Cutting flue hole in rendered wall - drill from inside?

[goosander]

I'm looking to get a new boiler fitted in a different location to the current boiler, so will need to drill a hole for the flue. A gas safe registered mate will be doing the install but I'll be doing some of the prep including drilling the flue hole.

The property is a 2nd floor flat with rendered walls, so was wondering what the chances are of drilling from the inside without making a mess of the rendering?

Has anyone any experience of doing this?

 

[cross thread]

good core drill no problem

 

[footprints]

Not ideal but your best chance will be a diamond core drill (they do not use hammer action) and make sure to clear the core about two inches from the end and the take your time using as little pressure as possible. If the render is sound you just might get away with it.

 

[dang32]

pilot drill from inside to get correct position then core drill from outside. normal practice

 

[Steelmasons]

pilot drill from inside to get correct position then core drill from outside. normal practice

Is it?

 

[PullerGas]

Is it?

Not how I do it either Steely.

 

[Steelmasons]

More BS...rather cut from inside than up a ladder outside.
Core cutter won't damage the outside brickwork in any case.

 

[goosander]

Thanks - footprints I'll go with your suggestion. If it was on the ground floor, I'd drill from the outside but no way I want to be up a ladder with a big core drill!

 

[oldbuffer]

Measure thickness of wall, subtract 6mm, mark shank of diamond core drill with tape. When drill is in wall to level of tape, keep drilling but with virtually no pressure. Diamond core drilling is really a circular grinding action, and needs very little axial force at the tip of the core, particularly in soft material.

 

[DP]

A few questions cold to mind when reading this thread.......
Why is the OP not asking the installer how and WHERE to make the hole
Orientation of the hole
Ice of the hole
If there is breakout on the other side, minimum as it would be, does it really matter?
I would have thought if you were the helper, nothing wrong with that as I often press the householder to help out to reduce the Labour charge, he would be the one to suggest how, what, where, when etc.......

 

[goosander]

The where is dictated by the location of the original boiler (not the current one) - I want to put the new boiler back to the original location, partly because its a sensible location and partly because the flue hole can then be made through the previously filled section of wall rather than drilling yet another in the wall. The original had a balanced flue so there is scope for a little bit of movement.

I don't mind a minimum amount of breakout, but was concerned that the the drilling might cause a big chunk of render to fall off but sounds like it should be OK if drilled carefully.

In reality I'll be doing most of the work for the install and will get my gas safe registered mate to OK it before starting work...

 

[oldbuffer]

I'd get your gas safe registered friend to mark the precise centre of the new flue hole for you, and tell you what diameter it needs to be. For some boilers you can drill an oversized hole, put the outside rubber on the flue, push it through and then pull it back to seal the outside. Particularly useful on a second floor flat. Inside still needs sealing though. Can only be done if the boiler manufacturer's instructions say so.

You may also find the freeholders will require you to make good any damage left by the old and / or new flue holes.

 

[ianmcd]

Be aware that if you are core drilling through a filled in balanced flue hole there is a good chance that the patched hole , is just built up and skimmed over as opposed to drilling an original wall,this gives a much higher chance of damage, i have seen lots of types of materials used to fill balance flue holes, before skimming over, have even seen foam pipe lagging used.

 

[PullerGas]

Be aware that if you are core drilling through a filled in balanced flue hole there is a good chance that the patched hole , is just built up and skimmed over as opposed to drilling an original wall,this gives a much higher chance of damage, i have seen lots of types of materials used to fill balance flue holes, before skimming over, have even seen foam pipe lagging used.

Now you said you'd not mention that.

 

[goosander]

Be aware that if you are core drilling through a filled in balanced flue hole there is a good chance that the patched hole , is just built up and skimmed over as opposed to drilling an original wall,this gives a much higher chance of damage, i have seen lots of types of materials used to fill balance flue holes, before skimming over, have even seen foam pipe lagging used.

Noted. I'll try and ascertain what they used to fill in the hole - assumed it would be brick but maybe not...