INTRODUCTION	LESSON 1	LESSON 2	LESSON 3	LESSON 4

 Lesson two shows how to install door frames in a non-destructive way.  No metal parts whatsoever are fixed to the stone supports.Only modern organic 'glues' and natural lime are used to fix the frames.  The fixing principle is two-fold: firstly mechanical fixing and secondly adhesion.  Polyurethane foam shares both principles as the plastic mass shows high cohesion to the stone and the frames (if wetted beforehand) and strong mechanical force due to its expansion and hardening.  Polyurethane foam is UV sensitive however and must be protected by a layer of lime.  This layer adds both to the cohesion and to the mechanical force.

Doors are mainly mounted with polyurethane foam and lime, while windows are mounted with polyurethane foam and SIKA FC 115 adhesive.  No lime is used on the outside of windows and the polyurethane foam must be entirely covered by the SIKA adhesive.  With windows lime is used on the inside for decorative reasons and to UV protect the mounting.  This second technique requires close tolerances between the frames and the stones and this is the main reason why it is of little use for doorframes on old buildings.  You will notice from the pictures that the openings are very irregular and often not rectangular or vertical.

•  The door frames are fit to the opening and this is often a moment of unpleasant surprises.
• It is essential to have a mechanical plane tool at hand as significant stone irregularities must be corrected on the frames.
• Individual stones can sometimes be entered into the wall (in the the present case the walls are soil mounted by carefully hitting them by the intermediary of a laminated wood block.
• Small pointed irregularities on non-cut stones are removed with the granite chisel (chasse).
• The frames are then fixed using wooden wedges, first by entering the wedges very loosely.
• Vertical seats in both vertical axes are verified by a water-level in order to prevent the doors from falling open or close. Adjustments are done by selectively entering the wedges.
• Solid supporting from below is done by using laminated wood blocks and wedges.
• Note that the wedges must be entered at or close to the corners of the frames.

•  After strongly tightening all of the wedges by hammer blows the doors are mounted.
• I always use a lever system built from a board and wooden blocks to help enter the doors. If necessary I also use a stone to get a seat for the controlling foot.
• If the doors jam the wedges might need adjustment.  This delicate operation should not be necessary if the frames could be placed in the door openings without forcing!
• Sprouting of the door frames is very important when using polyurethane foam.  It is however important not to force the sprouting and I tighten just to the point that the rather heavy metal tools will no longer fall down and can not be pulled out.

• The complete surface of door frames and stone wall which will receive the polyurethane mounting foam is next wetted with a pressurized pesticide sprayer with hand pump.
• Polyurethane foam is entered all along the interstices on the sides and if possible also above.  I try to always use the same make as the sticking and drying behavior can vary quite a bit.  One needs to develop a feel for this product in order to work cleanly.
• As soon as the surface is no longer sticky I start to push the expanded foam back in to the interstice.  I wear gloves for this and use my fingers a spatula and a file for this.
• The file is necessary for pushing the foam back into the interstice in order to permit the lime to be added later from finding a solid support.
• The pushed back foam will become very hard after complete drying (24h).
• It is only after complete hardening that I remove sprouting, wedges and bottom support.