ᐅ Is it possible to use a patio joint as a rainwater drainage channel?
Created on: 21 Nov 2017 15:52
W
wadi1962Hello Forum,
I have a cast concrete slab with tiles laid and glued on top. During construction, there were some issues with the slope. I have a large puddle that moves toward the house during heavy rain and definitely needs to be eliminated.
I was thinking of cutting a groove in the joint with an angle grinder, ideally with a slope toward the edge of the terrace... Downside: frost damage in winter due to standing water.
My question to you: Should I completely cut out the joint and install a small, shallow U-shaped profile? Does something like that exist for 5mm x 5mm (0.2 inches x 0.2 inches)?
Thanks and regards
Dirk
I have a cast concrete slab with tiles laid and glued on top. During construction, there were some issues with the slope. I have a large puddle that moves toward the house during heavy rain and definitely needs to be eliminated.
I was thinking of cutting a groove in the joint with an angle grinder, ideally with a slope toward the edge of the terrace... Downside: frost damage in winter due to standing water.
My question to you: Should I completely cut out the joint and install a small, shallow U-shaped profile? Does something like that exist for 5mm x 5mm (0.2 inches x 0.2 inches)?
Thanks and regards
Dirk
Hello Dirk,
In the construction industry, we sometimes refer to this as "damage control." However, I don’t see such a safeguard here.
A proper installation either includes concrete with a slope or concrete over which a sloped screed has been laid.
This substrate can then be covered, for example, with a DITRA mat, which is glued to the surface of the substrate.
This mat has ridges so that the screed or leveling compound, which now serves as the installation surface for ceramic tiles, does not stand "in water" and does not freeze in winter due to ice crystal pressure.
-------------------
Now you even have an installation surface with a reverse slope.
That means: rainwater is not directed away from the building facade.
Trying to cut grooves into something with an angle grinder is pointless activism that will lead nowhere. Ceramic tiles will be penetrated by water at least through the mineral grout during rainfall; and since the adhesive bed is always designed in such a way that voids inevitably form under the tiles over adhesive grooves, after rain and frost, your tiles will come loose from the substrate like the FDP during the Jamaica coalition negotiations!
The only reasonable solution I see is demolition and rebuilding as described at the beginning.
Everything else costs nerves, time, and money – and ultimately will not succeed!
Clear thinking and decisive action are required now – not a half-hearted DIY approach.
Anything other than a proper installation will fail sooner rather than later!
---------------------------
Regards, KlaRa
In the construction industry, we sometimes refer to this as "damage control." However, I don’t see such a safeguard here.
A proper installation either includes concrete with a slope or concrete over which a sloped screed has been laid.
This substrate can then be covered, for example, with a DITRA mat, which is glued to the surface of the substrate.
This mat has ridges so that the screed or leveling compound, which now serves as the installation surface for ceramic tiles, does not stand "in water" and does not freeze in winter due to ice crystal pressure.
-------------------
Now you even have an installation surface with a reverse slope.
That means: rainwater is not directed away from the building facade.
Trying to cut grooves into something with an angle grinder is pointless activism that will lead nowhere. Ceramic tiles will be penetrated by water at least through the mineral grout during rainfall; and since the adhesive bed is always designed in such a way that voids inevitably form under the tiles over adhesive grooves, after rain and frost, your tiles will come loose from the substrate like the FDP during the Jamaica coalition negotiations!
The only reasonable solution I see is demolition and rebuilding as described at the beginning.
Everything else costs nerves, time, and money – and ultimately will not succeed!
Clear thinking and decisive action are required now – not a half-hearted DIY approach.
Anything other than a proper installation will fail sooner rather than later!
---------------------------
Regards, KlaRa
KlaRa schrieb:
Because ceramic tiles will at least allow water to pass behind the mineral grout during rainy weather; and since the adhesive bed is always designed so that hollow spaces form under the tiles along the adhesive ridges during installation, inevitably after rainfall and frost, the tiles will detach from the substrate just like the FDP during the Jamaica coalition talks!
---------------------------
Regards, KlaRaSorry, I didn’t quite understand.
I don’t want to grind out the joint so that water runs under the tiles through the adhesive ridges... I want to cut a narrow groove (using a diamond blade) into the grout joint with a slope toward the edge of the terrace.
Of course, I realize an expert might pull their hair out over this... but I don’t want to remove the bonded terracotta tiles again.
Regards
Dirk
Hello Dirk. Please consider this: a slope of at least 1.5% is generally required for water to drain naturally.
For a terrace only 2 meters (6.6 feet) wide with a 1.5% slope, the reverse slope must first be accounted for, which would require about 3 cm (1.2 inches) of height difference. The joint would need to be cut so that it ends up approximately 4 cm (1.6 inches) lower than at the building facade. This is practically impossible to achieve in workmanship.
A tile with an installation thickness of around 15 mm (0.6 inches) plus 3 mm (0.1 inch) of tile adhesive, totaling 18 mm (0.7 inches) above the concrete, cannot drain water properly. Adequate drainage is even more out of the question, as we can calculate the volume such a joint cavity would need to have.
Therefore, we cannot achieve the necessary slope nor provide a sufficient joint or cut volume through which surface water could be drained.
In short: this is a "crazy idea" that simply won’t work!
Best regards, KlaRa
For a terrace only 2 meters (6.6 feet) wide with a 1.5% slope, the reverse slope must first be accounted for, which would require about 3 cm (1.2 inches) of height difference. The joint would need to be cut so that it ends up approximately 4 cm (1.6 inches) lower than at the building facade. This is practically impossible to achieve in workmanship.
A tile with an installation thickness of around 15 mm (0.6 inches) plus 3 mm (0.1 inch) of tile adhesive, totaling 18 mm (0.7 inches) above the concrete, cannot drain water properly. Adequate drainage is even more out of the question, as we can calculate the volume such a joint cavity would need to have.
Therefore, we cannot achieve the necessary slope nor provide a sufficient joint or cut volume through which surface water could be drained.
In short: this is a "crazy idea" that simply won’t work!
Best regards, KlaRa
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