1. In order to create a proper joint for a coffered ceiling using TRIMROC beams, we need to remove a part of the middle of one beam where the two pieces intersect, then trim the end of another beam.  This will create two pieces with a “male” and “female” that are joined together to create a seamless joint at a 45 degree angle cuts.

2. Start by measuring the width of the top of the beam.  In this case it’s 10”.

3. On a second beam, measure 10” from the centre on top.  We will be cutting at a 45 degree angle towards the centre of the beam.

4. The mitre saw will not be able to cut through the entire thickness of the beam.  We will need to keep the beam aligned with the fence on the saw.  A scrap piece of wood is used to ensure proper alignment during the cut. 

Coffered Ceiling Beam Joint Procedure

5. Line up the marks for the 10” width and angle the blade to cut towards the centre of the beam.  Do this for all four marks, double checking the width before each cut.

 

6. Once all four cuts have been made, flip the beam over and use a saw to cut the remainder of the piece with a hand saw.  Cut only as far as the other beam will intersect this piece.  In this case, we are cutting just past the ridge in this particular profile.

7. Using a knife, cut the beam from one angled cut to the other on the same side.  Cut through the hard shell and down into the foam. Snap off the excess as you go.

8. Once you’ve cut down far enough, the rest of the moulding should snap off fairly easily.

9. The next step is the preparation of the “male” piece that will fit into the part you just removed from the first beam. The key is to cut where the ridge ends.

10. On the second beam we will be using the ridge as a guide and cutting a 45 degree angle all the way down from there. This needs to be done for both corners. There is no need to use the piece of wood to act as a guide because we’ll be cutting the beam upside down. The mitre saw won’t be able to cut all the way through so it needs to finished with a hand saw.

11. Repeat the process on the other side.

12. Both beams are now ready to put together and the profile will match. Repeat the process on the other side. Once installed on the ceiling, join and fill any gaps with drywall compound.