Hi! I built a rock cabin with a 4 inch concrete roof. The roof has 2 layers of thoroseal and painted with UGL waterproof paint but I still have a few minor wet spots inside during heavy rains. Anyone know how to completely waterproof concrete? To look at the building copy and paste this site. Thanks for any help. http://www.geocities.com/PicketFence/Garden/8784/Rock3.html

-- kirk davis (kirkay@yahoo.com), January 07, 2000

Answers

Can't help you with the leak....just thought I'd say what a beautiful cabin!! How big is it? How long did it take you to build? Sue

-- Sue Landress (Sulandherb@aol.com), January 07, 2000.

Thank you Sue! That was very kind. The building is 15 feet by 15 with a nice size room upstairs. Its a cabin now but was built to continue adding on. I started a year and a half ago. Its taken a long time because I have never worked with rocks before and I needed to gather the money as I went. No debt! Also no electric and no help. Wouldn't it be fun if countrysiders had a spot to show picts of all their homes, projects, kids, animals etc? Anyway thank you for the post! Kirk

-- Kirk Davis (kirkay@yahoo.com), January 08, 2000.

Shingles and tar. And tar. Ride around to construction/roofing jobs, and ask if they have shingles/tar left over. You can take it away for a song! They have to 'pay' to remove the extra. Sweet dry deams. K

-- Kathy (catfish@bestweb.net), January 08, 2000.

What a pretty cottage! My opinion, based on 14 or so years in the masonry restoration and waterproofing field is that the products that you have already installed, while not altogether bad, are not optimal either.I believe that the best way to waterproof brick, block, concrete or stonework is with silane or siloxane blends in either a water or alcohol base. These are not surface sealers wich block the masonrys ability to breath, but are penetrating water repellants.The diference is this:A masonry sealer sits only on the surface of the substrate and prevents water from entering from the exterior. These products are prone to very small cracking due to ultra violet breakdown. Also they inhibit the water in the form of vapor to escape from the interior of your cottage. Penetrating water repellants act like a gore-tax jacket. Water molecules in liquid form are larger than water molecules in vapor form, by setting up a "shield " small enough to repell liquid but not so tight that vapor cant escape,your house can still breath.I know this doesnt help much now, but FYI. You could rent a sandblasting set up for a day or two and start over! Shingles and tar would be a maintenance nightmare in my opinion. Just wondering... Did you use some type of slip form system for your walls and how did you form the roof?

-- mike dorsch (mstydale@aeroinc.net), January 08, 2000.

Mike: I guess the walls are a sort of slip forming but to be honest I couldn't figure that technique out. The inside I braced plywood. The outside was a 2 foot by 4 foot plywood connected with bailing wire to the inside sheet. I filled the wall with concrete and layed the rock in blind. Next day I cut the wires holding plywood on,cleaned the joints and rock then rewired plywood to the next spot. I added vertical and horizontal rebar as I went along. The roof has conventional rafters with a thin osb plywood to support the concrete. I put 8 inch grid of rebar over the entire roof. I framed,with 2 by 4s, 16 inches, up the roof, then the length of the roof, to hold in a section of concrete. The pitch of the roof was such that I could lay a ladder flat against the roof and keep extending it as I went. Then bucket by bucket I poured each section. Each day I moved the frame higher until the roof was done. This was the only way I could figure out how to do it. Sounds like you are very experienced. Would you mind if I sent an e-mail question on occasion? Must be a stone mason secret club because its hard to find people that answer questions. Kirk

-- Kirk Davis (kirkay@yahoo.com), January 09, 2000.

Kirk, Mike's right that there are many different masonry sealers of varying suitablility for different jobs.

IF you are planning to use the concrete as the actual roofing material, I recommend you talk to a store which sells masonry products. Here in SW Oregon, we have Cascade Block. They manufacture concrete blocks and other concrete products, plus sell all kinds of masonry supplies.

I am uncertain about a couple of things about your house. (Before going there, though, I want to compliment you on the outstanding job you have done. I'm a semi retired builder, and I'm very impressed!) What are you doing about insulation? The reason I ask, is that the insulative value of any masonry product is extremely low, and you will want to be adding some hi R value product on either the inside or the outside of the house. I can't imagine covering your beutiful stone work either inside or out, but you will probably be wanting to put up a stud wall or something on the inside anyway. That way you could maintain the beuty of the building from the outside, and put up, perhaps, some nice cedar or pine T&G inside.

As far as the roof, if you DON'T already have a provision for insulation on the inside, one solution would be to install sleepers on the top of the concrete (preferably pressure treated), then add a set of rafters, between which you could put either R 38 fiberglass or Polystyrene.

Oh, one other question: are you sure the roof is actually leaking? If there is no insulation under the slab, the moisture could easily be condensation. That slab is going to get extremely cold, and any moisture generated by living activities (showering, cooking, breathing, etc,) indoors will condense on a cold surface. You need to have a vapor barrier between the living space and the insulation, ideally.

Good job, Kirk

-- jumpoff joe (jumpoff@echoweb.net), January 13, 2000.