Maybe you should just stay out of the roof space?

What problem is a hot roof cavity causing you?

Lol. Yeah I try to as much as possible ;-)

The idea is venting heat out in summer when it heats up. The heat radiates down into the living area (even with insulation) so I am hoping it can make the climate in the living space a bit better especially around the time when we go to bed. We have gas heating and no cooling in the home. Ideally you would use a heat pump for that but cost is somewhat prohibitive and wasteful never mind ugly and loud external units. And we don't need to get down to 18 degrees. I think just having less radiant heat from roof would probably suffice. But I think there is ample of know how that goes into that to get it right and I don't just want to DIY whack a hole in my roof and hope for the best. Humidity control may be another benefit. 

olivernz:

 

Hello all

 

I want to ventilate my roof space for some relief in summer. Anyone know someone in the Kapiti/Wellinton area that is passionate about the topic?

 

Cheers Oliver

 

simply put, don't bother. there is good reasons for ventilation in roof spaces but thats not to do with heat and it should already be done. one of the problems with excessive venting is it will suck more air up from in side the house which can make the issue worse and cause other issues like making the house colder in winter.

sounds like you need to install decent insulation. kiwis homes are typically poorly insulated. just because "its got insulation" does not mean its good. the other problem is many homes have a lot of windows and poorly insulated walls which let the heat in.

make sure you understand what the cause is first.

Re-paint your roof white or very light grey, this will markedly reduce the heat getting into the roof cavity in the first place. It's not all that expensive to do, and even cheaper if you can DIY.

How much insulation have you got in the roof space? Maybe you need another layer. Most ceiling are probably well under spec as you shouldn't be having this issue.. I would be looking at least R5 these days and think the new home requires is  R6.  You can get ridge vented capping  which a roofer maybe able to advise on.

PolicyGuy:

 

Re-paint your roof white or very light grey, this will markedly reduce the heat getting into the roof cavity in the first place. It's not all that expensive to do, and even cheaper if you can DIY.

 

+1 that will do more than ridge vents.

ridge vents are there to let moisture go out wit the air flow. but the airflow is still pretty small, its not going to enough to cool down a roof space.

The ask here was to point me to a professional that can help me with understanding if it is an option. 

Painting the roof is not an option. Since I have solar on there that's a major undertaking I'm not willing to do.

I saw the ridge vent stuff too. Would hope that's standard nowadays. I still need to have a look if I have that. Need to go up a ladder and have a look.

The house is from 2015 so relatively recent insulation. I think it's 3.6 or 4.x but I'd prefer more and that is certainly in the future of the house but I still think getting the temperature down within the roof space should make a difference. The internet itself -like on all topics- goes from OMG NO!!!! all the way to BEST THING I EVER DID!!!! So I think I need an actual expert that can tell me what's up and that is the person I am looking for and there won't be many around.

tweake:

 

simply put, don't bother. there is good reasons for ventilation in roof spaces but thats not to do with heat and it should already be done. ...

 

The reason why it wasn't done in NZ is that BRANZ did not perscribe it and actively consulted against it over the past years. This has now actually changed so that at least you can do it if you want to. Hence nothing to do with whether it works or not.

olivernz:

 

The ask here was to point me to a professional that can help me with understanding if it is an option. 

 

Painting the roof is not an option. Since I have solar on there that's a major undertaking I'm not willing to do.

 

I saw the ridge vent stuff too. Would hope that's standard nowadays. I still need to have a look if I have that. Need to go up a ladder and have a look.

 

The house is from 2015 so relatively recent insulation. I think it's 3.6 or 4.x but I'd prefer more and that is certainly in the future of the house but I still think getting the temperature down within the roof space should make a difference. The internet itself -like on all topics- goes from OMG NO!!!! all the way to BEST THING I EVER DID!!!! So I think I need an actual expert that can tell me what's up and that is the person I am looking for and there won't be many around.

 

  

 

The current building code is R6, so your insulation level is now considered low. Possibly go to R5.  It is possibly the cheapest option. If you have old downlights which you can't insulate over with glasswool, then you may need to replace them. You need to be very carful though that anything you insulate over in the roof can be insulated over otherwise you risk fire. 2015 , many of the lights probably aren't LED and may not be able to be insulated over  My understanding is that the roof ridge and soffit vents are more about venting out moisture so not sure how much they will actually cool a space. They have some specs at https://www.theroofingstore.co.nz/new-page-2    I have seen a new home with a big vent in the vertical wall of the  gable where there is roof space behind, and you could consider some form of mechanical ventilation to vent out heat.. 

PolicyGuy:

Re-paint your roof white or very light grey, this will markedly reduce the heat getting into the roof cavity in the first place. It's not all that expensive to do, and even cheaper if you can DIY.

olivernz:

 

tweake:

 

simply put, don't bother. there is good reasons for ventilation in roof spaces but thats not to do with heat and it should already be done. ...

 

 

The reason why it wasn't done in NZ is that BRANZ did not perscribe it and actively consulted against it over the past years. This has now actually changed so that at least you can do it if you want to. Hence nothing to do with whether it works or not.

 

the reason not to do it is because it pulls air up from within the house, including the moisture. that extra moisture is the cause of a lot of the problems. 2nd issue is that in winter those vents still pull your hot air out of the house that you paid to heat. it simply increases stack effect. now with new homes with led lights, they are far more air tight and that reduces the issue a fair bit. (btw that stack effect also pulls air up from under the house, eww).

you can change the ridge cap if you want. i doubt that will make much of a difference as the air flow is small.

i would add ceiling insulation and shading to windows, especially to north side of the house. 

tweake:

 

the reason not to do it is because it pulls air up from within the house, including the moisture. that extra moisture is the cause of a lot of the problems. 2nd issue is that in winter those vents still pull your hot air out of the house that you paid to heat. it simply increases stack effect. now with new homes with led lights, they are far more air tight and that reduces the issue a fair bit. (btw that stack effect also pulls air up from under the house, eww).

 

you can change the ridge cap if you want. i doubt that will make much of a difference as the air flow is small.

 

i would add ceiling insulation and shading to windows, especially to north side of the house. 

 

My neighbour imported one of these - https://www.bunnings.com.au/products/building-hardware/building-construction/ventilation/roof-ventilation

You are meant to put ventilation grills under the eaves so that it does NOT pull air from within the house. Also, during winter, it can be closed.