In the course of all the interior renovation of the utility entrance, I've started thinking about the installation of the new exterior door.
Since the floor in the utility entrance is currently 10cm lower (old oil tank room), we intend to break up the existing slab in the spring, insulate, and pour a new one. Along with this, we will likely break up the slab in the adjacent room as well to perform the same procedure there but also for some pipe replacement.
But back to the question. The door hole in the exterior wall is currently 100x200cm, but the door is a 100x210cm door with 10cm going below the interior slab.
The new door we've bought measures 100x200cm, so if we did a direct swap, there would be no issues. But now comes the challenge; we want to raise the interior floor by 10cm.
This means the door hole will be 100x190cm, leaving a 10cm gap. My thought is whether it's possible to cut the current 14x25cm (WxH) siporex beam in height. I can live with a slightly recessed threshold, but a full 10cm gap is not of interest.
How much dare we cut in height? Can the beam be reinforced in any way? For instance, cutting two grooves, one inside and one outside, and inserting flat iron for reinforcement?
Another option is to replace the beam with a leca, thus gaining 5cm, but that requires everything above the door to be rebuilt, which I am not too keen on...
Additional info is that it is an insulated felt roof, and the rafter above the door measures 5x18cm.
I think you should avoid nibbling on the lightweight concrete beam. No one knows how it's calculated and what it contains. It's better to base it on the loads that are current. From what I can read from the picture there are only two roof beams/trusses. If you can show a section of the relevant part of the house, one should be able to calculate the two point loads affecting the beam today, and with that information see which are the best alternatives.
I assume the ridge is supported by a wall? Is it snow zone 1.5 where you live? What is the c/c distance between the roof beams? I'll calculate it a bit later today.
There is likely a high risk that the beam has reinforcement at the bottom, and that the strength will greatly decrease if you cut that reinforcement. However, it might be possible to replace the beam with a slimmer one.
It's just a roof beam resting on the free part of the aerated concrete beam today. This roof beam represents a point load of about 5.2 kN. For safety's sake, if we assume it is located in the middle of the opening (= greatest impact), you can replace the aerated concrete beam with either a wooden joist, 45x120 C24, or a steel beam in the form of a VKR pipe 70x40 with 4 mm wall thickness. There are more options, but they are not large pieces.
In theory, it should just be a matter of placing a support under the roof beam and then cutting out the current siporex and inserting the new one, preferably the steel pipe, and then just cementing it in place?
After it has been in place for a couple of days, if I'm not mistaken, I should be able to cut the beam to the height I want without any issues? This way, I also avoid having to rebuild what's above?
Support under the affected roof beams.
Mill/drill the current beam and the 2-3 blocks sitting on top.
Build up approximately 10cm pieces on the supports.
Place a 45x145 in the middle in direct contact with the roof beams.
Cut the old beam to get two 50x250 pieces.
Then cut these to a height of 150mm, thus the reinforcement at the bottom should remain intact (?) and build them outside the rule.
