Painting and repairing a masonry bay window sill

Idonex

Hi,

The front bay window sills on our victorian terrace need a bit of work and i wondered what the best way to go about it was.

1. The first thing is all the paint is flaking off exposing the masonry underneath. Is it best to strip off all the paint with a scraper/sander/nitromors, then once bare paint with some stabilising primer then a few coats of masonry paint. Do i even need the primer on sound masonry. I couldn't work out from the label if it was only for new masonry that was still powdery?

Or scrape of the flaking bits then fill those bits, make a key on the bits with sound paint and just paint over with exterior masonry paint? If i went the latter route what do i use to fill an external masonry sill?

2. The joins where the left and right bay sills meet the middle sill are completely unfilled where the previous filler has fallen out. What do i use to fill a gap like this? Concrete? Most fillers seem to say only do a 5mm layer but this must be 2 inches deep with no bottom.

Thanks!

aboard_epsilon

Yes, strip the paint off ..with a hot air gun....

all of it

fill the gap with granulated mortar

this is a fine very hard concrete

mix is 6 units of Grano with 1 unit of sand and 2 units of the cement
grano is available at builders merchants ..about £3 for a 20 kg sack

put a load of layers of masking tape and hardboard maybe on it to act as shuttering...paint with pva ...push the mortar in with a stick...leave to go off for a few hours...take the shuttering off ..then try to trowel to smooth finish...a bit of water helps, ..wait four days before you paint.

before that stage
scrub the sill ..after stripping the paint ..power-wash it if you can ..it may look so nice then ..that you will maybe choose not to paint it ...perhaps you could sandblast it..if you have the gear.

if you do go ahead with painting ..let it dry out...mix the primer 50/50 with white spirate.....put on a couple of coats of that ..then full un-thinned primer/ undercoat..then the gloss


or you can go with just masonry paint..thinned down for the first coat..

or .
you could use floor/ door step paint ..a lot of people use floor paint on these sills..thin down as before for first coats...at a proper paint shop you can have the floor paint tinted to any shade of the original base you like ..some of the colours are way to bright especially the terracotta colour and need toning down.

all the best.markj

ormus

you cannot mix oil based paint and water based masonry paint.
if its had oil paint on before, itll all have to come off, before you use the masonry paint.
usually best/easier to stick with what was applied before.

stone7

Strip all the paint off all the stonework.

Painting stone is sacrilege.

earthlysparky

I stripped ours right back with a blow torch and scraper, and then painted with masonry paint. I felt quite silly painting sandstone with a sandstone coloured paint, but the ends of the sills were in quite a poor state and have had to be bogged up, which is quite unsightly.