Pointing Overhead

[chrisell]

The quick question - has anyone pointed an arched ceiling. Very deep gaps (every bit of mortar washed out - the mud inner is largely gone) - 4cm deep at the shallowest. Some are deeper than my fingers.

Gravity is not my friend - the "piping" bag can get inside some of the gaps but without compression gravity wins. Too deep for any tool beyond the end of an offcut.

There's probably 10m2 of arch where gravity becomes an issue. Every technique that works normally just leaves me or the floor covered in mortar.

Very old barn/farmhouse - not habitable - I'm not renovating just making good. This is a "cellar" -the actual rocks are pretty much self locked in place now given it hasn't failed after probably 40 years of resembling a waterfall inside when it rains - the floor is 6" deep in mud/mortar washout.

Obviously it's to small for me to actually stand straight - it's damp - and even with two work lights I always seem to be in my own shadow. So it's not a fun place to be.

Can't throw the mortar the gaps aren't big enough -

 

[stuart45]

A pneumatic pointing gun might be your answer.

 

[malcolm]

I use a pointing finger. An old flexible table knife cut down in width to fit iin the joints. Load it up with mortar and squish it in.

 

[Flyfisher]

Assuming the 'waterfall' issue has already been solved by fixing the roof so that rain no longer penetrates the building and the arch in question, would a different approach be possible or feasible?

Although not an arch, I had a somewhat unstable rubble wall to consolidate, which had significant voids as a result of a failed roof funnelling rainwater into the top of the wall over many years/decades. I was advised to use a lime-based 'slurry' poured into the top of the wall (after the roof had been fixed of course!) and allowed to percolate into the internal voids before setting and stabilising the wall. Ten years on, this seems to have worked well and the wall in question has remained solid so far.

Obviously an arch is a different challenge but, given that it sounds quite porous, I'm wondering if it would be possible to somehow temporarily 'line' the underside of the arch and then pour a slurry into the arch from the floor above? Depending on the curve of the arch, perhaps a sheet of hardboard or thin plywood would be adequate if suitably propped?

The lining would have to be removed before the slurry was hard enough to 'stick' within the arch voids but still soft enough to be tidied up, perhaps with just a stiff brush depending on how tightly the lining had been held against the brickwork.

Just a thought, if the above suggestions (which sound easier!) don't work.

 

[Cubist]

A bit of an echo of Flyfishers suggestion. Faced with a similar challenge I resorted to overlapping strips of Duck/Gorilla Tape to retain the mortar as I progressively filled the voids. I was careful though to leave the mortar to set firmly before removing the tape. Surprisingly little mortar pulled away with the tape and the final pointing up went well too. I did think though that perhaps the tapes adhesion was helped by the relatively smooth surface of the bricks.