Highly Glazed Extension

[RonnyRaygun]

I want to build a conservatory / extension onto the back of my house.
Because of the position and design it will be considered an extension and therefore there is no way of avoiding building regs.

The problem in having a fully glazed roof and mostly glazed front facade (sides will be masonry) is that this will greatly exceed the 25% of floor area regulation (even when the current patio doors are taken into account.

Can anyone confirm that the regulations still have to be adhered to when an external door separates the conservatory from the rest of the building?

Also, I have read that there are other options.

1. The window area / floor area can be calculated for the whole house and if less than 25% (with the extension taken into account) then the house complies with regs.

2. An energy assessment for the whole house can be carried out by an energy assessor and if the house meets current requirements then it complies with regs.

Am I correct in the above assumptions, and assuming option 1 doesn't comply (Having done a rough calc I think it will struggle) then what are the cost implications of getting an assessment done?

Cheers for any info and advice.

Craig.

 

[freddiemercurystwin]

If (for reasons you've not explained) the conservatory needs to comply with building regulations then AFAIK the 25% rule is applicable to the extension floor area not the extension + the original house. In which case SAP calcs will probably be required. It might depend on the Builiding Inspector tbh.

These are calculations that (in theory at least) prove the works will be thermally efficient enough to comply with the regs. The SAP assessor will ask you what your proposals are ie what U value your proposed glazing achieves, what insulation is being proposed for use in the cavity walls, floor insulation etc etc. Then if required the SAP assessor can beef up other thermal elements of the construction like increasing the floor insulation or using better blocks in any cavity walls you might be building etc to compensate. SAP's cost approx. £150 depending where you go. You can get cheap and cheerful online jobbies or speak to a local SAP assessor. Be careful who you use though as you'll likely need a little extra advice to achieve compliance. You'll need to supply Building Control the Calcs and inform them of what other measures are being taken to comply.

 

[RonnyRaygun]

If (for reasons you've not explained) the conservatory needs to comply with building regulations...

The main reason I think it will have to comply with building regs is that it will be situated closer than 1 metre to the boundary of mine and my next door neighbours' house. I have read this rule on a few websites but please correct me if I have got the wrong end of the stick.

AFAIK the 25% rule is applicable to the extension floor area not the extension + the original house. In which case SAP calcs will probably be required. It might depend on the Builiding Inspector tbh.

See under this heading:"To meet the Regulations in this case, there is a choice:" on the following website: http://www.conservatories4uk.com/building_regulations.asp

It seems to imply that the whole of the house can be taken into consideration to offset the larger glazed area of the conservatory. Having said that, mine will be more like example 1 on the website and able to be closed off from the rest of the house so it may be possible that the glazed area might not be such an issue.

I think a chat with a one of our local building inspectors might be on the cards...

 

[^woody^]

The main reason I think it will have to comply with building regs is that it will be situated closer than 1 metre to the boundary of mine and my next door neighbours' house.

Yes you have the wrong end of the stick.

Separation from the main house (ie a door) and area of glazing to walls and roof are the main defining points between conservatory and extension for b/regs purposes. But even then, area of glazing is often overlooked/ignored

 

[freddiemercurystwin]

If there is an external door seperating the conservatory from the rest of the house it should not need building regs approval.

If the conservatory wall is within 1m of a boundary then it should be of fire resistant materials so as to reduce the spread of fire ie a cavity wall rather than glass. This is in the Building Regs and you should adhere to it.

 

[freddiemercurystwin]

Doh, woody beat me, should've done a refresh before posting!

 

[RonnyRaygun]

Thanks guys.

So as long as I build the wall nearest the boundary to comply with current fire regulations, and leave the external patio doors in place, the current insulation requirements will not be an issue and the building inspector should be happy?

That's put my mind at rest.

 

[jeds]

To avoid building regs you must have a separating door (as mentioned) but also no fixed heating within the conservatory. The 1m rule will be satisfied by fire resisting materials.

 

[RonnyRaygun]

To avoid building regs you must have a separating door (as mentioned) but also no fixed heating within the conservatory. The 1m rule will be satisfied by fire resisting materials.

Am I right in thinking that a radiator can be on the same system as the rest of the house as long as it can be fully thermostatically controlled from within the conservatory?

 

[noseall]

Am I right in thinking that a radiator can be on the same system as the rest of the house as long as it can be fully thermostatically controlled from within the conservatory?

Wrong.

B.c. can and will interpret this as heated space.

 

[inspector01]

The rules state "independent controls" therefore a TRV is a suitable control and should be accepted by Building Control

 

[jeds]

The rules state "independent controls" therefore a TRV is a suitable control and should be accepted by Building Control

The point is that if the conservatory is heated from the fixed heating system then the envelope must comply with thermal regulations.