Calculation of the gable roof truss system calculator. Calculation of the truss system - we make the roof reliable
Specify the parameters of wooden rafters:
B- rafter width, important parameter defining reliability truss system. The required section of the rafter (in particular, the width) depends on: loads (constant - the weight of the crate and roofing cake, as well as temporary - snow, wind), the material used (quality and type: board, timber, glued laminated timber), length rafter leg, the distance between the rafters. You can determine the approximate cross-section of a beam for rafters using the table data (the width value is greater value from 3 columns, for example, with a rafter length of up to 3000 mm and a step of 1200 mm, the desired width value is 100 mm). When choosing the width of the rafter, be sure to take into account the recommendations induced in SP 64.13330.2011 " wooden structures” and SP 20.13330.2011 “Loads and impacts”.
| Rafter length, mm | Rafter pitch, mm | Rafter section, mm |
| up to 3000 mm | 1200 | 80x100 |
| up to 3000 mm | 1800 | 90x100 |
| up to 4000 mm | 1000 | 80x160 |
| up to 4000 mm | 1400 | 80x180 |
| up to 4000 mm | 1800 | 90x180 |
| up to 6000 mm | 1000 | 80x200 |
| up to 6000 mm | 1400 | 100x200 |
Y- roof height, distance from the ridge to the attic floor. Affects the angle of inclination of the roof. If it is planned to arrange non-residential attic, you should choose a small height (required less material for rafters, waterproofing and roofing), but sufficient for inspection and maintenance (at least 1500 mm). If it is necessary to equip a dwelling under a roof arch, to determine its height, it is necessary to focus on the height of the tallest family member plus 400-500 mm (approximately 1900-2500 mm). In any case, the requirements of SP 20.13330.2011 (updated edition of SNiP 2.01.07-85*) must also be taken into account. It should be remembered that precipitation can linger on a roof with a small angle of inclination (small height), which negatively affects its tightness and durability. However, a high roof becomes more vulnerable to gusts strong wind. The optimal angle of inclination is in the range of 30-45 degrees.
X– The width of the roof (without overhangs) is determined by the width of the outer perimeter of your house.
C- the size of the overhang, an important structural element of the roof that protects the walls and foundation from precipitation, is determined taking into account the climatic conditions of your region (SP 20.13330.2011) and the general architectural idea. For one and two-storey houses without organization of external water flow not less than 600 mm. If you arrange a drainage system, you can reduce it to 400 mm (SNB 3.02.04-03). According to the requirements of IRC-2012, paragraph R802.7.1.1 (International Building Code for 1-2 apartment individual residential buildings), the maximum length of the free overhang of the rafters, which does not require the arrangement of additional support struts, is 610 mm. The optimal overhang value is 500 mm.
Z- this is the distance from the top edge of the rafter to the saw. The size Z connected with the width of the rafter by a simple ratio - no more than 2/3 of its width (neglect of this rule significantly reduces bearing capacity rafters). Washed down is necessary for attaching the rafters to the Mauerlat - a support that takes the load from the roof and redistributes it to the load-bearing walls.
By checking the "Black and white drawing" item, you will receive a drawing close to the requirements of GOST and you can print it without wasting colored paint or toner.
Calculation results:
Rafter overhang length- this size should be used to mark the washed down rafters to the Mauerlat.
Overhang length will show how far it is necessary to extend the rafter beyond the perimeter of the house to obtain a given roof overhang ( WITH) weatherproof.
Calculating the total length of the rafter and overhang not hard to find out required amount lumber of the required length and estimate how much reagents are needed to treat wood from decay.
Calculation of the angle and section of the rafters: cut angle - this is the angle at which it is necessary to cut the ends of the rafters to connect them together. At the same angle to the edge of the rafter, the beginning of the gash should be measured. To maintain the same angle washed down on all rafters, it is desirable to use a template.
-> Calculation of the truss systemThe main element of the roof, perceiving and resisting all types of loads, is rafter system. Therefore, in order for your roof to reliably resist all influences environment, it is very important to make the correct calculation of the truss system.
For self-calculation of the characteristics of the materials necessary for the installation of the truss system, I give simplified calculation formulas. Simplifications are made in the direction of increasing the strength of the structure. This will cause some increase in the consumption of lumber, but on small roofs of individual buildings it will not be significant. These formulas can be used when calculating gable attic and mansard, as well as shed roofs.
Based on the calculation methodology below, programmer Andrey Mutovkin (Andrey's business card - Mutovkin.rf) developed a truss system calculation program for his own needs. At my request, he generously allowed me to post it on the site. You can download the program.
The calculation methodology was compiled on the basis of SNiP 2.01.07-85 "Loads and impacts", taking into account the "Changes ..." of 2008, as well as on the basis of formulas given in other sources. I developed this technique many years ago, and time has confirmed its correctness.
To calculate the rafter system, first of all, it is necessary to calculate all the loads acting on the roof.
I. Loads acting on the roof.
1. Snow loads.
2. Wind loads.
On the truss system, in addition to the above, the load from the roof elements also acts:
3. Roof weight.
4. The weight of the rough flooring and lathing.
5. The weight of the insulation (in the case of an insulated attic).
6. The weight of the rafter system itself.
Let's consider all these loads in more detail.
1. Snow loads.
To calculate the snow load, we use the formula:
Where,
S - the desired value of the snow load, kg / m²
µ is a coefficient depending on the slope of the roof.
Sg - normative snow load, kg/m².
µ - coefficient depending on the slope of the roof α. Dimensionless value.
You can approximately determine the angle of the roof slope α by the result of dividing the height H by half the span - L.
The results are summarized in the table:
Then if α is less than or equal to 30°, µ = 1 ;
if α is greater than or equal to 60°, µ = 0 ;
if 30° is calculated by the formula:
µ = 0.033 (60-α);
Sg - normative snow load, kg/m².
For Russia, it is accepted according to map 1 of mandatory annex 5 of SNiP 2.01.07-85 "Loads and impacts"
For Belarus, the normative snow load Sg is determined
Technical code of GOOD PRACTICE Eurocode 1. EFFECTS ON STRUCTURES Part 1-3. General impacts. Snow loads. TCH EN1991-1-3-2009 (02250).
For instance,
Brest (I) - 120 kg/m²,
Grodno (II) - 140 kg/m²,
Minsk (III) - 160 kg/m²,
Vitebsk (IV) - 180 kg/m².
Find the maximum possible snow load on a roof with a height of 2.5 m and a span of 7 m.
The building is located in the village. Babenki, Ivanovo region RF.
According to map 1 of the mandatory annex 5 of SNiP 2.01.07-85 "Loads and impacts", we determine Sg - the standard snow load for the city of Ivanovo (IV district):
Sg=240 kg/m²
We determine the angle of the roof slope α.
To do this, we divide the height of the roof (H) by half the span (L): 2.5 / 3.5 \u003d 0.714
and according to the table we find the slope angle α=36°.
Since 30° , calculation µ will be produced according to the formula µ = 0.033 (60-α) .
Substituting the value α=36° , we find: µ = 0.033 (60-36)= 0.79
Then S \u003d Sg µ \u003d 240 0.79 \u003d 189 kg / m²;
the maximum possible snow load on our roof will be 189kg/m².
2. Wind loads.
If the roof is steep (α > 30°), then because of its windage, the wind presses on one of the slopes and tends to overturn it.
If the roof is flat (α, then the lifting aerodynamic force that occurs when the wind bends around it, as well as turbulence under the overhangs, tend to raise this roof.
According to SNiP 2.01.07-85 "Loads and actions" (in Belarus - Eurocode 1 IMPACTS ON STRUCTURES Part 1-4. General actions. Wind actions), the standard value of the average component of the wind load Wm at a height Z above the ground should be determined by the formula :
Where,
Wo - normative value of wind pressure.
K is a coefficient that takes into account the change in wind pressure along the height.
C - aerodynamic coefficient.
K is a coefficient that takes into account the change in wind pressure along the height. Its values, depending on the height of the building and the nature of the terrain, are summarized in Table 3.
C - aerodynamic coefficient,
which, depending on the configuration of the building and the roof, can take values from minus 1.8 (the roof rises) to plus 0.8 (the wind presses on the roof). Since our calculation is simplified in the direction of increasing strength, we take the value of C equal to 0.8.
When building a roof, it must be remembered that wind forces tending to lift or tear off the roof can reach significant values, and therefore the bottom of each rafter leg must be properly attached to the walls or to the mats.
This is done by any means, for example, using annealed (for softness) steel wire with a diameter of 5 - 6 mm. With this wire, each rafter leg is screwed to the mats or to the ears of the floor slabs. It's obvious that the heavier the roof, the better!
Determine the average wind load on the roof one-story house with the height of the ridge from the ground - 6m. , slope angle α=36° in the village of Babenki, Ivanovo Region. RF.
According to map 3 of application 5 in "SNiP 2.01.07-85" we find that Ivanovo region refers to the second wind region Wo= 30 kg/m²
Since all buildings in the village are below 10m, coefficient K= 1.0
Meaning aerodynamic coefficient C is taken equal to 0.8
standard value of the average component of the wind load Wm = 30 1.0 0.8 = 24 kg / m².
For information: if the wind blows at the end of this roof, then a lifting (tearing) force of up to 33.6 kg / m² acts on its edge
3. Roof weight.
Different types of roofing have the following weight:
1. Slate 10 - 15 kg/m²;
2. Ondulin ( bituminous slate) 4 - 6 kg/m²;
3. Ceramic tiles 35 - 50kg/m²;
4. Cement-sand tiles 40 - 50 kg/m²;
5. Bituminous tiles 8 - 12 kg/m²;
6. Metal tile 4 - 5 kg/m²;
7. Decking 4 - 5 kg/m²;
4. The weight of the rough flooring, lathing and truss system.
Draft flooring weight 18 - 20 kg/m²;
Lathing weight 8 - 10 kg/m²;
The weight of the rafter system itself is 15 - 20 kg / m²;
When calculating the final load on the truss system, all of the above loads are summed up.
And now I will reveal to you little secret. Sellers of some types of roofing materials note their lightness as one of the positive properties, which, according to them, will lead to significant savings in lumber in the manufacture of the truss system.
As a refutation of this statement, I will give the following example.
Calculation of the load on the truss system when using various roofing materials.
Let's calculate the load on the truss system when using the heaviest (Cement-sand tile
50 kg / m²) and the lightest (Metal tile 5 kg / m²) roofing material for our house in the village of Babenki, Ivanovo region. RF.
Cement-sand tiles:
Wind loads - 24kg/m²
Roof weight - 50 kg/m²
Lathing weight - 20 kg/m²
Total - 303 kg/m²
Metal tile:
Snow loads - 189kg/m²
Wind loads - 24kg/m²
Roof weight - 5 kg/m²
Lathing weight - 20 kg/m²
The weight of the truss system itself is 20 kg / m²
Total - 258 kg/m²
It is obvious that the existing difference in design loads (only about 15%) cannot lead to any tangible savings lumber.
So, with the calculation of the total load Q acting on square meter We got the roof!
I especially draw your attention: when calculating, carefully follow the dimension !!!
II. Calculation of the truss system.
truss system consists of separate rafters (rafter legs), so the calculation is reduced to determining the load on each rafter leg separately and calculating the section of a separate rafter leg.
1. Find the distributed load on running meter each rafter leg.
Where
Qr - distributed load per linear meter of the rafter leg - kg / m,
A - distance between rafters (rafter pitch) - m,
Q - total load acting on a square meter of roof - kg / m².
2. We determine in the rafter leg the working section of the maximum length Lmax.
3. We calculate the minimum cross section of the material of the rafter leg.
When choosing a material for rafters, we are guided by a table of standard sizes of lumber (GOST 24454-80 Softwood lumber. Dimensions), which are summarized in Table 4.
| Board thickness - section width (B) | Board width - section height (H) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 16 | 75 | 100 | 125 | 150 | |||||
| 19 | 75 | 100 | 125 | 150 | 175 | ||||
| 22 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | ||
| 25 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 32 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 40 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 44 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 50 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 60 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 75 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 100 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 | |
| 125 | 125 | 150 | 175 | 200 | 225 | 250 | |||
| 150 | 150 | 175 | 200 | 225 | 250 | ||||
| 175 | 175 | 200 | 225 | 250 | |||||
| 200 | 200 | 225 | 250 | ||||||
| 250 | 250 |
A. We calculate the cross section of the rafter leg.
We set the width of the section arbitrarily in accordance with the standard dimensions, and the height of the section is determined by the formula:
H ≥ 8.6 Lmax sqrt(Qr/(B Rbend)), if the slope of the roof α
H ≥ 9.5 Lmax sqrt(Qr/(B Rbend)), if the roof pitch α > 30°.
H - section height cm,
B - section width cm,
Rizg - resistance of wood to bending, kg / cm².
For pine and spruce Rizg is equal to:
Grade 1 - 140 kg / cm²;
Grade 2 - 130 kg / cm²;
Grade 3 - 85 kg / cm²;
sqrt - square root
B. We check whether the deflection value fits into the standard.
The normalized deflection of the material under load for all roof elements should not exceed the value L / 200. Where, L is the length of the working area.
This condition is satisfied if the following inequality is true:
3.125 Qr (Lmax)³/(B H³) ≤ 1
Where,
Qr - distributed load per linear meter of the rafter leg - kg / m,
Lmax - working section of the rafter leg of maximum length m,
B - section width cm,
H - section height cm,
If the inequality is not met, then increase B or H .
Condition:
Roof slope angle α = 36°;
Rafter pitch A = 0.8 m;
The working section of the rafter leg is maximum length Lmax = 2.8 m;
Material - pine 1 grade (Rizg = 140 kg / cm²);
Roof - cement-sand tiles (Roof weight - 50 kg / m²).
As it was calculated, the total load acting on a square meter of the roof is Q \u003d 303 kg / m².
1. We find the distributed load per linear meter of each rafter leg Qr=A·Q;
Qr=0.8 303=242 kg/m;
2. Let's choose the thickness of the board for the rafters - 5cm.
We calculate the cross section of the rafter leg with a section width of 5 cm.
Then, H ≥ 9.5 Lmax sqrt(Qr/B Rbend), since the slope of the roof α > 30°:
H ≥ 9.5 2.8 sqrt(242/5 140)
H ≥15.6 cm;
From the table of standard lumber sizes, select a board with the nearest section:
width - 5 cm, height - 17.5 cm.
3. We check whether the deflection value is within the standard. For this, the inequality must be observed:
3.125 Qr (Lmax)³/B H³ ≤ 1
Substituting the values, we have: 3.125 242 (2.8)³ / 5 (17.5)³ = 0.61
Meaning 0.61, then the cross section of the material of the rafters is chosen correctly.
The cross section of the rafters, installed in increments of 0.8 m, for the roof of our house will be: width - 5 cm, height - 17.5 cm.
Online calculator gable roof, also called gable, will help you calculate the desired angle of inclination of the slopes, determine the cross section and number of rafters, the amount of materials per crate, the consumption of insulating materials, and at the same time take into account existing standards for wind and snow loads. You do not have to perform unnecessary additional calculations, because in this calculator most of the existing roofing materials are present.
You can easily calculate the consumption and weight of such common materials as shingles, cement-sand and ceramic tiles, metal tiles, bituminous and asbestos-cement slate, ondulin and others. If you are using a non-standard material, or want to get more accurate calculations, you can specify the weight of your own roofing material by selecting the appropriate item in the drop-down list of materials. The calculator makes calculations according to the current SNiP "Loads and impacts" and TCP 45-5.05-146-2009.
Specify roofing material:
Select a material from the list -- Slate (corrugated asbestos-cement sheets): Medium profile (11 kg/m2) Slate (corrugated asbestos-cement sheets): Reinforced profile (13 kg/m2) Corrugated cellulose-bitumen sheets (6 kg/m2) Bituminous (soft , flexible) tiles (15 kg/m2) Galvanized sheet metal (6.5 kg/m2) Sheet steel (8 kg/m2) Ceramic tiles (50 kg/m2) Cement-sand tiles (70 kg/m2) Metal tiles, corrugated board (5 kg/m2) Keramoplast (5.5 kg/m2) Seam roof (6 kg/m2) Polymer-sand tile (25 kg/m2) Ondulin (Euro slate) (4 kg/m2) Composite tile (7 kg/m2) ) Natural slate (40 kg/m2) Specify the weight of 1 square meter of coating (? kg/m2)
kg/m2
Enter roof parameters:
Base Width A (cm)
Base length D (cm)
Lift height B (cm)
Length of side overhangs C (cm)
Front and rear overhang length E (cm)
Rafter:
Rafter step (cm)
Type of wood for rafters (cm)
Working section of the side rafter (optional) (cm)
Lathing calculation:
Purlin board width (cm)
Lathing board thickness (cm)
Distance between decking boards
F(cm)
Calculation results
Roof pitch: 0 degrees.
The angle of inclination is suitable for this material.
The angle of inclination for this material is desirable to increase!
It is desirable to reduce the angle of inclination for this material!
Roof surface area: 0 m2.
Approximate weight of roofing material: 0 kg.
Number of rolls of insulation material with 10% overlap (1x15 m): 0 rolls.
Rafter:
Load on the truss system: 0 kg/m2.
Rafter Length: 0 cm
Number of rafters: 0 pcs
Lathing:
Number of rows of lathing (for the entire roof): 0 rows.
Uniform distance between the boards of the crate: 0 cm
Number of batten boards standard length 6 meters: 0 pcs
Volume of boards of an obreshetka: 0 m 3 .
Approximate weight of the boards of the crate: 0 kg.
General information about the gable roof
A gable roof (there are variants of the name "gable roof" and "gable roof") - the most common type of roof, in which there are two inclined slopes from the ridge to the outer walls of the structure. The popularity of this type of roof is due to their moderate cost, ease of construction, good operational qualities and attractive appearance.
In this design, the rafters different rays they lean against each other in pairs and are sheathed with boards of the crate. The end of a building with a gable roof has a triangular shape and is called a pediment (the name “tongue” is also found). Usually, under the slopes of the roof there is an attic space, naturally lit by small window openings located at the top of the gables.
Additional information about the calculation results
Roof slope- at this angle, the slope and rafters are inclined to the base of the roof. Roofing materials have individual limiting roof slope angles, so some materials may have an angle outside allowable norms. Whether your angle satisfies the selected material or not - you will find out in the calculation results. In any case, it is always possible to adjust the height of the roof (B) or the width of the base (A), or choose a different roofing material.
Roof surface area- the area of the entire surface of the roof, including overhangs. To determine the area of one slope, it is enough to divide the resulting value by two.
Approximate weight of roofing material- the weight of the selected roofing material based on the total area of \u200b\u200bthe roof (including overhangs).
Number of rolls of insulating material- the amount of insulating material necessary for the construction of the roof. The quantity indicated in rolls is required for the entire roof area. The standard roll is taken as a basis - 15 meters in length, 1 meter in width. The calculation also takes into account an overlap of 10% at the joints.
- the maximum weight per truss system. Wind and snow loads, the angle of inclination of the roof, as well as the weight of the entire structure are taken into account.Rafter length- the total length of the rafters from the roof ridge to the edge of the slope.
Number of rafters- the total number of rafters required for the rafter system at a given step.
Minimum cross-section of rafters / Weight of rafters / Timber volume
- The first column shows the sections of the rafters according to GOST 24454-80 Softwood lumber. Here are the sections that can be used in the construction of a given structure. The calculator proceeds from the total loads that can affect the structure of a given roof and selects the cross-sections that satisfy them.
- The second column shows the total weight of all rafters with the specified section, if they are used to build a given roof.
- The third column shows the total volume of this timber in cubic meters. This amount will be useful to you when calculating the cost.
Number of rows of battens- the number of rows of lathing that will be needed for the entire roof with given parameters. To calculate the number of rows of crates of one slope, you need to divide the resulting value by two.
Uniform spacing between boards- the distance that it is recommended to maintain between the boards of the battens in order to optimize the consumption of material and do without trimming it.
The volume of boards of the crate- the total volume of the crate for a given roof. This value will help you calculate the cost of lumber.
Approximate weight of batten boards- the total weight of the entire crate.
Properly selected and mounted roof will withstand any weather vagaries and will last for decades. What will be the roof country house, and what materials it will consist of, is determined at the design stage. It is better to entrust the technical nuances of design to professionals. Before making a final choice, the future owner needs to get an idea about the features various kinds roofs and (importantly) about the amount that the chosen design and roofing material will cost. At this stage, a roofing calculator will help you calculate the material for a gable roof, or any other - this is a quick way to get a detailed answer.
The calculator will help you estimate the cost of a roof in the early stages of planning
Online roof calculator
To find out the approximate cost of a roof, of various types, use the following calculator:
Calculation parameters for roofs and roofing material
Before calculating the roof of the house, the calculator will request certain data. One of them is the type of roof. There are two criteria by which you can determine the type of roof: the angle of the roof and the number of slopes (planes). If the angle of the roof zero, the roof is called flat, if more than zero - pitched. Pitched structures, in turn, are divided into types, depending on the number of slopes. In private low-rise construction, several types of roofs are common, including:
Shed. It looks rather modest, but the simplest constructively and the least expensive in construction. It is a plane supported by walls of different heights. shed roof can be seen on the garage, shed or modern project in high-tech style. Such constructions are described by a small number of parameters and are calculated for all online calculator Oh.
Common forms of pitched structures
Gable (gable). The most common classic version with two rectangular inclined planes connected by a ridge, and a centuries-old history. The vertical triangular planes between the slopes are called gables (tongs). In modern private construction, the symmetry of the slopes is an optional condition. They can have a different slope and vary in size (broken lines), which opens up great design possibilities. roof structures. A gable roof is ideal for an attic. For calculations on the online calculator, parameters such as the length and width of the slopes, the length of the overhangs and the height of the structure are used.
Hip (four-slope). The main slopes are called hips and look like trapeziums, and the pediments are located not vertically, but at an angle, turning into slopes. hip system much more difficult to design and install than the previous ones, but this is offset by increased structural stability. In addition, the hip roof allows you to raise the ceiling for the attic, making it much more comfortable. Payment hip roof on the online calculator certain subtleties(the base can be square or rectangular) and includes the angle of inclination of the slopes.
Multi-forceps. A complex structure consisting of several tongs (gable elements). The calculation of such a roof is a job for an experienced architect. There are online calculators that calculate the roof area of a three-gable roof, but they give a very approximate calculation result.
The complexity of the truss system of a multi-gable roof excludes independent planning
Attic. The slope consists of two elements: the lower, steeper, and the upper, gentle. This design allows you to increase the useful area of \u200b\u200bthe room, but in order to calculate it on an online calculator, you will need at least a preliminary drawing and understanding of the structure of the truss system.
Types of roofing materials
The issue of roofing material is also decided at the design stage. His choice is influenced not only by the preferences of the designer, but also by more real factors, including the amount of precipitation and the strength of the wind in the region. The online calculator makes it possible to find out not only the quantity, but also the cost of the selected material. A roof calculator is usually set up to calculate the following materials:
Decking.
metal tile.
Soft (roll) roof.
Rebate coating(steel, aluminum or copper).
Roof tiles. Ceramic (piece), flexible (soft), cement-sand, composite.
Slate(mainly for outbuildings).
Metal tile calculator (works with several types of roofs)
The main elements of the roof structure
Roof country cottage is not only a decorative detail and business card buildings, but also a complex engineering system. It includes a variety of building details, the main of which are the following:
Mauerlat. A beam that is laid on top bearing walls. It is a support for the truss system and transfers the load from the roof to the building.
rafters. Bars or boards located at an angle, the basis of the system. The online calculator allows you to calculate some parameters of the truss system.
Auxiliary elements. Racks, beams, girders and puffs serve to fix the rafters and strengthen the structure.
Skate. The upper edge of the roof, the intersection of the slopes.
crate. Lattice structure on which the roofing material is attached. For some types of roofing, continuous flooring is required. The lathing parameters on the online calculator are calculated quite well, especially for a roof of a simple design.
The main structural elements of the truss system
On our site you can find contacts of construction companies that offer the service of designing country houses. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".
What is calculated on the online calculator: types and possibilities
Even with ready-made drawings in hand, the future owner will not always find time for their careful study and painstaking calculations on paper. Among all the ways to solve the question of how to calculate the roof of a house, an online calculator will become the best option. There are two types of calculators that perform a certain type of calculation:
Standard Roof Calculator
The most common type, which allows you to get the basic parameters, from the angle of inclination of the rafters to the permissible load on the roof. In the calculation of roofing material, as a rule, there are all popular options (all kinds of tiles, slate, ondulin and other materials). Widely presented are calculators for calculating a single and gable and hip roof; there are billing services hipped roof or attic. The online gable or shed roof calculator is designed for simple tasks; more advanced calculation programs you need to download and install on your computer.
Fragment of an online hip roof calculator
Construction Calculator
For calculations, complex calculation algorithms are used, as a result, you can get not only tables of numbers, but also a set of detailed drawings, as well as 3D visualization. V construction calculator, as a rule, you can calculate the roof of any type. In addition to the main parameters, you can find out how much lumber is needed, choose the best insulation and vapor barrier. The drawings will show the layout of the truss system and the battens and will allow you to control the correct angle of inclination and the location of the rafters.
The device of an online calculator for calculating a gable roof
Calculator for calculating the truss system gable roof is an easy-to-use mechanism that allows you to perform basic structural calculations. The interface of any service has a convenient and intuitive look and looks like a set of empty fields with explanations. For the convenience of visitors, schematic images are placed next to the page. various types roofs with the parameters applied to them.
Before starting calculations, you should familiarize yourself with the designation of the fields
The user needs to enter in each field desired value(size) or choose from the available options. When filling out, you should pay attention to the dimension - parameters can be entered in cm or mm. After filling in the fields, you press the calculation key and get the desired result in the form of the following data:
Number of roofing materials. The calculator will allow you to calculate the amount of metal tiles (or other material) for a country house with a gable, hip or other roof.
Calculation of the truss system and roof gable. According to the given wall width and height to the ridge, the service will help determine the length of the rafters and the area of the roof gable.
To calculate the material for the roof of the house, the "gable" program will require you to enter the following values:
Roof dimensions. There are separate fields for entering height, width (on each side) and overhang.
Rafter dimensions. Sets the width and thickness, as well as the distance between the rafters and the distance to the edge of the roof.
Video description
About the calculation of the roof on the construction calculator in the following video:
Lathing parameters. Enter the width and thickness of the boards, the distance between them.
Roofing material parameters. If a roofing sheet is selected, set the height, width and overlap of the sheet.
The result of the calculation will be the following parameters:
Roof size. The height and width of the canvas, the total area.
rafters. Number and length of rafters. The volume of the required material (in cubic meters) is also calculated.
crate. The calculation shows the number of rows of boards, the length of each part and the volume of the boards of the crate.
Roofing material. The area of \u200b\u200bhydro and vapor barrier is calculated. So, if roofing material or glassine is chosen as the roofing material, the calculator shows the required number of rolls (based on the size of the roll), taking into account the overlap.
roofing material. The calculator determines not only the coverage area, but also the weight and the required amount of the selected material.
Calculator for calculating the main elements of a gable roof
Calculation of additional parameters
Many online services calculate additional, no less useful values:
Roof slope. The calculator will determine not only optimal value angle, but will also tell you if it is suitable for the selected roofing material. By changing the height of the lift or the width of the base, it is possible to achieve full compliance with the angle of the material.
Calculation of wind and snow load. For some areas, this load may be the determining factor for choosing the type of roof. You will need to enter additional information into the calculator: construction region, type of terrain, height to the ridge of the building, type of wood for the rafters.
Chimney calculation. For safe operation it is necessary to determine the height of the chimney relative to the roof ridge. Incorrect design may affect stable performance heating appliances and entail unplanned financial expenses (if rework is required).
When calculating the chimney, the presence of obstacles near housing is taken into account
Limitations in using the online calculator
Roofing calculators offered by Internet resources are an affordable and very fast way to get the necessary information. But like any mechanisms designed for the mass user, such calculators tend to use generalized methods of calculation. Worst of all, the calculation process is hidden from the person who turned to the calculator; it is very difficult to double-check the output information.
The calculator for calculating the roof of a house may contain some (permissible) parameter variations, which, nevertheless, will affect the final result. Among possible outcomes, which may contain inaccurate (approximate) values, occurs:
Determining the total amount of roofing material
The building material is never butt-to-joint, so the surface area of the roof and the area of coverage will always be different. When calculating, the roofing area is standardly increased by 15% - this provides a margin for overlap formation.
Video description
About calculating a gable roof with a free calculator in the following video:
If the roof has complex structure, the calculation also becomes more complicated, since an experienced designer simultaneously solves the additional problem of minimizing waste. For such purposes, different algorithms are used (with different cumulative errors and with different results), which one is embedded in the calculator is known only to its developers.
It is believed that the calculator helps to save on the purchase of building materials. But when installing the roof complex shape in this case, it often turns out that extra (often expensive) materials were purchased. The reverse situation, when there is not enough material and you have to pay for an unplanned purchase and delivery, is no less annoying.
Determination of the slope for the roof
Building codes prescribe minimum slope ratings for each roofing material. They are calculated taking into account the slope of the roof and additional indicators (wind and snow load). Specialists perform calculations in accordance with the norms of SNiP "Loads and Impacts" and additional design standards. It is not possible to check what indicators the roofing calculator uses in its work.
Some calculators take into account additional parameters (the presence skylights and drainage systems)
Roof calculation: how to avoid mistakes
Calculations can be done in one of the following ways:
Calculate the roof manually. If you have basic knowledge of geometry, you can make preliminary calculations manually. To do this, it is enough to stock up on paper, a pencil, an ordinary calculator, and remember that any roof is a set of simple shapes (rectangles and triangles), the calculation of the area of \u200b\u200bwhich is described by the simplest formulas from the school course. The method does not work well if the calculations become more complicated. They take a lot of time and increase the risk of error.
Calculate the roof online. It should be borne in mind that the values are always averaged; your planned home may require a custom solution.
Check the calculation of the roof with a calculator manually. Online roofing calculators are a convenient way to model a roof structure and find out the required amount of building materials. Payment simple designs it is easy enough to check, but if you do not have a specialized education, confusion with coefficients and percentages is inevitable. Differing results will cause lengthy rechecks and error checking, as well as distrust of the calculator's abilities (or your own).
Checking the results of the calculation will take time and care
Professional calculation of the roof. For preliminary calculations in order to determine the materials and construction of the roof, this method is clearly not suitable. But when ordering a turnkey house, the construction company will prepare a full-fledged project, which will indicate all the calculations for the calculations and the estimate. In addition, specialists can make preliminary calculations for you even at the stage of discussing the project.
Conclusion
Roofing online calculator is considered to be good tool to determine the main parameters future roof. But professional builders recommend using it only for a rough estimate of the quantity and cost of building materials. Also, the calculator can become an indispensable tool for comparing the costs of various technologies.This article provides a simplified method for calculating the truss system. You will learn how to quickly and correctly decide on the cross section of the rafters and the width of the span. The adapted mathematical calculation contains a minimum of formulas and leads to fairly accurate results.
There is a standard calculation method roof structure, brought into line with SNiP 2.01.07-85 "Loads and impacts" . It includes many rather complex calculations and reference values. A popular website service - online calculation of the gable roof truss system - will allow you to determine the amount of material with the utmost accuracy.
Note. The article considers a method for calculating the truss system of a gable roof with a hip, half-hip or pediment without additional structural elements- peaks, "birdhouses", towers, etc. and a slope angle of at least 45 °.
Where to begin
The traditional method assumes the following approach: the design of the roof and the section of the beams are selected for the design load. This does not fully meet the requirements today and the initial data in our case will be the following indicators:
- Requirements (wishes) for the roof structure. First of all, this refers to the presence of an attic (residential) floor, the location of skylights or the presence of an attic technical room.
- Existing sizes houses, or building boundaries. 70% of private houses are in relatively dense buildings, and this should also be taken into account when designing a roof. limited area plot and the possible requirements of neighbors regarding sunlight can make their own adjustments.
- Unification. The truss system is a multi-element structure. It is reasonable to try to bring maximum amount elements to one standard - the cross section of a board or beam.
The most difficult, oddly enough, is the first point. However, after a complete understanding of what functions the truss system should perform (direct or combined), you can proceed to the design stage.
Create a Sketch
This stage is one of the decisive ones, because in it we learn approximate dimensions elements. The main one - the truss truss - will become the basis for further calculations. The drawing itself will be based on two initial parameters:
- span between load-bearing walls. It is highly desirable that the anchor points of the truss system, which transmit vertical loads, be located along the axes of the bearing walls or supports. The distance from the projection of the ridge to the wall is called the half-span.
- The height of the ridge from the ceiling. This parameter consists of the functional features of the design - the height of the attic ceiling, an accessible attic or a "deaf" attic space.
As you know, 75% of simple truss systems are roofs with a straight and "broken" slope. This significantly affects the calculations, so we will immediately separate these types. Since any standard roof is based on a triangular structure, we will try to limit ourselves to one formula (the Pythagorean theorem):
- c 2 = a 2 + b 2
At this stage, you can quite accurately calculate the area of \u200b\u200bthe slopes and the consumption of roofing material along with the crate. To do this, it is enough to use the calculation of the gable roof truss system online, which is provided by many sites.
Straight equilateral slope
We transfer to the sketch the dimensions of the floor or the location of the load-bearing walls (the design does not always imply the presence of a wooden floor) on a scale. Then we mark the point of the ridge and draw straight lines to the walls, taking into account the accepted roof overhang. These lines can already be measured and multiplied by the scale - we get the length of the rafter leg.
In accordance with the chosen structure of the organization of the internal space (combined or divided), we place the under-rafter puff (crossbar) and determine its length. We place stops, slopes and vertical racks, observing the requirements that the site portal cited in the article "Do-it-yourself gable roof truss system". The spans should not be more than 2 m, and the rafters must necessarily have an intermediate brace. In this case, it is enough to adhere to the approximate limits of tolerances.
Applying the aspect ratio formula right triangle, you can calculate any of the sizes of the truss truss. The remaining dimensions can be removed from the drawing through the scale. The main task is to get the dimensions of each of the elements.
"Broken" slope
This type of roofing is always accepted in connection with the installation of an attic or a superstructure of a residential floor. It has one characteristic feature - a number of vertical posts at the intersection of the slopes and a rafter crossbar, which can be located both at the level of the top of these posts and under the ridge. Rows of racks and crossbars form the walls and ceiling of the attic space.
Similarly, we transfer the main elements to the drawing - first the walls and the floor, then a series of racks and crossbars (at the ceiling level), then we connect them with lines that will quite accurately show the shape of the break in the slopes.
After measurements and calculations, add up the lengths of all elements of the truss truss and add 10% to the resulting number. It will be total length one truss structure (UEC 1).
Selection of the section of rafters and unification
The cross section of the elements of the system, especially the rafter legs, directly depends on the span between the supports in the central part. Of all the lumber for the truss system, timber and board are suitable (not counting factory glued trusses). At the same time, the board has much best indicator ratio of section to bending strength. In our case, we are talking about the reliability of the rafters, for which the board is used, because. there is a margin of sinus depth for laying insulation.
Table of span width and rafter thickness
It is not recommended to arrange roof truss spans of more than 6 meters without intermediate supports.
Advice. When splicing two boards to create a vertical support, lay between them at the attachment points the trimmings of 25 mm boards (“bosses”) in increments of 300-400 mm. So the strength of the support will be higher compared to direct splicing.
After determining a sufficient section of the board, you can calculate the volume of one truss truss. To do this, we multiply the ODK-1 by the cross-sectional area of the board. The resulting volume of one farm (PF 1) will be used to calculate the total volume.
Calculation of the pitch of roof trusses
The pitch of the rafters of the attic rafter system depends on the thickness and design of the truss trusses.
Thickness Pitch Table
By dividing the length of the longitudinal (parallel to the ridge) wall by the selected step, we get the number of roof trusses (N). Accordingly, we can calculate the length of the board for trusses:
- JEC 1 x N
truss board volume:
- OF 1 x N or JEC 1 x S of the section of the board x N
Mauerlat calculation
If the truss system is arranged on hardwood floor, then the entire horizontal strapping refers to it. We will consider the option with a mauerlat on a stone wall.
Since vertical posts, struts and girders are included in the truss calculation, we have to calculate the horizontal strapping. There is a simple rule here - it should be at least a double rafter leg thick. If the total weight of the roof (together with the sheathing and roofing material and snow) is noticeably high, three layers of planks should be applied.
The volume of the Mauerlat board will be equal to the length of the load-bearing walls multiplied by the section of the board and by the number of layers. Mauerlat, made of several layers, will better bind in the corners.
total count
We add all the received volumes together and add 20% for waste and trimming. Quantity metal products and fasteners is determined individually. It is only known that the more of them, the better.
Note. All given values and proportions of dependence are taken from reference literature.
Despite its apparent simplicity, this adapted calculation can compete in accuracy with online truss system calculators. However, the final word always remains with the one who will execute the project.
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