Vents for flat roof?

[berty3000]

Hello,

My house has a 1970s flat roof extension on it. It was re-roofed earlier this year. Treated chip board stuff across the tops of the joists, with rubber lining over the top and upvc Fascia boards around the tops of the walls. Loft insulation was added between the joists.

What I do not understand is how this roof could ever be ventilated the way the main pitched roof is, with its breathable felt and soffit vents which I might add. The flat roof seems completely enclosed and I am concerned about condensation and sweating in there. Any recommendations on how to cheaply and easily ventilate it? Perhaps some kind of vents on the Fascia boards with louvres that don't allow rainwater in? Any suggestions?

Thanks

 

[noseall]

Hello,

My house has a 1970s flat roof extension on it. It was re-roofed earlier this year. Treated chip board stuff across the tops of the joists, with rubber lining over the top and upvc Fascia boards around the tops of the walls. Loft insulation was added between the joists.

What I do not understand is how this roof could ever be ventilated the way the main pitched roof is, with its breathable felt and soffit vents which I might add. The flat roof seems completely enclosed and I am concerned about condensation and sweating in there. Any recommendations on how to cheaply and easily ventilate it? Perhaps some kind of vents on the Fascia boards with louvres that don't allow rainwater in? Any suggestions?

Thanks

It's not just a case of making a few holes. You need through ventilation. Sounds like the insulation is woeful, also. I might consider a downed ceiling (access) or a re-roof with a warm deck.

 

[robinbanks]

What I do not understand is how this roof could ever be ventilated the way the main pitched roof is

Doesn't necessarily need to be. Add a vapour membrane or (better) more (sheet) insulation in a continuous layer, under the joists. If moisture can't continuously get in it can't continuously condense

 

[berty3000]

Doesn't necessarily need to be. Add a vapour membrane or (better) more (sheet) insulation in a continuous layer, under the joists. If moisture can't continuously get in it can't continuously condense

So the existing situation involves plasterboard ceiling internally (it wad overboarded earlier in the year), then the insulation above, then the boards and rubber above that. There is probably a little headroom above the insulation.

I am not aware of any moisture problems, either inside the room in question or between the joists above it, I am just wanting to take precautions to ensure no issues in future and want to find a straight forward solution.

It has all been replastered and redecorated internally so I'm not inclined to start going mental and removing ceilings or roofs. Also worth saying that when the previous roof came off for replacement (same types of board and rubber), there were no damp issues discovered within the roof. And it previously had little if any insulation between the joists.

 

[berty3000]

Just found this image on my phone which shows the insulation when roof was being done (that extension they are stood on goes further back). Looks like they put insulation in to near the top of joists so I don't suppose vents in the side fascia will be much use.