[0001] The present invention relates to a roof truss assembly consisting of beams of wood
and means for interconnecting the beams.
[0002] The manufacture of roof trusses by a carpenter on a building site demands great skill
and normally involves high costs. For this reason, one has instead chosen, to an ever
greater extent, to manufacture roof trusses in factories and deliver them ready for
erection on the building site. Since industrial manufacture is rational, it has been
possible to bring down costs but, in some cases, the transport to the building site
is a problem because of the lack of special vehicles. In addition, cost savings can
be reduced in cases where it is desirable to produce a small series of roof trusses
with special dimensions or of special design because the machines must first be properly
adjusted.
[0003] The object of the present invention is to make it possible to manufacture roof trusses
of every desired dimension, construction and roof pitch on the building site at a
competitive price. According to the invention, this object is achieved by the provision
of a roof truss assembly which has connecting means consisting of an insert member
in which beams to be interconnected are insertable into a position determined by the
desired roof truss configuration, and are fixable by nail or bolt means which are
driven through the walls of the insert members and the beam disposed therebetween.
[0004] The invention will be described in greater detail hereinbelow with reference to the
accompanying drawing which shows one embodiment of the invention in perspective.
[0005] The roof truss, generally designated 10 in the drawing, consists of beams 11, 12
and 13 of which the beams 11 and 12 form the upper chords of the truss while the beam
13 forms the lower chord. The beams 11, 12 and 13 are composed of flanges 14, 15 and
a web 16 in the form of a wire bent in zigzag which interconnects the flanges. These
beams give a highly resistant and light-weight roof truss. Instead of the beams illustrated
in the drawing, it is of course possible to use conventional roof truss wood. The
beams 11, 12 forming the upper chords are secured to each other by a connecting means
in the form of an insert member 17 consisting of two identical, parallel boards 19,
for instance of plywood, which are disposed opposite each other and nailed at 21 on
opposite sides of a wooden block 20, thus forming a spacer. The adjacent, outwardly
facing edge surfaces of the means 17 make an angle with each other which corresponds
to the desired roof pitch. As seen in the drawing, the end portions of the beams 11,
12 are insertable until the squarely cut ends of the beams abut against the spacer
20. The beams 11, 12 are so placed that their outwardly facing sides are flush with
the outer sides of the means 17, whereby the beams 11, 12 are placed with the desired
slope, which in the present instance corresponds to a roof pitch of 45
0. The beams 11, 12 are fixed in the insert member by means of nails 23 which are driven
through both of the boards 19 and the flanges of the intermediate beam. To this end,
the boards 19 on the outside have markings 22 which indicate where the nails 23 should
be driven in.
[0006] The beams 11, 12 forming the upper chords are joined with the beam 13 of the lower
chord by means of insert members 18 which also consist of two parallel, opposed boards
24 which, like the boards 19, are held at a distance from each other which corresponds
to the thickness of the beam flanges, by means of spacers 25, 26 which also serve
as stops and support means for the beam ends. The boards 24 here have two opposite
sides making an angle with each other which is determined by the roof pitch, in this
instance 45°, and being interconnected at the side facing away from the beams by means
of a short side which is at right angles to the side of the connecting means that
extends along the upper chord beam. The side of the means 18 which faces away from
the beams is located, as appears from the drawing, at a distance from the spacers
25, 26, and between these spacers and said side there are provided wooden blocks 27,
28 extending along the outer sides of the connecting means, thus defining a space
closed on three sides. In this space, a fixing portion 30 of a loose truss overhang
is insertable and fixable by nailing. If the roof to be made should have no truss
overhangs, said space is sealed by means of a wooden block 31 which is fastened with
nails.
[0007] In the manufacture of roof trusses by means of the roof truss assembly according
to the invention, the required amount of insert members 17, 18 are ordered from the
factory, it being necessary only to indicate the desired roof pitch. The means 17,
18 are then delivered together with beams 11, 12, 13, if such are not already available
on the building site since being also usable as framework elements, e.g. studs, in
housing constructions, and truss overhangs or, alternatively, wooden blocks 31. On
the building site, the beams 11, 12 and 13 are cut to suitable lengths. The beam ends
are then inserted in the insert members 17, 18 in the manner shown in the drawing,
whereupon nails are driven in at the indicated locations. Consequently, the manufacture
of the trusses is highly rational and, hence, they can be produced at a low price.
If use is made of beams 11, 12, 13 of the type shown in the drawing, the result will
be a light-weight roof truss with excellent physical properties.
1. A roof truss assembly consisting of wooden beams or girders (11, 12, 13) with flanges
of wood and a web of metal interconnecting said flanges, and connecting means (17,
18) in which said beams are insertable to be connected with each other, characteris-
ed in that each connecting means (17, 18) consists of a pair of identical nailable
boards (19, 24) which are fixed in opposed relationship on opposite sides of at least
one spacer (20, 25, 26) forming a stop for restricting the depth of insertion of the
beams (11, 12, 13) in said connecting means, and that the beams (11, 12, 13) to be
interconnected are insertable into a position determined by the desired roof truss
configuration, and are fixable by fixing means (23) which are driven through the boards
(19, 24) of said connecting means and the beam (11, 12, 13) disposed therebetween.
2. Roof truss assembly as claimed in claim 1, cha- racterised in that the truss base
connecting means (18), in addition to the space for receiving the beams (11, 12, 13),
has a space in which a shaft portion (30) of a loose truss overhang (29) is insertable
and fixable.
3. Roof truss assembly as claimed in claim 1 or 2, characterised in that the connecting
means (17, 18) are marked on the outside at the locations (22) where the fixing means
(23) are to be driven in for anchorage of the beams (11, 12, 13) and optionally of
said truss overhang (29) in said connecting means.
4. Roof truss assembly as claimed in any one of the preceding claims, characterised
in that the connecting means (17, 18) consist of plywood boards (19, 24) which are
nailed (21) on opposite sides of wooden blocks forming said spacers (20, 25, 26).
