I'm going to start work on my old foundation today, we have had the house moved, walls and windows cut out and getting the addition cribbed up tomorrow. I rented a mini hoe and I'm gonna start trenching out around the old foundation. I have a small crack that's been there for years but never leaked so I'll probably fill it with hydraulic cement once it's excavated. I want to make sure I have a good plan of attack and maybe see if there is anything I should do different, so: Once I excavate I have a friend that is gonna bring his truck by and sandblast all the old tar and dirt off so I have a nice clean slate. Next, patch the crack and check for others. I was gonna use Blueskin peel n stick but I'm considering brushing on Blue Seal waterproof rubber membrane, any input on this step????? Next is 2"xps insulation, hopefully I can find a cheaper supplier than HD ($25/sheet and 81 sheets!!), I'll spray foam the joints and then I want to add a dimple membrane. So far the only one I can find is Superseal. I'll spread out some 3/4" rock and set my drainage tile on it, fill with about 2-3' of 3/4" rock and wrap with cloth, then once my sub floor is on I'll backfill. The interior will be 2lb cc spray foam. How's that sound? I've never had any water problems but I don't want to take any chances. Thanks, Sean

Sounds good, I have not used Blueskin, but you are being redundant with water-proofing, that is good. I would put in drain-tile with a fabric cover on the bottom (no rock under it), cover it with rock and fabric on that. Fasten the dimple membrane really well, back-fill will try to pull it down. The dimple membrane with fabric on the back, Delta makes one, creates a flat surface and is much less likely to be dragged down.
When you back-fill do it in 12" lifts then compact with a jumping jack compactor, that will exert the least pressure on the wall, the least amount of movement to drag down the dimple membrane and will settle the least in the future.

Thanks, I'll see what I can find. What kind of mat do I wrap the drainage in and is the ridgid white drain pipe better than the flexable black coils you can buy?? Got it all dug out now and the old tar looks like black paint, I'm wondering if it needs to be sandblasted or can I pressure wash it and scrub it?? Not sure if the Blueseal will stick very well to the old stuff even though it's not flaking or peeling. Sean

Pressure washing and letting it dry should do it. But your excavation looks kind of tight. The corrugated with slots and a "sock" is what you want, the PVC is for drain-fields and has too big of holes. Surround the drain-tile with rock and cover the rock with 3-4' wide landscape fabric, then fill. Rock gravel or sand fill up against the foundation is a good idea.

Yea it is kinda tight, I'm pretty space limited and running out of places to put the dirt. It's about 2.5' across the front and I'm not overjoyed about working in there, at least it's only shoulder deep. Sean

It is tough to do a good job on a tight excavation.

Sounds like a plan. Only suggestion I'd make is to use a urethane or epoxy crack sealer. You won't be able to get enough cement into a small crack to do any good. The urethane flows pretty well and you don't have to move around in the tight space to get it in.

Thanks Jerry, I'll see if I can find some at the local HD. I'm gonna go with pressure washing tomorrow I hope and maybe get the Blue seal on while I'm at it. Nothing like being in a hole at 30 degrees Celcius all covered in rubber. The last couple of days have been fun running an excavator and today a Bobcat. Kinda scarey driving into that hole though. Took a few tries to get out. Thanks again, Sean