Sash windows and airtightness ?

[Post and beam]

Obviously the type of seal on a sliding sash window is going to be less effective than a traditional casement. But how much less effective?

I have been investigating masterframe sash windows, they look good. But if they are not compatible with a highly airtight build then i need to abandon them as an option.

Is anyone else using them and achieving good ACH figures or is the whole idea stupid?

[nod]

We’ve used them on our first build 

Award winning design 

Dont expect them to be airtight 

[Iceverge]

1 minute ago, Post and beam said:

is the whole idea stupid?

 

Investigating all avenues is anything but stupid. The quest for knowledge and discovery is what makes our houses on average much better than mass produced boxes. 

However if you do this and still go ahead the answer may be different................!!! 

 

 

I think you'll struggle to find an airtightness result for a house that uses sliding sash windows. I couldn't. 

 

If you search for "sliding sash windows drafty forum" on google you'll find plenty of examples. 

 

 

 

 

 

[Redbeard]

I worked on a house which had some (but not all) TF 3G sliding sashes. We got 2-and-a-bit m3/m2/hr. Not too unhappy with that. Under test conditions you could hear the seals beginning to 'give' as the tester cranked the fan up. But we still got 2-and-a-bit. Performance vs aesthetics; depends what you want most.

[nod]

The problem with sash is The mechanism can’t be made as airtight as other windows We are happy with ours as it was a planning condition 

But not on our current build