Which beam to choose for rafters

When designing your roof structure, selecting the appropriate beam for your rafters is essential. Important parts of a roof structure, rafters support and evenly distribute the weight of the roof covering. The beam you choose must guarantee structural integrity and be able to support the weight of the roof.

When selecting rafters beams, there are a number of things to take into account. The kind of material matters a lot; you can use steel, wood, or engineered lumber, such as laminated veneer lumber (LVL). Every material has particular advantages and disadvantages in terms of price, weight, and environmental effect.

Because they are readily available, reasonably priced, and simple to handle, wood beams are a traditional and popular choice for rafters. They are available in a variety of forms, including engineered wood goods like glulam beams that provide increased strength and stability and solid sawn lumber.

Because of their strength and longevity, steel beams are a good choice for areas with high snow loads or for spans that are longer in length. Although they are pest and moisture resistant, thermal expansion and conductivity must be carefully taken into account.

Wood fibers and adhesives are combined in engineered lumber, such as LVL beams, to produce a strong, stable beam that can frequently span greater distances than traditional lumber. Its consistent strength and size are engineered to minimize waste and guarantee dependable performance.

You must determine the weight of the roof material, the span between supports, possible snow loads, and other environmental considerations before choosing the size of the beams. Ensuring compliance and safety can be achieved by consulting structural engineers and local building codes.

Selecting the appropriate beam for your rafters is essential for maintaining the roof’s structural soundness and lifespan. Depending on the requirements for span, load-bearing capacity, and environmental factors, various types of beams, including steel, engineered wood, and solid wood, offer different advantages. You can choose a roof that not only satisfies building codes but also endures over time by being aware of the features of each type of beam and evaluating your own requirements.

When the rafters are better to make from the beam?

Boards are the typical rafter material. They are less expensive, simpler to install, and easier to process. However, there are instances in which using a beam for rafters makes sense. Here are a few of them:

1. When composite rafters from the boards can be replaced with a whole beam. The most reliable node of the rafter system is one that is not. Therefore, any unnecessary connections should be avoided.
2. When replacing the rafters of the old roof, if you want to cover it with a heavier roofing material. In this case, the height of the rafter legs cannot be increased, it remains only to increase their width.
3. If the quality of available boards is bad, but there is an opportunity to buy a good beam for a rafter system. This situation is not uncommon in areas remote from large cities.
4. When you need to guarantee to avoid shrinkage of the rafter system. Glued boards also exist, but they are not used to create supporting structures. Unlike glued beams.
5. When placing a roof without Mauerlat. The rafters from the beam have more the area of ​​the end, so the point load on the armo -piles is smaller.

Furthermore, the beam is employed as a decorative material for rafters. In open rafter systems, a massive beam looks better than thin boards. Particularly with regard to homes designed in the rustic or chalet styles.

Which beam is used for the roof: standards requirements

Supporting structural elements are called rafters. As a result, building standards govern what is needed for them. The principal ones are SP 64.13330.2017 "Wooden structures" and GOST 20850-2014 "DEVELOPS BLOW WORRED BEARD."

These documents state that the following materials ought to be on the wood rafters:

1. Well dried. The maximum moisture content of wood for supporting structures is 12%, but it is better if the humidity is 8% or less. Otherwise, an unimportant beam under load can be distorted, which will not affect its strength in the best way.
2. Selected or first grade. Only minor vices of wood are permissible: fused bitches that occupy no more than a third of width, core, prophecy. Material for roof rafters with more serious defects cannot be used. Such defects include reviews, wormholes, warping, unexplored and rotten knots, fungal lesions, etc.
3. Treated antiseptic and fire protection. It is desirable that the beam is saturated with antipyrene. It is good if the wood was loaded into a special bath – this gives a more reliable protection against fire. But for private houses, superficial processing is permissible.

Despite the fact that there are just three requirements, most people break them when building their homes. For instance, they purchase raw lumber for rafters in addition to irrelevant materials.

Two reasons are that they are not always available for purchase and that the lumber is well-dried. The savings will be conditional if you make rafters out of such a bar; a small reduction in construction costs annually could easily result in a significant roof renovation within a few years. particularly in the northern areas that have a lot of snowfall.

Rules of "smart" savings when buying a beam for rafters

Savings is not inherently flawed. All that needs to be done is to do this without endangering your strength and bearing capacity.

Observe these guidelines:

1. Choose lumber personally. The division of wood into varieties in the warehouses of lumber is quite conditional, therefore, in the second grade there is a bars that is quite suitable for rafters. You just need to find it.
2. Share critical defects and those that can be eliminated. In particular, wormholes, fungus, warping, through cracks are a marriage, you cannot let such a beam on the rafters. The opposite example is the review. If there is little bark, you can just clean it from the edges.
3. Buy cheap raw or poorly dried beams in advance and dry it for a year or two on your site. There is nothing complicated: just fold the beam in several rows, shifting them smaller bars for ventilation, and cover with tarpaulin to protect from the rain.

There are more general guidelines for saving money: take advantage of sales, purchase materials in bulk and off-season to receive a discount, and attempt to cut down on the number of middlemen between you and the manufacturer. If you have the chance, purchasing a forest straight from a sawmill is the best option.

Which beam is used for rafters: four selection criteria

The selection of rafters is not limited to meeting the three fundamental standards requirements. You also need to consider the beam’s size, look, breed, and variety of wood in addition to these factors.

Dimensions for rafters

For rafters, a beam typically measuring 100 x 100 mm or 100 x 150 mm is utilized. Rafts with this cross section have a high bearing capacity without being unduly heavy. Larger bars are rarely used because they heavily load the foundation. Additionally, because of its heavy weight, it is very difficult to lift on the roof and place by hand; a crane is required.

Type of timber

Three varieties of wood exist:

• whole;
• calibrated;
• glued.

Entire beam the most typical. They understand—just cutting a log. Just natural drying without any further processing. As a result, a complete beam is cheap and accessible and can be purchased in any town or city.

Calibrated beam Acquire the entire. All of these wood varieties are identical except for one extra processing step. You can use it to compare the size of the beam because it is processed on a specialized machine during that time. This indicates that there will be a deviation of a few centimeters between the cross section of the calibrated timber and the declared value, measured in millimeters. As a result, rafters work well with calibrated beams because they make it simple to remove the upper edges of the rafter legs from the plane.

The most glued beam. These are a few lamellas that have been adhered to one another so that the fiber orientations on adjacent boards differ. Given that glued beams do not warp or settle, this is the ideal material for rafters. However, because it is so expensive, they hardly ever use it.

Three main woods

In Russia, the following materials are typically used for the rafter system:

1. Pine. Construction classics, which gained popularity due to high strength, low price and prevalence. If you do not know which beam is used for roof rafters, take pine – you will not be mistaken.
2. Spruce. Less targeted, but more knotted wood. A good option for Mauerlat, but not for rafters: spruce wood is worse than pine holds the load on the bend.
3. Larch. Excellent strong wood, which in everything won by pine and spruce, except for one – prices. This is an expensive material, so use it not for rafters, but for finishing. This is more meaning.

Unusual choices such as rafters constructed from priceless woods like oak, fir, ash, and others are also acceptable. However, if the behavior of a pine tree under load is known, well, almost entirely, then not much is known about these rocks. As a result, there will need to be a larger margin of safety when calculating. Furthermore, these are substantial extra expenses.

Variety of wood

In accordance with the standard classification, wood comes in five varieties. Merely three of these are used for rafters and other supporting structures that go to the beam:

1. Selected variety – This is wood virtually without knots. There should be no more than two per meter. A selected beam is expensive, so it rarely goes to rafters.
2. First grade – Best material for rafters. Of the defects, only prophecy and core are allowed, as well as knots – healthy and partially fused, up to four pieces per meter.
3. The second variety – inexpensive wood, which is suitable for the crate and other poorly loaded elements of the rafter system. Bacterial and fungal foci are added to the permissible defects indicated earlier.

Before being used, second-grade wood with fungal lesions needs to be treated. Fluids containing chlorine are typically used for this. We refer to this procedure as whitening.

Selecting the appropriate beam for your rafters is essential to the longevity and steadiness of your roof. The choice is primarily based on the load and span specifications for your roof structure. Solid wood beams are an easy and affordable option for shorter spans and lighter loads. They are reasonably simple to install and offer sufficient durability and strength.

The advantages of engineered wood beams are particularly noticeable for longer spans or heavier loads. Because glulam beams and laminated veneer lumber (LVL) are designed to be stronger and more stable than solid wood, they can support larger roof areas without the need for intermediate supports. Because these beams are produced under carefully regulated circumstances, their performance and quality are always guaranteed.

Think about the roof design, local building codes, and weather conditions when selecting a beam. To ascertain the suitable beam size and type for your unique roof requirements, it is imperative that you speak with a structural engineer or other qualified professional. This guarantees that your roof will function well for the duration of its intended life in addition to meeting structural requirements.

In the end, the type of beam you use for rafters affects your roofing project’s cost-effectiveness and structural integrity. Through meticulous evaluation of span, load capacity, and environmental considerations, you can choose the ideal beam to ensure a sturdy and long-lasting roof that raises the overall safety and value of your house or structure.

Video on the topic

What wood is suitable for construction. Says the Construction Company Center for Housebuilding.

When it is profitable to buy a forest, lumber. How to choose and store boards and a beam for the roof in winter

Choosing and preparing forests for rafters.Processing of roof boards. Antiseptic