I'll be tearing down a deck in the near future to get the back of the house dug up and waterproofed. The deck is old and needs to be replaced anyway. I was thinking about a poured patio slab instead of a new deck but all this talk about cracking concrete is giving me pause. There are lots of attractive stone pavers and interlocking brick options available but I'm concerned that these will heave and shift. Can I use an extra deep base of sand or gravel with drainage tiles or some other method to eliminate shifting? I'm just north of the Danforth near Coxwell and the soil here is very sandy. We'll be digging right down to the footings and installing weeping tiles around the foundation so I could dig a bit more and put in drainage pipes in the patio area if it would keep the soil from heaving. Any free advice?
You owe me dinner on the Danforth.....
1. WRT to your weepers, etc.
Use the white 4" perforated PVC pipe from Home Depot. (Do not use the thin walled black shit wrapped in filter sock - it's fucking junk.) You will see the white PVC perforated pipe in the plumbing section along side the black ABS pipe. This is the good stuff. You want to install the weepers so that the bottom of the weepers is at the same elevation as the underside of your footings (or foundation wall). Always install the holes down!!! (So many idiots install the holes up thinking that the pipe catches the water that way, it does not. The pipe simply forms a conduit for the water to flow through. Now the good part, you want to encase the weepers in 6" of either 3/4" clear stone all round, or crushed stone (but I'm not so sure about using crush with weepers to be honest). The entire thing has to be wrapped with a Geotextile cloth (or filter cloth) to prevent fines from contaminating the weeper over time. You then connect the weepers to a sump, or a storm water drain. (Do not connect to a sanitary drain!!).
2. WRT to waterproofing.
Waterproofing is what keeps the water out. Many are under the misguided belief that the wall (especially a concrete wall) will keep the water out. It will not. A house is not a boat.
Do not skimp on water proofing. You've gone to all the trouble of digging out, installing weepers, etc. it's fucking stupid to use cheap waterproofing. (And by cheap, I mean that black shit in a can that you see idiots putting on with a roller. Utter crap.)
I have seen this stuff both in use and at trade shows and I'm most impressed with it. I would recommend you hire them to do your foundation walls.
http://www.advancedcoatings.on.ca/rub-r-wall-airtight.html
3. WRT to Styrofoam insulation
It’s the best way to insulate your basement as you keep the wall warm and there is a thermal break on the outside of the wall. But........
Be careful insulating with Rigid SM foam on the outside of foundation walls, especially in your part of the town. Termites are well known to dig through foam creating tunnels to get into your house. If the foam laps any wood rim joist, the termites will dig through the SM, right to the rim joist and then they are in and you have a huge problem on your hands.
4. Be careful insulating old masonry walls (rubble stone) or old concrete block walls. If you insulate on the inside, the wall will now be cold. The wall will wick moisture in the fall, then in the winter, since the wall is cold, the moisture freezes and blows apart the mortar or the block. The result is structural damage over time to your masonry foundation wall. Better to keep the wall warm in the winter through a bit of heat loss than to freeze an old masonry wall.