Typar and Sealer inside the basement or just Typar?

Question

Basement. House Circa 1950, Ontario Canada

Previous owner for 5 years had some water leakage near the furnace, but that was all the water problems they had.

We are adding another downspout going into a rain barrel on that side of the house.

Last HUGE rain we had, our drain backed-up in a lot of the houses on the street and flooded our basement enough to ruin it IF it was finished. Our sump pump couldn't even handle the flow (we're the only ones on the street with a SP too!)

We plan on installing a ball-c**k in the drain to prevent that from happening again.

I plan on using Typar on the inside of the cinder block basement before I metal stud.

Should I roll on a sealer as well or would it just be a waste of money with all the other things we're doing?

Answer 1

The correct way to deal with basement water problems is to divert the source of the water before it penetrates the basement.  It sounds like you plan to work on that.

Typar on the inside of a block wall will do absolutely nothing for you.  Typar is an air infiltration barrier, nothing more.  It is NOT waterproof or moisture proof.  It is specifically designed to let water vapor pass so as not to trap it inside the house.

If you get the water away from the house properly, you should not have any problems with water coming in.  You may still have dampness, in which case a good coating of Drylock or Sta-Dri will help considerably.  

If you really need a membrane of some sort, it should go on the outside of the block wall so the water is stopped before it enters the block.  Obviously more work and expense than putting something on the inside, but much better for the health of your foundation.

For a vapor barrier, stick with plain old 4 mil plastic sheeting.  Cheap and effective.  I would not count on this to help with weeping through the wall - you need to take care of that with one of the damp-proof coatings or membrane outside.  But as a vapor barrier, it should be fine.