Roof ventilation for future loft conversion Information, help and tips on many areas of roofing including trusses, tiling, venting, insulation etc....

[Plumber89]

Hi. Sorry if its a rookie question. My expertise is mainly plumbing.

I am having a re-roof done on a pretty standard end-terrace house (2 up 2 down, ~110 yr old house). My question is about what ventilation is needed as roofers are giving me different opinions.

The attic is currently unlivable, insulation at joist level etc. The plan is to convert the attic to a bedroom in a couple of years time, which I have explained to the roofers who came to quote.

One roofer says breathable membrane with a dry ridge system is enough. Another says it will need vented ridge system with vented soffits too. This quote is quite a bit more expensive.

Is one right? Or could they both be right and it won't make much difference?

Just don't want to spend thousands and have condensation issues down the line when converting the attic.

Appreciate any advice

[stoneyboy]

Hi plumber89
Either method is ok but if you choose the breathable felt option the area between the felt and the room insulation will get incredibly hot so adding eaves and ridge vents will reduce this. Rather than ridge vents you could use vent tiles just below the ridge.
Whether you will notice any appreciable difference in the attic room temperature between the two methods is difficult to predict. If you are having a re-roof suggest you go for a combination.
Regards S

[Plumber89]

Thank you for the reply!