couple questions about drilling into concrete-block foundation wall

[patandchickens]

The questions are academic now, as the job is as done as it's gettin' and gonna have to be "good enough"... but I'm rather puzzled by a couple things and would like to know what was going on.

I was attaching a ledger board for a deck onto a concrete-block foundation wall. Never done that before, my only hammer-drill experience has been putting anchors into a concrete slab, the lead sleeve type. Some weird things happened, can anyone please explain for me?

1) sometimes it was extremely easy to drill into the blocks (in fact one was probably no worse than drilling thru an inch or two of wood, rather odd) but many of them were extremely difficult, darn near impossible to get the last 1" or so of the hole. Every muscle in my body is KILLIN' me. It was not a drillbit issue -- I went thru four bits (the ones sold with the hardware - possibly a mistake on my part), but easy vs hard holes did not correspond to how long I'd been using a particular bit. It also did not correspond in an obvious way to what part of a cinderblock the hole was going into. Are some blocks filled with different am'ts of concrete? Or what?

2) I used some fancy-@ss "super sleeve" (something like that) anchors, kind of like steel versions of drywall anchors. A sleeve with a lag bolt into it, with a thin nut at the end of the bolt that when you tighten it the sleeve is buckled into being wider so it theoretically jams against the hole sides and locks the bolt in place. On some of them it seemed to work that way. On others, I could not tighten the bolt, it just spins and spins and spins an infinite number of times. Any theories? I do not see how it's possible for the nut to have come off. Stripped threads while hammering it into hole? Or what?

(am not terribly worried, I think it's pretty overbuilt in terms of number/size of fasteners, but I don't like being mystified)

3) It took me 2 1/2 hours to put in 14 of these fasteners (3/8" x 4") and every muscle in my body is now KILLING ME. Is it supposed to be that hard, or did I do something wrong? Yes, I did have the hammerdrill set on 'hammer' LOL

Thanks for any "retroactive advice" or interpretation, as I'd like to at least learn something from this,


Pat, who has had no back deck for a year and a half now due to putting off this particular step, and clearly I was RIGHT to fear it But yay me, now I can proceed to the actual deck construction, which I am MUCh more comfortable with

 

[Marianne]

Boy, I got nuthin' ...other than to say that we've been there. But I was watching and offering moral support while DH was slaving.

My first guess is maybe some blocks have a different, harder aggregate... or some blocks were filled with concrete pour (which I'm sure at least some were) and who knows what kind of aggregate or cleanup rubble, brick chunks, etc they had in that. Here it's pretty common for some blocks to be empty.

I remember my ex son in law telling DH to use soapy water (?? or something really simple like that!) when he was trying to attach a header to a poured foundation. The rest of the drilling was like going into soft wood.

You have my sympathies. Time to break out the homemade vanilla or something.

 

[lorihadams]

I agree, sometimes the block gets filled in places with extra mortar or gravel. If you happened to get into a spot that had been filled some then that could explain the variations.

When we did the foundation on our garage my dad just poured some of the extra mortar into the holes in the cinderblock to get rid of it once we were done. It can't hurt anything. Then we had to fill a whole section with gravel where we were going to pour the entrance to the garage with concrete for the apron. That may have happened. Some may have gotten filled with dirt, some of ours ended up with some dirt in the blocks when they were backfilling the trench around the foundation.

As for the bolt issues, I don't know on that one. You may have had some stripped threads or you may have not had anything for the bolts to bite into so they just spun around?

 

[gettinaclue]

I got nothing for ya, but I asked DH who has drilled through MANY block foundations and this is what he said:

Where it was hard to drill - sounds like it was filled with concrete or some such. Mortar is actually softer than the concrete block and shouldn't have given as much resistance as drilling the block itself.

Blocks are set staggered. Depending on the swell in your area (and he has no idea about swell way up that way). every other hole or more may have had to be filled with concrete and rebar and it sounds like that's what you were hitting when it was difficult to drill.

He's got nothing for you on the bolts. He's guessing (without seeing it) that the ones that bit were where you drilled thru concrete and the ones that spun are where there was nothing in the holes and nothing for the bolt to bite.

He said given the opportunity, they always drilled through the mortar to avoid hitting concrete filled holes.

Hope this is clear and helps.

 

[The Old Ram-Australia]

G'day, what do you all think of this method.
The drill bit, Tungsten bit,like the type they use to put a hole in a tile in the bathroom.
Drill the holes at a LOW speed so little heat is generated
Use Dynebolts to secure timber to the concrete
http://www.google.com.au/search?rlz...ie=UTF-8&q=bolts+to+secure+timber+to+concrete

It wont help you ,but it may assist others,with the same task,regards,.............................T.O.R............................