ᐅ Basement originally partially constructed with concrete, now possibly fully built with masonry.
Created on: 19 Jan 2017 00:04
K
Kaspatoo
Hi,
In previous discussions and offers, we agreed with our provider (architect/owner of the construction company, including their own site, excavator, employees, etc.) to build the basement roughly half in 24cm (10 inches) thick concrete and the other half with masonry.
The background is that we have a sloped site, and the basement is about half above ground level, containing two living rooms. The rooms at the rear, towards the slope, are a heating room, storage room, and bathroom.
We do not have a soil report. The soil is clay/loam-like (my father-in-law called it red marl). So, it is not very permeable. Above us runs the road, and beyond that, the slope continues for about 50-100m (55-110 yards), then you reach the top of the hill. Two more plots will be developed above us. The house and road are roughly at the same level (plus a step).
We now want to finalize the contract details. The architect recently called me and said he would prefer to build the entire basement with masonry (thickness unknown but thicker than 24cm (10 inches)), including drainage. The drainage would not clog because it would be in a gravel bed.
I have researched and, as expected, I am uncertain about which option is better and what questions I should ask the architect or what details should be agreed upon.
Basically, there are two methods: waterproof concrete (often called a white tank) and sealing with bitumen or plastic membranes (often called a black tank).
Regarding the cost of both options, I have read very different statements; for some, one was more expensive, for others, the other was. Or it was previously like that, but now they say the costs are about the same. The waterproof concrete method is said to be much more common nowadays.
I also found, but only from one source (other sites had exactly the same text), that bitumen variants last only about 30 years, while waterproof concrete easily lasts 80 years. Is there any truth to this? Has anyone had to remove their soil because water appeared after 30 years?
Back to the upcoming discussion with the architect. Should he provide a written guarantee of watertightness? Is the concrete method definitely waterproof and generally requires less long-term warranty? What else should I pay attention to (I won’t sign immediately, but a more confident approach wouldn’t hurt)? What might be a rough but reasonable wording for both options in the contract?
Thank you very much.
In previous discussions and offers, we agreed with our provider (architect/owner of the construction company, including their own site, excavator, employees, etc.) to build the basement roughly half in 24cm (10 inches) thick concrete and the other half with masonry.
The background is that we have a sloped site, and the basement is about half above ground level, containing two living rooms. The rooms at the rear, towards the slope, are a heating room, storage room, and bathroom.
We do not have a soil report. The soil is clay/loam-like (my father-in-law called it red marl). So, it is not very permeable. Above us runs the road, and beyond that, the slope continues for about 50-100m (55-110 yards), then you reach the top of the hill. Two more plots will be developed above us. The house and road are roughly at the same level (plus a step).
We now want to finalize the contract details. The architect recently called me and said he would prefer to build the entire basement with masonry (thickness unknown but thicker than 24cm (10 inches)), including drainage. The drainage would not clog because it would be in a gravel bed.
I have researched and, as expected, I am uncertain about which option is better and what questions I should ask the architect or what details should be agreed upon.
Basically, there are two methods: waterproof concrete (often called a white tank) and sealing with bitumen or plastic membranes (often called a black tank).
Regarding the cost of both options, I have read very different statements; for some, one was more expensive, for others, the other was. Or it was previously like that, but now they say the costs are about the same. The waterproof concrete method is said to be much more common nowadays.
I also found, but only from one source (other sites had exactly the same text), that bitumen variants last only about 30 years, while waterproof concrete easily lasts 80 years. Is there any truth to this? Has anyone had to remove their soil because water appeared after 30 years?
Back to the upcoming discussion with the architect. Should he provide a written guarantee of watertightness? Is the concrete method definitely waterproof and generally requires less long-term warranty? What else should I pay attention to (I won’t sign immediately, but a more confident approach wouldn’t hurt)? What might be a rough but reasonable wording for both options in the contract?
Thank you very much.
Iktinos schrieb:
See #post 10 😉No.
That refers to the construction joint / waterstop (as a structural element of a presumed waterproof concrete structure, often called a “white tank”) as a potential weak point in a concrete wall.
The waterstop is not made of concrete.
However, the joint can of course be a weak spot or source of defects, whether due to design or workmanship issues.
Even with perfect joints, concrete as a building material naturally allows some water vapor to pass through, although very little (see above, “shot glass formula”). If this vapor transmission is also unwanted, the waterproof concrete structure can be additionally coated with a black bitumen-based membrane.
What would be an appropriate description or term for a proper waterproofing system for a masonry basement?
So far, I have mostly read about bitumen, thick coatings, membranes, as well as plastic alternatives to bitumen.
Are all these equally effective?
Regarding the claim about durability—concrete vs. masonry (30 years vs. 80 years)—is there any truth to this, or is it just fear-mongering?
So far, I have mostly read about bitumen, thick coatings, membranes, as well as plastic alternatives to bitumen.
Are all these equally effective?
Regarding the claim about durability—concrete vs. masonry (30 years vs. 80 years)—is there any truth to this, or is it just fear-mongering?
Hello Kaspatoo,
I don’t see a reason for a waterproof tank (tank waterproofing). Let me guess: your basement won’t be below the groundwater level. It will just have normal soil moisture, which you need to keep away from the exterior wall. Additionally, you want to protect the house from surface water that might flow down the slope during heavy rain. To manage the rainwater, you should build a wall around the property. Otherwise, the water will eventually pool in front of your house.
Since I’m not a fan of concrete for walls (concrete doesn’t breathe), I would prefer a masonry basement. On the outside, apply a thick-bitumen coating, perimeter insulation, and then a dimpled membrane. If installed properly, that gives you double protection. Then add drainage, and your problems will be solved.
Why should bitumen come loose after 30 years? It’s mechanically pressed against the basement wall.
Steven
I don’t see a reason for a waterproof tank (tank waterproofing). Let me guess: your basement won’t be below the groundwater level. It will just have normal soil moisture, which you need to keep away from the exterior wall. Additionally, you want to protect the house from surface water that might flow down the slope during heavy rain. To manage the rainwater, you should build a wall around the property. Otherwise, the water will eventually pool in front of your house.
Since I’m not a fan of concrete for walls (concrete doesn’t breathe), I would prefer a masonry basement. On the outside, apply a thick-bitumen coating, perimeter insulation, and then a dimpled membrane. If installed properly, that gives you double protection. Then add drainage, and your problems will be solved.
Why should bitumen come loose after 30 years? It’s mechanically pressed against the basement wall.
Steven
Steven schrieb:
And since I’m not a fan of concrete for walls (concrete doesn’t breathe), I would prefer a masonry basement.The above-ground wall that “breathes” is already a great old wives’ tale.
That this would also work underground, sealed with bitumen or something similar, surrounded by damp soil, is truly a miracle of engineering (or imagination).
Hello Alex
a more detailed explanation for you: Of course, no wall “breathes.” It has no lungs and does not draw in oxygen. The term “breathing” refers more to the ability to absorb and release moisture.
You can best notice this when you have been inside an old concrete bunker.
Steven
a more detailed explanation for you: Of course, no wall “breathes.” It has no lungs and does not draw in oxygen. The term “breathing” refers more to the ability to absorb and release moisture.
You can best notice this when you have been inside an old concrete bunker.
Steven
Similar topics