Hello everyone,
my next question about electrical installation...
Our extension (timber frame) has 60mm (2.4 inches) wood fiber insulation boards on the outside. What should be considered when, for example, installing switches and sockets on the exterior?
Basically, I assume that the cable is routed from the inside through the insulation and vapor barrier to the outside and then properly sealed.
(Complete wall build-up: 60mm (2.4 inches) wood fiber, 200mm (7.9 inches) mineral wool, 15mm (0.6 inches) OSB, and then the interior installation level. There is no foil vapor barrier installed, but the OSB panel joints are taped.)
There are special mounting boxes for the wood fiber insulation boards (e.g. Kaiser 1159-55). With 60mm (2.4 inches) thickness, space is quite tight. In such cases, do you drill the hole for the box all the way through, or do you try to leave some material intact? In the Kaiser video for this box, the box is embedded within the insulation board. It is 55mm (2.2 inches) deep and designed for insulation boards thicker than 60mm. I’m not sure if my 60mm will be enough or not.
I haven’t found other boxes so far.
Also, I assume one tries to avoid drilling through the vapor barrier as much as possible. Is it possible then to route cables within the insulation board itself (for example in a channel)? This is also shown in the Kaiser box video – although on the interior side.
Or do you actually drill everything through?
Best regards and thanks for your insights,
Chris
my next question about electrical installation...
Our extension (timber frame) has 60mm (2.4 inches) wood fiber insulation boards on the outside. What should be considered when, for example, installing switches and sockets on the exterior?
Basically, I assume that the cable is routed from the inside through the insulation and vapor barrier to the outside and then properly sealed.
(Complete wall build-up: 60mm (2.4 inches) wood fiber, 200mm (7.9 inches) mineral wool, 15mm (0.6 inches) OSB, and then the interior installation level. There is no foil vapor barrier installed, but the OSB panel joints are taped.)
There are special mounting boxes for the wood fiber insulation boards (e.g. Kaiser 1159-55). With 60mm (2.4 inches) thickness, space is quite tight. In such cases, do you drill the hole for the box all the way through, or do you try to leave some material intact? In the Kaiser video for this box, the box is embedded within the insulation board. It is 55mm (2.2 inches) deep and designed for insulation boards thicker than 60mm. I’m not sure if my 60mm will be enough or not.
I haven’t found other boxes so far.
Also, I assume one tries to avoid drilling through the vapor barrier as much as possible. Is it possible then to route cables within the insulation board itself (for example in a channel)? This is also shown in the Kaiser box video – although on the interior side.
Or do you actually drill everything through?
Best regards and thanks for your insights,
Chris
Our wall construction is similar; we are also planning to use Kaiser boxes for the exterior. According to the datasheet, they can be used with panels starting at 60mm (2.4 inches) and are airtight. I would run an empty conduit through the 20cm (8 inches) insulation layer to each box and also connect it airtight through the OSB board on the interior side. Alternatively, you can route only the cables through the facade and install the boxes after plastering, which will gain you a few millimeters depending on the plaster thickness. You should not have a vapor barrier in a wooden house with the described wall build-up; the wall becomes increasingly vapor-permeable from inside to outside. This means your airtight OSB board has a higher vapor-retardant effect than the wood fiber board on the outside, allowing water vapor to take the easiest path out through the entire wall assembly, preventing moisture from accumulating in the middle.
Is there a practical tip on how to best handle the empty conduit (without me having tried it myself so far)?
The exterior wall (wood fiber insulation board, batt insulation, and 15mm (0.6 inch) OSB) is already prefabricated and closed.
That means installing the box from the outside is no problem.
As for the empty conduit going through the layers, it means drilling through and then somehow threading the conduit through. Does this usually work without problems, or is there something to watch out for / a tip on the best way to do this?
The exterior wall (wood fiber insulation board, batt insulation, and 15mm (0.6 inch) OSB) is already prefabricated and closed.
That means installing the box from the outside is no problem.
As for the empty conduit going through the layers, it means drilling through and then somehow threading the conduit through. Does this usually work without problems, or is there something to watch out for / a tip on the best way to do this?
If everything is already closed up, you can also just run your individual conduit. I’m not sure if you can simply drill a hole through the mineral wool insulation with a drill bit and then push it through. You should also seal the hole on the OSB board, for example with Kaiser 9059-46 or a similar product.
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