gpo

Hi all...let me give you a quick rundown of what I am working with and planning on doing.

Our house is 100 years old...there is about a 12x6 section of the basement that used to just dirt floor...I believe it was the old coal room. My in-laws were the previous owners the house and used it as a rental. My FIL just poured some concrete on top the dirt floor..maybe 2in thick...just to make it a usable space. Well now I am planning on putting a small workshop in the area so I want to take out the old concrete and do it properly.

I have done patios before, but nothing indoors, so I am wondering what I should do around the perimeter where the concrete will be meeting the basement walls and edge of the existing concrete. I am planning on putting down a vapor barrier as well as a gravel base. I am just not sure how to handle the perimeter of the new section. Since it is a basement, will just basic concrete mix be sufficient, or do I need something different? Given the size of the space, should I groove it and use mesh/rebar?

Any tips or suggestions are appreciated. Thanks in advance!

nealtw

I would expect any settling in the dirt so I doubt if you need any steel or grid, not that it would hurt anything if you want to put it in.
A layer of sand is easy to level and makes a nice surface for the poly to sit on. If the floor is close to ground level outside we insulate either the foundation wall below the floor or below the floor against the out side wall for 2 ft. Around the perimiter we use sill gasket stuck to the foundation with acoustical sealant. Never see groves cut in a basement floor.

CallMeVilla

I always include mesh because that is cheap and strong insurance against cracks. I am not sure if you are excavating to get a level floor throughout. If so, I would use bonding solution at the junction of old and new cement.

Have a great project!

BridgeMan

If you attach strips of preformed bituminous joint filler to the exterior walls, with the tops of them at finished grade elevation, they will provide a cushion to accommodate any minor settlement of the slab (should it happen) and also give you a guide for how high to place/finish the new concrete. You don't need anything special in terms of the new concrete, just a decent 3000 PSI (or better) mix will work just fine. A 4" thick slab will require just about 1 C.Y., so you'll probably be batching it yourself. If you use a prepackaged mix, such as Quikrete 5000, about 42, 80-lb. sacks will be required. Cutting the total pour in half by using a removable form down the middle will make for easier work as well as better placement/finishing access. Don't rush the finishing operation, and pour as stiff a mix as possible, since indoor placements always require longer for the bleed water to evaporate off.