Nothing seems straightforward. 
 

Moved onto speccing the rooflights. Specced no trickle vents. Doubles lead time and adds a huge amount to the cost. They told me that they have a case study showing air tightness isn’t impacted when the trickle vents are closed. I’ve asked for a copy of it. Sticks in my throat to pay significantly more for them not to fit trickle vents. 
 

Does anyone have any experience of this? What did you do? 

Edited November 24, 20223 yr by Kelvin

I can't imagine that to be true. Trickle vents are generally a flimsy piece of plastic I wouldn't have thought they provide a suitable airtight seal. 

Try a different supplier?   We went for the triple glazed ones from Roof maker. Great thing about them is they don't have that ridiculous bump along the top edge that Velux have.  When we bought, prices were similar.

 

Simon

Farko?

I chose standard centre pivot Velux windows with the trickle vent.  I seriously objected to paying more NOT to have something fitted.

 

The standard Velux trickle vent is part of the opening mechanism, and when shut seems a whole lot more air tight than a normal window with a flimsy trickle vent above the window pane.

 

Air testing did not show any particular air leak around the vent mechanism when shut.

 

House is meeting the predicted heat loss so no major problems.

We had Farko in the previous house and the other half said she’d rather have no windows than those. We did have a lot of trouble with them. 

10 minutes ago, ProDave said:

I chose standard centre pivot Velux windows with the trickle vent.  I seriously objected to paying more NOT to have something fitted.

 

The standard Velux trickle vent is part of the opening mechanism, and when shut seems a whole lot more air tight than a normal window with a flimsy trickle vent above the window pane.

 

Air testing did not show any particular air leak around the vent mechanism when shut.

 

House is meeting the predicted heat loss so no major problems.

Good to know. They have a passiv certified window too and it’s not entirely obvious if it has the opening mounted vent or not. 
 

Did you go for centre pivot over top hung for any particular reason? Ours will be triple glazed, top hung, and 94x160 so will be quite heavy. 

In our case there was no advantage in the top hung, not needed as a means of escape, just made it harder to install, more to go wrong and cost more.

Yes they are a lot dearer at around £300 per window. We have six; two twin top hung windows, a single over the stairs which is centre-pivot, and a fixed rooflight on the flat roof over the entrance hallway. An extra £1200 or so against the total build cost isn’t budget busting but it’s the £1000 here and there that can add up to be budget busting. 

Edited November 24, 20223 yr by Kelvin

6 hours ago, Iceverge said:

Farko?

Or Fakro even 😄. We put a Fakro roof window in our last house as we didn't want Velux. Worked as it should, no problems.

They are supposed to be good for sure. We had five Fakro windows in the last place and had problems with four of them. One of the the blinds failed. Easy to replace unless you have some special size that they no longer supplied so we had to get a third party replacement. It never matched the blind in the other window in the room so I eventually replaced that too. Then the handle snapped off another one. The other two were very stiff to close. I managed to fix one of them but the other one had failed so once I eventually managed to get it closed we never opened it again 😂 

Did you just go with trickle vents then Kelvin? We've had ours - with trickle vents - installed and I'm wondering about airtightness issues now. I know others have used Fakro and got vent blanks made to address this but spoke with the Velux rep today and he wasn't aware of anyone doing similar (and seemed to think the windows were airtight with the trickle vents closed, albeit not an expert on the matter). 

I went to a showroom that had VELUX windows (having never seen them up

close before) The vents are very different in VELUX windows compared to the sliding kind I was more familiar with in previous rooflights. I did ask about whether they could be deleted but more out of curiosity. They suggested they probably could do it but were very cagey about warranty etc and they would be very expensive as they’d need to be custom made. Therefore they are triple glazed and standard.