Stupid question… are these vents to help ventilate roof space?

dr_bogenbroom

Hi,

I posted a question recently asking the best way to fill gaps above my windows, but I’ve been having doubts. 

I have 2 small rooms (WC and cloak room) in this section of my house:

Above each window is a gap of about 3-4mm pictured below:

There are no soffit vents to this small section of roof and I can’t see any sort of ventilation- both small rooms have heating in them. 

I want to block these gaps as part of a plan to make these rooms warmer ad they are freezing in winter, but I don’t want to block any ventilation to the roof space. 

Is there any way these gaps could have been left to act as vents for this roof space?

Thanks.

FreeBear

The gap along the top of both windows are down to sloppy measuring & fitting. They do not provide any ventilation for the roof space. Just get on an plug the gaps best you can.

dr_bogenbroom

FreeBear said:

The gap along the top of both windows are down to sloppy measuring & fitting. They do not provide any ventilation for the roof space. Just get on an plug the gaps best you can.

That’s good enough for me, as ever thanks @FreeBear!

dr_bogenbroom

Out of curiosity is there any reason why soffit vents wouldn’t be fitted on this small section? I’d have thought condensation would still be a risk with the rooms below being heated? I do need to install insulation in this section as well but as previously advised I’ll do it from inside 

stuart45

The ventilation should be put in the soffit, or the eaves. However, there's probably some ventilation getting to the roof space from there, although that wasn't the intention. You shouldn't be getting a draught in the room from there, even with that gap.

dr_bogenbroom

stuart45 said:

The ventilation should be put in the soffit, or the eaves. However, there's probably some ventilation getting to the roof space from there, although that wasn't the intention. You shouldn't be getting a draught in the room from there, even with that gap.

Yeah there are no draughts - it’s likely a very minor contributor to the problem. I’ve read that draughts in the cavity can make rooms feel colder though, is that true? 

stuart45

dr_bogenbroom said:

Out of curiosity is there any reason why soffit vents wouldn’t be fitted on this small section? I’d have thought condensation would still be a risk with the rooms below being heated? I do need to install insulation in this section as well but as previously advised I’ll do it from inside 

It could be that no insulation was added to this part of the roof. Is there any access to this part? Condensation risks increase with insulation at joist level.

stuart45

dr_bogenbroom said:

stuart45 said:

The ventilation should be put in the soffit, or the eaves. However, there's probably some ventilation getting to the roof space from there, although that wasn't the intention. You shouldn't be getting a draught in the room from there, even with that gap.

Yeah there are no draughts - it’s likely a very minor contributor to the problem. I’ve read that draughts in the cavity can make rooms feel colder though, is that true? 

Convection currents in the cavity can increase the U value of the wall to be greater than a 9inch solid clay brick wall. A small amount of ventilation is useful through weep vents, but air bricks and open cavities are well out of date.

dr_bogenbroom

stuart45 said:

dr_bogenbroom said:

stuart45 said:

The ventilation should be put in the soffit, or the eaves. However, there's probably some ventilation getting to the roof space from there, although that wasn't the intention. You shouldn't be getting a draught in the room from there, even with that gap.

Yeah there are no draughts - it’s likely a very minor contributor to the problem. I’ve read that draughts in the cavity can make rooms feel colder though, is that true? 

Convection currents in the cavity can increase the U value of the wall to be greater than a 9inch solid clay brick wall. A small amount of ventilation is useful through weep vents, but air bricks and open cavities are well out of date.

This is a mid nineties house and I don’t see any air bricks - ground floor is solid 

dr_bogenbroom

stuart45 said:

dr_bogenbroom said:

Out of curiosity is there any reason why soffit vents wouldn’t be fitted on this small section? I’d have thought condensation would still be a risk with the rooms below being heated? I do need to install insulation in this section as well but as previously advised I’ll do it from inside 

It could be that no insulation was added to this part of the roof. Is there any access to this part? Condensation risks increase with insulation at joist level.

I poked a small camera through a light fitting hole and couldn’t see any in there however lighting was poor - I’d probably just replace the existing inside roof with insulated plasterboard if that would work? 

FreeBear

dr_bogenbroom said:

stuart45 said:

dr_bogenbroom said:

Out of curiosity is there any reason why soffit vents wouldn’t be fitted on this small section? I’d have thought condensation would still be a risk with the rooms below being heated? I do need to install insulation in this section as well but as previously advised I’ll do it from inside 

It could be that no insulation was added to this part of the roof. Is there any access to this part? Condensation risks increase with insulation at joist level.

I poked a small camera through a light fitting hole and couldn’t see any in there however lighting was poor - I’d probably just replace the existing inside roof with insulated plasterboard if that would work? 

Have a pitched roof over a bay window without any real access to the void. A neighbour had the tiles stripped and added insulation from the outside. I opted to take the ceiling down internally (messy, dirty job), and put loads of insulation in from below.

Insulating from the inside means having to redecorate, and makes a lot of mess (especially if you have a lath & plaster ceiling). Doing it from outside would require scaffolding (or a decent tower), but if you can get away without disturbing the hip tiles & lead flashing, would be less messy. It really depends on how easy it is to lift the tiles and if there is felt underneath.

Another option is to cut a hole in the "ceiling" by the door and crawl in to the void from there.