It is no secret that self-tapping screws hold very poorly in aerated concrete. Even the dowels do not help. A similar problem is also relevant for brickwork. A hanger screwed to a brick wall can be easily “pulled out” directly with self-tapping screws.
In today's article, I will tell you a little secret that will allow you to securely fix self-tapping screws in loose surfaces. Forget about special expensive fixtures, everything is much easier!
When repairing, they often use simple plastic 6 mm dowels and 3.5 or 4.2 mm self-tapping screws. This mount is suitable for wood surfaces and plasterboard walls. But it cannot be called reliable. Walls made of aerated concrete or red brick are very loose, and therefore self-tapping screws do not want to stick to them.
There are universal dowels that are popular with builders. They are orange in color and long. Experienced repairmen call them "sorts", this name is "folk". I believe that two sorts screwed into the hole will hold up fairly securely.
How is the problem of poor-quality fastening solved? I advise you to use dowels or self-tapping screws with a large diameter. I'll try to explain it in plain language.
Self-tapping screws not exceeding 4.2 mm are often screwed into dowels with a diameter of 6 millimeters. I recommend taking screws with a larger diameter, say, 5 millimeters.
Universal dowels provide increased reliability. In length, they surpass ordinary "sorts", due to which the adhesion area of the base with the dowel increases.
It is allowed to drive two "sizes" into one hole. In this case, self-tapping screws of a larger diameter should be used to increase the reliability of the connection. Doesn't sound very plausible, but it really works! Do not believe it - try it yourself!
If you take screws and dowels of a larger diameter, you will immediately notice a positive result. You will be able to achieve the maximum grip area.
If I have to work with aerated concrete, I use dowels with a diameter of 8 mm, and self-tapping screws - 6 mm. As a result, the fastening is very strong.
Another little tip. If you drill holes into which you will screw the dowels, then avoid hitting (we are talking about using a hammer drill). In the case of using a drill, it is better to take a victorious drill.
The photo below shows two options for aerated concrete dowels. I have used nylon screw dowels before. To be honest, the impressions from working with them were only positive. I have not yet come across metal dowels, but someday I will definitely try them.
This is all the information I wanted to share with you! If someone disagrees with what I have told, I will be happy to hear constructive criticism.
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