ᐅ Joints in the Garage – What Is Their Purpose?

Hello,

we have a precast concrete garage. The garage was assembled on site. The concrete slab floor consists of several elements. There are joints between these elements, about 2-3cm (about 1 inch) wide. According to the supplier, these joints are not usually sealed. No reason was given. However, they said they have received several inquiries from homeowners about this and that, upon request, they can fill the joints with silicone.

No one could explain to me the purpose of these joints. I guess they are expansion joints. But whether they also serve a function regarding water infiltration is unclear to me. Does anyone know? In principle, standing water could collect in these joints. But is that really a good thing? I am also wondering if, conversely, soil or roots could grow through from underneath... there are strip footings and gravel under the garage.

So the question is: should the joints be sealed with silicone (which will surely weather over time, look unattractive, and is not made to last forever) or just left open? Could there be drawbacks to either option? The garage is ventilated continuously anyway.

Does anyone have experience with this or heard about it?

Please post a photo.

Best regards in brief

Here are three examples. I hope you can see what I mean.

So? I would really appreciate a brief evaluation.

Nafetsm schrieb:
When asked, the supplier said these joints are not usually sealed. They didn’t provide a reason. However, they mentioned they have received several inquiries from builders questioning this and would seal them with silicone upon request.

This probably ranks number one in the "Germany’s dumbest answer" contest. If the manufacturer can’t provide a constructive reason, who else could?

You can spot amateurs by the fact that no matter if you ask them “four times seven” or Mozart’s year of death, their answer is always “silicone.” It doesn’t get any more ridiculous. Neither silicone nor expanding foam are cure-alls, but some people like to use them that way.

Ask a good building materials supplier what they have for concrete expansion joints. Expansion joints around 2cm (1 inch) or more are made where concrete components meet components made of other materials. And/or at extensions to prevent immediate settlement cracks. Some of these joints are actually air gaps, but more often they are sealed or filled with elastic materials.

This is generally done in cases of wall junctions. If I understand correctly, this concerns only the floor here. What about the walls?

I suspect a simple reason: the lifting straps used to move the beams are that wide, and after placing, the beams are not pushed together.

Such joints don’t serve a lasting purpose—unless the strip foundations below are also in separate sections. Water infiltration would be disastrous; just google how potholes form in roads (exactly that way). Also, a little oil sometimes seeps out there, which would be unwelcome.

The joints should be sealed watertight—precisely what simple-minded folks always blurt out as the universal answer from their silicone gun. Your building materials supplier will surely have better solutions.

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Thank you for the response. There are no visible joints on the walls. I cannot say how they were sealed since they were painted over.

In this specific case, it only concerns the floor. The foundation strips underneath were shaped like an H. There are two of them.

So, what would be the appropriate material to seal this? Sand, for example? Which elastic compound would be suitable?