Judith,
I agree with Bob and Trevor. If you are going to put anything heavy on the shelf you need to support it deep in the wall. Sounds like you are stuck on the idea of using your "beautiful cast iron brackets" for this installation. Why not use them on a smaller shelf in another part of the house? What I would suggest is that since you have already a flavor of purlins in and about the structure, use that to advantage and make some 1-1/2" X 22" or 23" dowels. Bore them 10" into your 12" wall, seat them with PC and set the shelf on them. You could round the fronts and have them proud of the shelf or make them shorter to be flush with the leading edge of the shelf. Either way, the peg would be embedded well into the wall, have plenty of strength to support whatever you put on the shelf and look cool too. AND if you really really like those beautiful brackets, you could even install them under the baby purlins.
Ron
From: JUDITH WILLIAMS <williams_judith@hotmail.com>
To: papercreters papercreters <papercreters@yahoogroups.com>
Sent: Thursday, March 22, 2012 5:00 PM
Subject: [papercreters] Attaching things to papercrete walls
I did really well in getting the cement in my mix down to 1/2 bag per 200 gallon mix. Now that I am ready to hang a shelf I am worried it might be too heavy for the wall. The screws may pull out. I have been thinking of all sorts of different ways to make sure the shelf doesn't fall down. I even looked at some of those fancy fasteners but don't know what to buy. There are some that have a plastic part the goes into the hole first and some that have little wing thingies that stick out if you put them into drywall. I also thought I would glue a decorative piece of punched tin to the wall behind where the brackets will go. I just don't know, but I want that shelf up there soon. It's a 2x12 12 feet long to span an entire wall. I have 4 beautiful cast iron brackets to hold it up.
Follow progress on the new project at http://www.papercretebyjudith.com/blog
More papercrete info at http://squidoo.com/papercretebyjudith
Follow progress on the new project at http://www.papercretebyjudith.com/blog
More papercrete info at http://squidoo.com/papercretebyjudith
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