Recommendation points
- What a weird stuff
- Practical application of beams
- Selecting beams and supporting them correctly
- Connection and docking
- Sewing the ceiling
- Thermal insulation and flooring
Among the exotic building solutions, projects with wooden I-beams stand apart. We will help you find out the main features of working with such material, we will touch on the design and assembly of interfloor ceilings on wooden I-beams.
What a weird stuff
The assembly technology for I-beams is quite simple. Imagine a 25ร80 board with one or more longitudinal slots. Two such boards are oriented parallel with grooves to each other. Rectangular OSB plates are inserted into the grooves, the product is glued together and, possibly, filled with polyurethane. Before us is an example of an interesting and bold technological solution, aimed mainly at insulating roofs and floors without cold bridges.
It would seem, why complicate everything and abandon the natural strength of massive and glued beams? Because the use of beams has a number of advantages: accelerated installation, ease of use, sufficiently high-quality insulation of structural and airborne noise. When used correctly, these advantages overlap the relatively high cost of the material, moreover, due to the orientation of the fibers of the central shelf, a wooden I-beam is comparable in reliability with a solid wood.
Practical application of beams
The extensive use of wooden I-beams is obvious from the variety of their types and sizes. After treatment with fire retardants or water repellents, beams acquire additional properties and become suitable for most dry repair projects. On them, in particular, you can build a good and very warm floor, walls, partitions or a rafter system.
Almost immediately after installation, the structure is ready for plasterboard cladding. In addition to gypsum plasterboard, it is not forbidden to use gypsum plaster, shingles and cement plaster or any type of siding.
For example, consider the process of assembling a simple interfloor floor with high density mineral wool filler (120-140 kg / m3) 250 mm thick with a permissible load of 400 kg / m2 and a span of 8 meters.
Selecting beams and supporting them correctly
When using wooden beams on such projects, you have to constantly balance between ensuring the required load-bearing capacity and the own low weight of the floor. When working with a pine beam, a span length of up to 6 meters is allowed, however, 300ร1500 mm beams would be needed, while the maximum deflection would be more than 10 mm.
The I-beams used are 400 mm high with 40ร90 mm flanges and 10 mm thick posts. The free space between the shelves is almost 320 mm, which is quite enough for laying 250 mm of insulation and 15 mm of boards for filing. The center distance of the beams is selected for the width of the insulation, but not less than the recommended one, that is, 40 cm.
When installing beams on load-bearing walls, the depth of the bookmark is at least half the height of the beam, in this case โ 200 mm. Although manufacturers often indicate a shallower depth of bookmark, it is better to ignore such recommendations and play it safe. You should not overdo it either โ with a frequent step of the beams, this negatively affects the strength of the walls. In addition, it is better to leave a bearing layer for such an overlap..
The ends of the beams are coated with bitumen mastic to the depth of the bookmark, installation is carried out only after complete drying. It is better to align the beams immediately ideally, for this they are laid on small bumps of the set cement mortar as on non-removable beacons, and then the position of each I-beam in the common plane is adjusted. After drying, you need to overlay the beams with a crown row and fill up the niches with cement mortar.
Installation of beams on frame walls or self-supporting insulated wires must be accompanied by mechanical fastening. To do this, you can use triangular scarves made of 20 mm plywood or buy metal brackets. The edges of the beams should be recessed from the outer plane of the walls by at least 50 mm and sheathed outside with moisture-resistant plywood.
Connection and docking
There are quite complex floor configurations in which beams can be joined to increase their length or connected at right angles to form lintels. The beams of the main span should not be joined outside the load-bearing walls or columns, but in some cases this may be required, for example, when the ceiling enters the bay window niche.
To connect the beams to one of them, it is necessary to cut the shelves by at least 4 beam heights. The center post is cut to the same distance and the groove is cleaned on the other side. The beam is spliced โโand, if possible, glued with casein glue with the obligatory installation of an oppression of 2-2.5 kgf / cm2. After drying, the joint on both sides is reinforced with butt strips โ one or more boards of 25 mm, well fitted between the shelves. The pads are pulled together with self-tapping screws and screwed to the outer shelves in 20 cm increments.
For rectangular abutment, special steel brackets should be used. The flanges of the adjoining beam must be cut to the depth of entry, while the beam to which the adjoining is performed should remain intact. As for consumables for fastening, you will find them in abundance from manufacturers and distributors of beams, as well as methods for calculating floors, rafter systems and walls, as well as more specific connection methods.
Sewing the ceiling
The next stage is extremely simple: on the lower shelves of a wooden I-beam, a filing board of arbitrary thickness is laid, which is fixed in an arbitrary way. Planks can also be laid with a gap, using a rough board as a support for thermal insulation, especially when it comes to dense materials such as stone wool or EPS. This will slightly reduce the weight of the floor..
Boards should not be fitted too tightly, leave a 3-5 mm gap for deformation during shrinkage. If you want to immediately lay the lining under the varnish, leaving the beams open, take the trouble to isolate the insulation from spilling and weathering, leave a gap at the ends of the laths of at least 2-3 mm.
You can also refuse to bookmark the boards like this and hem the ceiling with, say, chipboard. However, the described approach allows you to avoid downtime: after all, the finished ceiling is not mounted quickly, and you need to use the ceiling.
Thermal insulation and flooring
When laying the insulation, it should be exposed to mechanical stress as little as possible. The remaining gaps and joints of the plates must be filled with polyurethane foam. If there is free space in the ceiling, as in our case, this can lead to the appearance of booming sounds when walking..
The effect is quite typical for wooden I-beams: with a long span, the height exceeds the thickness of the insulation layer. One way to solve the problem is to fill the space with less dense filler, that is, glass wool or foam chips..
A more costly way is to prepare two layers of subfloor. The first is made of edged boards, the second is made of 9-13 mm moisture-resistant plywood. A damping substrate is laid between the layers, and the usual isolon will be enough. At a certain cost, such a floor is really stable and will not โknockโ through.
After laying the heat insulator, it is convenient to carry out a rough electrical installation, performing wiring inside the ceiling on both floors. To do this, it is allowed to make holes in OSB of about 50 mm with a distance between them of at least five diameters.
Can you provide more information on interfloor floors that are constructed on wooden I-beams? How do they differ from other types of floor constructions? Are there any advantages or disadvantages to using this method? What are the recommended materials and installation techniques for interfloor floors on wooden I-beams? Any insights would be greatly appreciated!