I have had trouble finding good information on the proper anchors for fastening to masonry, particularly soft brick. The BIA gives no conclusive recommendations, referring only to the suggestions of proprietary anchor manufacturers.
Sleeve anchors appear to be the most common suggestion, and I have used lead expansion sleeves in the past, but it is very difficult to not over-torque and get slippage and rotating of the sleeve. Additionally, the pilot hole must be precise to have the anchor operate at full strength and this is difficult in softer brick.
Any suggestions?
Replies
How much weight are we talking here?
Across the board--everything from shelving to wall mounted fixtures to bannisters and railings.
Disc-
I renovated an 1870 Pioneer Cottage in Salt Lake City a few years back. I stacked a few of the bricks I had removed from and interior wall in the backyard thinking I might do something with them later. After one winter I had a pile of clay. Soft enough for ya? The exterior walls were all made of the same clay, I mean brick, beneath stucco.
I found that the lead lags worked well, but I used a hammer drill bit smaller than that called for by the lag anchor. If the anchor called for a 3/4" bit, I used a 5/8" bit and hammered the lag into the hole. This seemed to work well and (while still being careful) I couldn't get the anchors to slip. As far as "how strong were they?", well, I used them to anchor a ledger for the high end of a shed-style roof addition on the back of the house and felt comfortable walking around on it during installation of the shingles. Sorry if that's not quantitative enought for ya.
Jason
"Across the board--everything from shelving to wall mounted fixtures to bannisters and railings."
Expanding fasteners tend to fracture the bricks. You can bore the holes oversize, then set any threaded fastener in epoxy. As long as they are dry, epoxy bonds great to brick, since it is do porous. You are still hostage to the bonding strength of the bricks to each other, obviously.
I use West System epoxy with 404 High Density filler for fastener bonding, though there are similar products premixed. If you coat the threads with a thin coat of grease or wax, the fastener may be removable, but it is a better bet to use studs as pictured below.
http://www.westsystem.com/
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Edited 2/9/2005 10:09 am ET by csnow
If you cant get lead shields to work, Hilti makes epoxy anchors for all different materials, and they work very well.
Tapcons are a great product.. Just make SURE the bit is new (no over sized holes)..
If it is really soft not sure if Tapcons will work.
http://www.confast.com/products/tapcon-concretescrew.asp No I don't work for them...
I have drilled all sorts of brick and used hardwood dowels hammered in.. I have some in brick and cement block for years... Never loosened up..
I use a lot of Tapcons, but, for appearance work, don't you sometimes hate that they are BLUE ?
Greg
Blue.. Wooden caps or paint them! Geeeeee
I have tried lead, plastic or zinc shields and lags and sometimes they work but they sometimes cause the bricks to crack. Those soft bricks lack tensile strength. Anything that grips by spreading in a hole can blow the brick apart.
I have had a bit more luck using Tap-cons. They operate by a slightly different principle. They cut threads in the hole. A much smaller stress to the brick itself.
Go wide 1/4" if possible and long but not through the brick. Try the drill bit they specify, normally 3/16" for a 1/4" screw, but be prepared to go a bit thinner. 5/32" or so, plus or minus 1/64", seems to leave more meat for the screw to grab. Greatly increases pull out resistance in my experience.
Especially in this case don't power drive the screw tight. You can power drive them most of the way but take up the last 1/8" or so by hand. Stop when it pulls in. Too often people try to torque Tap-cons and it causes the screw to strip. Destroying most of the holding power.
Of course try to arrange the fasteners, whatever you use, so they are primarily in shear.
That epoxy suggestion also sounds worth a shot. Don't have any experience with bricks and epoxy but in concrete it works great as long as you follow those instructions to the letter. Cleaning the hole, mixing the epoxy (where it doesn't do it on its own) and setting are critical for a good bond.
4Lorn has it right, Tapcons for light and medium duty work - they're easy to work with. Hilti epoxy anchors work well for heavier loads but the actual bearing strength of the wall itself should also be considered at this point.
Wally
the 1790s side of my house is soft brick (hand made, I've even found some w/ fingerprints) the 1850s side is not so soft, but in both cases I've been able to get deck screws and tapcons to "take" without even pilot holes. The face spauls a little so they need to be rather long, but they firm up to the point I've torqued the heads off a couple times using 18v cordless drill/driver.
Same with lags, I've had 'em bite so hard I was able to break the head off, then the bolt right beside that would spin like a top! Grrrrr.....
Don't forget the square peg in a round hole...drive a square piece of SOFT wood into a hole of the same diameter and then drive the fastener into the wood plug. Old bricklayers would lay "deadmen" in to attach chair rail, door jambs, etc. Same principle. On occasion I've removed a brick & mortared in a dead man.
It seems like your choices are Tapcon or epoxy, or a mix.
The square drive Tapcon (McFeeley's) are a huge improvement over Phillips drive. Drilling without hammer may work best. If you're doing a number of Tapcons the kit with the convertible drill/drive is efficient or just use a two drill setup.
Lots of the same answers as the above. When you look at the hole no matter what it's only as strong as the surrounding surface. So heres a couple of Ideas. When you drill the hole you can use a expanding type fastener but Vac it clean, don't worry if its bigger then perfect, load it up with construction adhesive and leave to dry over night, then fasten away. If you use wood deadman in soft brick drill plug hole larger then plug,vac out clean, fill with crazy foam,insert plug. Ideal to let sit over night and to predrill proper screw hole size. It's slow cause you have to wait but worth the results.