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Despite being able to do many things, there are always extra things you will need to know, learn those things here

Tools Required
Spirit Level
Tape Measure
Scribe Guide
Coping Saw
Panel Saw

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It would be nice if all surfaces were straight and flat with all corners square, with walls which are meant to be vertical being so. If thing were this way then everything in DIY would be very much simpler indeed. But, as you probably know, things are very much 'stacked up' against us, no matter what we attempt to do; be it floors that are out of level, corners that are out of square, with what appears to be flat walls having lumps and depressions in them. In reality, this means that if we are working up to theses surfaces, compensations and adjustments will have to be made to put things right which is a skill all of its own, and needs to be mastered if you are serious about DIY. Scribing is used in conjunction to all sorts of jobs, such as fitting kitchen worktops, boxing-in pipes, partitioning, and skirting boards to mention just a few. In fact, when working up to any surface, scribing is very often required.

Panel Wall

If a partition wall consisting of panels was being constructed at a right angle to an existing wall, the first panel of the new wall would need to be set vertically, so that every panel that follows would also be set the same way. But, if the first panel butts up to a surface that is not vertical such as the example in Fig 1, then a problem exists before the job even starts, and if not corrected, the error will be transfer to the entire wall, as shown in Fig 2 and 3. It is unlikely that the existing wall can be altered, so the solution must lie with the first new panel, but logic tells us that if one edge of a rigid panel is set out of plumb, the opposite edge must also be the same.


The answer to this problem is a technique called scribing, which, when translated into practical terms means; 'To copy closely the profile of a surface onto an adjacent material, then cut and fit the material to fit this profile'. This means that: the edge of the first panel that butts up to a none vertical meeting wall will need to have its edge copied and cut so that the cut shape will be the same angle or shape of the none vertical surface, enabling it to fit exactly without altering the opposite edge which remains vertical.
As with any skilled job, scribing is a technique that if not fully understood, can present many problems. This is due to not only the fact that the profile marking and cutting needs practice, but compensations also needs to be made regarding the dimensions of the finished product. This is due to the material being scribed being reduced in size and altering position, making allowances necessary to compensate for these differences, which must be taken into account before any cutting is made.

In the case of a plasterboard stud partition wall for example, when working up to an existing wall that is irregular, the first board is usually fitted where the second board would go, this makes it easier to set this board vertically and in the correct position without any obstructions from the wall. This leaves the vacant gap between the existing wall and the edge of what will become the second board for another board to fit into. To compensate for any differences having to be made to the board by the scribing cut, the timber studding will have been setout so that the width of the vacant gap would be equal in width to that of the board at the widest point, as in Fig 4. 
In this situation where the board needs to be scribed to a none vertical surface, the board will need to be placed in position as shown in Fig 5, in this case with the bottom edge up to the wall and overlapping the board that already in place. While in this position, place a spirit level on to the overlapping edge and adjust the board until vertical and draw a short line at this point onto the second sheet. It follows that if the line overlaps the second sheet by say 25mm from its edge, then, a maximum of 25mm will need to be removed from the wall edge of the first board for it to fit the opening. However, because the existing wall is irregular, rather than making a straight 25mm cut, this edge will first need to be scribed to the wall. To do this, tack the board in this position where it overlaps, ensuring that it is vertical, and using a purpose made guide, set it so that the distance between the its edge (that is against the wall) and the slot is 25mm.
Now, because the vacant slot is equal to the width of the board at the widest point, this gap will be seen between the board and wall as shown in Fig 5. Working from the top, place the guide against the wall, and carefully run it down the wall to the full length of the board, and you will notice that the line will copy the irregular shape of the wall, and at the same time, transfer it onto the board, which, when cut to this shape, will fit perfectly to both edges.

The left hand drawing shows the scribe guide in position at the top of the board with the gap for this example at 25mm. On the right, the same scribe guide at the bottom position showing the difference in the gap between the two as in Fig 6.

When cutting to the scribe line you will need to make allowances depending on the material that you are using. Some materials require tight tolerances were others do not. In the case of plasterboard for you can allow at least 6mm between the board and the wall.

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