cold new construction

Goldengirl

Just finished an upstairs extension and refurb in the last few months.
Have had problems with a cold corner in our new room, despite thick slab internal insulation ( 92.5 mm)
Any advice on how to remedy this ?
Builder is hard to get back to finish , never mind fix something like this.

Gumbo

Goldengirl wrote: »

Just finished an upstairs extension and refurb in the last few months.
Have had problems with a cold corner in our new room, despite thick slab internal insulation ( 92.5 mm)
Any advice on how to remedy this ?
Builder is hard to get back to finish , never mind fix something like this.

Find the source first.
Thermal image survey.
Air leakage test.

Goldengirl

kceire wrote: »

Find the source first.
Thermal image survey.
Air leakage test.

Thanks kceire.
Any idea of a good firm in Dublin, by PM?

Goldengirl

If anyone has any recommendations, by PM, I suppose, it would be helpful, or any experience in dealing with similar issues , please?

nailer54321

I would also be greatful for recomondations for companys who do thrtmsl imaging and air leak testing.

mickdw

Can you give some detail as to the construction type, layout, airtightness detailing?
Does the room have 3 external walls possibly?
Ventilation type?
Heating?

Goldengirl

mickdw wrote: »

Can you give some detail as to the construction type, layout, airtightness detailing?
Does the room have 3 external walls possibly?
Ventilation type?
Heating?

Hi Mickdw, mine is three external walls, solid block on flat construction over steel rsj s on hollow block original downstairs.
Ventilation , passivent , manual control, fresh 90db.
Gas heating, new boiler , 3 zones with thermostats, radiators.

mickdw

The passivent you describe is just a through wall vent with manual setting if I remember right.
Its possible this has been poorly located and is allowing driving winds to enter.
What u value is the wall supposed to be? Are you sure the correct insulation has gone in there. What is the exact wall make up?
Have you a ventilated attic over? How is that insulated and has airtightness been looked after?

Goldengirl

mickdw wrote: »

The passivent you describe is just a through wall vent with manual setting if I remember right.
Its possible this has been poorly located and is allowing driving winds to enter.
What u value is the wall supposed to be? Are you sure the correct insulation has gone in there. What is the exact wall make up?
Have you a ventilated attic over? How is that insulated and has airtightness been looked after?

Yes, very likely re position of vent , unfortunately. On outside north facing wall. Above my head !
Have to close at night lately so useless really .
Open during day . No condensation as yet but would be concerned about that going forward if we have to keep shutting the vent .
Also feel draughts blowing behind it when windy which is taking the warmth out of the insulated wall.

Not sure about u values of walls, but the correct thickness insulation slab has gone in , 100 mm thick solid , steel mushroom fixings.
Not sure how much if any airtightness but gaps were taped at ceiling and joints.
Again this was not supervised by me just architect visits so relied on that . Did request everything be draught proofed when discussed with architect and builder.
Attic is ventilated at eaves.. 300 mm plus rockwool insulation.

mickdw

I'd check to see if the vent is properly built into wall so that all ventilation is coming through the vent, not around it.
I'd then experiment temporarily sealing vent for an evening and single heating cycle to see is this the full problem.
If so, look at an alternative vent arrangement such as on a more sheltered wall or window vent Install.
If still cold with temporary sealed vent, check for cold air running behind wall slab - see if cold air can be felt at skirting or around window board.

Goldengirl

mickdw wrote: »

I'd check to see if the vent is properly built into wall so that all ventilation is coming through the vent, not around it.
I'd then experiment temporarily sealing vent for an evening and single heating cycle to see is this the full problem.
If so, look at an alternative vent arrangement such as on a more sheltered wall or window vent Install.
If still cold with temporary sealed vent, check for cold air running behind wall slab - see if cold air can be felt at skirting or around window board.

Only 0.5 to 1 degree lower by wall from central room temp, on one of those probe things from Lidl when vent closed... Don 't know how accurate it is but was reading a big difference, about 4 degrees, last week during that storm! Think need to do all of what you advise except will leave the vent in same position but maybe fit a " wind cowl" which I have seen the suppliers have. Don' t like the idea of moving it or putting anything in my new windows, although I appreciate your help and advise, Mick.
I will leave this and get back when we have tried to rectify some of the problems.
Thanks again.