25% Glazing/Openings and Unheated Areas

[stb654]

Seems like a silly question but as far as i'm aware the regs doesn't make it obvious..
If you are building an extension where you have used up 25% of the allowance already,but you need to add another opening to the existing structure, in this case an external door into the garage, would this add to the allowance? As far as I can see this should not be a problem because the garage is unheated so is technically redundant from any energy based calculations in the first place.

Many thanks.

 

[^woody^]

The 25% criteria applies to the specific extension, not the whole house.

 

[tony1851]

By 25%, do you mean the rule whereby you can have new glazing up to 25% of your new floor area? You can also add the areas of any existing windows/external doors which will either be covered over or disappear due to the extension, so the new allowable glazed area may be a bit more than 25% of your new floor area.
I might be wrong here but would disagree with Woods - I think a new door in the garage would count against your glazing allowance because, as the garage is unheated space, it is effectively external. Although it may be unrelated to the extension, it qualifies as 'works and fittings'and so comes under Part L of the regs.

 

[Leofric]

As far as I can see this should not be a problem because the garage is unheated so is technically redundant from any energy based calculations in the first place.

If we are talking about maximum permissible glazed area relating to heat loss from heated rooms I think you are correct .

 

[Leofric]

the door to the garage would be classed as an external opening so needs to form part of the 25%

Are we talking about a new door from the house into the integral garage or a new door from the outside into the garage

 

[Notch7]

you need to add another opening to the existing structure, in this case an external door into the garage, would this add to the allowance? As far as I can see this should not be a problem because the garage is unheated so is technically redundant from any energy based calculations in the first place.

Im confused.
If its a new door in the garage that leads to the outside, Id assume ok.

If its a new door from house into garage, as others say, thats part of the 25%

If it was me, Id just do it and see how observant the building inspector is. If it gets picked up, you will need a whole house SAPS. Something thats easier to achieve compliance if your house is old and poorly insulated. If its pretty modern with up to date double glazing, its a bit more tricky. One option is to upgrade the lighting in yoyr house to low energy LED lighting. Im absolutely sure your existing lighting is 50mm halogen spotlights, incandescent 60 watt bulbs.....

 

[Leofric]

Yes new door from house into garage.

Yes if that is the case heat loss from house to garage needs to be considered ,but is that what stb64 means ?

If its a new door in the garage that leads to the outside, Id assume ok. - Yes

If its a new door from house into garage, as otheds say, thats part of the 25%

- Yes

Perhaps stb64 can clarify what is proposed.