In the present territory of Poland there are over 2000 surviving wooden temples of various religions, built in the 19th c. or earlier.. The classifications used so far overlook sacred buildings with a double structure of outer walls. In such cases a log construction (German Blockwand) or vertical-post log construction (German Bohlenständerwand) wall is surrounded with a very closely adjoining skeleton on a ground beam. Among the 260 wooden temples surviving in Great Poland such a structure is found in 35, built in the 17th and 18th c. and exhibit several variants of solving the roof-bearing function. When the roof is supported solely by the skeleton and the carcass does not carry its load, we are dealing with the so-called 'Umgebinde' construction. Another variant, in which the load of the roof is carried by both elements of the double-wall structure, the carcass and the skeleton, can be called a 'Quasi-Umgebinde' construction. Both 'Umgebinde' and 'Quasi-Umgebinde' temples can be found in the valley of the Notec River. 'Umgebinde' churches have survived in Chojna and Jaktorowo (in the Paluki region), and 'Quasi-Umgebinde' ones in Nowe Dwory and Herburtowo (in the Walcz region). The Catholic churches in Chojna and Jaktorowo were founded in the 18th c. by noblemen and estate owners, Jakub Mielzynski and Jakub Lakinski, respectively. They were built by the same carpenter, which is evident from their architectural shape, characteristic construction solutions, material treatment and assembly markngs. The ones in Nowe Dwory and Herburtowo are former Protestant churches in Dutch order villages. The church in Nowe Dwory was built by Jan Czarnkowski in the 17th c. for Dutch and Flemish settlers. It is the only sacred building preserved connected with Dutch settlement in Poland. Its original log construction was transformed into a 'Quasi-Umgebinde' one around the year 1700. The church in Herburtowo, built by the carpenter Johan Schöneecke in 1782, is probably a copy of an earlier temple, built there by the same carpenter who transformed the log church in Nowe Dwory into a 'Quasi-Umgebinde' one. The application of the 'Umgebinde' and 'Quasi-Umgebinde' construction in the four above-mentioned churches was almost certainly connected with the natural conditions in the valley of the Notec, which in the 17th and 18th c. was a wet area plagued with floods and strong winds. Additionally, there were not enough forests that could supply high-quality timber, while sparse roads and the unregulated river did not facilitate transporting wood from other regions. 'Umgebinde' and 'Quasi-Umgebinde' constructions were considered a guarantee of the durability and stability of churches in such conditions. The same applies to other double-wall wooden churches in Great Poland, most of which were erected in wet river valleys or on boggy ground near lakes. (20 Figures).