# Forum Home Renovation Roofing  Cathedral ceiling - too hot in summer and too cold in winter

## chookabt

:No: We purchased a house in 2010 that has a cathedral ceiling in the kitchen / dining.  The room is quite large, approx 50m2.   The first summer in the house wasn't very hot, so it wasn't until this summer that I realised that the room CAN NOT stay cool! This in turn affects the rest of the house.  And of course, in winter it is the coldest part of the house. But doesn't have the same affect on the rest of the house as summer. We need to do something about cooling for summer, but I just can't justify running it, considering how much it would cost to cool the room. 
Does anyone have any tips on how to improve the temperature conditions in this room? Both summer and winter?   
We have just begun (last night) our first steps in the renovation for this room. Ripping out a window, pushing a wall out level and removing the kitchen, so we will be insulating where we can.  
Thanks!

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## SilentButDeadly

1. Lift the roofing material
2. Fit bulk insulation between rafters or if no room then use Air Cell or similar
3. Replace roofing material 
...then look at how room itself breathes and allows air to circulate.  Check out a book called Warm House Cool House by Nick Hollo.  Or the Your Home website.

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## Farmer Geoff

Agree with SBD - the first thing to check is roof insulation.  If that is better in total than R2.5 then changing your roof colour may not be cost effective unless it is just a paint job.  
Re heating - the air near the ceiling is probably quite cosy in winter but you don't sit up there! Perhaps a ceiling fan could move warm air down though the draft can make it seem cooler.  
Re cooling - can you vent that air to the outside through an opening double glazed skylight or big high wall vent or window and replace the air with cool stuff from shady south side of the house, with entry as near to the floor as possible? A purpose made vent which draws air through a hessian covered mesh tube in your garden which is kept damp with drippers or a micro spray can give you free evaporative cooling on days when your outside humidity levels are low enough. With that floor area you may need a vent area of at least a quarter of a square metre to get a good convective flow happening - less if you have a fan forced arrangement. A retro fit pet door can work as the inlet for air.  
Definitely recommend Warm House Cool House book plus keep an eye out for Sustainable House Day. Houses open on the day often have lots of good ideas.

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## Bloss

Easiest is to drop in some EPS or other foam board style insulation sheeting from underneath then paint or clad. Eg: Foilboard® Ceiling Insulation - Insulated Roofing Panels or RMAX - ThermaWallPlus®, ThermaSilver®, ThermaAdvantage®, ThermaFlex®, ThermaRoof®, ThermaProof Must follow instructions to get good thermal sealing. What sort of roofing material is it?

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## shauck

Dare I say, put in a lower ceiling which is also insulated above, giving double insulation?

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## chookabt

Thank you all! Great suggestions - I have thought about lowering the ceiling, but the cathedral is one of the features that I really love about the house. :Roll Eyes (Sarcastic):

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## Bloss

> Dare I say, put in a lower ceiling which is also insulated above, giving double insulation?

  mmm - that's was what I was suggesting ie: not altering the angle or removing the cathedral, but adding another layer underneath the existing internal lining whatever it is.  Pics would help . . .

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## shauck

> mmm - that's was what I was suggesting ie: not altering the angle or removing the cathedral, but adding another layer underneath the existing internal lining whatever it is.  Pics would help . . .

  Yeah, I actually meant a flat/horizontal ceiling. I know it loses the cathedral ceiling which is why I figured it wouldn't be a popular answer. I'm also assuming there's already a ceiling at rafter height. Can you see the rafters, is the ceiling between rafters or does it cover them? Bloss's idea is more suitable to your aesthetic.

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## Farmer Geoff

If internal doors are open, warm air will pool in the highest spot in the house but it would be ideal to know where most of that heat energy is coming from before spending $$. eg western facing windows in another room may cause air to heat up but then that air moves to your cathedral ceiling. That may continue to happen no matter how much insulation you add to that ceiling. Need to indentify and improve the weakest links. A cheap way to locate the weak links can be to put light coloured shade cloth curtain 100mm or so outside western windows and/or shade cloth draped over parts of the roof whose angles suggest heat ingress is likely. If you can feel temp differences with your hand on protected and unprotected surfaces inside then you are starting to narrow it down.

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## Bloss

Some of  :What he said:  , but additional insulation will improve things regardless. An easy and cheap option whether you increase insulation or not is to use a ceiling fan as high into the cathedral peak as you can get - summer-winter switchable too, although the air will circulate in any case due to the room shape. 
This is one of the few cases where one should leave the fan going when there are no people in the room. Fans work to cool by passing a flow of cool air over a moist skin surface so causing evaporation and skin cooling. No skin in the room, no cooling impact - so simply wasting energy (albeit not all that much). 
In this instance the fan is for circulation and to get air out of trap-points - if people are in the room then they will feel cool in summer and in winter the air being moved is likely to be warmer from the rising heat caught at the top of the cathedral then being pushed down by the fan (which can be at slowest & quietest speed. 
But whatever choices and checking of thermal breaks and heat inflows (such as large windows etc) and so on you do (and all those are good things to follow up on) adding more insulation (and doing it properly) will improve the living comfort levels all year round at low cost. BTW - read the Insulation Manual in the Forum Library if you haven't already. 
Of course in any house of any shape the 1st actions are: seal all places air can leak such as around doors and windows (noting that cold always moves to warmer, however it might 'feel' otherwise - that's just physics!), keep direct sun off windows and walls in summer and capture or direct it inside in winter (so external blinds, shades, awnings, trees vines etc outside and multi-layer heavy sun-block curtains, pelmets etc inside). These are actions to take well before double or triple glazing, films, or more dramatic and expensive options. 
This assumes good ceiling insulation is in place - heat rises and the sun shines on the roof so that's the primary target - that's why adding to the underside of your cathedral ceiling makes sense. Especially if you DIY some or all and can save labour costs.

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## Moondog55

Does the cathedral roof end at an outside wall/? 
  If it does there is possibly one additional thing that could be done, and that is venting the hot air to the outside though either a louvred box ( you can get insulated louvres, although I can't fine a link I  know they exist ) or with a large extraction fan.
Mechanically venting the hot air would work very well if you had a cold sink attached to the house through which you could pull cool air. The cold sink would be on the shaded side of the house naturally, cooled with a shade house full of water loving ferns etc and spray irrigated.
The passive measures already mentioned take first priority tho

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## Bloss

Solar chimneys (vents) in cool climates require careful thought and knowledgable design - good to think of in a new house design, but treat with caution for any retrofit. I 
One of the better ideas (but hasn't yet succeeded - too early to a new market IMO) was SunLizard Sun Lizard | Home Page | Welcome - no longer in business.

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## Farmer Geoff

Good call on the Sun Lizard type of gadget. Google 'solar air heater'. We made a cheap one as a trial a couple of years ago and it works well. When it's 12 degrees and sunny outside, we have 35 degree air coming into the house through a 100mm computer fan for about 4 hours a day. It has a surface area of only about 2 sq m so it might max out at only one Kw equivalent but we will make a 20 sq m model on the garage roof for a planned new house.  
Note that a well designed solar passive house will already be pretty comfy when conditions are right for the solar air heater so it's ideal to run the warm air into the cooler southern side of the house and best if there is enough thermal mass to store some of the heat. Recirculating design worthwhile to minimise unwanted drafts and make max use of whatever heat is already in house. In Melbourne the sun angle in winter might make a north facing vertical wall mounted model a possibility. Common in europe. Big vents top and bottom might allow a decent convective current so fan maybe not needed but need to close vents at night to stop reverse air cooling.

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## Bloss

> Note that a well designed solar passive house will already be pretty comfy when conditions are right for the solar air heater so it's ideal to run the warm air into the cooler southern side of the house and best if there is enough thermal mass to store some of the heat. Recirculating design worthwhile to minimise unwanted drafts and make max use of whatever heat is already in house. In Melbourne the sun angle in winter might make a north facing vertical wall mounted model a possibility. Common in europe. Big vents top and bottom might allow a decent convective current so fan maybe not needed but need to close vents at night to stop reverse air cooling.

  Yes - but what we should have are simply well designed houses - we don't. For a very low additional cost we can build houses which are comfortable all year round , and in any climate zone, and need no heating or cooling. The problem we face is the retrofit of older houses to make them comfortable  without massive injections of energy - we churn at about 2% a year so in 40 years we will still be using around 60% of what we currently have.

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## Moondog55

> Yes - but what we should have are simply well designed houses - we don't. For a very low additional cost we can build houses which are comfortable all year round , and in any climate zone, and need no heating or cooling. The problem we face is the retrofit of older houses to make them comfortable  without massive injections of energy - we churn at about 2% a year so in 40 years we will still be using around 60% of what we currently have.

   :What he said:  :Iagree: 
Amen

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## BaysideNana

Chookabt, my living area is 50m2 with cathedral ceiling and I have only used the heater (r/c aircon) for two nights so far this winter...they were the Sun night of the long weekend in June, and 1st August...after 15 minutes on both nights I had to turn the heater off, it was becoming too hot.  Some nights while watching TV I might put a small throw across my feet/ankles but that's all I've needed all winter.  Last weekend it was blowing a gale from the east-coast-low hanging off the coast and temps were down to 5c overnight.  Every night when turning in, I check the thermometer in the kitchen and it's never been below 23.4 then I check it first thing in the morning and the lowest has been 22.3.  During the day it's usually around high 24's to mid 25's and during summer day temps are around low 20's because I'm a fresh air freak and have all doors/windows open.   
The ceiling at the highest point is (I think) 4200/4300mm above floor level...builder couldn't tell me how high and it's not on the plans, I don't have a laser measure and it's impossible to hold a metal tape up for that distance.  Being a new house (18 months old) it was built under BASIX regs so all exterior walls are insulated as is the ceiling, then anticon blanket is under the colorbond roof as well.  The living/dining has a 3200 stacker door and kitchen area has a 2400 both opening onto a large alfresco (7870 x 4300)on the north side.  So it's a big room, high ceilings, lots of glass but still I don't need a heater during winter and I put it down to all the insulation....in addition to this I fitted aluminium venetians to all glass for insulation and privacy and close these blinds around 5pm each arvo to keep cold out and heat in.  House is on a slab and flooring is polished porcelain tiles which retain natural heat as well.  When designing the house I put cavity slider doors leading out of this area, which are also closed late arvo during winter and while I planned for it to be as energy efficient as possible I have to admit that I fully expected to use the heat cycle of the aircon for most of the winter as I had to in the previous house, so not needing any heating has been welcomed.   
In summer I don't need the aircon as all windows have another window opposite and draw a nice cool breeze through the house, so in reality having the aircon sitting there is a waste...but...it can be used if there is an extreme weather condition. 
Maybe none of the above really helps your situation except the addition of insulation, which I would suggest be fitted wherever possible.  Also, the rangehood in the kitchen, can it be closed off when not being used?  they draw lots of heat out of the room during winter...we found that in a previous house. 
Yesterday I inspected a house with REagent and thought about this thread....it also had cathedral ceilings but with a skillion roof and clerestory windows ,and these windows had automatic electric shutters fitted which must have been for thermal reasons because I wouldn't think it would be due to security reasons..but you never know?   The REagent didn't know how they operated or anything about them and the house was unoccupied so I couldn't ask for details but wondered if this might be another option if you have clerestory windows...you didn't mention them so I suspect not?  The much smaller living area in this house had both slow combustion heater and aircon fitted and it was easy to see both are used quite often.  There was only one sliding glass door, approx 2400mm, on the north side and a window on the south side approx 1200 wide with a similar size in the kitchen.  The hall to bedrooms/bathroom/etc couldn't be closed off from the living area so the heater or aircon would be heating/cooling quite a large area.  This house was really cold during the inspection.   
Good luck with your reno, don't forget to post some photos.    :Smilie:

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## jazzabel4

We have the same issue but found installing 2 ceiling fans made a huge difference. I wouldn't have believed it, but the winter setting on the fans pushes the heat back down and it's a marked difference.  If you are up for more expense: Dulux Acratex has a roof coating with some impressive insulation properties. Not sure how much it is but we have to redo our roofing shortly so will look into that.

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## Bloss

> If you are up for more expense: Dulux Acratex has a roof coating with some impressive insulation properties. Not sure how much it is but we have to redo our roofing shortly so will look into that.

  That is a very expensive option with low resulting efficiency - to be done after the other suggested options if at all.

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