Hello everyone,
I have decided to finally work on my garden next summer.
Besides planting, I want to redesign the terrace: a glass roof (from Steda) measuring 6m * 2.50m (20ft * 8ft) and a new terrace with porcelain tiles measuring 6m * 2.80m (20ft * 9ft).
I have already removed my old terrace:
> Bankirai decking and substructure
> coarse gravel (approx. 6-8cm (2.5-3 inches))
I will dispose of the wood or hopefully find someone who wants it, as it would be a shame to waste it.
I would like to reuse at least part of the gravel.
Regarding the new build-up:
> Total depth is currently about 20cm (8 inches). I will excavate about another 20 cm (8 inches) (clay soil).
> Installation of a separation fleece to separate the new layer from the clay (subsoil)
> Approx. 30cm (12 inches) frost protection layer 0-22
> 8cm (3 inches) drainage concrete
> 2cm (0.75 inches) tile thickness
> Slope approx. 1° (due to the roof, I expect little water here; this was also the case with my wooden terrace before, even without wind-driven rain)
Now to my challenges:
> I would like to use/compact the coarse gravel as part of the frost protection layer—a roughly 5cm (2 inch) layer underneath. What do you think about that? This would save me some new gravel and avoid full disposal. Is this feasible?
> Currently, there are about 20 foundations (for the former terrace substructure) in the ground, about 50cm (20 inches) deep (relative to the new terrace height). Do these have to be removed, or could I leave them, place the gravel around them, and then put the drainage concrete directly on the foundations?
For both topics, my main concerns are the tedious and costly disposal as well as sustainability. However, I also don’t want to risk the terrace being pushed up in the next few years. I’m hoping for valuable advice here.
I will provide photos later.
Thank you very much,
Regards,
thorsten2016
I have decided to finally work on my garden next summer.
Besides planting, I want to redesign the terrace: a glass roof (from Steda) measuring 6m * 2.50m (20ft * 8ft) and a new terrace with porcelain tiles measuring 6m * 2.80m (20ft * 9ft).
I have already removed my old terrace:
> Bankirai decking and substructure
> coarse gravel (approx. 6-8cm (2.5-3 inches))
I will dispose of the wood or hopefully find someone who wants it, as it would be a shame to waste it.
I would like to reuse at least part of the gravel.
Regarding the new build-up:
> Total depth is currently about 20cm (8 inches). I will excavate about another 20 cm (8 inches) (clay soil).
> Installation of a separation fleece to separate the new layer from the clay (subsoil)
> Approx. 30cm (12 inches) frost protection layer 0-22
> 8cm (3 inches) drainage concrete
> 2cm (0.75 inches) tile thickness
> Slope approx. 1° (due to the roof, I expect little water here; this was also the case with my wooden terrace before, even without wind-driven rain)
Now to my challenges:
> I would like to use/compact the coarse gravel as part of the frost protection layer—a roughly 5cm (2 inch) layer underneath. What do you think about that? This would save me some new gravel and avoid full disposal. Is this feasible?
> Currently, there are about 20 foundations (for the former terrace substructure) in the ground, about 50cm (20 inches) deep (relative to the new terrace height). Do these have to be removed, or could I leave them, place the gravel around them, and then put the drainage concrete directly on the foundations?
For both topics, my main concerns are the tedious and costly disposal as well as sustainability. However, I also don’t want to risk the terrace being pushed up in the next few years. I’m hoping for valuable advice here.
I will provide photos later.
Thank you very much,
Regards,
thorsten2016
Hello Thorsten,
I just hope that you are beginning to recognize the weaknesses of online surveys. They do provide information, true.
But who inputs that information, whether expert knowledge is involved, and if so, to what extent, a layperson cannot tell.
What’s important is that you ask yourself questions.
For example, why does an outdoor terrace need a frost protection box?
You cannot protect exterior components like a concrete slab from frost. Nor is it necessary.
And so, one card in the house of cards built on supposed expert knowledge from the internet collapses!
What is needed is drainage—to redirect water beneath the new slab. For this, you have to consider not only the surrounding site topography but also the soil composition and assess it accordingly. Clayey soil and a pit filled with gravel are completely pointless because in that case, water cannot be drained.
If you have “normal” soil, then a gravel layer is sufficient to prevent water from standing beneath the slab.
There is no such thing as “concrete screed”!
Concrete and screed differ in their installation method, sieve curve, and flow characteristics.
These are all different for concrete and screed.
The term “firewater” is known from Western movies as a term for alcohol, but otherwise it makes no sense because of its inherent contradictions.
The same applies to “concrete screed.” It is a misleading term, which unfortunately can be found in public, such as in hardware stores.
Back to the topic.
I cannot and do not want to give you a detailed construction recommendation here. Anyone who thinks they can build a trade with their own hands MUST be aware of the applicable technical regulations. Whether layperson or professional makes practically and legally no difference.
Although I have already given you sufficient hints in my last post about how thick the supporting structure (here: the screed in outdoor areas) should be and how the drainage beneath the slabs should look.
With a slab thickness of 2cm (0.8 inches), these do not have any load-bearing capacity. They must not be installed on pedestals but must be able to transfer point and surface loads under pressure to a correspondingly flexurally rigid substrate!
-------------
In conclusion, I can only advise against trying to create such a planned slab on your own as a layperson without the necessary expertise and relying only on a local hardware store as a material supplier and half-knowledge from the internet. The risk of total damage is clearly visible here—at least to the expert.
Best regards, KlaRa
I just hope that you are beginning to recognize the weaknesses of online surveys. They do provide information, true.
But who inputs that information, whether expert knowledge is involved, and if so, to what extent, a layperson cannot tell.
What’s important is that you ask yourself questions.
For example, why does an outdoor terrace need a frost protection box?
You cannot protect exterior components like a concrete slab from frost. Nor is it necessary.
And so, one card in the house of cards built on supposed expert knowledge from the internet collapses!
What is needed is drainage—to redirect water beneath the new slab. For this, you have to consider not only the surrounding site topography but also the soil composition and assess it accordingly. Clayey soil and a pit filled with gravel are completely pointless because in that case, water cannot be drained.
If you have “normal” soil, then a gravel layer is sufficient to prevent water from standing beneath the slab.
There is no such thing as “concrete screed”!
Concrete and screed differ in their installation method, sieve curve, and flow characteristics.
These are all different for concrete and screed.
The term “firewater” is known from Western movies as a term for alcohol, but otherwise it makes no sense because of its inherent contradictions.
The same applies to “concrete screed.” It is a misleading term, which unfortunately can be found in public, such as in hardware stores.
Back to the topic.
I cannot and do not want to give you a detailed construction recommendation here. Anyone who thinks they can build a trade with their own hands MUST be aware of the applicable technical regulations. Whether layperson or professional makes practically and legally no difference.
Although I have already given you sufficient hints in my last post about how thick the supporting structure (here: the screed in outdoor areas) should be and how the drainage beneath the slabs should look.
With a slab thickness of 2cm (0.8 inches), these do not have any load-bearing capacity. They must not be installed on pedestals but must be able to transfer point and surface loads under pressure to a correspondingly flexurally rigid substrate!
-------------
In conclusion, I can only advise against trying to create such a planned slab on your own as a layperson without the necessary expertise and relying only on a local hardware store as a material supplier and half-knowledge from the internet. The risk of total damage is clearly visible here—at least to the expert.
Best regards, KlaRa
T
thorsten201631 Oct 2021 15:20Hello KlaRa,
Thank you very much. Everything sounds quite understandable so far.
What I haven’t fully understood yet is how exactly the drainage mat works in your description.
Shouldn’t the drainage mat be installed above the screed (between the screed and tiles)?
Water usually seeps in from above, for example through the joints.
The water doesn’t drain through the screed, so it would need to be diverted above the screed.
Good luck
thorsten2016
Thank you very much. Everything sounds quite understandable so far.
What I haven’t fully understood yet is how exactly the drainage mat works in your description.
Shouldn’t the drainage mat be installed above the screed (between the screed and tiles)?
Water usually seeps in from above, for example through the joints.
The water doesn’t drain through the screed, so it would need to be diverted above the screed.
Good luck
thorsten2016
thorsten2016 schrieb:
What I still don’t quite understand is exactly how the drainage mat works in your description.
Shouldn’t the drainage mat be installed above the screed (between the screed and the tiles)?
Water usually penetrates from above, for example through the grout lines.
The water doesn’t drain through the screed, so it should be drained above the screed.
Good luck
Thorsten You recognize that the topic is complex.
My answer to your question: There is the option to install a screed on top of a drainage mat, as well as to seal the surface of the screed and then apply a drainage mat on top, onto which ceramic tiles or slabs are bonded with a mortar bed.
Both options are possible.
In the first case, the drainage mat serves to prevent the screed—which is always porous and allows (rain)water to slowly pass through its structure—from standing with “wet feet.” This would be the case if the screed in an exposed exterior area was simply laid on a separating layer without considering an upper sealing and drainage layer.
Otherwise, the screed can freeze and be damaged by frost action due to ice formation and the resulting structural breakdown.
-------------------------------------
Regards, KlaRa
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