Strengthening rafters - what is it?
Quite often homeowners are faced with the problem of sagging the rafters. This is due to excessive savings or incorrect design. If the rafters are not reinforced in time, they can break, which in the end leads to costly roof repairs.
The concept of strengthening rafters implies a set of works to correct the deflection and strengthen them for further trouble-free operation. It is also necessary to process the knot of the "legs" arrival to the ridge, which will additionally relieve the load from their middle part.
Strengthening the rafters - choose the strategy, we prepare for the work
There are two ways to strengthen .The first is to increase the thickness of the beams, and the second is to increase their width. The first option is used only when it is impossible to increase the width of the beams for any reasons, since with the same amount of material used, the structures reinforced by the second method have much greater resistance to bending loads.
There are also various ways of fastening reinforcing bars to rafters: wire, nails, self-tapping screws, using threaded studs. The most reliable way to increase the width of the beams, it is we will consider.
For preparation for operation we release the entire working surface from the skin, open the fastening points of the rafters and assemble the following tool : a set of wrenches, a set of miter heads with a ratchet, a drill, a screwdriver, a hydraulic cylinder, a bulgarian. Since these jobs are very responsible and time consuming, they can not be performed by one person.
How to strengthen the rafters - practical advice
First of all, pay attention to fixing the rafters to the ridge. If they dispersed there, then first the efforts of several people, if necessary using a jack, we join the upper ends.
Then, using perforated metal strips, plywood or, at most, a two-centimeter board, using self-tapping screws, we strengthen the junction of the beams on both sides. If the rafters are joined on the ridge, then we strengthen the joints under it.
Next, we need to remove the deflection of the rafters. For this we use the hydraulic cylinder. Before the beginning of these works it is necessary to strengthen the places of joining the structure to the Mauerlat, for which the board from below to the rafter beam( with increasing thickness) or from the side( with increasing the width) is screwed onto the board, which will rest against the Mauerlat bar and will not allow the legs to move apart when working with the hydraulic cylinder.
For a good stop of the hydraulic cylinder from inside, at the ends of the opposite rafter rails in the places of the greatest deflection we screw self-made triangular wooden supports with self-tapping screws.
Next, gently working hydraulics, straighten the rafters and fix them in this position with any improvised board with a thickness of at least 3 cm using self-tapping screws. That is, if you look from the side, you get something like the big letter "A".
How to strengthen the rafters - extend the beam
In order to build rafters, proceed as follows. First of all, we prepare the beam, identical to the existing one in size( the width may be slightly different).For convenience of the subsequent work we fix it to the already existing beam with several screws.
Then, using a drill, drill through through 30-50 cm through holes through two fastened bars together. Holes are not located on one line, but go in the form of "snake" to improve resistance to bending of this design.
Next, insert the holes studs, pre-cut into size, at the ends of which, we nail self-locking nuts, first putting the washers under them. The tightening of the rafters is done until the characteristic crackle of the tree.
To reinforce the rafters in the second method, we perform the same work in the same order except that the reinforcing bar must be fixed to the inner end of the beam and the holes are aligned.
