We Cover The Roof With Ondulin

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

Pros and cons of ondulin roofing material

Ondulin occupies a special place among the abundance of various modern roofing materials

. And although this material has existed in the construction market of Western Europe and the USA for more than half a century, in our country it has not been used for another twenty years.

Ondulin, one might say, is a distant relative of a very well-known roofing material in our country. Only roofing material is cardboard impregnated with petroleum bitumen, and in ondulin, polyester fabric or fiberglass fabric is used as a reinforcing base, and modified bitumen is used as a waterproof layer. Being modified at the molecular level, bitumen acquires new properties: significantly greater resistance to solar radiation (does not fade, does not deform).

The elasticity of the material increases many times over a wide temperature range, which prevents cracking in frost, increases resistance to atmospheric precipitation and aggressive external environment - it does not rot and does not rust even in the most adverse conditions.

The advantages of ondulin include the relatively low weight: a standard sheet of 950x2000 millimeters weighs six kilograms. The manufacturers of this roofing material give a 15-year warranty, but it serves 50 years or more. With properly laid crate and qualified installation, ondulin is able to withstand significant snow loads - up to 300 kilograms per square meter, as well as gusts of wind up to 192 kilometers per hour.

Ondulin sheets bend quite well along and across the wave. With a radius of curvature of five meters, they can be laid on curved surfaces.

In some respects, ondulin has an advantage over other roofing materials. For example, in comparison with slate, it is four times lighter and more elegant (four colored types, versus one gray). In addition, ondulin does not contain environmentally hazardous asbestos.

If we compare it with a black iron and galvanized steel roof, then it does not oxidize, does not heat up, does not make noise when it rains. Compared to profiled sheet and metal tiles, ondulin is somewhat cheaper (albeit quite a bit). There is several times less condensation under it, which has a positive effect both on the condition of the under-roof space and on the rafters and lathing.

In addition, a continuous crate is not always required for laying ondulin, since the small weight of the sheets eliminates the need to strengthen it. But when installing slate or ceramic tiles, this is necessary. Ondulin can be easily cut into several parts, thus combining colors. This allows you to give the roof a harmonious look, suitable for a single architectural style of any buildings on the site. Moreover, all these manipulations do not in any way affect the waterproofing properties of ondulin.

The advantages of ondulin include the fact that for the complete installation of most types of roofs, there are almost all additional parts, such as special ridge and gable elements, valleys covering aprons, roof fans, ventilation pipes and combs, as well as various self-adhesive insulating tapes.

But along with the advantages of ondulin, there are also obvious disadvantages. Firms - manufacturers and sellers, praising this roofing material in every possible way, prefer to keep silent about some of them.

First of all, it must be said that the sheets of ondulin are easily crumpled even under light loads, so you should be extremely careful to move along them during installation. Standing on them in full growth is completely impossible, otherwise dents inevitably appear on the waves, which remain forever. No amount of tricks will help eliminate them.

When cutting material with any tool, uneven edges are inevitably formed, which, due to the viscosity of the bitumen, cannot be processed. It is very difficult to evenly adjust the overlaps of the sheets, since ondulin does not have hard, well-defined edges.

Special attention should be paid to special nails with which the sheets of ondulin are attached to the crate. The disadvantages of using them begin with their preparation for use. Since the metal nail and the plastic washer with the cap are separately in the package, when pushing the nail into the hole of the plastic washer, it keeps getting stuck due to the thread applied to it. It should not be forgotten that this procedure takes place on the roof. If this manipulation is done in advance, then working with a nail sticking out of the washer is very inconvenient.

Another problem is the use of nails directly when installing ondulin sheets on the roof. First, I will give literal instructions for the correct use of nails: “In order for the plastic head of the nail to snap into place, the nail must be driven properly:

• if you do not finish off the nail, its metal head will interfere with the plastic cap;
• if you hit the nail too hard, you run the risk of deforming the plastic washer, which can prevent you from snapping the plastic cap …”.

This is the essence of all the troubles, since the mistakes (even the slightest inaccuracies) cannot be corrected. When hammering in a nail, exceptional accuracy is required, since it is impossible to pull out an incorrectly driven nail, because the soft surface of the ondulin will be irretrievably damaged with all the ensuing negative consequences.

And how to achieve the required accuracy, for example, when laying sheets on steep roof slopes or when spans more than one meter, or even on a slightly vibrating crate? A very serious problem. Any mistake when hammering in a nail will turn into serious trouble, which makes the installation of sheets very, very difficult.

None of the manufacturing companies even mentions the degree of fire resistance of ondulin, and the bitumen included in it is a very flammable material. Sellers could not clearly answer this question.

Another, in my opinion, drawback, although not significant, is the poverty of the ondulin light range. There are four colors in total: red, brown, green, black. And all these are dark, difficult for visual perception of tones.

Laying ondulin

Now, if, after discussing all the pros and cons, you still chose ondulin, we proceed to laying it on the roof. This operation is actually not too complicated and not very laborious, if not for the nails … But I already repeat myself!

We start, of course, with the lathing device. If the angle of inclination is from 5 to 10 degrees, a solid sheathing of boards or thick plywood is required. The end overlap in this case is 300 millimeters, the side overlap is two waves. At an angle of inclination of the roof from 10 to 15 degrees, a lathing is constructed with an interval of 450 millimeters along the axes. The end overlap is 200 mm, the side overlap is one wave. At an angle of inclination of the roof from 15 degrees and above, a crate is arranged with an interval of 600 millimeters along the axes. The end overlap is 170 mm, the side overlap is one wave.

For the convenience of laying the sheets of ondulin, the lathing bars should be nailed to the rafters along the axes at the same distance from each other. That is, strictly parallel. For this it is desirable to make a template (Fig. 1). It is more practical to mark the sheets with colored pencils, since chalk, for example, is quickly erased. For more accurate marking, you can use a sheet cut of the same ondulin (Fig. 2).

You can cut the sheets with a hacksaw on wood (preferably with large teeth) lubricated with any technical oil so that the teeth do not get stuck in the cuts.

The sheets should be started from the edge of the roof opposite to prevailing winds. Although I believe that this is not necessary at all. The second row begins with laying half of the sheet (Fig. 3) so that there is an overlap of three rather than four sheets at the corner joint. This makes styling much easier.

Ondulin sheets are nailed to the crate along each wave at the end of the sheet and the end overlap, as well as on both sides of the side overlap. The rest of the sheet is nailed through one wave to the intermediate battens of the lathing (Fig. 4). To fix one sheet you need 20 nails. To fasten the sheets of ondulin to the metal base, special self-tapping screws are used - stelfix.

Practical advice. If it happens that the plastic cap, despite all efforts, does not snap into place (damaged or distorted), then do so. Unfold the plastic washer (fig. 5, position a), with its free part towards the slope. Then press the plastic washer against it as tightly as possible and gently drive a regular thin nail into it (Fig. 5, position b). To eliminate possible leaks, grease the cap of the clogged stud with any waterproof glue.

The fastening of the ridge elements should also start from the opposite side of the prevailing winds. The overlap should be 125 millimeters. For the correct design of the roof rib, use gable or ridge elements. It is necessary to nail them on each wave of the sheet joining them.

For the design of valleys (valley - the space between two roof slopes forming an incoming angle), for example, a side joint with a chimney or a dormer window, special ondulin valleys are required. An additional lathing is required to fasten the valleys.

It is possible to waterproof the roof joint with the same chimney, with a roof window and other superstructures on the roof using self-adhesive unduflesh tapes. It is best to use the lining material ondutis as a vapor barrier.

To close the gaps of the sheets on the cornice and the gaps between the ridge elements and the ondulin sheets, so that birds and debris do not penetrate there, relief strips (special plugs) are used (Fig. 6).