many will disagree with this but the same principle applies for me,work out how long you think it would take you to do it,this work is priced higher in my case and i do these usually when its raining(gives me something to do on the rainy days)same with guttering etc,if you can't clean windows when its raining drop onto the guttering or conservatories(again some may not agree on this)priceing wise its a bit of a minefield and to be honest down to how deep the customers pockets are/how big the job is/and how well you sell the job to them,for instance i did a facia/soffitt and gutter clean yesterday,conservatory roof included-plus up sold cleaning of windows and frames and rest of conservatory for £110.
i was happy/the customer was so happy days,it took me four hours and a bit to do,so you could look at the earnings per hour at less than £30-but rainy day-still working and earning,.
as a rough guide for conservatories anywhere from £45 upwards and facias etc price on time you would think it takes you to clean them,its still a relatively new market and there really is no right or wrong price just what the customer might accept-don't panic and under sell your self be brave and say ££££ then keep stuumm let the customer decide on the offer yes or no 9 times out of 10 its either yes or could it be a bit cheaper-your call then.
hope this helps a bit-kev