer face layers prior to pressing;

c) pressing and heating the mat until the resin sets, wherein the OSB so formed has a homogenous vertical density profile.

2. The method of claim 1 , wherein the moisture content of the core layer is about 10% to about 30% while the moisture content of outer face layers is less than about 10%.

3. The method of claim 2 , wherein the moisture content of the core layer is about 20% while the moisture content of the outer face layers is below about 8%.

4. The method of claim 3 , wherein the resulting OSB has an average density of less than about 641 kg/m 3 (40 lb/ft 3 ).

5. The method of claim 4 , wherein the resulting OSB has an average density of less than about 561 kg/m 3 (35 lb/ft 3 ).

6. The method of claim 5 , wherein the OSB has an average density of about 481 kg/m 3 (30 lb/ft 3 ).

7. The method of claim 1 , wherein the resulting OSB has a lowest core density greater than about 80% of the highest surface density.

8. The method of claim 7 , wherein the OSB has a lowest core density greater than about 85% of the highest surface density.

9. The method of claim 8 , wherein the OSB has a lowest core density greater than about 90% of the highest surface density.

10. The method of claim 1 , wherein the average density of the OSB is less than 1.5 times the density of the wood species used in the OSB.

11. The method of claim 10 , wherein the average density of the OSB is less than 1.4 times the density of the wood species used in the OSB.