Is it possible to see how an old foundation slab was poured?
I have a house built in 1933 that stands on a granite foundation in a sloping site (the whole area is pure rock), the house's basement is in the form of a rectangle, and in the middle of this "rectangle" is one load-bearing wall (brick masonry) that runs parallel to the "rectangle's long side". At 3 door openings, one can see a crack that runs parallel in the wall's direction and corresponds with the outer dimension of the load-bearing wall.
What I need to know is whether the foundation slab was poured after the granite foundation was raised and if the load-bearing middle wall was then built up on the foundation slab, or if the outer walls and load-bearing wall were done first and if the foundation slab was then poured in.
Anyone know old 1930s construction techniques?
I have a house built in 1933 that stands on a granite foundation in a sloping site (the whole area is pure rock), the house's basement is in the form of a rectangle, and in the middle of this "rectangle" is one load-bearing wall (brick masonry) that runs parallel to the "rectangle's long side". At 3 door openings, one can see a crack that runs parallel in the wall's direction and corresponds with the outer dimension of the load-bearing wall.
What I need to know is whether the foundation slab was poured after the granite foundation was raised and if the load-bearing middle wall was then built up on the foundation slab, or if the outer walls and load-bearing wall were done first and if the foundation slab was then poured in.
Anyone know old 1930s construction techniques?
Probably what you see in the basement is just a cast floor! With the description you give of the house "granite foundation..." I think they might have been careful with the use of cement (=concrete).. Expensive at that time!
Hmmmm...?
Do my suspicions hold that the floor itself was cast after the outer walls and the load-bearing middle wall (made of brick) were erected? In the garage, the bottom slab is about 50 cm thick with rubble underneath when I look down into the inspection shaft around the drain (a hatch of 60 x 40 cm), the drain is located there under the bottom slab against the rubble.
Do my suspicions hold that the floor itself was cast after the outer walls and the load-bearing middle wall (made of brick) were erected? In the garage, the bottom slab is about 50 cm thick with rubble underneath when I look down into the inspection shaft around the drain (a hatch of 60 x 40 cm), the drain is located there under the bottom slab against the rubble.
Yes, your suspicions are probably correct. From what I understand, it was quite common to erect the exterior walls of the house and the central wall first, and then pour the basement floor afterwards.
The builder described our house quite well (built in 1936-37 in Stockholm). The slab in the basement can be broken with a hammer. There are certain places where it is harder and thicker, but it is usually between 1-3 cm thick, with a lot of sparsten underneath.
Buy a recoil-free rubber mallet at Jula and give it a try. It can even be fun, as in some cases, the underlying layer has sunk a bit, giving you air directly under the slab.
SWEHJO on the forum has a great book from the 40s that describes the aforementioned building technique. If you're lucky, he might publish some pictures...
The builder described our house quite well (built in 1936-37 in Stockholm). The slab in the basement can be broken with a hammer. There are certain places where it is harder and thicker, but it is usually between 1-3 cm thick, with a lot of sparsten underneath.
Buy a recoil-free rubber mallet at Jula and give it a try. It can even be fun, as in some cases, the underlying layer has sunk a bit, giving you air directly under the slab.
SWEHJO on the forum has a great book from the 40s that describes the aforementioned building technique. If you're lucky, he might publish some pictures...
Becoming even more uncertain now.
I know that, for example, the steps outside the house were constructed using the "procentning" principle, where a lot of blasted rock was thrown in with a bit of concrete on top. But the 50 cm thickness of concrete at the cleaning well in the garage suggests a "bunkergjutning" of the foundation slab. The house is built with solid materials; all craftsmen swear and curse over the tough wood that is at least 30 mm thick, resin-rich so that the reciprocating saws wear out, the beams are 4 x 9 inches, the load-bearing planks are 2 by 2 inches, etc. We haven't tackled the basement floor yet, but it is in "like new" condition despite being 70 years old. The only downside is that it gets pretty cold in the summer, causing it to become soaking wet with condensation.
I know that, for example, the steps outside the house were constructed using the "procentning" principle, where a lot of blasted rock was thrown in with a bit of concrete on top. But the 50 cm thickness of concrete at the cleaning well in the garage suggests a "bunkergjutning" of the foundation slab. The house is built with solid materials; all craftsmen swear and curse over the tough wood that is at least 30 mm thick, resin-rich so that the reciprocating saws wear out, the beams are 4 x 9 inches, the load-bearing planks are 2 by 2 inches, etc. We haven't tackled the basement floor yet, but it is in "like new" condition despite being 70 years old. The only downside is that it gets pretty cold in the summer, causing it to become soaking wet with condensation.
TN-Funkis! The thickness at the cleaning well doesn't necessarily indicate what you think. In my 1930s house in Stockholm, I also have an iron cleaning hatch (with a cleaning well underneath) in the basement floor, and it looks like the slab is extremely thick there. But don't be fooled by it. In my case, it was only around the cleaning hatch that it was so thick. They simply cast a small "box" just around the cleaning hatch. In places where I've chipped the basement floor elsewhere, it was between 3 and 10 cm thick. I think they laid down the sewer pipes, filled with stones, and then cast a thin layer on top. Since they wanted to have a cleaning well, they didn't fill with stones just around this, which makes it look like the slab is very thick around it. However, you're not really sure until you start with the jackhammer... I have several rooms left to chip up and sometimes worry about the thickness myself. However, I mostly worry that the whole house will collapse when chipping away the basement floor...
Aha, since several people here have torn up basement floors in 1930s houses, did you find rebar or was it just "thrown-on concrete"?
The reason for the question is that I tried to trace old cast iron plumbing with a metal detector, but it basically beeped everywhere on the floor. In the absence of a good plumbing diagram (the original doesn't match reality), are there any tips on how to trace pipes when there is rebar present?
The reason for the question is that I tried to trace old cast iron plumbing with a metal detector, but it basically beeped everywhere on the floor. In the absence of a good plumbing diagram (the original doesn't match reality), are there any tips on how to trace pipes when there is rebar present?
Reinforcement-vahettereförnåt-iron? Nah nah, steel also seemed to be a luxury item in the 30s. However, eternit was probably cheap ;D
Rock-hard Stockholm rock 1 millimeter under the concrete:
http://www.fasting65.se/byggdagbok/dagboken/maj/kallare_500/IMG_0952.jpg
...though most often it was clay and spar-stone:
http://www.fasting65.se/byggdagbok/dagboken/maj/kallare_500/IMG_0944.jpg
Rock-hard Stockholm rock 1 millimeter under the concrete:
http://www.fasting65.se/byggdagbok/dagboken/maj/kallare_500/IMG_0952.jpg
...though most often it was clay and spar-stone:
http://www.fasting65.se/byggdagbok/dagboken/maj/kallare_500/IMG_0944.jpg
And I join the comments of Synpunkters and Fasting65s which are also in line with the book from the 30s-40s that I have. Excavate where the house is to be, build basement walls, cast a box around the future inspection well for the sewer, lay in the sewer and then pour the floor. If I remember correctly, reinforcement is also not included in the basement floor work description in that book. And I don't have it in my house from '36 (which is currently being broken up)...
I think I will pay a visit to our library (which hasn't been closed down yet .....).
Swehjo's book is highly interesting, may I ask about the author, publisher, and year of publication?
Another thing that strikes me when you are crafting so extensively, what "new" materials do you use when replacing the old ones? It's quite easy to use some "modern" material that then doesn't fit with the construction of the 1930s, I'm thinking of all the threads about new insulation where it is easy to encounter various moisture problems and more.
Swehjo's book is highly interesting, may I ask about the author, publisher, and year of publication?
Another thing that strikes me when you are crafting so extensively, what "new" materials do you use when replacing the old ones? It's quite easy to use some "modern" material that then doesn't fit with the construction of the 1930s, I'm thinking of all the threads about new insulation where it is easy to encounter various moisture problems and more.
We laid the sewage pipes in a gravel bed which we then cast over. Nothing fancy. Didn't have the energy, time, or desire to rebuild the basement according to modern principles with insulation, drainage, reinforcement, underfloor heating and God knows what else.
Here is another one in the club with a thin foundation slab without reinforcement! The house was built in '39. It had a layer of fine concrete on top about 5 cm, then a rough concrete mixed with various stones about 10-15 cm. Under that was clay (old lake bed).
When I refilled, I tried to follow all the rules of the art with ground fabric, draining gravel layer, insulation, and concrete. I haven't noticed any moisture migration yet, but that is probably because the underfloor heating isn't connected yet... (I have one room left to finish this spring.)
When I refilled, I tried to follow all the rules of the art with ground fabric, draining gravel layer, insulation, and concrete. I haven't noticed any moisture migration yet, but that is probably because the underfloor heating isn't connected yet... (I have one room left to finish this spring.)
"Small house construction through own work, Do-it-yourself book for home builders, Instruction book compiled by Stockholm City Property Office Small House Bureau"
The year of publication is 1963, but the images, technical solutions, and work descriptions have a much more 1930s feel, so it seems to be a reprint...
No, no ISBN number :
The year of publication is 1963, but the images, technical solutions, and work descriptions have a much more 1930s feel, so it seems to be a reprint...
No, no ISBN number :
Just have to chime in and say that in my house from the '50s, in many parts it was faster to use a crowbar than a drilling machine since the machine mostly created dust while the crowbar could break off larger areas. Around 3cm of casting on crushed stone. And my sewer pipes are made of concrete and not cast iron. Cast iron is in the vertical stacks.
What are the pros and cons of only drilling the parts of the slab where the sewer runs?
(large basement = a lot of rubble and the problems of storing all the stuff)
Then there's the so-called "relining" (you insert a type of epoxy sleeve into the old sewer which is then pumped up under high pressure, - supposedly lasts for another 50 years?)
(large basement = a lot of rubble and the problems of storing all the stuff)
Then there's the so-called "relining" (you insert a type of epoxy sleeve into the old sewer which is then pumped up under high pressure, - supposedly lasts for another 50 years?)