Firestopping around HRV ducting?

BigGeorge

I've for metal HRV ducting which passed from the HRV unit on the ground floor up to the first floor. The installer just cut out squares in the plasterboard & 18mm OSB above & ran the round ducting through leaving large gaps

Have bee advised that firestopping around these opes are necessary, they are up to 100mm wide. Not sure that this entails.

Would prefer to do DIY obviously- if it means putting the red fire bags in or rolls of insulation or an expanding foam sealant into the gaps then I'd be happy to do it myself but just need info to get started. Many thanks

Poor Uncle Tom

Are we talking about a single dwelling unit, not a guest house or a business or multiple houses in one block?

BigGeorge

Yep, own self build single dwelling house

Poor Uncle Tom

Then any filling up around the ducting would be from a 'sealing' point of view rather than 'fire stopping'. What materials you use would be up to you but it would make sense to use something that would insulate against sound travel.

Internal soil pipes, wash hand basin, shower and bath waste pipes, laundry chutes, radiator pipes and most stairwells can breach the floors in an average house without fire proofing, why would the HRV ducting be different?

You can use fire stopping materials to seal around the holes made for the ducting, but you don't have to.

sinnerboy

I would pack the floor voids around the ductwork with rockwool - not fibreglass. Seek at provide min 200mm around the ducts within the voids. Then carefully fill back the ceiling with plasterboard and skim and trim the flooring over as tight as possible.

An HRV system can quickly conduct smoke and fire around a building so 2 other safeguards I would recommend - ( not in b regs mind you but if it was MY house....)

1. Link the HRV fan motor to your smoke alarms system so the the power is cut to the motor when the fire alarm is activated.
2. Use only metal fire rated , intumescent sealed ceiling inlets/outlets fitted with fusible link dampers so the the opening slams shut in case of fire.

sinnerboy

Poor Uncle Tom wrote: »

Internal soil pipes, wash hand basin, shower and bath waste pipes, laundry chutes, radiator pipes and most stairwells can breach the floors in an average house without fire proofing, why would the HRV ducting be different?

Add recessed lighting too to the list of fire hazards in the home that are poorly covered by technical guidance part B . In my opinion.

Depending on the application / size of opening then

1. intumescent silicone (seal celing to small metallic pipes )
2. rockwool packing to floor void ( large diameter pipes )
3. construct laundry chutes only of metal and place fire doors to the rooms top and bottom of the chute route ,
4. and use intumescent "socks" over recessed lighting points. Is what I would recommend.

BigGeorge

Great advice fellas, have done most of the above already. Will fill the various gaps as suggested - Many thanks