Venting into the roof cavity.

[artful bodger]

Have been renovating a 1950's brick and tile home and would like to put an exhaust fan in the bathroom to get rid of steam and one in the kitchen to deal with the cook top.
Is it acceptable to vent these straight into the roof cavity?, the roof has a decent pitch and there is a fair bit of space up there. Also being tiles is it a rather free breathing space. Any thoughts appreciated.

[rwbuild]

Kitchens MUST be vented externally either through the eave /external wall or through the roof with a non combustible duct (metal), bathrooms not a problem.

[chemfish]

Edit,

It's ok to vent bathrooms to roof cavity in Queensland but I've always thought it dodgy, my personal preference is to vent all your humidity outside.

[ian]

Poster artful bodger (http://www.woodworkforums.com/members/96171-artful-bodger)
Location "Tasmania"

Venting the bathroom steam into the roof cavity sounds like a quick way to create rain in the roof space -- you might even get snow and ice in winter.
nuff said??

[artful bodger]

Kitchens MUST be vented externally either through the eave /external wall or through the roof with a non combustible duct (metal), bathrooms not a problem.

I was afraid someone might say this (about kitchens) as I reckon there is a good chance the eaves have asbestos in them and I'm not sure about how to go through tiles. I have seen plenty of similar aged houses that have a simple fan in the ceiling over the cook tops/oven that do vent into the roofspace but guess they were put in like that decades ago and standards/rules have changed.

[artful bodger]

Poster artful bodger (http://www.woodworkforums.com/members/96171-artful-bodger)
Location "Tasmania"

Venting the bathroom steam into the roof cavity sounds like a quick way to create rain in the roof space -- you might even get snow and ice in winter.
nuff said??

I have noticed with corrugated iron roofing here that on really frosty nights water forms and ices up on the underside of the roofing anyway, even without an extraction fan from the bathroom. Have not seen this with tiled roofs but have not been watching.

[Beardy]

Venting to the roof space was common practice in that era, particularly as there was no sarking so the roof space breathed. Is is not an ideal solution though
Modern roofsoaces are sealed and they are always vented externally

[rwbuild]

If anyone has been in a roof where a non ducted kitchen exhaust fan is located will know about the build up of grease in that general area and how many times does anyone clean the range hood filters, come on, be honest.
Vented bathrooms into roof spaces is not a particularly detrimental but the number of 2 storey or flat roofed houses with vented bathrooms into ground floor ceiling spaces is a recipe for long term problems, humid moist air in a non vented cavity is a NO NO. You should see what it does to plasterboard and flooring....:((. Temperate climates and above is ok for ducted bathrooms into roof area but NEVER in sub alpine or alpine regions, they must be ducted. Also remember that in bush fire zones any external ducting MUST have approved metal screening to prevent ember attack entering the structure.

[Toymaker Len]

The kitchen has to be vented outside because of fire risk. You don't want your kitchen exhaust blowing flames into the roof space if oil etc. catches fire. Basically the metal tube goes straight up and one tile is removed and replaced with a piece of flashing with a hole for the exhaust in the middle of it. Not too difficult but I'm glad it's not me doing it.

[rwbuild]

1950 house = brittle Marseille pattern terracotta tiles, very flimsy 40 x 20 brittle oregon tile battens with rusted nails and probably 25 to 27 degree pitch. Unless you are very agile, suggest you get a plumber to do it. You probably won't have any spare tiles around the house but if some break or crack you can get matching ones from any of the restoration period second hand yards

[ian]

also with a 1950s house.
any largish flat surface = probable asbestos

[ian]

I have noticed with corrugated iron roofing here that on really frosty nights water forms and ices up on the underside of the roofing anyway, even without an extraction fan from the bathroom. Have not seen this with tiled roofs but have not been watching.
extractor fan = a lot more moisture than what is in the atmosphere itself.
on a cold morning the air in the roof space is probably saturated (because of the low temps) adding steam from a shower implies rain in the roof.

30 years ago sister and brother in-law had mildew running down the wall adjacent to a ceiling vent -- don't recall if the roof was iron or tile. This was in Bathurst.

[artful bodger]

Is it generally considered the job of a plumber or electrician, or both to install exhaust vents?.

[rwbuild]

Both

[Beardy]

Is it generally considered the job of a plumber or electrician, or both to install exhaust vents?.

If there is some tricky flashing work to do then a plumber may need to be involved but first port of call is an electrician as it will need wiring up and see how you go from there if a plumber is needed

[artful bodger]

Looks like I am going to have to vent outside the roofspace by the sounds of the replies. Not overly keen to go through the brittle 1950's tiles so looks like it will be cutting holes for the vents through the asbestos eaves.
Wondering how the best way to cut say a 150mm dia hole x 2 through asbestos sheeting might be. Obviously a good dust mask. But what would be the best tool?, jigsaw, holesaw etc. Not really experienced in cutting this stuff.

[Handyjack]

If it is asbestos; test first. If positive have the sheet (or more) professionally removed and then replace with cement sheet which you can with the right PPE and tools cut a hole to suit your needs.

[truckjohn]

If I could figure out how to swing it - I would much rather work the vents back out the underside of the eaves if possible.... Then you don't have to deal with the prospect of new roof leaks.

Barring that.....

The "Best" way to do this is to contact a good roofer... Likely - you go mucking around up there and you will break a bunch of those old brittle tiles.... Do the roof penetration wrong and you are the proud owner of a leaky roof....

Always always have a real roof guy do holes in roofs..

Like your plaster job - find a fellow who knows how to work on this sort of roof and you will be time and money ahead on the job.

On who runs the vents.... If it's vent fans - then generally whoever runs installs the fan runs the ducts. Any mechanical contractor should be able to do it....

[ian]

Looks like I am going to have to vent outside the roofspace by the sounds of the replies. Not overly keen to go through the brittle 1950's tiles so looks like it will be cutting holes for the vents through the asbestos eaves.
Wondering how the best way to cut say a 150mm dia hole x 2 through asbestos sheeting might be. Obviously a good dust mask. But what would be the best tool?, jigsaw, holesaw etc. Not really experienced in cutting this stuff.
As HandyJack advised there is no "best way" to cut through asbestos sheeting. Best is to replace one or more sheets with modern cement sheet and cut your holes in that.
Don't know the rules in Tassie, but in NSW a homeowner is allowed to remove and dispose of up to 10 sq.m themselves.
Just remember to
1. wear appropriate PPE
2. wet the material down
3. punch the nails / clouts through the sheet
4. don't use a hammer to smash it up.


BUT
your tiles only date from the 1950s. While brittle, they won't be impossibly so. (my Sydney house had tiles dating from much earlier which could be walked on with care.)
I'd be looking to vent straight up through the tiles and not touch the eaves. If I did need to touch the eaves, I'd look to replace all of the asbestos sheeting.

[Beardy]

Your eaves will be just as brittle as your roof tiles so there is just as much chance you will crack your eaves cutting a hole
Venting through the roof is no big deal, you only need to remove one tile and replace it with a preflashed cowl, not a difficult job to do you just have to be careful not to do more damage.

[rwbuild]

Best way to cut asbestos sheet is with a grinder fitted with a diamond tile blade.

Mod edit Do NOT do thishttp://www.woodworkforums.com/images/smilies/smilie%20signs/hellno.gif

[DavidG]

best way to cut asbestos sheet is with a grinder fitted with a diamond tile blade.

:hellno:

[cjbfisher]

best way to cut asbestos sheet is with a grinder fitted with a diamond tile blade.

do not do this.
There is no safe way to cut asbestos, and it should be left alone unless it is being completely removed.
I repeat, do not do this.
Cutting with a grinder produces huge amounts of very fine airborne dust,

[rwbuild]

Im so glad that everyone picked up on this, I did this deliberately to reinforce the point

[cjbfisher]

A dangerous way to make a point. You only need one person to read that and then take off, grinder in hand, before they read the rest of the thread.

[rwbuild]

I stand chastised, in hindsight it was a stupid way to make a very important point

Probably best if one of the moderators removed that particular one please

[DavidG]

Let it stand as a lesson to think before you write :smack: