Abstract: An insulation filled building plank having two spaced apart boards held together and separated by webs having dovetail connections with the boards and being at an angle to the longitudinal axis of the plank so that any transverse cut of the plank will cut a web is produced on apparatus which first cuts matching dovetail grooves on surfaces of the boards arranged face to face after which the boards are turned to have the dovetail surfaces facing each other and the apparatus pulls dovetails of webs into the grooves in the boards from a magazine and then the apparatus fills the spaces between the webs and boards with an in situ foamable insulation.

Abstract: Joining planks to form a wall construction. Each plank has a wooden facing member on each side and there is insulation between the facing member and in each facing member there are jointing surfaces facing away from a surface of the facing member and to this surface another plank is joined and metal connecting members are inserted with connecting arms which are in contact with the jointing surfaces of the contacting facing members of contiguous planks. There is no metallic contact across the joined planks between the connecting members which have arms in contact with the jointing surfaces of the parallel facing members of the planks which are to be joined.

Abstract: An insulation filled building plank having two spaced apart boards held together and separated by webs having dovetail connections with the boards and being at an angle to the longitudinal axis of the plank so that any transverse cut of the plank will cut a web is produced on apparatus which first cuts matching dovetail grooves on surfaces of the boards arranged face to face after which the boards are turned to have the dovetail surfaces facing each other and the apparatus pulls dovetails of webs into the grooves in the boards from a magazine and then the apparatus fills the spaces between the webs and boards with an in situ foamable insulation.