Air Vents - Cavity Wall

John Electrician33

Hi - house is approx 20 years old - cavity walls - white insulation boards in cavity.

House very drafty - there is air vents in each room - was told be BER guy that having a 4 inch pipe connecting outside vent cover to inside cover (thus creating a tunnel effect) was the WRONG way to fit vents (old way of doing it) - he said remove the 4 inch pipe and just leave the outside/inside vent covers in place.

Any advice please?

DOCARCH

That advice does not sound right to me. All that would mean is lots of air movement in the cavity, which is not great for heat loss.

muffler

John Electrician33 wrote: »

was told be BER guy that having a 4 inch pipe connecting outside vent cover to inside cover (thus creating a tunnel effect) was the WRONG way to fit vents (old way of doing it) - he said remove the 4 inch pipe and just leave the outside/inside vent covers in place.

Are you sure he didnt tell you to fit a pipe?

MicktheMan

Chances are the vents are not the major cause of your draughts.

Regarding "tunnel effect", never heard of it!

PMBC

John Electrician33 wrote: »

Hi - house is approx 20 years old - cavity walls - white insulation boards in cavity.

House very drafty - there is air vents in each room - was told be BER guy that having a 4 inch pipe connecting outside vent cover to inside cover (thus creating a tunnel effect) was the WRONG way to fit vents (old way of doing it) - he said remove the 4 inch pipe and just leave the outside/inside vent covers in place.

Any advice please?

That advice is completely wrong. One of the coldest houses I ever visited had the arrangement your BER man suggested and was built about 1950. A lot of people who did the BER course had little or no background in building or building science. To stop cold drafts you would need to fit a baffled wall vent and, in my recollection these only became available in the 1990s. You still need the vents.

John Electrician33

Where would I get vent baffle vents in Dublin. Would I need to remove the existing 4inch pipe or is it just the outside and inside covers that need to be replaced?
Thanks

Metric Tensor

Although there's limited information here I don't think the vents are your draught problem.

I'd look for other sources of air infiltration before spending money on the vents:

Check around windows and doors
Suspended Floors
Penetrations through walls, floors, ceilings
Check around skirting and architraves

Basically all discontinuities in your building fabric. If you give a better description of your house age, style and method of construction the posters here might be able to point you in the right direction. It's a very common problem but caused by different things in different places (and rarely the vents!)

Edited to add: Is your house "dry lined"?

John Electrician33

House is a bungalow - 20 years old - cavity walls - not dry lined - vents in each room - timber floors on battens but insulation in between battens.
Master big bedroom ie end room at end hallway with 2 external walls is particular cold in morning - was thinking of 4 options

1 - Walltite - pumped liquid foam insulation into cavity - sounds good - has anyone tried it - there is existing white polystyrene in cavity

2 - Dry line this bedroom but would loose space in bedroom

3 - Beads

4 - External insulation just on these two external walls of bedroom - its at back of house so would look ok

Any views / advice please

MicktheMan

John Electrician33 wrote: »

House is a bungalow - 20 years old - cavity walls - not dry lined - vents in each room - timber floors on battens but insulation in between battens.
Master big bedroom ie end room at end hallway with 2 external walls is particular cold in morning - was thinking of 4 options

1 - Walltite - pumped liquid foam insulation into cavity - sounds good - has anyone tried it - there is existing white polystyrene in cavity

2 - Dry line this bedroom but would loose space in bedroom

3 - Beads

4 - External insulation just on these two external walls of bedroom - its at back of house so would look ok

Any views / advice please

2,3 & 4 will have little if any impact on your heat loss if air leakage is predominant. 1 might but I've read about and also seen wall cracking as a result.

Best advice I can give is you really ought to consider having a proper survey done first before spending (big) on stuff that might not improve the situation or cause other issues.