how many roof / sofit vents required for this garage conv.?

[kitessurfer]

HI,
How many sofit vents and roof vents required plse for this roof of my garage conversion please?
View media item 1451
I plan to use these types of tiles, any drawbacks on the flush profile over the raised profile type? In particular as I need one to use with adapter to link with my WC/shower fan. could it be with the flush profile the moisture will get under the other tiles in the long term?

http://www.klober.co.uk/product3.php?id=74

http://www.klober.co.uk/product3.php?id=113

thanks for any advice..
KS

 

[^woody^]

If you had used a breathable membrane instead of traditional sarking felt then you could have purchased a whole role and then sold the rest on, for less than the cost of two tile vents and the soffit strip/vents and actually have been in proffit!

Soffit should be a continuous 10mm or 50mm circular vents every 500mm

 

[kitessurfer]

Thanks Woody,
ok, the roof isn't new, part of the existing garage. I can see the benefit of the breathable felt etc..
OK on the spacing every 50cm, thanks. Do you have a gut feel on the number of vents though in the roof needed? It will be closed off rood space. By the time I fit 20cm insulation there's no space left for storage in this 'mini loft'
thanks
KS

 

[^woody^]

2 at high level

Don't forget that you will need to fit some eaves tray to keep the insulation off the felt and allow air from the eaves vents into the roof space - you may have to take off the tiles at the eaves to do this

 

[kitessurfer]

Thanks Woody,
OK, I need to get to know about these trays. In this photo see the brick that has been half knocked out. I believe this has been made to vent through to the eves, although having said that there's no vents in the sofits to start with. Above the lintel holding the block work front wall of the house are a number of 'slots' in the mortar between the blocks, I expect they're there to vent the cavity along with this brick at the eves both endeviour to get some air flow.
View media item 1460
In this photo ignore the celotex in the roof, that's coming down and I'm going with conventional insulation, all 20cm of it above the joists.
thanks
KS

 

[^woody^]

Have a look at www.klober.co.uk/product2.php?id=2 or www.klober.co.uk/product2.php?id=15 which should explain things

 

[SurreyRoofingEstimator]

The vent spacing isn't a `gut feeling' issue, you need the equivalent of a continuous 10mm gap at the eaves and with a lean-to the equivalent of 5mm at the top edge which can be achieved with tile vents (that are sold by Klober too)

 

[^woody^]

In reality in this particular situation, there is going to be enough ventilation via the sarking felt laps and naturally around the roof, so that unless you have to (ie doing under b/regs application) then I would not bother with any [ugly/expensive] tile vents.