Hi, we installed chimney caps on our chimneys, but the chimneys are quite old and the mortar has started to crumble. The cap has increased the wind's ability to move the crown, especially on one chimney that after two substantial storms has now shifted a few centimeters sideways.
Luckily, the chimney cap is below the crown and prevents the crown from falling down. At least until the next storm. The problem is that the roof has a 45-degree pitch, so you can't just go up there casually. It should ideally be calm and dry.
So my question is whether I should find a good day to go up, lift it off, scrape it clean from mortar and do the same with the bricks, and then glue it with PL800? The chimney is currently used as a duct for the kitchen fan.
Or should I wait until it’s summer and warm so I can mortar it back with mortar?
I really don't want to wait until summer due to the risk that it might fall off and damage the roof and, in the worst-case scenario, harm us or someone else.
Luckily, the chimney cap is below the crown and prevents the crown from falling down. At least until the next storm. The problem is that the roof has a 45-degree pitch, so you can't just go up there casually. It should ideally be calm and dry.
So my question is whether I should find a good day to go up, lift it off, scrape it clean from mortar and do the same with the bricks, and then glue it with PL800? The chimney is currently used as a duct for the kitchen fan.
Or should I wait until it’s summer and warm so I can mortar it back with mortar?
I really don't want to wait until summer due to the risk that it might fall off and damage the roof and, in the worst-case scenario, harm us or someone else.
Well, you answered your own question.DanielF said:
Personal safety comes first. Others who may be harmed, but naturally, it should also be safe for the person who is going to fix the crown....
Block off the risk area if necessary until it's fixed.
A bit unsure if PL800 works for this job, or if I have to wait until I can use murbruk. That was the question. 
I don't think PL800 will help for long. If the cement has started to deteriorate, it has. The glue will only adhere to the surface and not bind itself at the depth you would require. The long-term solution is to build a new crown from a stable base.
You might be able to secure the crown by constructing a temporary support out of some beams.
Two beams in an inverted V on each side of the chimney, and a beamed collar around the crown. Also a pair of beams between the lower part of the V-legs and the crown support. This way, the force is transferred from the crown to the roof.
Something like this:
http://www.fasadokakel.se/showroom/skorsten-villa-laenkarna/faerdigbyggd-staellning.aspx
You might be able to secure the crown by constructing a temporary support out of some beams.
Two beams in an inverted V on each side of the chimney, and a beamed collar around the crown. Also a pair of beams between the lower part of the V-legs and the crown support. This way, the force is transferred from the crown to the roof.
Something like this:
http://www.fasadokakel.se/showroom/skorsten-villa-laenkarna/faerdigbyggd-staellning.aspx