Is the spectacle stone absolutely necessary? ? ?

Is spectacle stone absolutely necessary for insulating double chimneys?

I have had some doubts for some time.

The reason is that I can't find anything called "Meganeishi" even if I search for it on English websites.

There is a penetrating kit that has the same shape as the penetrating kit sold at the mountain chimney shop instead of the spectacle stone.

The photo below is a penetrating kit that is on sale at Yama no Entotsuya.

It is sold under the name Wall Thimble on Amazon in the United States, so please check it out if you are interested.

Also, if you know something similar to the Japanese glasses stone, please let me know.

Maybe my search method is bad.

So if you don't have a glasses stone, you can't penetrate the wall? ? ? I don't think so.

If you look at the manuals and construction examples issued by European and American manufacturers, there is no mention of spectacle stones.

It only says to use Wall Thimble as above to go through the wall.

And this Wall Thimble has 5cm air space around it.

Class A insulated double chimneys are considered safe if they are kept at least 5 centimeters away from combustible materials.

The insulated double chimneys sold at Yamano Entotsuya are made in the same factory on the same line and with the same manufacturing method that have cleared the same Class A standards.

There are no regulations regarding chimneys in Japan, so we do not import chimneys that have been tested to see if they meet the standards.

But the quality seems to be the same.

Also, if you look into the Building Standards Act and Fire Service Act, there are certainly regulations regarding chimney penetration through the wall.

Roughly speaking, 15 cm from the chimney should be made of incombustible materials such as spectacle stones.

So from here on out it's just my opinion .

It is not in line with the Building Standards Act, but I think it will be the basis of the way of thinking.

If you are going to build it yourself, please think about a safe construction method for yourself by referring to this.

When penetrating a wall with an insulated double chimney with an outer diameter of 200 mm, it is necessary to make a hole of at least 300 mm x 300 mm or a diameter of 300 mm and insert the insulated double chimney there.

Since this is just a minimum standard, I think there is no harm in taking additional safety measures such as making the area around this 5cm frame with silica gel.

By the way, please pay attention to the opening size when penetrating the roof.

300 mm laterally to the slope of the roof is fine, but be careful about the vertical direction.

While the chimney is installed vertically, the sheathing boards and rafters of the roof are sloped.

Therefore, it is necessary to widen the distance as the gradient increases.

Actually, it seems that it will be 320 mm or 350 mm or such a number.

The steeper the slope, the larger the dimension.

Please be a little careful there.

In fact, I think I'll know if I turn the roof and check it after the chimney construction.

Let's go back to Meganeishi.

Of course, if you are worried about it, it is good to put something called a spectacle stone.

However, if you follow the Western way of thinking, basically you don't need a spectacle stone for the penetrating part of the wall.

I think you can use a penetration kit .

So where did the realization of the need for a spectacle stone come from?

I have a memory that the wood-burning stove that appears in the drama from the northern country had something like a stone stuck in it...

However, come to think of it, traditional Japanese stoves such as daruma style stoves and clock style stoves were constructed with a single chimney.

Even now, when I go to the countryside, I often see old private houses with single chimneys and white smoke.

If you are working with a single chimney, the distance from combustibles should be at least 45 cm as explained in the previous blog.

For that reason, it is speculated that something called spectacle stone was placed in the wall to reduce the distance.

Of course, this is all speculation on my part, so I can't say for sure.

But do you need a spectacle stone?

If you ask me, I would like to say that it is not absolutely necessary.

Glasses stones are not cheap either.

However, by inserting a spectacle stone, you can be sure to keep a distance of 5 cm or more from combustibles.

Therefore, if you feel safe to put it in, I think you should use it.

It is safe and secure if you take sufficient measures for further safety.

But! ! !

If you put a combustible material such as plywood on top of the Megane Stone, it will be completely meaningless! ! !

Make sure that the insulated double chimney is at least 5 centimeters vertically, horizontally, and diagonally away from combustibles!

If you follow these rules, it's just a matter of whether you're good at DIY construction or not.

Of course, the issue of chimney sagging is separate.

The sagging will prevent a safe distance of at least 5 cm from combustible materials.

Also, if the chimney is not cleaned once a year, soot and tar build up, which can ignite a chimney fire.

Please note that as common sense!

All construction workers should acquire knowledge of construction methods to prevent falls from high places and fires.

see you soon

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