Good afternoon, dear guests and subscribers of my channel!
My parents started building a house 2 years earlier than me. The cottage they are building differs from the rest with non-standard solutions, so I often visited them to emphasize something new and some interesting solutions for myself. And, since I really love construction and I know that soon I will also start building a house - it was very interesting for me to watch the construction progress live.
Once, when I came to my parents, I found a team of roofers who were assembling composite shingles and started a dialogue with one of the roofers. The man has been dealing with roofs for 32 years, we started talking about all types of materials and began to discuss budget options in a little more detail.
At that time, an expert revealed to me the secret that instead of the so often used OSB boards, it is better to use plywood.
But why does everyone use OSB?
The specialist says that advertising played a very important role here and the lion's share of advice falls on word of mouth.
Few people know that GOST itself says that any, even the lowest-grade plywood - IV grade, not the essence of FC or FSF, has moisture protection. And that's a fact.
Both FC and FSF are both materials that have moisture protection, but for FSF it is more reinforced. If we take OSB, then OSB-1 and OSB-2 have no protection from water at all, in contrast to the admissibility of using OSB-3 and OSB-4 in humid conditions.
In addition, even if plywood is a little more expensive, it has higher static bending strength (plywood 30-35 MPa, OSB 15-30 MPa) and tensile strength along the fibers (plywood 20 MPa, OSB - 12 MPa), which is also prescribed in GOST.
Of course, I was puzzled, but a little later, when I was already faced with construction, I checked this statement.
I took OSB-3 and the simplest low-grade plywood FK 4/4, dipped them into water for a day.
After that, I brought out% swelling and% deformation.
OSB swelled in water during the day and increased in thickness by 2.3 mm, which cannot be said about plywood, which increased by 1.4 mm.
If you are interested, I have a very detailed article about this, which proves everything thanks to the experiment. Here's a link:Experiment: water resistance. Test of the lowest grade FC plywood and popular OSB (OSB-3) "
As a result, I got the result of experience, which proved that low-grade plywood deforms much less than "His Majesty" - OSB-3. The water absorption of materials is practically the same, but the deformation of the OSB is very uneven, and after a day, the pieces of wood begin to peel off the OSB.
After a day of exposure in water (sample A):
This means that if any shingle was fixed on the roof in violation of technology, then a year or two and swelling is ensured.
The roofer said that he never advises to lay OSB under shingles, but if the customer insists, then cover the OSB flooring with a fully lining carpet, which is actually more expensive than using a moisture-resistant plywood FSF.
If, nevertheless, the choice is between OSB and plywood, then it is better to overpay 20-30 thousand rubles, because this is a roof house, which should stand for several decades, and 30,000 rubles is only ~ 1% of the total cost houses.
I hope you enjoyed the article, and moreover, it became useful!
Thanks!
Read also:
Experiment: water resistance. Test of the lowest grade FC plywood and popular OSB (OSB-3). The results are surprising
Why pour concrete if the blind area can be done much easier and cheaper (3 options for arrangement + my photos)
Should I buy building materials in winter or wait for spring? (I worked at a construction base, I talk about pricing)