Detached Garage Outbuilding - Part L Building Regs

[joe90]

Just now, DevilDamo said:

No it isn’t. PD doesn’t have a limit but has to be seen to be incidental to the dwelling house.

Like @Nickfromwales I was confusing planning with building control 🤯 the limit is 50% of the curtlige.

[ADLIan]

Less than 50m2 & no heating/cooling then exempt from Part L energy efficiency requirements. Simple!

[joe90]

5 minutes ago, DevilDamo said:

but why is the OP stating his engineer is spec’ing external cavity walls,

That’s a question @mac_1 should be asking his engineer.?

[DevilDamo]

34 minutes ago, Temp said:

With reference to my post above about the Application of Volume 1...

 

I think what you need to meet is Table 4.1 in Volume 2 "Buildings other than dwellings" (not Table 4.2 in Volume 1)

 

https://www.planningportal.co.uk/applications/building-control-applications/building-control/approved-documents/part-l-conservation-of-fuel-and-power/approved-document-l-conservation-of-fuel-and-power-volume-2-buildings-other-than-dwellings

 

That says new walls should have a u-value of 0.26 W/(m^2.k).

 

 

I think you’re right as the Introduction in Volume 1 states that it only covers self-contained dwellings and not rooms for residential purposes of which this outbuilding  would be. I’ve had BC tell me in the past an outbuilding that has ancillary or incidental use to the dwelling would need to meet the same u-values as if it was an extension.

[ETC]

9 hours ago, mac_1 said:

Hi, 

 

I have recently demolished my detached garage at the rear of my property, it was a an old concrete panel shed with an asbestos roof. Submitted some plans and got approval to put up another structure with a roller shutter door facing the street entrance and some bi-folds on the front elevation facing the house.  

 

My structural plans specified that the cavity walls read like this; 

CAVITY WALL TO ACHIEVE MINIMUM U VALUE OF 0.28W/M²K: NEW CAVITY WALL TO COMPRISE OF 100MM CONCRETE BLOCKS. FULL FILL CAVITY WITH 50MM DRITHERM32 CAVITY INSULATION AS MANUFACTURER'S DETAILS. INNER LEAF TO BE 100MM BLOCK K VALUE 1.13, E.G. LAFARGE STANCRETE. INTERNAL FINISH TO BE 12.5MM PLASTERBOARD ON DABS. WALLS TO BE BUILT WITH 1:1:6 CEMENT MORTAR.

 

My structural engineer stands behind the above explaining that it is more than sufficient for the type of building and I am in full agreement with him. The outbuilding/garage will hardly be used and the reason I needed to rebuild it was because my garden required a full overhaul/landscaping (didn't want to spend £ doing the garden only for it to get ruined when the shed eventually gets demolished later on). 

 

I am having an issue with the building control officer (private building control) who is citing the new building regulations, namely Part L 

1.1 Please clarify the proposed insulation types and thicknesses to the roof, floor and walls, the thermal elements should meet or exceed the standard U-Values set out in AD L table 4.2. (copy attached) The walls should be no worse than 0.18 W/M²K, the roof no worse than 0.15W/M²K, and the floors no worse than 0.18W/M²K.

 

He has told me that the cavity needs to be 150mm thick. I have stated that it's a garage (non habitable) with a roller door that faces the street. How would I expect to achieve these U values with a roller door that spans 3.5m wide! I did mention that it is a detached building that will be used mainly for storage and potentially a small workshop for myself.  He did mention on the phone that if I am not looking to heat the space than I could get away with 100mm cavity. 

 

I have proceeded to build it with 100mm cavity (which I was going to do in any case, even if the structural plans specified 50mm) but I would still like to reply with him as I am convinced that these more stringent U values that came into effect last month shouldn't really apply to a garage. 

 

The garage is detached and the external dimensions are approx. 5.5mx6.9m - total 38sqm. 

 

Have read a few things online where Part L doesn't apply to building under 50sqm - but want to get some advice from this community. 

 

Any help would be more than appreciated. I don't fancy rubbing the inspector up the wrong way but it is completely nonsensical to try to build this garage with a 150mm cavity wall insulation.  

 

 

If you’re not heating it why do you need to insulate it?

[ETC]

9 hours ago, dpmiller said:

Why does a shed need bi-folds and a cavity?

Or heating?

[Temp]

12 minutes ago, DevilDamo said:

I think you’re right as the Introduction in Volume 1 states that it only covers self-contained dwellings and not rooms for residential purposes of which this outbuilding  would be. I’ve had BC tell me in the past an outbuilding that has ancillary or incidental use to the dwelling would need to meet the same u-values as if it was an extension.

 

On the other hand...

 

https://www.legislation.gov.uk/uksi/2010/2214/regulation/2/made

 

 

Quote

 

“room for residential purposes” means a room, or a suite of rooms, which is not a dwelling-house or a flat and which is used by one or more persons to live and sleep and includes a room in a hostel, an hotel, a boarding house, a hall of residence or a residential home, but does not include a room in a hospital, or other similar establishment, used for patient accommodation;

 

 

So it's not even a room for residential purposes. 

[Temp]

14 minutes ago, Temp said:

On the other hand...

https://www.legislation.gov.uk/uksi/2010/2214/regulation/2/made

So it's not even a room for residential purposes. 

 

OK so in Volume 2 it says..

 

Quote

 

Application

 

0.3 The guidance in Approved Document L, Volume 2 applies only to buildings other than dwellings. In a mixed-use building, this document should be consulted for building work in those parts of the building that are not dwellings. This document gives guidance for building work in both new and existing buildings.

 

NOTE: Dwellings are self-contained units. This approved document applies to both of the following, which are not dwellings.

 

a. Rooms for residential purposes.

b. Buildings that contain only rooms for residential purposes.

 

For dwellings, Approved Document L, Volume 1: Dwellings applies. 

 

 

So it's clear !

 

The Building Regulations say its not a Dwelling or a Room for Residential Purpose.

 

Volume 1 only applies to Dwellings. 

Volume 2 only applies to Rooms for Residential Purpose (or buildings containing Rooms for Residential Purpose).

 

So neither volume 1 or 2 applies to a garage or workshop.

 

 

Sorry for all the edits.

 

Edited July 16, 2023 by Temp

[ETC]

FFS it’s a detached non-habitable building with no heating. No insulation is needed. Tell your BCO to wise up!!!

[mac_1]

53 minutes ago, DevilDamo said:

Yes but why is the OP stating his engineer is spec’ing external cavity walls, albeit meeting the pre-June 2022 regulations?

The engineer specified cavity wall as good practice for moisture prevention. 

[DevilDamo]

1 hour ago, ETC said:

FFS it’s a detached non-habitable building with no heating. No insulation is needed. Tell your BCO to wise up!!!

The OP said it would be heated for if/when they decide to work in there. So this appears to be more of a heated outbuilding as opposed to an unheated garage.

Edited July 16, 2023 by DevilDamo

[ETC]

8 minutes ago, DevilDamo said:

The OP said it would be heated for if/when they decide to work in there. So this appears to be more of a heated outbuilding as opposed to an unheated garage.

My bad……if it’s heated you should insulate it……….I wouldn’t bother putting in heating. Just put a jumper on.

[mac_1]

6 minutes ago, ETC said:

My bad……if it’s heated you should insulate it……….I wouldn’t bother putting in heating. Just put a jumper on.

The issue isn't about insulating it, it is about how much the BCO wants me to insulate it. I am going to build it with 100mm cavity with 100mm insulation. The BCO is citing 4.2 of Volume 1, where he wants the walls to achieve 0.18 u value, this in my opinion is excessive and not really achievable since the plans propose a roller shutter along the road facing elevation spanning 3.5m! 

 

Also, I am of the opinion that since it is a detached outbuilding at the rear of the property (in no way linked to the house) it shouldn't be subject to the U value targets applicable to let's say an extension.

[joe90]

36 minutes ago, DevilDamo said:

The OP said it would be heated for if/when they decide to work in there. So this appears to be more of a heated outbuilding as opposed to an unheated garage.

I disagree, I have an infared heater above my bench in case it’s very cold if I am standing there, completely different from a heated building. Frankly I think the “engineer” and BI are taking the OP for a ride.

Edited July 16, 2023 by joe90

[DevilDamo]

10 minutes ago, joe90 said:

I disagree, I have an infared heater above my bench in case it’s very cold if I am standing there, completely different from a heated building. Frankly I think the “engineer” and BI are taking the OP for a ride.

I agree. I think the main issue here is that because the drawings show and note insulated cavity walls, that is taking the building more away from what is known and seen as a garage and more a habitable space. And this is why the BCO is requesting a fully compliant building. If they stuck with a single skin garage, then once inspected and signed off, the OP can do what they want.

[kandgmitchell]

Blimey, what a palaver over a detached garage. The structural engineer should stick to structural engineering rather than worry about moisture prevention, loads of garages are built as single skin. As for the BCO they need to read Regulation 21 - Application of Energy Efficiency Requirements. Paragraph 1 applies them to buildings, paragraph 2 then exempts those buildings listed in paragraph 3 and Paragraph 3 says (d) standalone buildings other than dwellings with a total useful floor area of less than 50m2. Patently a garage is not a dwelling.

 

This is the statutory legislation, the Approved Documents are simply guidance on how to comply. It's always useful to start at the top just to see if there is a legal basis is for some of the more extraordinary demands one hears. In this case Part L doesn't apply to your garage but should you wish to insulate it then that is entirely your own choice as to how much insulation you use and the Building Regulations have no opinion on that.