ᐅ Screed on the terrace keeps cracking—is this normal according to the construction management?
Created on: 20 Sep 2021 09:16
A
Ade123Hello,
we have a concrete terrace slab, on top of which a sloped screed was applied around mid-2020. This screed is floating.
The plan was to tile the terrace this year (with waterproofing and drainage mat). Unfortunately, cracks keep appearing, which the screed installer more or less properly filled with sealant. About a month after the first sealing, two of the sealed cracks opened up again. This time I sealed them myself, and these have held so far. Unfortunately, new cracks have since appeared, which I have also sealed.
Our terrace (4 x 10 meters (13 x 33 feet)) now has a total of five cracks spaced about 1–3 meters (3–10 feet) apart. These cracks start from the outer edge and run toward the house wall, with lengths of around 2–4 meters (6.5–13 feet). In some cases, hollow sounds can be heard, mostly around the outer corner areas.
After consulting with our construction manager, the only feedback we received was that this is normal because we did not protect the terrace from moisture and weather influences with, for example, tiles or similar finishes.
The terrace is fully covered, and when it rains, only a very small area (at most 2 square meters (22 square feet)) gets wet, always in the same spot.
Was it a mistake not to tile the terrace because I wanted to wait and see if the screed would crack further, or is the construction manager’s statement simply incorrect?
we have a concrete terrace slab, on top of which a sloped screed was applied around mid-2020. This screed is floating.
The plan was to tile the terrace this year (with waterproofing and drainage mat). Unfortunately, cracks keep appearing, which the screed installer more or less properly filled with sealant. About a month after the first sealing, two of the sealed cracks opened up again. This time I sealed them myself, and these have held so far. Unfortunately, new cracks have since appeared, which I have also sealed.
Our terrace (4 x 10 meters (13 x 33 feet)) now has a total of five cracks spaced about 1–3 meters (3–10 feet) apart. These cracks start from the outer edge and run toward the house wall, with lengths of around 2–4 meters (6.5–13 feet). In some cases, hollow sounds can be heard, mostly around the outer corner areas.
After consulting with our construction manager, the only feedback we received was that this is normal because we did not protect the terrace from moisture and weather influences with, for example, tiles or similar finishes.
The terrace is fully covered, and when it rains, only a very small area (at most 2 square meters (22 square feet)) gets wet, always in the same spot.
Was it a mistake not to tile the terrace because I wanted to wait and see if the screed would crack further, or is the construction manager’s statement simply incorrect?
@ Ade123:
If the terrace slab was poured, it was probably done without any slope formation.
However, the claim that a floating screed with slope has been installed caught my attention! How exactly was the slope in the screed achieved, is my "tricky" question?
It can and must only be the case that a bonded screed with slope was applied on the concrete slab, or, as the only alternative, thermal wedge insulation if there are living spaces underneath the terrace.
Why floating – my first question is, what is meant by that, and
how was the slope in the screed achieved, my second question?
The usual installation method for constructions without rooms underneath in outdoor areas (from bottom to top):
- Base slab
- Sloped bonded screed
- Waterproofing layer as edge-bonded or edge-welded membranes
- Drainage board
- Cement screed with frost-resistant aggregates, strength and thickness: CT-C20: 55mm (2 inches) or CT-C30: 50mm (2 inches)
- Not mandatory but recommended with ceramic tiles as a top layer: mineral-based sealing slurry
- Ceramic tiles
-------------------------------------------
The screed cracks are due to stresses that very likely could have been prevented with proper planning.
The fact that additional cracks appeared after resin injection without further mechanical load suggests reasons other than faulty screed installation.
No matter what a site manager says!
-------------------
I hope these general statements are helpful: KlaRa
If the terrace slab was poured, it was probably done without any slope formation.
However, the claim that a floating screed with slope has been installed caught my attention! How exactly was the slope in the screed achieved, is my "tricky" question?
It can and must only be the case that a bonded screed with slope was applied on the concrete slab, or, as the only alternative, thermal wedge insulation if there are living spaces underneath the terrace.
Why floating – my first question is, what is meant by that, and
how was the slope in the screed achieved, my second question?
The usual installation method for constructions without rooms underneath in outdoor areas (from bottom to top):
- Base slab
- Sloped bonded screed
- Waterproofing layer as edge-bonded or edge-welded membranes
- Drainage board
- Cement screed with frost-resistant aggregates, strength and thickness: CT-C20: 55mm (2 inches) or CT-C30: 50mm (2 inches)
- Not mandatory but recommended with ceramic tiles as a top layer: mineral-based sealing slurry
- Ceramic tiles
-------------------------------------------
The screed cracks are due to stresses that very likely could have been prevented with proper planning.
The fact that additional cracks appeared after resin injection without further mechanical load suggests reasons other than faulty screed installation.
No matter what a site manager says!
-------------------
I hope these general statements are helpful: KlaRa
Similar topics