| 摘要 |
PROBLEM TO BE SOLVED: To make the height of a ridge the same as that in a general land and to increase strength of a roof in a snowy area using rafters with high beam depths by gradually reducing cross section height dimensions of the rafters supporting sheathing roof boards toward the ridge in a prescribed range. SOLUTION: In a rafter 2 supporting a sheathing roof board 3, an inclined surface 22 is formed at an inclined angle of 8 deg. to a lower surface 23 of an intermediate part and a cross section height is formed so as to be gradually reduced toward ridge member 4. A dimension L1 which gradually reduces from a cross section height dimension H2 to H1 of the rafter 2 is made a range of 1/3 or below of an entire length L of the rafter 2. A lower end part lower surface 24 of the rafter 2 is formed so as to be parallel with an upper surface of an eave beam 5 and in a substantially horizontal state in a range of a length L3. By providing a rafter mounting fitting 41 of a U-shape in cross section on the ridge member 4 and the eave beam 5, both ends f the rafter 2 are fixed. The height of a ridge becomes the same, even if wood with high beam depth is used, according to a dimensional change in the rafter 2, the beam depth is high in an intermediate part generating maximum bending moment and stress concentration in the mounting part does not exist. As a result, roof strength can be made larger compared with general land.
|
