Fire stopping to services
November 25, 2016
Since the final airtightness test we have been finishing off some internal tasks, one of which is fire stopping and insulating the internal portion of the SVP that remains on show in the Utility room until the cupboards get fitted. As this is also our venting soil vent pipe (the part that goes directly to the outside) this one needs to be insulated - we used 40mm of foil faced Rockwool pipe insulation as this has a relatively good conductivity and resists condensation on the external face.
The thermal bridge caused by the soil vent pipe is entered into the PHPP calculation, so the choice of insulation is important from that perspective.
As the SVP passes perpendicular through the intermediate floor construction, and the penetration is larger than 40mm diameter, the hole needs fire stopped in some way. This is a point we come up against with Building Standards repeatedly, particularly in relation to MVHR ducting passing through the intermediate floor. We are in complete agreement about the need for fire stopping these sizes of holes however it would be useful if there was consistency in approach between the various council's in terms of acceptable methods! Hopefully over time, as MVHR becomes more common, this will happen.
Anyway, here are some photos of the sequence for both insulating and fire protection to the SVP:
Firstly I started to plasterboard the lowered ceiling. This is the position of the fire protection as the main ceiling above has several large holes in it.
Next I insulated from the top down (with the section of pipe in the ensuite above already insulated, including the portion passing through the floor construction). I also tested the fire collar for fit and to enable me to mark the ceiling for supporting batten positions.
Then I added the supporting battens.
Next I fitted the plasterboard with a division just to the side of the collar so that I could access it from above to check the insulation was nice and snug against the plasterboard. This is one occasion where the fire protection trumps the insulation! The 12.5mm thickness of plasterboard is missing as the pipe collar manufacturer requires it be fitted immediately adjacent to the pipe, rather than another 40mm out-with and against a flexible material.
Then the remainder of the ceiling was fitted and the joints all sealed with filler, before the collar was screwed through the ceiling to the battens above.
Finally, a shot of the remainder of the pipe insulation being cut to fit, including notching around the pipe collar.