Why can't I get my drill bit all the way through this brick wall?

You're likely hitting a blue brick or a high-density engineering brick. These are common in structural areas and are significantly harder than your standard red brick. If your drill bits are snapping, it’s a sign that you're generating too much heat or applying way too much pressure without the right impact. Using a standard cordless drill on its 'hammer' setting often isn't enugh for these spots becasue they don't have the actual piston power to fracture the material. You need to switch to an **SDS rotary hammer drill**. Unlike a regular combi-drill, an SDS machine uses a pneumatic mechanism to punch the bit forward. It makes a world of difference. If you don't want to buy one, you can usally rent one for a few hours. Also, make sure you're using a high-quality tungsten carbide-tipped bit. The ones that look like a 'cross' or a four-cutter head at the tip are much better at staying centered and won't bind as easily as the cheap two-cutter bits. Another trick is to start with a much smaller pilot bit, maybe 4mm or 5mm, and then step up to your final size. This reduces the surface area the bit has to grind trough. Keep the RPMs relatively low; spinning the bit at max speed just creates friction and melts the tip, which is why they're snapping on you. If the bit starts getting too hot to touch, stop and let it air cool. Don't dip it in water while it's red hot or the thermal shock will crack the carbide. Whatever you do, don't use construction adhesive for floating shelves. Those brackets act like a lever, and the weight of the shelf plus whatever you put on it will eventually peel the glue right off the masonry or pull the plaster away from the brick. It's a huge safety risk. If you absolutely cannot get through that specific spot, your best bet is to shift the bracket slightly to hit the **mortar joints** instead. It’s alot softer and will still hold plenty of weight if you use a decent wall plug.

While the previous mention of engineering brick is certainly a plausible diagnosis for such localized resistance, I suspect you might acutally be encountering a rogue piece of flint or particularly large aggregate within a concrete lintel that wasn't properly documented on your floor plan. If you are determined to persevere, ensure you are utilizing a genuine SDS-plus bit with a four-cutter head rather than a standard two-cutter, as the latter tends to chatter and wander when it meets a substrate of varying density, leading to the exact snapping torque you described. Additionally, verify that you haven't inadvertently switched your drill into rotation-only mode, because attempting to grind thru high-strength masonry without the mechanical percussive action is a foolproof method for glazing the bit tip and rendering it permanently useless.

Have you ruled out that you're just hitting a metal lintel or an old steel support beam? I know you mentioned checking for plates, but if the house has been renovated, those beams can be buried deeper than a standard stud finder picks up. If you've alredy snapped two bits, it realy sounds like you're grinding against steel rather than just hard masonry. Maybe try a cobalt bit on a slow speed just for a second to see if you get any metal shavings? If it's steel, no amount of hammer action is going to get you thru without the right bit.

Reminds me of a job I did back in '84 where I spent half a day burning trough bits before I realized I was hitting an old chimney fireback. If it's as stubborn as you say, pull a bit of the dust out with a pipe cleaner. If it's grey and gritty, it’s just tough masonry, but if it's black or metallic, you’ve got real trouble. Back in the day, we’d sometimes just take a cold chisel and a heavy hammer to the spot to 'star' the hole and break the surface tension before the drill coud even grab. Give it a few solid whacks to see if you can chip it—if the chisel bounces back, you aren't getting through without a diamond core.

Update: Checking the dust was a great call. It’s definatly grey and gritty, so the engineering brick theory seems spot on. I switched to an SDS drill like some suggested and finally made it trough, but now I’ve hit a second layer that feels even harder. Is it normal for these structural bricks to be doubled up like that?