Scribing

Table of contents for this scribing page. Scribing Skirting, or Baseboards. | wall sheets | roof flashings |

Scribing is a term for fitting one  building part, neatly to another.    It could be fitting a sheet of wall material around ceiling beam, it could be  fitting a ceiling sheet around plumbing pipes or fitting shelving into into an odd shaped cupboard. All these jobs can be tricky and if not measured and cut right, could waste you material, or time and effort.

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Scribing Skirting, or Baseboards.

The main reason that scribed joints are used is that timber shrinks in width far more than it does in length.  By using a scribed joint rather than an internal mitre joint the effect of shrinkage is minimised.  Also it is possible to arrange the scribed joints pointing away from the most common viewpoint (usually the doorway of a room) and so present the best appearance.

Scribing - A piece of skirting that is scribed at one end and mitred at the other

Here is a shot of a piece of skirting.   On the left end it has a 45 deg. mitre cut.  On the right hand side is the scribe cut.

Scribing - Standard views of a piece of skirting.

Here are the standard views of the same piece.  If you look at the top view, you will see that the left side is a standard internal mitre, done with a mitre saw or a hand saw in a mitre box.  

The right side from the top looks almost identical, but it has a couple of right angle bits, showing that the timber is cut square to achieve the same look as the mitre.  

On good quality joinery work, these small square sections are the only way you can tell if the joint is mitred or scribed.

OK,so how to do it.  Scribing like this always starts with a mitre cut.  Look at the red line in the sketch above. That is the shape that the mitre forms with the face of the board.  So I use the mitre cut as a guide for making the square cut.   I take my panel saw or tenon saw and cut out the straight sections first and then I cut the curved section with a sharp coping saw.  because the back is not seen, I usually undercut the back a bit, to make sure of a good fit on the face.  Above is a sketch of a lot simpler skirting with a rounded top. A simple scribing.

Of course if you had a plain rectangular board to use, then the scribing would be a straight cut.

click here for the hand saws to use.

Here is a page with photos of scribing a timber cornice with a coping saw.

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Wall Sheets

Scribing - A couple of nails or screws in a position that will enable the next sheet to be held in a position that will allow accurate marking out.

In the sketch above I am trying to show a wall that I need to clad with plasterboard.  It could be any sheet material.  The size of the beam and the sag in the ceiling are a bit exaggerated to show clearer what's going on.

Lets say I am using 1350 wide sheets (4'6").  I fix my first sheet and do a bit of measuring.  Yep my next sheet will do the rest OK.  So I measure down from the lowest point 1400, to give me 50 play', and I whack a couple of temporary screws into convenient studs to hold the sheet.  

I cut my next sheet to width and rest it on the screws.

Scribing - Sheet in position and finding the distance to offset the marking from the ceiling and beam etc.

I Have set my screws level and the bottom sheet is level.  I know that the top sheet has to go up 560 to sit on the bottom sheet.  So all I have to do is plumb the important points from the ceiling 560 from the ceiling.  I could use a level and a tape measure easily to do this and then join up the marks and cut it.  The measurements MUST be vertical, not square off the ceiling line.

Scribing - Detail of the method of marking.

A way that I like to do sometimes is cut a bit of scrap timber to the size, in this case 560.  That way there is only one measurement being made, less chance of mistakes.

I put a bit of a point on it so I can turn it into the angled corners.  I then put  pencil marks on the bottom.  

Sometimes I can hold my pencil on the bottom of the stick, a small spirit  level held to it and just about draw a long pencil line instead stopping for each point.

The little bit behind the beam that I can't reach with my stick I just draw the back parallel to the front.  That little corner,(The shaded bit at the back of the beam) could cause problems in a stiff material and have to be cut off and patched in later,  but in something a bit flexible like plasterboard I would try to bend the right side of the sheet out a bit as I was lifting it into position and so spring it in.

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