Cavity Wall Insulation

j4cse · 25 Mar 2008

Hi, I have just had a quote for cavity wall insulation.They said that I would need an air brick fitted in one room,because of the gas fire in there.
When the fire was fitted we blocked up the old vent as the regulations at the time meant we didnt need one, ie:the kw of the fire.
Is it required because of a possible condensation problem?
Is it really required as this added £35 to the quote.
Many Thanks
J4cse

rssteve · 25 Mar 2008

what has rule 6 got to do with it?

diyisfree · 25 Mar 2008

The reason for the air vent is not to stop condensation but more importantly stop you from killing yourself.

It is there to let air into the room to aid combustion. If your room is well sealed up, eventually your fire would burn all the oxygen in the room.

You would slip asleep watching coronation street and unfortunately you wouldn't awake to see tomorrows episode.

£35.00 seems a small price to pay for possibly saving someones life.

^woody^ · 25 Mar 2008

I've never understood why it is in the insulation installers remit to install an air brick for a gas appliance, and why they can refuse to install cavity insulation if there is no ventilation to the gas appliance?

noseall · 25 Mar 2008

^woody^ said:
I've never understood why it is in the insulation installers remit to install an air brick for a gas appliance, and why they can refuse to install cavity insulation if there is no ventilation to the gas appliance?

covering ones ass?

you can get sued if you sneeze these days. or even if you don't.

^woody^ · 25 Mar 2008

Possibly, but adding insulation is unrelated to the ventilation requirements of the house, and unrelated to any gas heating appliance.

I can't see how adding insulation would affect a gas fire in any case

diyisfree · 25 Mar 2008

Im sure they have an obligation to point it out to you but not sure if they can refuse to carry out work unless they fit one ?

Maybe its all to do with british gas offering the service?

^woody^ · 25 Mar 2008

I am aware of several companies around here who will not do the insulation if there is no ventilation to a gas fire or other appliance that should have one.

Whether its just an good earner for them to fit air bricks, or there is some actual obligation on them, I don't know.

j4cse · 25 Mar 2008

diyisfree said:
The reason for the air vent is not to stop condensation but more importantly stop you from killing yourself.

It is there to let air into the room to aid combustion. If your room is well sealed up, eventually your fire would burn all the oxygen in the room.

You would slip asleep watching coronation street and unfortunately you wouldn't awake to see tomorrows episode.

£35.00 seems a small price to pay for possibly saving someones life.

Is that saying,that by not insulating your cavity walls,it can then be used to airiate the room through the cavity and poor insulation. This would suggest that we are relying on walls not to be very well insulated if you have no air brick.My gas fire is set into the wall and the chimney used as the flu.The company said they cannot do the work unless the air brick is fitted.

diyisfree · 26 Mar 2008

No, Its not meant to read that by NOT insulating your walls you will be ok not having a vent

The vent will not break into the cavity merely pass through it. Usually a 100mm diameter plastic tube is inserted through the cavity so air entering the room is from outside.

The chimney being used as the flu is the norm unless you have one of the new fluless fires that most corgi guys run away from. The point of the vent is not to expel fumes but allow fresh air in to prevent oxygen depletion

Mixter · 20 Jul 2008

This is an interesting one. Im due to have CWI installed quite soon, but i was never asked if i had any gas fires (i have one), and wether the room had a vent (which it doesnt). Is there a chance they are going to come, see the fire, see theres no vent, and require one to be fitted?
I have to say, of all the gas fires ive seen in folks houses, its never always been accompanied by a vent in the room!
I also agree that having a gas fire with or without a vent, seems to have no bearing on wether walls are insulated or not. A vent should be a required regulation across the board if its that important (and yes, im aware a fire has to 'breathe'), otherwise, i dont see how one fire can be any different from the next when it comes to needing to be vented or not?

webby613 · 1 Aug 2008

as noseall said, they are just covering their ass! but you will not need a vent if your fire (I'm assuming it is an open flued gas fire) is under 7kw.
Do you have any openable windows or doors in the room (to outside) This provides natural ventilation called Adventitious ventilation and is used when calculating size of vent required if you really do need one.
Check your fire and I bet its 6.9kw or just under.

^woody^ · 1 Aug 2008

Can you explain where this requirement comes from, and why the installers need to fit ventilation as part of cavity wall insulation? its not in th e b/regs is it?

It seems that the installers are implying work which is outside their remit and responsibility, and when I have asked some installers why they fitted the vents, they just reply " for the gas fire", but don't actually know why they are fitting the vents and where their remit comes from - I would have thought it would come under the scope of a CORGI registered installer to determine air requirements for gas appliances.

webby613 · 4 Aug 2008

I'm not actually sure myself why the installers check for ventilation, as you rightly say, this is the responibility of a corgi registered engineer.
I am curious myself now and will ring the company that recently installed our cavity wall insulation and ask them.
I will also check my corgi book tonight to see if there is anything in there about to cavity wall insulation relating to ventilation and will let you know.

chessspy · 4 Aug 2008

£35 quid, are you taking the p?
I wouldn't get out of, (or into) bed for £35.
here is the equation,
GF+NV= CM-> YD
Where,
GF= Gas fire.
NV= No Ventillation.
CM= Carbon Monoxide, (= Poisonus gas)
=> Means 'leads to'
YD = You dead.

diynot

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Cavity Wall Insulation

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