Thinking about cutting window opening to make sliding door in cast concrete wall.
 

I believe this would be possible because there should be a lintel above the window. Anybody had this done? Would appreciate names of contractors who do this sort of thing.
Thanks.

Contractors
 

Try Doc's Restoration. They did a small project for me that came out perfectly. Small, yet they assigned a project manager, inspected the site to validate the planned repair and had a quality assurance person inspect the finished product before asking for final payment. The person that actually performed the patch, texture and repair also fixed a lousy patch I had done previously - on his own volition.

My first thought would be to contact the county building department to find out how involved this would be. IMHO if (big if) you are not making the opening wider you can probably get away with it, however if you are planning to widen the opening this will be much more complicated. I have no idea of the construction details for the cast type construction, but I suspect replacing the lintel will be very messy, complicated, and expensive.

As said above, it's going to depend on what kind of construction you have and how it was all formed. I suspect there's no way you'll get a Building Permit, with a Structural Engineer's stamp on the plans.

The odds are, this is going to be way more complicated that you think ... especially if this was "tilt-up" construction.

Why would a cast concrete wall require a separate lintel? The concrete is a monolithic structure above the window and around it to the bearing surface at the slab. Depending on the orientation of the embedded steel in the wall, it ‘should’ even be possible to add a double slider in place of a single-hung window. Penetrating radar above and around the window to document steel placement would be prudent, I think. Then, of course, a nod from an engineer, the ARC, AND the building department. From there, grab the wall saw!

Perhaps because many walls (if not all) in The Villages are not "cast concrete" poured in place, they're "tilt-up" walls. The Masonary/CMU structures are another variation.

Even a cast in place wall might not be able to accommodate what the poster has in mind. Where do you come up with the assumption that a cast concrete wall is a "monolithic structure"?

Originally Posted by ltcdfancher View Post
Why would a cast concrete wall require a separate lintel? The concrete is a monolithic structure above the window and around it to the bearing surface at the slab. Depending on the orientation of the embedded steel in the wall, it ‘should’ even be possible to add a double slider in place of a single-hung window. Penetrating radar above and around the window to document steel placement would be prudent, I think. Then, of course, a nod from an engineer, the ARC, AND the building department. From there, grab the wall saw!

Brian L99 is correct. Concrete walls are not monolithic structures. Built of concrete only, they would fail if there were any openings or any movement of foundation or shrinkage as the concrete cures. They require reinforcing steel since concrete has very little tensile strength. Concrete slabs have cuts made so that the inevitable shrinkage cracks that occur during curing are controlled and not unsightly.

Concrete walls will have reinforcing steel placed in the wall at the appropriate locations to provide the tensile strength to carry the loads around the designed openings. Cutting an opening for a double slider will be much larger than any reinforcing placed to span a single window. I do not see how any structural engineer will approve any design to create an opening larger than the original single window without extensive external steel reinforcing.

Unfortunately, that theory (expansion cuts) works about 30% of the time. Maybe 50%-60%, if you cut the mesh before you pour the concrete and make your expansion joint cuts along the wire mesh cut. I've yet to see a large concrete slab, that doesn't have a "crack" or 2, somewhere other than along an expansion cut.

As you point out, Concrete has extremely low tensile strength, but high compressive strength. We occasionally use "structural slabs" which have reasonably good tensile strength (& can be monolithic), but that strength comes from the steel design. The problem with them, is once you have to cut into the slab, you defeat the entire design premise.

Especially if is post cured tensioning can’t cut any of those tensioning cables.

It seems to me that we’re all making the same claim. Before grabbing the wall saw, we must know the location, orientation, and sizes of all reinforcing members inside the tilt-up or cast-in-place wall. The structural engineer would need to agree that the structure would not fail. Forgive my ignorance for claiming that a 8’-10’ high, 8” thick, long slab of concrete and steel could be monolithic. I am a product of the Florida Education System; somewhere the system failed me.

Where would that technique be used, other than on a bridge? Just curious, not that I'm planning to build any bridges.

Don't worry. Unless you're building large buildings, it's not a major structural failure 😂😂

Our neighbor did this in their master bedroom in CYV. Took out windows and put in French doors in block construction. However he is a contractor and did the work himself. Looks awesome.

Block isn’t the issue. OP probably has tilt wall construction. When developer, started using this method some have brought up concerns on if walls could be structurally changed. So far I haven’t seen a thread or post that has given a definite answer

I’m assuming that the opening size of the sliding door matches the opening size of the frame for the window. If not, it will look sort of shoddy, like cheap replacement windows in an old house.

Double checking to make sure it is a CAST concrete wall (solid concrete, poured in place). The Villages also has a lot of concrete block walls and for the past few years a lot of Superior Wall System walls with two inch thick high strength pre-fab concrete and concrete studs. All can be dealt with, but they are different. Concrete block walls are pretty easy to cut with the right tools. Poured concrete walls are a lot harder to cut, but it can be done. The 6:00 psi concrete in Superior walls is the hardest to cut. (Personal knowledge.) Before the prefab casting, the manufacturers insert a 2x10 pressure-treated lumber box for each window opening. It’s pretty easy to remove the bottom of that and put in longer legs. It’s not weight bearing, really, and the whole box could be removed. There will probably be electrical wires running through the superior wall, and those will need to be rerouted by an electrician.

Cutting concrete like that is immensely dusty, and the diamond blade on the saw needs to be cooled with flowing water, too, so that can easily be tracked around. It’s a project, and it’s not cheap.

The ORIGINAL design for the tilt up wall would have included the necessary reinforcement (aka lintel beam) in the design of the wall unit. If the OP wants to WIDEN the opening this would void the original design. Therefore, I stand by my original comment, the OP needs to get the original house plans and possibly a structural engineer to review the original design to see if this is feasible.

Agree!

Do a lot of research before using Doc's.

Lintels are not always used in Tilt Up construction, as they're not necessary in many cases. Tilt Up is different than Block/CMU construction, as it has a reasonable degree of tensile strength. It all depends on the size of the opening and the frame of what you're putting in the opening.

Knowing that The Villages puts a huge effort into saving money, I'd be surprised if their Tilt Up walls use cast in place lintels for every window .. but I've never watched one of them being built.