ᐅ Calcium silicate block with cavity: Which fasteners are suitable for a balcony solar power system?

P.S. How about a sieve sleeve and injection mortar? If you want it to be rock solid and not have to worry about anything else, I would consider that.

11ant schrieb:

However, this exterior wall construction has a poor U-value. So your main challenge for fastening will likely be the insulation material that will be added during an energy retrofit.

Will I ever insulate this gable wall? Maybe it would be better to add an extra layer to the roof? Alternatively, the modules could be installed on the roof: two facing forward and two facing backward (morning and evening sun). The roof was redone with Braas tiles around 1980. Where you can look inside, there are fiberboard sheathing panels, with insulation stretched behind them, and old wooden boards covering the interior. Where the rooms meet the roof slopes, probably nothing has been done. That’s why adding an extra layer would make sense, but it exceeds my budget.

So if the modules go on the roof, I will need a roofer! And then you can only hope they don’t make any mistakes.

nordanney schrieb:

P.S. How about using a sleeve anchor and injection mortar? If you want it to be rock solid and not worry about anything else, I would consider that.

Sleeve anchors are available in almost endless lengths. The more internal partitions the anchor has, the better.

I just found a picture of the wall from the inside (the modules are supposed to be installed on the outside). There was a neat crack that I sealed with mortar class 2. The bricks themselves were originally mortared using a mortar produced by local companies at the time. It must have been some kind of lime mortar (possibly with some clay content?), and often a bit of cement was added. The masons preferred working with that.

This means that with this type of mortar, the bricks do not hold together very firmly (so it’s best to use 4 fastenings per rail). And in the upper right, those must have been wood wool panels (Heraklit boards), if I remember correctly. The question is why they were there, for what purpose, and how thick are they?

Felix571 schrieb:

I just found a picture of the wall from the inside (the modules are supposed to be installed on the outside here).

Then you probably mean the inside of an exterior wall. However, the size of the blocks does not suggest hollow blocks around 300mm (12 inches); these appear to be blocks of the 2DF format. When the window door (?) was bricked up, you should have actually seen the entire wall structure in detail (?).

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11ant schrieb:

Then you probably mean the inside face of an exterior wall. However, the size of the bricks does not suggest hollow blocks around 300 mm; these are apparently bricks of the 2DF format. When bricking up the patio door (?), you should have actually seen the entire wall structure in detail (?)

The structure is a later (1958) 1.50 m (5 feet) extension, without a basement (unfortunately causing mold problems for me in summer, which wasn’t the case before). I don’t know what it originally looked like; I only removed the wallpaper (plus some polystyrene insulation) and found the horizontal settlement crack. There used to be a balcony above, which was later enclosed. You can no longer see any sign of it in the room above. Unfortunately, the extension seems to have been done somewhat poorly. There are vertical settlement cracks about 30 cm (12 inches) behind the old wall.

I was also puzzled because these are 240 mm (9.5 inch) hollow blocks (according to the construction description). Still, there is about a 4 cm (1.5 inch) cavity. My question is, how many internal webs do the blocks have?

Felix571 schrieb:

I was a bit puzzled too, they are 24cm (9.5 inches) hollow blocks according to the building description. Still, there is about 4cm (1.5 inches) of air. My question is, how many inner webs do the blocks have?

Your picture and your description do not match—I recommend consulting an architect experienced in working with existing buildings before proceeding with what seems to be extensive remodeling work. You described drilling into a 300mm (12 inches) calcareous sand hollow block, so according to your description, you would realistically encounter a cavity after about 4cm (1.5 inches) of material.

However, the photo shows a rather unusual free-standing structure (note the shut-off valve in a riser passing through a lintel (?)) of a wall leaf made only of stretcher bricks in a 2DF format. This does not sound like hollow blocks but rather solid bricks with just a small handling hole, suggesting a cavity wall construction. This could indeed reach the mentioned 28cm (11 inches) thickness, and depending on the drilling point, you might have hit an (egg-shaped) handling hole after 4cm (1.5 inches).

Also, a hollow block sized 15DF wouldn’t have chamber and web structures comparable to a porous brick but likely an oval cylindrical handling hole and several cylindrical hollow chambers. So your house should first be investigated with structural engineering forensics rather than relying solely on the original building description. Blondi is probably not bricked in there, but it does sound like Pandora’s box.

A 30cm (12 inches) thick exterior wall would be almost avant-garde for that construction period—likewise, if it had been built from calcareous sand hollow blocks. A monolithic calcareous sand wall would most likely be laid with 2DF stretchers and 3DF headers. On the other hand, your photo only shows 2DF KS stretchers, and you mention bricks and a total thickness of 28cm (11 inches). This would suggest a cavity wall consisting probably of 2DF brick stretchers on the outside, 2DF calcareous sand stretchers on the inside, and an (unfilled?) 5cm (2 inches) air cavity in between.

As you can see, it’s well worth a thorough investigation—not just to figure out where to hang some small modules. Show us the drawings from the building file.

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