Contents
Ondulin roofing is an inexpensive option, but it looks attractive. With the proper quality of ondulin, it is better to use it than slate.
How to make a crate, how to fasten ondulin, with what fasteners and in what order – everything in the article.
Slope and step of the crate
The minimum allowable roof slope for ondulin is 5°. In regions with heavy snow and/or wind load, the slope should be at least 15°. The material is attached to a solid flooring (recommended by Onduline) or a crate – a wooden bar or boards stuffed parallel to the roof overhang. The maximum allowable batten pitch depends on the angle of inclination of the slope:
- Roofs with an inclination angle of 5° to 10° must have a continuous decking (OSB, plywood and other sheet materials).
- If the roof has a slope of 10° to 15°, you can fill the crate in increments of up to 450 mm along the axes.
- For a roof of 15° or more, the maximum distance between the lathing bars is 610 mm along the axes.
In regions with a high amount of precipitation, on those sides where snow usually accumulates, it is better to reduce the fastening step of the crate timber up to 15-25 cm or, in general, make a continuous flooring.
For regions with hot summers, it is better to make the crate solid, regardless of the roof slope. In the sun, the material becomes soft and sags between the bars of the crate. It does not restore its former shape, so precipitation accumulates in places of deflection. These are recommendations based on operating experience in our country.
The distances between the bars of the crate should be the same – it will be easier to fasten the sheets. A cut of the bar of the required length as a pattern will help to withstand the step of the crate (as in the figure above in the right corner).
Fastening to the crate
Крепеж
Ondulin is attached to the crate using special nails or self-tapping screws. They differ from ordinary ones in the presence of a sealing plastic washer. This fastener provides a softer and more elastic fixation, at the same time protects against the penetration of precipitation through the fastening holes.
Which is better, nails or screws? Nails are reliable enough to work with them faster and easier. They are used when fastening to a wooden crate.
It is preferable to use modern fasteners with one-piece caps that do not need to be snapped into place.
Self-tapping screws take longer, but they are necessary when attaching to solid plywood or OSB decking. It is difficult to drive nails into them. Self-tapping screws are also used if the crate is made of metal profiles.
The location of the sheets and their overlap
When laying ondulin, do not confuse the front and back sides of the material. The back has a rougher surface. To create a reliable roof, you need to follow a few rules:
- We start laying from the roof overhang, moving up.
- We start the first row with a whole sheet, the second – with a half, i.e. in a checkerboard pattern. Then we alternate in this way – alternately whole, then half. By laying the material in a checkerboard pattern, we avoid the appearance of joints where four sheets intersect at once.
- The sheets should be positioned so that the prevailing winds do not blow into the joints (left figure).
The second point is the overlap of ondulin sheets. Each subsequent vertical row should overlap one or two waves of the previously laid one (laying with an overlap / overlap). We shift one wave on a roof with a slope angle of more than 10 °, two on flatter ones (from 5 ° to 10 °).
Ondulin can be cut with an electric jigsaw, a hand-held circular saw or a conventional wood saw. To prevent the cutting edge from becoming clogged with bitumen, moisten the hacksaw with water from time to time. Pre-draw the cut line with a well-marked marker.
Horizontal rows are also laid with an overlap. Laid on top overlaps the bottom. This entry depends on the angle of inclination. For roofs with a slope of more than 15 °, the approach is at least 170 mm, with a slope of 10 ° to 15 ° – 200 mm, and for a slope of 5 ° to 10 °, sheets should be laid one on top of the other by 300 mm.
How to strengthen
For installation we use only special fasteners. Nails should go into the timber to at least half of its thickness. We calculate the length of the nail as follows: the height of the wave, plus 2/3 of the thickness of the beam. We take the nearest longer length.
You have to drive nails through the material and you need to hit exactly the bar the first time. No extra holes in the roof. In order not to miss, use a lace. With one end we tie it to the previously hammered nail, with the second – to the nail hammered into the crate behind the edge of the sheet. Between them, pull the cord, which will show where to put the tip.
Important!
Regardless of whether you use nails or self-tapping screws, make sure that the head of the fastener does not leave a significant recess in the roofing material.
How many nails / self-tapping screws go to the sheet, the order and scheme of their installation
The number of nails for fixing the ondulin to the crate depends on the angle of inclination of the roof slope. Each sheet should include:
- For roofs with an angle of 15° or more – at least 20 nails per sheet.
- A slope of 10° to 15° requires 25 nails per sheet.
- On slopes with a slope of 5° to 10°, we fasten each sheet using 20 nails.
We drive nails or screw self-tapping screws into the crest of the wave. This is to ensure that water has less opportunity to seep under the roofing material.
The layout of nails / screws for a slope of more than 15 ° is shown in the figure above. Please note that the sheet is first attached at three points: bottom left, bottom right and top left. Then you drive the nails of the bottom row into each wave, then the middle ones in the first row and in the second.
For a roof with a continuous deck and a slope of 5 ° to 10 °, the scheme is similar to that shown for a roof of 15 ° or more.
Next, fix the following sheets in the same row to about half the length of the overhang. And only then proceed to the installation of the second row of roofing sheets. The procedure for attaching ondulin in the second row is similar, only it must be started from a half sheet. Half the fasteners fit here, but we hammer in the nails in the same sequence.
Only the last top row will differ – it will be necessary to install fasteners on the top into the crest of each wave.
For a roof with a slope of 10° to 15°, the fastener installation scheme will be different. Here we will make three intermediate rows of fasteners and hit the nails through three waves (diagram in the photo above). The order in which we hammer in the nails is similar: first the outer three, then the bottom row and the middle ones.
Decoration of the overhang, sides
The maximum overhang for ondulin is 7 cm. The drainage system must be done with this in mind. To make it easier to maintain the length of the overhang, nails are driven into the front board, the caps of which will stand at a given distance. A cord is pulled between them and the edge of the roofing material is leveled along it.
To attach the dropper, two bars are stuffed parallel to the overhang, the distance between which is equal to the length of the dropper shelf. First, a dropper is attached, then the first sheet of roofing ondulin is laid and its overhang is exposed.
To prevent birds from nesting under the roof and large insects from crawling, a board and a wire grate are installed along the overhang.
You can use a cornice filler.
The filler of the eaves is designed to protect the under-roof space from debris, birds and insects.
The design of the sides of the roof can be done in two ways. The first is to wrap the roofing material and nail it to the side board (pictured below on the right).
At least half of the wave must be wrapped on the board. In this case, we will use shorter ondulin nails, which must be driven in after 20-25 cm.
The second way is with the help of a finished gable profile.
The option using a gable profile is more laborious and costly, but also more reliable and aesthetic.
The gable profile covers the wind board and the two extreme waves of the roofing material. Nails are driven into the plane of the roof into each beam of the crate, into the side board in increments of 20-25 cm.
The gable profile can be made of ondulin (recommended by the manufacturer), or it can be made of metal (right picture below).
How to make an adjoining ondulin roof to a wall
For lateral junction of ondulin to the wall of the house, a water-repellent sealing tape is used. This can be material from ondulin manufacturers or any other tape with suitable properties.
The tape is fixed (possibly with nails) on the wall, at a height of 10-15 cm from the roof surface. The second edge is laid on the roofing material. It is desirable that the tape running along the slope overlap two waves (fig. on the left below). The tape is additionally pressed against the wall with a metal bar of the same color as the roofing material, or to match the wall.
To guarantee “non-leakage”, you can make a strobe in the wall and insert the upper edge of the tape into it, filling the remaining space with frost-resistant silicone. And only then cover the top with a bar.
There is another design option for the side connection, which may not look as aesthetically pleasing, but which is more reliable. The edge of the ondulin sheet is simply wrapped onto the wall and fixed there using a Z-shaped profile. The surface of the profile, which will be adjacent to the wall, is smeared with silicone mastic before fastening. Thus, maximum tightness is achieved.
The main functions of the covering apron are the hermetic connection of Ondulin Tiles with vertical structures (walls, chimneys, ventilation outlets), insulation of sheet joints on the roof ridge and end junctions. The profile completely repeats the wavy shape of the roofing material.
The apron is laid on top of the sheet of roofing material and pressed tightly against it. For a better seal on the wall, you can put a rubber band or a regular manufacturer’s sealant.
The apron is attached to the wall, and then it is also covered with a sealing metal strip (see the figure above). The edge of this strip can be hidden in a strobe by additionally smearing it with frost-resistant silicone or filling the remaining gap with cement mortar.
We make out the ridge of the roof
To design the junction of two planes of the roof, a ridge element is used.
To fasten the element, a wide board or two bars are nailed along the ridge board. The board should have a width that is slightly larger than the length of the shelf of the ridge element. The upper edge of the roofing sheet is nailed to one of its edges (close to the ridge), and the edge of the ridge element is nailed to the second.
Cheaper to nail two bars. The upper one is about 5 cm away from the ridge – the upper edge of the ondulin sheet is attached to it. The lower bar is stuffed at a distance 3-4 cm less than the length of the shelves of the ridge element. If the width of the shelf is 15 cm, then the distance to the second bar will be 11-12 cm. The edge of the covering element is nailed to it.
The ondulin ridge element has a standard length of 100 cm, so several pieces are required. They are laid one on top of the other with an overlap of at least 12,5 cm (some manufacturers recommend at least 15 cm). It is necessary to arrange the ridge elements so that the open joint is directed against the direction of the prevailing wind (so that it does not blow into it).
Connections on a multi-gable roof (valleys)
The junction of the roof planes at an angle is called the valley. It is here that most of the precipitation flows and special attention must be paid to waterproofing. All knots must be well fitted.
If you want more reliability, make a solid flooring in the valley, not a grating one, stick / fuse / nail a rolled waterproofing suitable for outdoor use on it. Coating/liquid waterproofing materials can also be used. Then you can already fill the crate.
There are two variants of the valley device – with and without insulation. In any case, a galvanized and painted plate is laid in place of the bend, along which water will flow. This plate is included in a set of additional elements that can be purchased from the manufacturer of the roofing material. It will definitely have the recommended dimensions (see the laying diagram). But no one will forbid using a third-party one if it has the same parameters.
On a roof without insulation, the plate is laid on the boards, with insulation – directly on a solid flooring or crate. Fastened with nails / self-tapping screws with a waterproofing gasket. They are installed along the long side.
To reduce the risk of leaks, you can additionally fill the caps with washers with silicone.
Start mounting the plates from the bottom, moving up. So the joint will be directed along the drain. The upper fragment covers the lower one with a run-in of at least 20 cm. For reliability, you can coat the joints of the plates with silicone or liquid waterproofing.
Ondulin over slate
You can lay ondulin on top of old roofing materials. On top of a soft roof – on a stuffed crate with the same parameters as when installing a roof from scratch. You can put ondulin on top of slate. But be sure to assemble the crate – the sizes of the waves do not match.
For the crate, bars are laid in the lower part of the wave. Their section is selected so that the upper face is higher than the crest of the slate wave. The maximum distance between the bars is 80 cm. They are fastened through to the base crate with long nails or self-tapping screws.
Cross bars are attached to the longitudinal bars. It can be a board with a thickness of 20 mm. The maximum step is 45 cm. They are fixed with two nails to the bars at each intersection. Ondulin is attached to the crate assembled in this way.
It is possible to increase the slope of the roof without altering the truss system. To do this, additional supports or a board are installed at the top point of the roof. The bars of the secondary crate are already attached to it (see the photo above on the right).