Good afternoon, dear guests!
This page describes 7 mistakes that are often made when building roofs. This article contains information with which an unknowing person can control the progress of the installation work of roofing systems, as well as pay attention to the quality of the roof when choosing a ready-made new house built for sale by any the developer.
There are a number of articles on my channel that describe the problems of private houses built specifically for sale. All materials are based on my personal experience and the experience of colleagues who are professionals in construction. Here are some similar publications:
1. House for sale from a private owner or mistakes that make themselves felt over time
2. "Urgently selling a house. Owner". How to understand in 20 minutes that you have a house for sale in front of you? (8 signs)
But, I have not yet described the roof and this is the first article where gross construction mistakes are selected. Of course, I understand - you need to be a professional in order to immediately see the house - to identify problems, but these tips will help you to see significant flaws in the roof.
The first mistake is related to the drainage system. Despite its inexpensive cost compared to the roof itself, it performs a completely expensive function - ensures the drainage of water from the roof into the storm sewer, preventing water from collecting in the immediate vicinity of the foundation of the house.
1. Gutter system
The main task of the drainage system is to divert ALL water flowing from the roof, further from the base of the house. But in order to do this, it is important to take into account the area of the slope and the throughput of the gutter, which transports water into the vertical drainage pipe. And one of the main rules says that the maximum length of the gutter to the first funnel should be no more than 12 m long.This means that when the distance to the funnel is already 12.5 m - an overflow may occur through the gutter and all the water will whip into the blind area and clearly penetrate under her. Those. the streams of water will alternately layer and in the end - the volume of the gutter will not be enough to carry the entire storm flow to the funnel.
If the length of the roof overhang is more than 12 m, then the drainage system must take one of the two structures below:
2. Monolithic belt
This topic deserves special attention and the design of the belt largely depends on the future roof.
The rafter system can be spacer and non-thrust.
A spacer system is a system that exerts a pushing force on the walls of a house, i.e. the force vector is directed horizontally from the axis of the house and, in fact, moves the walls apart. In spacer systems, a monolithic belt under the roof must be closedaround the entire perimeter of the house.
As soon as a ridge beam appears in the rafter system, supported on the central wall through the rack or a tightening lying on the Mauerlat, the system automatically gains rigidity and stops expanding walls. In this case, the roof loads the walls only vertically. In this case, a monolithic belt is either not done at all, or is performed only under the Mauerlat, since carries out the function of redistributing the load from the roof to the walls and there is no need for him to compensate for the thrust (thrust simply not).
3. Sheathing and rough flooring
Each type of roof requires a different approach to system design. For example, for metal roofing it is a counter-lathing and a lathing, for flexible (bituminous) shingles it is a counter-lathing and a solid lathing or lathing and flooring made of moisture-resistant plywood or OSB-3 (-4).
But, for any roof - it is important that the counter-lattice is made of a bar with a minimum thickness of 40 mm, providing the necessary ventilation gap. In practice, many private developers, saving money, are laying an ordinary 50 mm wide board, without even making a ventilated ridge.
I saw with my own eyes how they save even on a regular crate, laying a board not 25 mm thick, but 20 mm thick.
For shingles, the thickness of plywood or OSB should be at least 12 mm., The lion's share of developers is 9 mm thick.
4. Rafter step
Of course, the pitch of the rafters and their cross-section depend on the length of the rafter legs, on the rigidity of the sheathing and on the severity of the finishing roof covering, which is carried out according to the project. It is impossible to name the step unambiguously, while covering all roof structures.
But, the average value, which can be guided by, is such that for metal tiles, corrugated boarding and ondulin with a six-meter rafter leg, the step is from 60 to 100 cm. If the attic is cold - the section of the bar is 50 * 150, If the attic floor is 50 * 200.
For slate and for clay tiles, due to their heaviness, the rafter pitch is 60-80 cm, for soft tiles it can vary from 60 to 150 cm.
5. Wood grade and condition
It is important that all wood involved in the construction of the roof must be cleaned of bark, wane and impregnated with an antiseptic.
The shed must be cleaned off:
The supporting elements should be free of large knots, since they break the longitudinal working wood fiber, which is a weak point. The presence of a knot increases the likelihood of a rafter leg breaking during operation of the roof under wind and snow loads.
6. Films and membranes
Today, the market offers a great variety of different films / membranes, which have a front (outer) and back (inner) side. It is forbidden to confuse the parties, otherwise the product will cease to fulfill its function of directed vapor permeability. Here you can always check the correctness of the installation: each manufacturer has a website where detailed instructions are posted, and the Internet has already penetrated almost every phone.
Also, overlap is important. If the superdiffusion membrane (the one that is closer to the roofing) is laid along the water drain, then the vapor barrier is overlapped along the steam with the obligatory gluing of the joints.
Incorrectly executed overlaps - 99% moisture penetration into the insulation!
7. I twist and twirl wherever I want
The fastening of each roofing material has its own characteristics, which the manufacturer always tells about in his brochures / booklets / technological maps.
Always look at FIRST SOURCE, don't listen to "we've always done this"!
The photo shows the incorrect installation of metal tiles.
The self-tapping screw should be staggered under the protrusion of the previous wave (the correct location is shown by the arrow).
From the author
In conclusion, I would like to note that there is always a human factor. Whether it's the work of a builder, careless delivery or invisible defects of the manufacturer in the absence of proper quality control.
Therefore, I recommend that you do not make the inner finishing coating immediately, so that the roof after installation will show its "joints" under a few torrential rains. Then you will have the opportunity to correct mistakes at low cost, without disrupting the finishing interior decoration.
Perhaps that's all. I hope this article was useful to you!
Thanks for attention!
"Hello! I am entitled to 150 cubic meters of wood. " I decided to honestly take my share of preferential timber from the state: results
"We breathed mold all the time?" - asked the wife. I ripped off the boards and crawled into the underground, which was without ventilation for 45 years