just put my planning for 2 storey ex in. In the mean time thought i'd get some quotes from builders. I want to do most myself to try and save on labour. I plan the builder to do all brick work and roof, also put the floor in as they work off it.

Im hoping to dig my own foundations, then they can start with pouring them to there taste.

Ground floor is a garage, normal founds , states 150mm slab in garage. I take it i dig founds. pour concrete, then build walls up to DPC, then level the garage floor out and add the 150mm slab with DPC then. Then continue with walls. Am i correct or is the slab done at another time?

also i need to add a new soil stack. i have the old brick manhole inspection things. what is the accepted way to add to these. can i just install new pvc pipe in and cement around hole used to get in. Or do i have to change to a proper new chamber?

thanks