Is it OK to run gas pipes vertically on gable end from ground floor to loft combi boiler

You cannot run gas pipes vertically within a wall space. It is against current Gas Safe regulations.

The gable end of a building, to which this question refers, is not implying that the gas pipe would be within the wall. However, gas installation pipework can be run vertically or horizontally wherever the current regulations permit it to be installed and externally on a gable end infers no contradiction of the current gas regulations. If a pipe is to be installed within a wall, this is permitted, provided that the installation pipework is installed so as to be protected against failure caused by movement of the wall. So, as long as the gas installation pipework is installed correctly and within the regulations then the installation on an external gable end is absolutely fine, both vertically or horizontally. The installation pipework must also be sleeved the the wall as it enters/exits a building.

Yes as long as it's done correctly there is no issue.

If the gas pipe is running externally up the wall the installation engineer must simply ensure it is properly supported, and protected where necessary. The entry from the exterior gable end into the loft space must be sleeved and sealed. Subsequent safety tests are required. Best Wishes Brandon

I am assuming that you mean externally in which case it will need to be properly clipped and not liable to accidental damaged. If internally and enclosed it needs to be in a continuous duct with ventilation top and bottom.

Yes on the outside

You can’t run them in the cavity. You can run the gas pipe externally on the gable end. As long as it is done by a qualified gas engineer and with in regs of pipe size and clip distances.