Expert: Daniel Humphrey - 2/9/2009

Question
Hi agian, thanks for answering my question, your information is very helpful. I would like to know if I need to use water proofing on the blocks? and I would like your thoughts on running the plumbing and wiring on all the outer walls so that I don't have to run anything under the slab. I am planning on building a mexican style home between 5 and 6 thousand sq. ft. I would also like to know, if I build a few rooms can I live in them while I continue to build?

Answer
Dear Lee,

Yes, you will need to waterproof the blocks and mortar seams on all exposed outer walls. It can be as simple as a transparent masonry sealant.  Paint works fairly well for this,  as does a stucco finish.

Running plumbing in the blocks is labor intensive and must be planned very well. It is not recommended. Just as plumbing beneath a slab cannot be fixed, neither can plumbing inside a block wall. Putting the plumbing so close to the outside places them at risk of freezing.

Wiring is often run inside the blocks, using direct burial wire. But likewise, it is labor intensive and requires precise planning that is sometimes hard to follow when you're busy just laying the blocks. It is done in cases where there is no other good alternative.

Five or six thousand square feet is very large for a house--like three houses. If you're going that large, you could build part of the structure about 12' x 50',  complete with plumbing for a bath and kitchen and continue to build as you occupy that smaller space. Frame in large openings that can remain sealed until the rest of the building is nearly complete; then you can open your little temporary home up to the larger floor plan.

A good plan is everything!

Daniel