Hello
I am in the process of completing the slab for a somewhat heated conservatory. The conservatory will have one or possibly two load-bearing columns. The glass wall of the conservatory, where the columns will be, is one of the house's two load-bearing exterior walls.
Some basic weight mathematics in brief:
The span of the house is 12 meters and if you include the eaves and such, it is 13m / 2 (two long sides of the house) that the wall supports, tiled roof, snow load zone 3.
The glass wall is almost 10 meters long, so one can say it is 75 (7.5m wide * 10m long) square meters of roof that the wall supports.
I think that with snow load zone 3, the wall should be able to support 300 kg per square meter (that's right, 3kN/m2). The snow can then weigh 300 x 75 m2 of roof, 22500kg. Tile, say 50 kg / m2, about 4000 kg.
Say 27 tons for the entire roof with roof trusses and all. Divided between two walls (the other has nothing to do with the conservatory), 13.5 tons each.
This wall will have three (or possibly 4) load-bearing points, one at each end and one in the middle of the glass sections. The one in the middle will then take about half of the entire load over the conservatory, totaling about 7 tons.
To ponder:
I plan to cast this slab next week hopefully and I wonder if there is any reason at all to have insulation under these columns, or if it will just deform unnecessarily.
I'm thinking of insulation of the type XPS300 that e.g. Buildmax sells, it supports 30 tons/m2. Short-term load, if I remember correctly. The load here is very concentrated. Of course, the concrete distributes the pressure a bit, but still. Alternatively, we could use two columns, which I otherwise prefer to avoid because one is simply more elegant than two. However, two columns feel more stable than one, even if the engineer has calculated that one is sufficient. I don't know what's most sensible.
It won't be 25 degrees warm in winter, there is underfloor heating and insulating glass. It will always be above freezing, but it will likely be quite cool during the winter, so it's a place where you CAN skip insulation if necessary.
Concrete questions:
1) Is it justified to insulate under a column or will the insulation just deform and you will have ugly settlements quite soon?
2) One or two columns, what would you do?
The engineer has provided the following two options for me regarding columns:
Option 1: (1 column)
longitudinal beam 140 x 495
140x140 columns at the ends
140x315 in the middle
Option 2: (2 columns)
longitudinal beam 140 x 315 (thinner)
140x140 columns at the ends
two intermediate columns at 140x180 each after one third of the span.
edit: Correction after Mikael_L
I am in the process of completing the slab for a somewhat heated conservatory. The conservatory will have one or possibly two load-bearing columns. The glass wall of the conservatory, where the columns will be, is one of the house's two load-bearing exterior walls.
Some basic weight mathematics in brief:
The span of the house is 12 meters and if you include the eaves and such, it is 13m / 2 (two long sides of the house) that the wall supports, tiled roof, snow load zone 3.
The glass wall is almost 10 meters long, so one can say it is 75 (7.5m wide * 10m long) square meters of roof that the wall supports.
I think that with snow load zone 3, the wall should be able to support 300 kg per square meter (that's right, 3kN/m2). The snow can then weigh 300 x 75 m2 of roof, 22500kg. Tile, say 50 kg / m2, about 4000 kg.
Say 27 tons for the entire roof with roof trusses and all. Divided between two walls (the other has nothing to do with the conservatory), 13.5 tons each.
This wall will have three (or possibly 4) load-bearing points, one at each end and one in the middle of the glass sections. The one in the middle will then take about half of the entire load over the conservatory, totaling about 7 tons.
To ponder:
I plan to cast this slab next week hopefully and I wonder if there is any reason at all to have insulation under these columns, or if it will just deform unnecessarily.
I'm thinking of insulation of the type XPS300 that e.g. Buildmax sells, it supports 30 tons/m2. Short-term load, if I remember correctly. The load here is very concentrated. Of course, the concrete distributes the pressure a bit, but still. Alternatively, we could use two columns, which I otherwise prefer to avoid because one is simply more elegant than two. However, two columns feel more stable than one, even if the engineer has calculated that one is sufficient. I don't know what's most sensible.
It won't be 25 degrees warm in winter, there is underfloor heating and insulating glass. It will always be above freezing, but it will likely be quite cool during the winter, so it's a place where you CAN skip insulation if necessary.
Concrete questions:
1) Is it justified to insulate under a column or will the insulation just deform and you will have ugly settlements quite soon?
2) One or two columns, what would you do?
The engineer has provided the following two options for me regarding columns:
Option 1: (1 column)
longitudinal beam 140 x 495
140x140 columns at the ends
140x315 in the middle
Option 2: (2 columns)
longitudinal beam 140 x 315 (thinner)
140x140 columns at the ends
two intermediate columns at 140x180 each after one third of the span.
edit: Correction after Mikael_L
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Well, I'll start with a small correction.tobbew said:
If there are three columns, with two at the ends, with distributed load, the one in the middle will take half the load, almost 80kN, and the outer columns will share the remaining half of the load.
But then I don't really see what the question was, if there was one ...?
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Late response, maybe too late.
But it is common to reinforce the slab locally where the column goes down. A bit thicker concrete + reinforcement. This is to ensure the slab can withstand the load + to distribute the forces better.
Then, as a rule, stronger insulation is placed under this part.
As you write, e.g. 300-insulation.
But it is common to reinforce the slab locally where the column goes down. A bit thicker concrete + reinforcement. This is to ensure the slab can withstand the load + to distribute the forces better.
Then, as a rule, stronger insulation is placed under this part.
As you write, e.g. 300-insulation.
Thank you Mikael, but this has been set in stone for half a year now.
I actually don't remember exactly how it turned out, I know I made a solid vot, and on someone's advice, I made a fan shape of reinforcement to withstand tension better, under the pillars. And there was insulation, about 300kpa or something similar.
I think it turned out well. The pillars are currently standing and supporting the roof with all the snow, so far nothing has moved.
Thanks for the help!
I actually don't remember exactly how it turned out, I know I made a solid vot, and on someone's advice, I made a fan shape of reinforcement to withstand tension better, under the pillars. And there was insulation, about 300kpa or something similar.
I think it turned out well. The pillars are currently standing and supporting the roof with all the snow, so far nothing has moved.
Thanks for the help!