Question About Pre Cast Lintels.

Dbower

I am a wood and metal framer by trade but am about to do an addition at my house of out block. I know that you typically run rebar up the sides of your window and door openings. Are the pre cast lintels notched out to allow the rebar to run up to your tie beam and allow you to pour the concrete? It may be a dumb question but I am trying to get out all the questions I have before I get started and make sure its done right. Thanks.

NJ Brickie

No lintels are not notched. You would terminate your rebar below the lintels then start it again above if needed. Or you could build a form across the opening and lay bond beam block across the opening and knock outs over the jambs. Lay rebar in the bond beam, extend atleast 8" on both sides with the rebar and bond beam then grout solid. With the knock outs above the jambs you will be able to allow the vertical rebar to pass through in your jambs.

Dbower

Well in my case my lintel would be in the second to last course of block just under the bond beam. I don't have my plan from the architect yet so I'm not sure what his detail will be on it. What is typical in that situation?

dakzaag

Just curious why you are building the walls out of CMU?

I think the rebar is probably overkill, you should get satifactory results with grout but if the rebar floats your boat, it won't hurt anything.

NJ brickie described how I would do it. Never seen precast lintels with a hollow core for verticle rebar.

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NJ Brickie

You do not have to fill the entire jamb unless that is what is specified in the plans. Many times only filling 16" down on the jambs is specified. If this was a job where i could make the call I would fill the jambs solid, lay the lintels across, then lay your bondbeams for the last course. I would not worry about tying that section into the bond beam.

Dbower

I just got out an old plan and in the detail it states 1 number 5 rebar in filled cells from footing up into bond beam with min bar lap of 25". That why I was wondering how to get the bar up through the lintel. It even shows it that way on the cast crete web page.

stacker

i would do it the way brickie says.in fact that is how i do it.wiether it be a solid bottom bond beam or a knock out.with a solid bottom you would need to notch out for the grout and rebar to continue down the window jam.

ok i went back and read a little more of your post.where you are that close to the top bond beam,i would use a horse shoe or make a horse shoe bond beam and lay it as a solider,and run two sticks of rebar in it and pour it all solid.
not knowing how wide the opening is.but here is what i do for smaller openings.
i cut a 2x8 to the opening width.place a couple 16 penny nails 3/8 down from the top of the board,and use that as a temp until i have poured and it has cured.then remove the board.
good luck

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masonlifer

I think I would drill a hole through the precast; pour the jamb to the top of the window, and then place the precast and push the rebar down through the hole.

NJ Brickie

Cast Crete is not something we use in this part of the country. That product (beside the 4" unit) is basically a bond beam. Around here we used solid lintels (like cast crete 4"). If it is an 8" wall we would typically use two 4" lintels side by side, 12" wall three side by side. You get the idea. But if you want to use the cast crete system you would cut the flat bottom out on both sides to allow the rods to pass through. When you do this you would flip the lintel over, cut the bottom out but stay the thickness of the walls away from the sides. You don't want to cut into the walls of the lintel. If i was to guess the walls are 1 1/2" thick. So you would mark 1 1/2" off each side. I don't know what amount of bearing the manufacturer specs but it most likely 8" min. If this is the case you would make your cuts around 7" long. If this product is expensive I would just build a form and lay bond beam across the opening like I said before, because it basically the same system.

NJ Brickie

I would not do it this way. Drilling precast lintels can damage them. And you would not get much grout, if any around the bar to make it worth while. Precast lintels have rebar in them. If you drill through the bar it will greatly reduce the strength of the lintel. Or if you go next to the rebar and expose it, you open up the rebar to rust issues. Rust would take along time to do any damage but why do it?

Dbower

Thanka for the info so far. The cast crete products seem to be used here quite often (tampa. FL). I figured maybe to just notch it to allow the bar up to the bond beam. It also specs out to pour the lintel and have 1 number 5 in it. It sound basically like what you are talking about forming your own but I would prefer to use the pre cast one just for ease of use. I have two 3' wide openings and one 6' wide.

NJ Brickie

Just out of curiosity what does that product cost? Is it sold by the LF?

Dbower

Its sold by the foot. Not sure on the price. I haven't bought any in quite a while and the prices of materials have been changing. If you go to their website I think it shows the lintels already notched on the ends. If so that would make it even easier. I will be pricing them tomorrow and I'll let you know what they cost.

concretemasonry

The proper way is to fill the cores of the block adjacent to the opeing and insert a rebar (no wig material cost).

Build 2x bucks flat for use to support the lintel and brace them if necessary depending on the opening span. Build a bond beam/lintel (probably 8" high) over the opening and brace the bucks to carry the load. you can get both open bottom or solid bottom bond beams almost anywhere in the civilized world. The lintel should go at least 8" wider than the opening on each side and run the vertical rebar up into the lintel. Put in some horizontal rebar. Pour the vertical cores with grout (not mortar) and the lintels at the same time and continue the wall as high as necessary. After a few days (hopefully a week if a load bearing wall) or whenever the windows are ready for installation , knock out the supports and the 2x. - You can keep the supports in for a while if you are doing roofing or framing above.

Depending on the coursing, you can combine the bond lintel with the bond beam (or tie beam around the wall top). Then you just support and get 16" high lintel block. If you have an existing bond beam above it is just a push, shove and jam in mortar situation unless you have a good designer.

The use and availability of precast lintels is generally limited to the eastern U.S. since in place lintels/bond beams are more economical and faster than precast unless you are building a multi-story hotel.

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laybrick

Do you really think it would go any where if you ended the rebar, set the lintel on, lay durowall across & lay the bond beam? If there's an issue with it moveing in or out, drill a couple of 2 inch deep holes in the top of the lintel and pin it into the bond beam

TomWitcomb

Per Florida code it is notched..go to the cast crete site you will see.In florida all blocks either side of opening must be filled with concrete and rebar.
For the top course you use bond beam cmu. which has horizontal rebar. Rebar is inserted thru opening in the bond beam down each side of the opening.This verticle rebar is tied to the bond beam steel and to the footing steel {there are holes in the cmu at ground level to be inspected before the bond beam pour. before the pour these holes at ground level to be covered with ply }

Tom