Bathroom extractor through rubble-stone wall

[f-llewellyn]

Hi there guys. Bought my first house a few months ago and am sorting some things out that I thought needed doing to the property.

Currently, the only airflow the bathroom has is a small windows that's deep inset into the wall so I thought I'd install an inline extractor fan through into the loft and out the side of the house. I decided to go from the inside, as the wall butts directly up to a narrow pavement and didn't want to have to hire scaffolding and get the necessary permissions to erect it.

Bought a core drill set, along with an SDS drill and got to work last night. After 3 hours, my wall looked like this:


Not sure if it was due to the type of stone, or the uneven cutting surface, or (most likely) my own ability. The drill would either bind up on the wall, or bounce around if I tried to go faster. I could only get it to grind against it extremely slowly. I did drill a pilot hole, but it wasn't much help.

Eventually I managed to get through by peppering the circumference and hitting it out. After pulling out all of the rubble I could, I was still left with some stones too big to be removed and a very uneven cutting surface the other side.


When trying to drill through the outer course, it was extremely tough and I doubt my core drill set will be of much use. I'm starting to think I'd be better off getting a professional core driller on the case as they'll likely do a far better job than me in far less time.

Does anyone have any advice?

 

[a twig]

Having faced a similar situation in my old place (funnily enough with the same core drill set) I ended up just using a 10mm SDS masonry bit that was longer than the thickness of my wall and stitch drilled it out, then tidied up after with a bolster and chisel, ran hard pipe through the wall and pointed it in with an NHL mortar before making connections / adding grilles etc

 

[a twig]

Given the situation you are in I’d consider enlarging the hole on the inside by one or two more stones so you can pull out anything you need to, then rebuild / replace as required.

You’ll need to do some remedial work on the outside even if your original plan had worked - while probably possible with a ladder, hiring a small scaffold tower would likely be easier / safer

 

[Jahouli]

Would it feasible to to vent through a roof tile vent instead?

 

[Flyfisher]

Having faced a similar situation in my old place (funnily enough with the same core drill set) I ended up just using a 10mm SDS masonry bit that was longer than the thickness of my wall and stitch drilled it out, then tidied up after with a bolster and chisel, ran hard pipe through the wall and pointed it in with an NHL mortar before making connections / adding grilles etc

Snap! Been there, done exactly that (might have been a 12mm SDS bit though )

My rubble wall has a lot of flint within it and I've yet to find anything that will drill or cut through a lump of flint. The best my SDS hammer drill will do is vibrate the flint until it is loose within the wall at which point a chisel and lump hammer can be used to break up the flint or, more likely in my experience, dislodge it completely so it can be removed. The end result is a hole through the wall far larger and more irregular than needed, or wanted!

The solution then is to line the hole with a length of suitable pipe, for which I've used 110mm drainage pipe, and then fill the gap surrounding the pipe with lime mortar (I generally use NHL2) and bits of rubble if the gap is large enough, being careful to force the mortar well into the wall void with a suitable piece of scrap wood. The end result is very neat but it's a real palarver and few people will understand how it can take half a day or more just to 'drill' a hole through a wall !