Hello!
I'm planning to build my own fireplace insert with lightweight concrete blocks around it. However, we need to raise the stove, which weighs about 130KG, approximately 40cm more. It has legs that are about 40 cm, so in total, it needs to be raised about 80cm.
What I plan to use as the "foundation" for the stove legs are LECA blocks because the entire construction will be on a wooden floor, and I want to keep the weight as low as possible. I have considered using 19x19x59cm LECA blocks standing as four legs and then trimming them to the height I need (about 40cm). To further strengthen it, I've planned to mortar the legs together with parts of LECA in the dimensions 9x19xlength between the standing blocks. What do you think about this? The other option I'm considering is stacking the blocks on top of each other, i.e., two next to each other and then two above in the other direction. What do you think?
I'm planning to build my own fireplace insert with lightweight concrete blocks around it. However, we need to raise the stove, which weighs about 130KG, approximately 40cm more. It has legs that are about 40 cm, so in total, it needs to be raised about 80cm.
What I plan to use as the "foundation" for the stove legs are LECA blocks because the entire construction will be on a wooden floor, and I want to keep the weight as low as possible. I have considered using 19x19x59cm LECA blocks standing as four legs and then trimming them to the height I need (about 40cm). To further strengthen it, I've planned to mortar the legs together with parts of LECA in the dimensions 9x19xlength between the standing blocks. What do you think about this? The other option I'm considering is stacking the blocks on top of each other, i.e., two next to each other and then two above in the other direction. What do you think?
The weight is absolutely not a problem for the lekablock, but it might be harder to make it completely stable with standing blocks. For example, if you were to fall and catch yourself on the stove.
Thanks for the response. Yes, I have also been a bit worried that it might become unstable to place the block upright even if I mortar them together and reinforce with some iron. Now I'm leaning towards laying two in one direction on the bottom and then two in the other direction above, similar to a log cabin or a "#" sign. I will also reinforce here with a couple of rebar through the construction with mortar because a 130kg stove is not something you want to fall 80cm down to the floor... 
A Type 3 block has a compressive strength of 30 kg/cm² with uniform pressure over the entire surface. No point load.
You should probably ask a konstruktör about that.
But 35 kg would then only need just over a cm2 to be distributed. 100x100mm would withstand 3 tons.