ᐅ Which conduit pipes should be installed under a precast concrete garage with strip foundations?
Created on: 4 Oct 2025 14:19
M
mk_2021
Hello everyone,
Soon our precast concrete garage will be installed directly adjacent to the house. We have already planned an opening in the floor to allow for a power distribution box for the garden electricity to be mounted inside the garage. In addition to the power cable, other cables will be routed there, such as network cables. All cables will be underground cables coming from the multi-utility supply.
The strip foundation has already been built. The subcontractor laid three DN110 (4-inch) KG pipes through the foundations and cut them flush. In the last foundation, a DN75 (3-inch) HT pipe was installed with a slight overlap. To make matters worse, the distances to the edge of the garage vary by up to 10cm (4 inches).
What can I do to make cable pulling as easy as possible afterwards and to prevent the pipes in the foundations from clogging?
1) Run an 80mm (3-inch) slotted flexible drainage pipe completely through, to avoid water accumulation, and secure it to the HT pipe with cable ties? I would only bury the pipes slightly so they remain stable. Or would it be impossible to pull cables through these pipes afterward?
2) DN110 (4-inch) KG pipe. Because the pipes in the foundations are cut flush, I cannot connect them with couplings. Is there another way to connect them? Maybe butt-joined and secured against slipping with a bit of mortar?
3) DN75 (3-inch) HT pipes? Of course, this reduces the diameter immediately and I would also have to work with bends and calculate carefully in advance.
Or is there an even simpler solution? In total, it’s only about 9m (30 feet), fairly straight but not completely. Since everything is under the garage, the stress from external forces should be minimal.
Many thanks for any ideas and experiences!
Soon our precast concrete garage will be installed directly adjacent to the house. We have already planned an opening in the floor to allow for a power distribution box for the garden electricity to be mounted inside the garage. In addition to the power cable, other cables will be routed there, such as network cables. All cables will be underground cables coming from the multi-utility supply.
The strip foundation has already been built. The subcontractor laid three DN110 (4-inch) KG pipes through the foundations and cut them flush. In the last foundation, a DN75 (3-inch) HT pipe was installed with a slight overlap. To make matters worse, the distances to the edge of the garage vary by up to 10cm (4 inches).
What can I do to make cable pulling as easy as possible afterwards and to prevent the pipes in the foundations from clogging?
1) Run an 80mm (3-inch) slotted flexible drainage pipe completely through, to avoid water accumulation, and secure it to the HT pipe with cable ties? I would only bury the pipes slightly so they remain stable. Or would it be impossible to pull cables through these pipes afterward?
2) DN110 (4-inch) KG pipe. Because the pipes in the foundations are cut flush, I cannot connect them with couplings. Is there another way to connect them? Maybe butt-joined and secured against slipping with a bit of mortar?
3) DN75 (3-inch) HT pipes? Of course, this reduces the diameter immediately and I would also have to work with bends and calculate carefully in advance.
Or is there an even simpler solution? In total, it’s only about 9m (30 feet), fairly straight but not completely. Since everything is under the garage, the stress from external forces should be minimal.
Many thanks for any ideas and experiences!
T
Teimo198810 Oct 2025 12:24If the pipes are not secured with concrete, you need to find a way to firmly attach them to the base. They really have to be stable; otherwise, you won’t be able to pull anything through them. Kabuflex is also an option, but it would be even more difficult to secure on loose soil.
If you bury the pipes, I would recommend casting concrete around the trench and pipes to ensure they hold securely.
If you bury the pipes, I would recommend casting concrete around the trench and pipes to ensure they hold securely.
Teimo1988 schrieb:
If the pipes are not secured in concrete, you need to find a way to firmly connect the pipes to the ground. They really have to be stable; otherwise, you won’t be able to pull anything through them. Flexible pipes like Kabuflex can also be used, but they are even harder to secure on loose soil.
If you bury the pipes, I would suggest pouring concrete around the trench including the pipes to ensure they hold firmly. Thanks. Would you use flexible drainage pipes or bury them, or would you prefer rigid PVC pipes? Neither option is really watertight anyway 😉
For example, could I bury the new rigid PVC pipes as deep as possible and then connect them directly to the pipes installed in the foundations, seal the joint somewhat (e.g., with geotextile fabric), and then quickly and roughly secure everything with concrete around it?
T
Teimo198810 Oct 2025 19:32I would prefer to use a sewer pipe (also known as a drain pipe) because it makes things easier.
Teimo1988 schrieb:
I would prefer to use a PVC pipe (KG pipe) because it’s easier to work with.So, it turned out to be a PVC pipe (KG pipe) after all. However, I haven’t pulled anything through it yet. So, it remains exciting 😉 Thanks a lot for the help.T
Teimo198825 Oct 2025 09:42mk_2021 schrieb:
So, it has now become a PVC pipe. However, I haven’t pulled anything through it yet. So it remains exciting 😉 Thank you for the help.You’re welcome, and good luck with pulling it through!Similar topics