Velux trickle vent

PoGee

We get a bit of a breeze through the attic hatch into the hall  in winter. I usually block it off with insulation board and tape during this time of year. Should the velux trickle vent be open or shut? The roof is 2-3 years old and has around 5 vents and multiple vents on the soffits. 

WIAWSNB

The Velux trickle vent is for ventilating your room, and not the roof. 

If your roof is only 3 years old and has numerous soffit vents, that's good - just ignore it. The loft space will be cold and draughty, and that's exactly what you want - it'll be dry. As long as you have good 'loft insulation', then the loft has nothing else to do with ventilating your house. Ignore it. 

The Velux vent is to keep your room fresh, and remove excess moisture which would otherwise condense as droplets on the panes - is there any in the morning? 

Does this vent simply close by pushing the hinged cover back into place? That's what mine does.

Edit - I think I misunderstood. Where is this Velux? In the loft?! In which case it doesn't really matter if the Velux vent is open or closed, as the soffit vents already provide more draught than that! 

But, you need to get your trapdoor sealed properly. Does it lock down? If so, I'd have thought a strip of foam seal would do the job? And, is it insulated on top? 

Explain where this Velux is, please. 

PoGee

The velux is in the attic. I'd asked the roofers to fit the velux, in case I decided to make it into a loft roof. It's just used for storage at the moment. Yes, it's like a hinge that when pushed, seals the window. I wondered whether closing it would result in condensation within the attic. The attic insulation is farely thick.

WIAWSNB

PoGee said:

The velux is in the attic. I'd asked the roofers to fit the velux, in case I decided to make it into a loft roof. It's just used for storage at the moment. Yes, it's like a hinge that when pushed, seals the window. I wondered whether closing it would result in condensation within the attic. The attic insulation is farely thick.

Closing that trickle vent shouldn't have any negative effect at all. But it won't have any positive effect either. Ie, that loft space will remain - as it should - very draughty due to the soffit vents.
You need to seal around your hatch, and add insulation to its top if there isn't any. That's the solution.

Confirm, please - the sides and slopes of the loft have not been lined?

PoGee

That's correct - sides/slopes not insulated but has some sort of boarding over beams, then membrane and tiles in top. 

Swipe

As above, address the bad seal around your loft hatch.

WIAWSNB

PoGee said:

That's correct - sides/slopes not insulated but has some sort of boarding over beams, then membrane and tiles in top. 

Ok, so it has sarking boards on the outside of the rafters. You can see the rafters?
And I guess it's cold and draughty up there?! I bet it's also dry?
The Velux vent is for when/if you ever convert that room into a 'habitable' space by lining it with insulation, which must be done correctly. Then the loft will become part of the house and not the roof.
Until then, it'll make zero difference to anything whether the trickle vent is open or closed. One could argue it fractionally improves loft ventilation, but I doubt it's measurable. 
So, I'd close it simply for the reason of keeping it clean, otherwise dust will build up in it. But, if you see condensation forming on the inside glass, reopen and see if that sorts it.
And sort yer 'atch

Albermarle

PoGee said:

The velux is in the attic. I'd asked the roofers to fit the velux, in case I decided to make it into a loft roof. It's just used for storage at the moment. Yes, it's like a hinge that when pushed, seals the window. I wondered whether closing it would result in condensation within the attic. The attic insulation is farely thick.

Just in case you are not aware, to make a loft into a habitable space/bedroom, is a proper/expensive  building job. 
Also modern roofs are more tricky to convert

PoGee

WIAWSNB said:

PoGee said:

That's correct - sides/slopes not insulated but has some sort of boarding over beams, then membrane and tiles in top. 

Ok, so it has sarking boards on the outside of the rafters. You can see the rafters?
And I guess it's cold and draughty up there?! I bet it's also dry?
The Velux vent is for when/if you ever convert that room into a 'habitable' space by lining it with insulation, which must be done correctly. Then the loft will become part of the house and not the roof.
Until then, it'll make zero difference to anything whether the trickle vent is open or closed. One could argue it fractionally improves loft ventilation, but I doubt it's measurable. 
So, I'd close it simply for the reason of keeping it clean, otherwise dust will build up in it. But, if you see condensation forming on the inside glass, reopen and see if that sorts it.
And sort yer 'atch

The main reason I closed it was - I saw the start of a wasps nest at the ventilation latch, on the inside.