Any reccomendation for attaching strong back to sloped garage floor (concrete)?

[TomMcKinney]

Hopefully within the next 30-60 days I will have moved everything in the garage anough to build a strongback for my next project.

Even if its a stich and glue--though likely strip planked, I'll want a strong back to keep things nice and straight since everythime I try it the "easy" way I mess it up. Would like to attach the strong to concrete floor of garage, which is sloped for drainage.

I do not like the idea of drilling holes into the concrete for anchors, but not sure what other methods there are- anyone have advice/experience in this area? What about building a plywood floor on sleepers? Don't want to spend that $$$$ but if I keep making stuff, which I'm sure I will maybe it will be worth it.

While typing this I thought of the following--
Level 2x2x 16ft sleepers, 16 inches OC, 8ft wide, then scribe to match floor slope.

Cut to scribe line and cover with 4 sheets of 3/4 underlayment.- work area of 16 by 8 should be more than enough--thoughts?
Thanks
Tom

[Thorne]

Sounds good, but the cheap route would be to build the strongback and just use a good tube adhesive (like PL Premium) to glue it to the concrete.

[GregH]

I'll second Thorne's suggestion--if you're concerned about the PL sticking, don't be. I've used this method twice, and it works great.

[Paul Girouard]

Make it in the shape of a "L" and bolt it to the floor with these , http://www.simpsonanchors.com/images/product/mainpagebuttons/titenhd.jpg

You'd have to drill a holew in the concrete and drive the bolt with a impact driver you could shim the whole works or cut the strong back on the right tapped so it would be level and straight.

You could fill the resulting holes with epxoy when you where done with the boat.

Link : http://www.simpsonanchors.com/catalog/mechanical/

[JimConlin]

It may seem a bit heretical, but if the whole setup will be light enough to be moved around, I like to keep it moveable. For small boats , i have a box beam on which i set up the molds,etc. The beam itself is stiff and stable and hog or twist won't sneak in. It gets set upon various things to adjust the working height and even angle. If things need to be level for some operation, i'll level it with shims. I've been thinking of getting a lift platform to put under it.

[Frederick Bolton]

My mother broke her foot two months ago and had to have a wheel chair ramp installed on the back door of her house. Nice patio area. The company that rented her the ramp said she would need to set anchors in the concrete and drill sets into her door tread. When she called I told her not to let them do it and that I would take care of it. I used a hand wire brush to clean the dirt from the concrete and put two nickel sized drops of PL Premium down under the lower end on the ramp. The ramp was alminum. I told her not to use it for 24 hours. The next day it was solid as Sears. Two months later it was still solid. I used a thin sharp wood chissel to slip under and tap and it came loose without to much effort. Cleaned up the aluminum fairly easy as well.

I would suggest nailing some galvanized nail plates to the bottom of your strongback supports. That way when you glue it you will be gluing metal to concrete. If you want to move it later a thin chissel will break it loose and not danmage your strongback. I also like the idea of keeping it portable so this would let you do that.

[mcdenny]

http://www.imagestation.com/picture/sraid220/p6c1e337c3961c06ee76e8f1926c29427/ebb1c0c4.jpg

Use little stubs of 2x6 to raise strongback to level plane. Glue to concrete with PL Premium, drywall screw to strongback sides. Works great, a good whack with a hammer will break the glue joint when its time to remove.

[Alan]

I wouldn't discount the idea of drilling into the floor too fast.

I attached my strongback to a concrete floor using "Tapcon" screws. They are available most anywhere and are very easy to install and are very strong. Be sure you use the special matching Tapcon drills. You don't need large holes like you might with lead anchors. I don't recall exactly, but I think I used 1/4 inch screws. After I finished the boat, I just backed out the screws and put a little concrete dust in the holes. The holes are virtually invisible now.

[Bruce Hooke]

I seem to recall someone here saying that PL premium and similar adhesives will stain the floor. This might end up being more visually objectionable than a few holes that have been filled with epoxy.

[Peter Malcolm Jardine]

Second vote for Tapcons. Painfully easy, and fill the holes afterward. Tapcon is the contruction industry standard for attaching interior framing to the concrete.

[Figment]

...and let's remember that this is the floor of the GARAGE, folks.

If you keep your garage floor so pristine that a few screw holes or lumps of adhesive are going to be considered eyesores, you need to spend less time in the garage and more time on the water.

Perspective.

[paladin]

I used a few layers of fiberglass tape and epoxy....afterwards chipped it loose, cleaned the areas, and repainted dad's garage...looked better after the boat project...

[ssor]

I have a neighbor that emptys his garage twice each year and washes the walls and the floor. He washes his lawnmower after he uses it and allows it to dry outside before he puts it away. In the winter time he sweeps and mops the car parking spaces every week.
They even rake leaves three times a day in the fall.

[Tylerdurden]

I use un-strut, or b-channel as its called and anchor them at each side near or to the walls. I can level and move the strongback from side to side as the project moves along. That keeps from drilling in the center of the floor and allows me to anchor on a dirt floor. slight trip hazard but you get used to it and its not a hassle.I have built fixtures from overhead to eliminate that. Once you have used enough of it you will find you have enough pieces around to do almost anything

http://www.tyco-unistrut.com/

The stuff is the greatest for jigs and fixtures and is totally adaptable.
Doing a lot of one off composite type stuff I have found it the easiest and quickest to work with. In combination with threaded rod its infinitely adjustable. You can hook up with your local electric supply and they can help you out. Just have catalog numbers with you as these guys are not fabricators and something will always be lost in translation.

[capt jake]

On the big boat at Devlin's, we leveled the base frame with hardwood shims. After all was level to our liking, we shot 'Great Stuff' expandable foam under all of the corners and joints. This bonded it to the floor and kept it from moving during the built. Easy to clean up afterwards also. Just don't touch it for a day, in order to give it enough time to cure.

[merlinron]

having spent my life's working hours attatching things to concrete, i might give a few suggestions.....
1) tap-cons suck....especially when driving them into poured concrete. they're ok in concrete block, but they don't drive into poured concrete very good at all, the older the concrete, the worse they drive. although, if you do get one to drive home and tighten up, they do hold good. i would use one of the various types of "red-heads or simple "lag shields". of course, they require a bigger hole in the slab. the advantage of read-heads is that they are permanent and make a removeable attatchment. you can "unbolt" whatever is anchored and the threaded insert will stay in the slab tightly to be used again. if you sink the red head below the surface of the slab just right, you can turn a flat heat machine screw into the insert and it will come out flush with the surface of the slab to close the hole up untill it is needed again.
2) although pl is good, there is better stuff around, namely "sono-flex" it is the stuff that is used to caulk the joints in precast concrete structure to aluminum window units and such. it holds onto literally anything like crazy, stays flexible enough to not break it's hold from expansion/contraction movements. i have had to remove large windows during remodels and you literally have to cut it away from the window to get the window out. a small 3-4 inch spot that doesn't get cut will keep you from pulling a 2-300 lb. window out of it's opening. i have seen it pull concrete off the casting instead of breaking.
3) build your stiff back frame, lay it on some visqueen, and pour concrete into the "boxes" of the frame. it will make very stiff and heavy enough that you will be able to reef on the stiff back all you want....concrete weighs about 135 lbs./cu.ft. yet it will be able to be moved if need be.

[Bob Cleek]

There are lots of ways to skin a cat. Construction adhesive is great if you want to fasten wood to concrete. However, I would myself opt for a moveable strongback. Such an item can be used over and over again. All it takes is a rigid wooden framework that is level with casters attached. Get the casters heavy enough for the size of the boat and use the ones with the locking levers on them. Use casters with threaded posts on them so that you can adjust them up and down easily with a wrench. Position the strongback and adjust the caster heights to make it level. The huge advantage of this arrangement is that when you have set up your molds to the level strongback, you can then move it around as much as you like and not worry about it. There WILL come a point in the construction when it will be much easier and more efficient to have more room on one side or another or at one end or the other and so on. A moveable strongback solves this problem. Also, on a nice day, you can roll the whole shebang outdoors and sand away to your heart is content without having to worry about cleaning up the dust!

[seo]

One good thing about using bolts in lead shields is that you can unbolt and move the project if you need to, then put it back right where it was. Concrete drills work all right, so do star drills if you're feeling like a steel-drivin' man, lord, lord. It is a pain when you get half-inch down into the cement, and hit a hard rounded baby-head of aggregate sticking up, and the drill keeps skating off it. My very little experience is that star drills work better in that unhappy event. Once the project is over the holes can be grouted in, and won't have any practical effect. It the appearance bothers you, you're spending too much energy on the appearance of your garage floor.

[dmede]

Doesn't appear as if anyone has asked the boat particulars? What boat are you building? Size and weight will matter in what type of strong back you build. I personally don't see any need to lock your building setup to the floor for smaller boats, and strip built boats are typically very light for their size. Just build a sufficiently heavy building frame and mark the corners once it's leveled.

I've built three boats on temp building frames not attached to the garage and it's never been a problem. In fact the ability to move your frame around can be very handy. My currrent build is a heavily built 14' skiff with a building frame on rollers. It's nice to roll her out of the garage and get that whole space for work when needed. In this case the frame must be built extra strong and tight to be sure it won't flex when moving.

dave

[brad9798]

I agree with Figment ... drill the holes ... use lead sets ... or whatever.

Fill when finished.

I for one don't lose sleep over crap on my garage floor ...

[Mike Dawson]

I have used body putty to hold down building jigs. Shim the strongback level (or lag bolts screwed up into the bottom of the legs for easy heigth adjustment) then plop a mound of body putty around each leg. A few hammer blows will break it loose when your done.