On 20/05/16 22:21, Tim Lamb wrote:
Right we have covered the windows:-)

Question 2 concerns Posi-joists. Anyone have any reportable experience?

I have been told they creak.

For a similar load and span, I have been told they need a deeper section
than timber. But a plumber/wireman dream for easy access.

Heating designer is opposed because you can't cut a slot through the top
section to return the underfloor heating pipes.

The cottage will have 3 dormers leaving a small triangular space above
the eaves. I have been wondering about the practicality of keeping this
space warm (inside the insulation) and using it to return the heating
pipes. Sucking of teeth from engineer concerned about multiple air lock
sites.

Any thoughts?



I used mine (triangular voids) to contain cable basket trays.

The pipes will run in front and above this space at the expense of a
couple of inches of room space - and will have removable panelling for
easy access to pipes and wiring.

This also solves your joists problem - run along, then drop down
alongside the joist. No holes or notches.

With a sealed system, I don't see any issues (small bits of air tend to
get blown through and there should not be any large amounts of air after
pressurising. The plumber can add a bleeding valves at the high points
to aid filling the system.