ᐅ Maintenance of Granite Exterior Stairs – Dealing with Damp Spots?

Hello everyone,

About 2 1/2 years ago, we installed new outdoor stairs. In the lower area, the granite slabs were laid over the existing precast concrete slabs. Now, moisture is appearing in some spots, which barely goes away (except during the summer when it is warm). Currently, the stairs always look like moisture is rising from underneath. Is there a product I can apply to prevent the moisture from coming through? Or what can be done here?

PS: I took the photo when it was generally rather damp. You can also see moisture in other areas like the pathway. However, these damp spots persist for a long time, even though most of the slabs have already dried out a long time ago.

Thank you.

That looks like moisture coming from above, which dries last in joints and small cracks.
For roofs with roofing felt, this would indicate leaks.
The only solution is to wait for it to dry.
I wouldn’t apply any coatings due to the risk of slipping.
Our steps are 15cm (6 inches) thick and made from single pieces, so they dry more evenly.

Nida35a schrieb:

This looks like moisture coming from above, which is the last to dry out in joints and small cracks.
For roofs with bitumen felt, this would indicate leaking spots.
The only solution is to wait for it to dry,
I wouldn’t apply any coating because of the risk of slipping.
Our steps are 15cm (6 inches) thick and each made from a single piece, so they dry more evenly.

Above these steps, we also have solid granite block steps, which also dry evenly. However, there is air flowing underneath.
By coating, I meant something like impregnation—to prevent moisture from penetrating into the stone.

The moisture is in the joints, so you cannot apply any coating.
And any coating applied to the surface will be damaged by the weather, but unevenly, meaning new spots will appear.