mac_1 Posted July 16, 2023 Share Posted July 16, 2023 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. Link to comment Share on other sites More sharing options...
dpmiller Posted July 16, 2023 Share Posted July 16, 2023 Why does a shed need bi-folds and a cavity? 1 1 Link to comment Share on other sites More sharing options...
joe90 Posted July 16, 2023 Share Posted July 16, 2023 You state it’s a garage so why cavity and bi folds , future change of use 🤷♂️, I know, it’s for your prestige classic car, you can take it out on the street (hence the roller shutter door) or sit and look at it from the house/garden (hence the bifolds) 🤣. Link to comment Share on other sites More sharing options...
mac_1 Posted July 16, 2023 Author Share Posted July 16, 2023 6 minutes ago, dpmiller said: Why does a shed need bi-folds and a cavity? The bi-fold to the front elevation is mostly aesthetic to keep in line with the rest of the house, from the back room of our house I don't really want to be looking out at a concrete wall. It's can't be classified as a shed, it was an old detached double garage originally and the footprint is far bigger than a shed. Link to comment Share on other sites More sharing options...
mac_1 Posted July 16, 2023 Author Share Posted July 16, 2023 1 minute ago, joe90 said: You state it’s a garage so why cavity and bi folds , future change of use 🤷♂️, I know, it’s fir your prestige classic car, you can take it out on the street (hence the roller shutter door) or sit and look at it from the house/garden (hence the bifolds) 🤣. If I was planning to change the use I would make sure I had a feed for water and connect into the soil pipe. I don't really have a use for the garage other than for area to bring back bits from work to work on at home and storage. 1 Link to comment Share on other sites More sharing options...
joe90 Posted July 16, 2023 Share Posted July 16, 2023 Part L covers dwellings, not garages 43 minutes ago, mac_1 said: am having an issue with the building control officer (private building control) who is citing the new building regulations, namely Part L Point out that it’s a GARAGE not a dwelling so part L does not apply (he should know that, that would worry me about his competence). 1 Link to comment Share on other sites More sharing options...
mac_1 Posted July 16, 2023 Author Share Posted July 16, 2023 1 minute ago, joe90 said: Part L covers dwellings, not garages Point out that it’s a GARAGE not a dwelling so part L does not apply (he should know that, that would worry me about his competence). exactly that, i don't want to offend him but it does strike me like he doesn't really know what he is doing. he is a junior, and my engineer has told me to ask for someone more senior Link to comment Share on other sites More sharing options...
Dave Jones Posted July 16, 2023 Share Posted July 16, 2023 dont even need a cavity for a garage, single skin is fine! Link to comment Share on other sites More sharing options...
mac_1 Posted July 16, 2023 Author Share Posted July 16, 2023 he has sent me the following from the regs - not even sure this is correct since the existing garage was demolished completely Link to comment Share on other sites More sharing options...
Temp Posted July 16, 2023 Share Posted July 16, 2023 Presumably the BCO wants 150mm cavity so it can have 100mm insulation and 50mm cavity. If the outside is rendered you could probably fully fill your 100mm cavity and keep the BCO happy. Just a thought. Link to comment Share on other sites More sharing options...
joe90 Posted July 16, 2023 Share Posted July 16, 2023 Tell him what he sent you is for a dwelling (which means something you live in, not a garage), it says so in the top line. I hope your not paying for this crap advise, I would escalate to someone more senior (or sack him 🤷♂️) 1 Link to comment Share on other sites More sharing options...
DevilDamo Posted July 16, 2023 Share Posted July 16, 2023 Assume the internal floor area is at least 30sq.m? Will the room be habitable/heated or not? Link to comment Share on other sites More sharing options...
mac_1 Posted July 16, 2023 Author Share Posted July 16, 2023 2 hours ago, DevilDamo said: Assume the internal floor area is at least 30sq.m? Will the room be habitable/heated or not? The external footprint is 38sqm. I would like to have a small plug in electric wall radiator for the winter if I am working in there. Link to comment Share on other sites More sharing options...
joe90 Posted July 16, 2023 Share Posted July 16, 2023 5 minutes ago, mac_1 said: The external footprint is 38sqm. Ah, the limit for PD IS 30sqm. Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 16, 2023 Share Posted July 16, 2023 22 minutes ago, joe90 said: Ah, the limit for PD IS 30sqm. Still doesn't affect the classification of use though? Just pushes it into needing PP? Link to comment Share on other sites More sharing options...
joe90 Posted July 16, 2023 Share Posted July 16, 2023 1 minute ago, Nickfromwales said: Still doesn't affect the classification of use though? Just pushes it into needing PP? Agreed. Link to comment Share on other sites More sharing options...
Temp Posted July 16, 2023 Share Posted July 16, 2023 Quote Application 0.3 The guidance in Approved Document L, Volume 1 applies to dwellings only. In a mixed-use building, Approved Document L, Volume 2: Buildings other than dwellings should be consulted for building work in parts of the building that are not dwellings. NOTE: Dwellings are self-contained units. Rooms for residential purposes and buildings that contain only rooms for residential purposes are not dwellings; Approved Document L, Volume 2: Buildings other than dwellings applies. My bold. Link to comment Share on other sites More sharing options...
Temp Posted July 16, 2023 Share Posted July 16, 2023 44 minutes ago, Nickfromwales said: Still doesn't affect the classification of use though? Just pushes it into needing PP? Not even that. The 15 and 30sqm limits are BC only. For Planning/permitted development you are PDR until half the original land is built on. 1 Link to comment Share on other sites More sharing options...
joe90 Posted July 16, 2023 Share Posted July 16, 2023 3 hours ago, DevilDamo said: Will the room be habitable/heated or not? Detached Garage Outbuilding Link to comment Share on other sites More sharing options...
Temp Posted July 16, 2023 Share Posted July 16, 2023 (edited) 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). Edited July 16, 2023 by Temp 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 16, 2023 Share Posted July 16, 2023 15 minutes ago, Temp said: The 15 and 30sqm limits are BC only. Indeed. I just got word blind after researching / reading regarding mine, so after that info-overload the brain just starts to slip here and there! Agreed, BRegs approval needed over the 30m2, and PD rights remain (subject to T&C's). It's hard enough trying to remember all this and also try and find a guy with a micro that can do muckaway atm, with 2 of my mates having sold up after lockdown to drive HGV. 1 Link to comment Share on other sites More sharing options...
joe90 Posted July 16, 2023 Share Posted July 16, 2023 21 minutes ago, Temp said: That says new walls should have a u-value of 0.26 W/(m^2.k). Wow, I can understand a non dwelling being say an office or somewhere where people work and needing heat should be insulated but a shed or garage for storage only? Mad. Link to comment Share on other sites More sharing options...
DevilDamo Posted July 16, 2023 Share Posted July 16, 2023 1 hour ago, mac_1 said: The external footprint is 38sqm. It doesn’t matter. What’s the internal floor area? But I assuming you’re not able to lose 8sq.m with the external wall thicknesses and which is why it requires BR’s? Link to comment Share on other sites More sharing options...
DevilDamo Posted July 16, 2023 Share Posted July 16, 2023 1 hour ago, joe90 said: Ah, the limit for PD IS 30sqm. No it isn’t. PD doesn’t have a limit but has to be seen to be incidental to the dwelling house. Link to comment Share on other sites More sharing options...
DevilDamo Posted July 16, 2023 Share Posted July 16, 2023 30 minutes ago, joe90 said: Detached Garage Outbuilding Yes but why is the OP stating his engineer is spec’ing external cavity walls, albeit meeting the pre-June 2022 regulations? Link to comment Share on other sites More sharing options...
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