[james peters]

sandstone sills
I have cleaned these before using hypo, and they came up good. but I have some to do that are quite bad ( not the one in the photo )
will a strong mix of hypo and hot water be ok, or will I need something else like pressure wash ?

many thanks

[Smudger]

You don't use hot water with hypo

I would pressure wash first ( but not essential ) then use 14% hypo mixed 50/50

15 mins dwell rinse off

Repeat if not completely gone

Darran

[james peters]

You don't use hot water with hypo

I would pressure wash first ( but not essential ) then use 14% hypo mixed 50/50

15 mins dwell rinse off

Repeat if not completely gone

Darran

cheers  Darran

Is there any reason why I shouldnt use hot with hypo?

[Smudger]

I can't remember the exact reason  without trying to go back looking for the answer - but do recall hot water has an adverse effect on how hypo works

Darran

[Splash & dash]

Easiest way is buy cheap chick toilet bleach squirt it on brush it in leave for  30 muinits rinse off looks like new , and costs £1 a bottle , or hypo mix 4-1 if that doesn’t work do it a bit stronger until you get the desired results .

[Splash & dash]

I can't remember the exact reason  without trying to go back looking for the answer - but do recall hot water has an adverse effect on how hypo works

Darran

Yes cold water with hypo warm to hot water with biocides 👍

[Phil J]

I'm with splash & dash, thick bleach from aldi at about 40p a bottle, squirt it on, brush it in, leave to dwell for 30 minutes, and rinse off should come up a treat.

[Slacky]

I'm with splash & dash, thick bleach from aldi at about 40p a bottle, squirt it on, brush it in, leave to dwell for 30 minutes, and rinse off should come up a treat.

And hide the empties....

[swanson]

Got these on my house tried  cleaning with bleach didn’t touch it so ended up painting them .
They look like new now.

[Spruce]

I thought that bleach and plants under the sills aren't an ideal combination.

[Smudger]

I thought that bleach and plants under the sills aren't an ideal combination.

cover them over and rinse them off after
bleach will take the colour out of the leaves but rarely wipes out a complete plant

Darran

[Phil J]

Looks like stone chippings under the sill, can't see any plants in the picture?

[robbo333]

If you're doing the first floor sills too (and the ground floor) just be careful of the runoff.

[Smudger]

Looks like stone chippings under the sill, can't see any plants in the picture?

I took the question to be general - where you might encounter the green stuff - not this particular job

Darran