Drilling hole in drywall?


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Old 11-09-11, 11:07 AM
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Drilling hole in drywall?

Hi,

i am a total noob at diy, however i have purchased a pull up bar and i want to install it correctly. The wall is i believe drywall (it is very hard).

Please see this photo of the screws and plastic that is required to attatch the pull up bar on the wall:

The screws and plugs

The screws are 8mm and the plastic is 12mm. What size drill bit do i need is what i would like to know? Should i drill an 8mm hole, a 12mm hole or a 13mm hole? I really don't know and i am scared to make a mistake. Also is a concrete drill bit suitable? I see a 13mm concrete drill bit for sale. I just don't know if the hole needs to be slightly bigger than the plastic plugs or not. I really need to do this perfectly else the pull up bar probably won't hold the load correctly.

I bought this tool for the task:

BLACK&DECKER

It has both hammer and rotation modes and accepts drill bits up to 13mm.

Apologies that it is in Chinese but i live in China now. Thanks for advice.
 
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Old 11-09-11, 11:22 AM
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Welcome to the forums.

I have no insight into Chinese construction but I know here I would be looking to attach this to the studs (the structure of the house) and not just the drywall. That said, you want the anchors to fit tightly into the hole in the wall, so certainly no bigger than the anchor (you said 12 mm).

If this is drywall, any standard bit for wood or metal is fine, you do not need a concrete drill bit.
 
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Old 11-09-11, 11:28 AM
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No weight bearing item (beyond a towel bar maybe) should be attached to drywall/plaster. Now, if there is concrete or block behind the surface there are anchors available, but I wouldn't use the plastic ones.
 
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Old 11-09-11, 11:36 AM
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It's not really a wall but kind of a separation that splits the room into two parts. It's about 2 or 3 feet lower than the surrounding ceiling and 1.5 feet thick.

The problem is i only see 11mm and 10mm bit avaliable not 12mm. Would the plastic plug fit into a 11mm hole or 10mm hole correctly? Also i guess i might as well get the concrete drill bit since it's probably not drywall entirely. When i tap the wall it is absolutely rock solid as if i'm tapping granite, and i think it might actually be a load bearing concrete structure of some kind as it kind of looks 'out of place' in the room.

I'm wondering if this is good:

BLACK&DECKER

As for not using plastic plugs, the pull up bar does come with mental anchors but they are massively thick (like 20mm) and i'm not sure if i'd ever be able to get them out again!

Seen here:

Imagebin - A place to slap up your images.
 

Last edited by whitelines2; 11-09-11 at 12:07 PM.
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Old 11-09-11, 12:02 PM
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Use a regular twist drill for wood. A masonry bit will not drill in wood and WILL tear it up. You can tell easily by tapping a SMALL phillips screwdriver or even a nail in the spot you want to drill. If it goes in a bit then stops, you either have steel or concrete under the surface. If it penetrates, meets resistance , but keeps going, then you have wood. If it penetrates and then meets no resistance, you have a void between structural members and will need to find another place.

If it's wood, use the bit that is closest to the body of the bolt (the diameter not including the depth of the threads). You won't use any anchors if you have solid wood.
 
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Old 11-09-11, 12:09 PM
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Thanks...

i guess i'll drill a small test hole first to see whats up.
 
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Old 11-09-11, 12:11 PM
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Sorry, not understanding - you said it stops two or three feet short of the ceiling but you think it's weight bearing? Can you provide some pictures of this wall?
 
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Old 11-09-11, 12:14 PM
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ok will take some pics one minute.
 
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Old 11-09-11, 12:21 PM
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1
2
3
4

Hope that gives you an idea.
 
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Old 11-09-11, 12:31 PM
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Probably just a decorative way to support the structure.

One thing you need to make sure of is that no water, electric or ventilation runs through there.

I'll just about bet that you'll find it's concrete or steel.

You might get a better insight (as would we) if you can tell us about the size of the whole building. If you have access to a utility space (janitors room, storage closet, boiler room, electrical room) you might see bare walls. I'd be guessing concrete, as wood is not normally used in large structures and is not as common in other countries as in the States. Concrete and steel are pretty much the materials of choice.
 
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Old 11-09-11, 12:35 PM
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Hmm it is adjacent to the kitchen (an open kitchen) so you might have a point about utilities running through there. The kitchen has no such partitioning wall along the ceiling. The kitchen used to be in this room that i showed in the photos, but they moved the kitchen out of there.

EDIT: i just noticed that one area of it has a hollow sound, so some cavity is there. Most of it has a solid sound when tapped, but one area on the side and to the right on the top has a definite cavity sound. Also there is some water leakage damage near the base, like a circular patch... no idea why...

I guess i should try another wall... The other wall in that room has on the other side the public hallway in this building. I'm guessing these are normally drywall with concrete inside? I can't imagine they partition my apartment from the rest of the building with just drywall...

The building is a high rise, around 25 floors, build in 2005. This apartment is 100m2 and has hotel style air conditioning in some rooms.
 

Last edited by whitelines2; 11-09-11 at 12:58 PM.
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Old 11-09-11, 12:54 PM
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Ah, the pictures helped me quite a bit - I had this wall going from the floor up not the ceiling down in my head.

This looks like a beam of some kind to me, I would try to find out what's inside, there may be sufficient structure here.
 
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Old 11-09-11, 01:01 PM
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Please see:

Imagebin - A place to slap up your images.

These parts in red have a definite hollow sound when tapped, but not other areas... strange no? That black arrow points towards the gas utility meter for the apartment. Looking at the meter i see metal pipe leading towards that structure i wanted to drill into. Ummm... i'm scared to drill there now.
 
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Old 11-09-11, 01:56 PM
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Not an expert, but I know cheap wood construction is rare in most Chinese cities and the important walls are generally concrete, concrete block or brick. The framed (wood or steel studs) are often secondary portions that were built after the building is up and enclosed and may be drywall.

Try to drill some exploratory small holes (easy to patch) to see what is really there for support. That will give you an indication what may work for the location you want.

Dick
 
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Old 11-09-11, 02:13 PM
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Ok,

i am scared about gas, electricity etc... i'll have to drill extremely slowly and inspect the hole often. If i find a suitable area of concrete i will still use plastic anchor with screws instead of the metal expansion one, as with the latter i could never get it out again.
 
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Old 11-09-11, 02:17 PM
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It's pretty common to use anchors which cannot be removed - you tap them further into the surface or they fall down behind when you're done using them. For weight bearing like this, you want to use the beefiest attachment you can.
 
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Old 11-09-11, 02:25 PM
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The power drill i have wont let me use a drill bit big enough to make a hole for the metal expansion anchors...

schmidt

That's the actual item, it says in chinese it can take 150kg no problem with the screws plus plastic anchors. I'm 81kg.

The screws are 7cm long. There are existing holes in the wall that are 3cm deep, but i can't tell when the drywall ends and concrete begins. However surely 7cm will dig a decent way into the concrete so the screws plus plastic anchors would have a nice foundation to grip into.

I'm not an expert but... it seems like it should be fine just based on common sense (assuming the drywall isn't 7cm thick in my apartment lol).
 
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Old 11-09-11, 02:48 PM
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I can't read Chinese but that seems to be a pretty thorough website.

How big a bit do you need for the metal anchors? Some of the bigger bits will have reduced shafts to fit in to the drill's chuck.
 
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Old 11-09-11, 02:57 PM
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Ah good question, i just looked at the pic before, but it says 12mm for the metal anchor... my power hammer thingy can go up to 13mm bit.

But eight 7 inch screws snugly fitting into a wall... i think the metal anchor is overkill. Maybe if i weighed like 120kg it would be worth the hassle. Other websites are advertising this product as handling up to 350kg with easy (i presume that's with the metal anchors into solid concrete or something).

No-one has said definitively yet, for the screw/plastic solution i should be drilling around a 10mm or 11mm hole? Because the plastic anchors are 12mm and if i make the hole too big i presume they won't function correctly. The photos on that website seem to show the plastic anchors going into holes just slightly bigger though, and it looks like drywall.
 
 

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