Drilling Advice

[Zol]

Hi

Been doing DIY a couple of years now and a recent purchase of power tools means I can sort a few tasks I've been wanting to do. Which brings me to a question around drilling.

I'm looking to replace the rotten fence battens which hold the Arris Rail to the brick pillars. These are hidden behind bushes and so I've decided to replace the battens with metal Arris brackets. My question is around drilling new holes for the Arris brackets as the old screws have rusted with some snapped off in the holes. If I'm using a size 6 - 70mm screw with a brown rawl plug (which requires a 7mm drill bit). I'm told I should drill the depth of the screw (so around 70mm or slightly deeper).

The main question is, is it standard practice to drill the entire hole depth using the 7mm drill bit? Or would it be better to drill a narrower like pilot hole the depth of the screw using say a 6mm drill bit and then finish off using the 7mm drill bit to drill the depth of the plug?

I have a number of projects which involve drilling into brick and after upgrading my combi to an sds, I'd like to get my head around best practice for hole depth and size etc.

Thanks

 

[jj4091]

Personally I would drill slightly deeper than the length of the screw not the plug and if you are using a hammer drill you should be ok with a 7mm drill bit alone unless perhaps if they are engineering bricks which can be very hard.

 

[GhostIntMachine]

Drill the holes 7mm all the way and a wee bit deeper than needed. This is standard practice. Life is too short to faff around drilling different size segments of hole. In any case, if for any reason you don't get a decent fix with a single plug, it can be necessary to knock a second or even a third plug down the 'ole to get a decent fix, especially on old masonry - this is not doable if the hole is too small

 

[Zol]

Personally I would drill slightly deeper than the length of the screw not the plug and if you are using a hammer drill you should be ok with a 7mm drill bit alone unless perhaps if they are engineering bricks which can be very hard.

Thank you, yes I will make sure I go slightly deeper than the screw.

 

[Zol]

Drill the holes 7mm all the way and a wee bit deeper than needed. This is standard practice. Life is too short to faff around drilling different size segments of hole. In any case, if for any reason you don't get a decent fix with a single plug, it can be necessary to knock a second or even a third plug down the 'ole to get a decent fix, especially on old masonry - this is not doable if the hole is too small

This was what I was wondering. If it's not standard practice, I'll just drill the whole hole at plug gauge. Thanks

 

[GhostIntMachine]

If it were it'd take joiners forever to fit anything... There was a theory I came across years ago that a long screw in a hole with a single plug in hole in vertical wall would tend to wedge itself in should the plug ever loosen off. Certainly seems to work for sign boxes

 

[Old Salt]

Place a wrap of tape around the drill bit at the depth you need. It saves having to faff around checking the depth of the drilled hole.

 

[Harry Bloomfield]

If I'm using a size 6 - 70mm screw with a brown rawl plug (which requires a 7mm drill bit). I'm told I should drill the depth of the screw (so around 70mm or slightly deeper).

A 70mm long screw, screwed into a 70mm deep hole, seems way over the top to me, unless there is something like deep render to get through first?

40 - 50 mm depth, into brick, or stone, would seem adequate to my mind.

 

[Zol]

Place a wrap of tape around the drill bit at the depth you need. It saves having to faff around checking the depth of the drilled hole.

Good tip, I used elecrical tape on my combi drill after seeing someone else do the same. The new sds has a depth gauge so hopefully that will make life easier!

 

[Zol]

A 70mm long screw, screwed into a 70mm deep hole, seems way over the top to me, unless there is something like deep render to get through first?

40 - 50 mm depth, into brick, or stone, would seem adequate to my mind.

It's just red brick pillars and the screws have to hold the fence panels between the two pillars (the panels are 7ft wide with two arris rails). I have a couple of large selections boxes of screws, the box I'm using for screwing into the bricks has lasted ages and there's plenty of screws. If 70mm is completely unnecessary though, I could go with a 50mm instead as the set has them in a size 5? If I went with the 40mm screws they only go up to a size 4 which would mean using the red plugs instead of brown? Thanks

 

[jj4091]

A 70mm long screw, screwed into a 70mm deep hole, seems way over the top to me, unless there is something like deep render to get through first?

40 - 50 mm depth, into brick, or stone, would seem adequate to my mind.

The op was talking about fixing what sound like thin metal brackets to the bricks with 70mm screws. If he only drills the holes 40-50mm deep there is going to be several mm of screw head sticking out and the brackets will not pull up to the wall.

 

[Munroast]

slightly off topic - if you are going to be drilling a brick or block wall and you have a choice of where the fixings go - do you prefer the mortar joint ? - I have found it can me more consistent, bricks esp can have big air spaces in them

 

[Harry Bloomfield]

The op was talking about fixing what sound like thin metal brackets to the bricks with 70mm screws. If he only drills the holes 40-50mm deep there is going to be several mm of screw head sticking out and the brackets will not pull up to the wall.

True, but all the more reason, to use shorter screws.

 

[Odds]

slightly off topic - if you are going to be drilling a brick or block wall and you have a choice of where the fixings go - do you prefer the mortar joint ? - I have found it can me more consistent, bricks esp can have big air spaces in them

I'm not keen on drilling into mortar in our house and prefer brick in general to provide a secure hold on the screw.

A piece of tape wrapped around the bit is a nuisance and a guide is always better.

 

[Munroast]

True, but all the more reason, to use shorter screws.

yeah, 60mm of screw in the wall is pointless (no pun intended) unless there is a special reason like its rotton old sandstone or something. if its good quality brick mortar stone then 40mm is more than adequate for a 5.0 screw

anyway, there is not much point than the screw being longer than the plug, you just want the point stuck out of the end