mattpdx

I tore off some 70s fake lava rock off my indoor filreplace and want to replace it with some cultured stone.

I'm starting with the corners and have all the corner pieces. Thing is, I want things to line up perfectly with the (vaulted) ceiling and have a piece picked out that will fit perfectly up there.

This stuff is probably too heavy to work from the top down, but I'd still like the top along the ceiling to look neat and perfectly fitted, if there is any cutting necessary I can do it along the floor.

Would this work for the corners at least? Place the stone I want on top, mark a line on the cinder block with pencil. Leave a gap, test fit a stone below it and do the same thing. All the way down to the bottom (and keep track of the order of the stones).

Then, start working with actual mortar from the ground up, placing the stones as they were pre-fitted. Then I should end up with the perfect piece in the perfect position on top.

Does this sound reasonable?

nealtw

I have seen brick layers lay out a hole wall on the floor to make sur arches work and fit so I think that should work.

BridgeMan

No reason it wouldn't work, as long as you very carefully mark each piece and its location. Should be quite a jigsaw puzzle, putting everything into place.

I've only installed cultured stone one time (several decades ago), but I did it from the top down to avoid the problem you're describing. And just a few days ago, I noticed the local hardware store's new addition being faced with cultured stone, again from the top down. Maybe you could consider doing it that way, and save yourself a lot of fit-up and marking/measuring time.

mattpdx

Yes, actually I would like to do it top down, but not sure if the mortar will be enough to hold everything in place without some kind of bracing?

nealtw

Put up a few peices and if they don't stay in place, scrape off the mortar and start from the bottom.

BridgeMan

The mortar should readily hold everything in place, if mixed stiff enough and with the right water/cement ratio, such that the set time isn't compromised. Be sure to use a notched trowel when spreading it, too. At the local hardware store job I mentioned earlier, there's no sign of things not staying in place.

If you're worried about things wanting to obey the laws of gravity (slowly slipping down while the mortar is still loose), why not put in a few strategically-placed drywall screws to hold things until the mud sets? If the block underneath is soft enough, you might not even have to drill pilot holes. Remove them the next day, patch the holes with mortar.

resurfacer

Starting from the top, pre-fit a section and build a ledge from lumber to support the stone. You can use morter instead of cement, apply to the vertical surface, back butter the stone, apply the stone to the wall with a side-to-side motion. The Idea is to create A suction by removing the air. A rubber hammer can help. Tile installed in this mannor would require mechinal help to remove from the wall. Good luck defacing your fireplace.
Other fireplace resurfacing options can be viewed on the website link provided in my profile