Iam planning a herbspiral for a kindergarden.
The spot is next to the house. The house got drainage all around and the herbspiral will be half ontop of that gravel.
The house lays on top of a small manmade hill about 2 meters high. The hill is fill material, big stones, clay, gravel, cement, bricks and such things.
The climate is cold temperate going down to -10 in winters. Location is oslo in norway.
I think this looks like pretty darn well drained area.
But since its the first time i build anythin with mortar i thought i better doubble check with as many as i can!
So i got repurposed bricks for material and i wanna build the spiral with mortar so that its safe for a kindergarden. I wanna build a the outer ring of the spiral a bit wider so it can function as a bench also. And for the kids to stand on to reach the top of the spiral
I spoke with a landscape architect from my area and he suggested to go all the way with cement foundation just to be safe. But im not too found of the idea of using cement..
I think it will be enough to put a drainage layer with stones ( bigones, small ones, gravel, sand) about 50 cm deep and build with bricks and mortar on top of that.
But do i have to fill the drainage up til groundlevel with gravel or can i start building with the bricks under the ground level? Maybe 20-30 cm with stones/gravel is enough since its already drainage in place from the house?