one-story brick veneer house with concrete block foundation. Adding a small room – wood frame on block foundation. Can ventillate the addition crawlspace with a grill in the block, but its on the rainy side. Can also punch through into the existing crawlspace.
If I punch out an opening in the existing block foundation, I assume I need lintels. How should I support things until lintels are in place? Probably a 16 x 32 opening is sufficient for access and ventillation. It would be one block below the sill, but several feet above where the brick veneer starts. Both block and brick would need a lintel. I doubt anything would crack if I just did it, but if it needs support, how?
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As a minimum, the top course of a block foundation or stem wall is poured solid with one continuous #5 rebar embeded in the pour. At least that's part of my method. Also, rebar is embedded vertically every four feet and in each corner and those cells are also poured solid. On a very small stemwall the mason will mix and pour the cells but on larger jobs I usually end up pouring every cell solid because of the minimum amount of pump mix I have to order.
With that in mind, and if your top course really is poured solid, then removing that small amount of block below requires no extra support.
Brick and mortar are a little more fragile. Although it's possible that joints are firmly packed and adhered I would saw cut the vertical edges of your planned opening then carefully remove the bricks starting in the center of your plannned opening and work out and up to the last course to be removed. Then kerf the mortar on either side of the opening and insert a steel header. Then remove the rest of the brick.
Another way to do such a small, hidden opening would be to saw cut the complete opening and then shore it with 2 by 12 PT or a welded metal frame.
OK; I'll give it a try. I'll saw it out. Probably less stressful than taking it out brick by brick. If something cracks, I'll worry about it when it happens.